Inflammation is a notable driver of organ injury in critical illness and promotes barrier disruption, microcirculatory impairment and metabolic dysfunction (5,28). Piezo1 regulates inflammatory responses in endothelial cells, macrophages and neutrophils and couples mechanical cues to immune signaling (9,14,21).

In vascular endothelial cells, Piezo1 participates in force-sensing and the regulation of vascular function (21). For example, flow-induced Piezo1 activation promotes ATP release and initiates downstream vasodilatory signaling (29). The aforementioned studies support a role for Piezo1 in converting flow-associated mechanical stimuli into endothelial signals, but do not directly establish its involvement in downstream inflammatory signaling pathways.

In macrophages, Piezo1 modulates mechanosensitive Ca²⁺ signaling, cytokine production and polarization (14,30). In neutrophils, Piezo1 senses mechanical signals during transendothelial migration and enhances bactericidal function (24) and participates in shear-induced neutrophil extracellular trap formation (31). Piezo1-mediated immune regulation involves defined molecular mechanisms and is not merely an accompanying phenomenon under abnormal mechanical stimulation. Geng et al (25) found that bacterial infection or lipopolysaccharide stimulation can induce the formation of a complex between toll-like receptor 4 (TLR4) and Piezo1 in macrophages, coupling pathogen recognition signals with Piezo1-mediated Ca²⁺ influx. Ca²⁺ signaling activates the Ca²⁺/calmodulin-dependent protein kinase II (CaMKII)-mammalian sterile 20-like kinase 1/2 (Mst1/2)-Ras-related C3 botulinum toxin substrate 1 (Rac1) axis, promoting actin cytoskeletal reorganization, pathogen phagocytosis and mitochondria- and phagosome-associated reactive oxygen species production, thereby enhancing bacterial clearance (25). Piezo1 deficiency, CaMKII inhibition and loss of Mst1/2 or Rac1 attenuate the associated bactericidal response, providing causal evidence for this pathway (25).

Coupling between mechanosensing and immune function is observed in neutrophils. Mukhopadhyay et al (24) reported that increased membrane tension as neutrophils pass through narrow endothelial junctions activates Piezo1 and induces Ca²⁺ signaling, which subsequently stabilizes hypoxia-inducible factor-1α (HIF-1α) and promotes NADPH oxidase 4 (NOX4) expression, enhancing bactericidal activity. These findings suggest that Piezo1 participates in sensing mechanical constraints during neutrophil migration and links mechanical signals with the regulation of antibacterial function. However, NOX4 expression in neutrophils and its specific contribution to bacterial killing are disputed. Knaus et al (32) questioned the evidence for NOX4 expression, the specificity of the antibodies and inhibitors used in the aforementioned study and the mechanistic interpretation of NOX4-mediated bacterial killing. The original authors cite transcriptomic analyses and genetic interventions, while acknowledging that contributions from other NOX isoforms cannot be excluded (33). The specific role of NOX4 in mechanosensitive signaling, reactive oxygen species production and antibacterial activity in neutrophils, as well as its relationship with NOX2 and other NADPH oxidase isoforms, therefore requires further independent validation. Thus, in the aforementioned models, Piezo1 serves as a regulatory node linking pathogen recognition, mechanosensing and immune responses rather than an independent initiator of inflammation. Its amplifying effects may involve enhanced inflammatory responses or increased phagocytosis and bacterial killing and should not be equated with tissue injury. Extending these mechanisms to persistent inflammation and organ dysfunction in acute and critical illness requires direct, disease-specific evidence.

Barrier dysfunction is a consequence and an amplifier of persistent inflammation; vascular leakage, edema, impaired microvascular perfusion and local hypoxia can further aggravate inflammation and tissue injury (17,23,34). Piezo1 has bidirectional effects on barrier function that must be interpreted in association with the mode of mechanical loading, inflammatory context and downstream signaling. It contributes to endothelial junction disruption and increased permeability in models of elevated pulmonary microvascular pressure and mechanical stretch in an inflammatory context (17,23), whereas endothelial Piezo1 maintains adherens junctions and protects the vascular barrier during high-volume mechanical ventilation (13).

In injury models, Piezo1-mediated Ca²⁺ signaling activates calpain, promoting adherens junction protein degradation or junction disruption and thereby increasing endothelial permeability and vascular leakage (17,23). Conversely, in a protective stretch model, calpain cleaves and inactivates Src, limiting vascular endothelial cadherin (VE-cadherin) phosphorylation and maintaining junctional stability (13). These findings suggest the targets of Ca²⁺-dependent downstream signaling and the cellular context provide clues to understanding the divergent effects on barrier function.

Piezo1 contributes to vascular tone and microcirculatory regulation (29,35). In endothelial cells, flow-induced activation promotes ATP release and downstream vasodilatory signaling (29). In erythrocytes, Piezo1 links mechanical stimulation with Ca²⁺ influx and cell volume regulation (36).

During critical illness, inflammation, hemodynamic instability and altered tissue mechanics may destabilize these regulatory mechanisms and affect vascular reactivity, erythrocyte rheology and microvascular perfusion, thereby worsening tissue hypoxia and organ injury (37). Hypoperfusion and edema alter local mechanics, creating reciprocal interactions among mechanical stress, inflammation and barrier injury. How Piezo1 signaling is coordinated among different barrier-associated cell types and how this coordination varies by organ are insufficiently defined.

Metabolic dysfunction in acute and critical illness is linked to inflammation and tissue hypoperfusion, with mitochondrial dysfunction, reactive oxygen species accumulation and inadequate energy supply representing important components (5,38). General studies of Ca²⁺ biology show that disrupted Ca²⁺ homeostasis affects mitochondrial function and contributes to cellular stress and apoptosis (39,40). These findings provide a biological basis for the metabolic effects of mechanosensitive Ca²⁺ signaling, but do not establish that these changes are mediated by Piezo1. Piezo1-associated metabolic effects should be discussed in the context of specific models. For example, in macrophage infection models, Geng et al demonstrated that TLR4/Piezo1 signaling promotes mitochondria- and phagosome-associated reactive oxygen species production via the CaMKII-Mst1/2-Rac axis and enhances bacterial clearance (25). Independently, West et al showed that TLR signaling promotes mitochondrial recruitment to phagosomes and enhances mitochondrial reactive oxygen species production and bacterial killing through a TRAF6-ECSIT-dependent mechanism (41). In the aforementioned macrophage infection models, reactive oxygen species contribute to host defense and cannot directly be equated with mitochondrial injury or bioenergetic failure.

Accordingly, when changes in Piezo1-associated Ca²⁺ signaling and reactive oxygen species are observed, their cellular functions and direction of effect require further clarification. In sepsis-related intestinal epithelial injury, GsMTx4, a peptide inhibitor of mechanosensitive ion channels, attenuates the increase in Ca²⁺, mitochondrial reactive oxygen species accumulation and loss of membrane potential in TNF-α-treated cells (15). Mitochondria-targeted antioxidant intervention also improves tight junction protein expression (15). These findings provide disease-associated mechanistic support for a link between Piezo1-related Ca²⁺ signaling and mitochondrial stress, although the in vitro results are limited by inhibitor specificity and the cell model.

Despite the mechanistic evidence from the aforementioned models, evidence remains insufficient to establish whether Piezo1-associated mitochondrial stress represents a shared mechanism across organs, impairs ATP production or influences metabolism through AMPK or mTOR. General studies of mitochondrial Ca²⁺ signaling and AMPK-dependent energy sensing provide biological context but do not establish Piezo1-related metabolic pathways (39,42). Establishing causality requires genetic manipulation of Piezo1, assessments of metabolic function and downstream rescue experiments in disease-relevant models.

The effects of Piezo1 on cell survival should be assessed on the basis of intervention results in specific models. In sepsis-related intestinal barrier injury, intestinal epithelial-specific Piezo1 deletion attenuates epithelial apoptosis and barrier injury, providing direct evidence for Piezo1 involvement in cell injury in that model (15). However, apoptosis findings from a single model cannot be generalized to a universal role for Piezo1 in driving different forms of regulated cell death, nor do changes in Ca²⁺ or oxidative stress alone establish a specific cell death mechanism.

Damage-associated molecular patterns released by injured or dying cells can activate innate immunity and influence inflammation and tissue injury (43,44). These studies provide context for understanding the interactions between cell injury and inflammation but do not directly establish Piezo1 involvement. Whether Piezo1-associated cellular injury forms feedback relationships with inflammation, barrier function and microcirculatory dysfunction remains to be validated in disease models.

These processes constitute a mechanistic network in which Piezo1 may participate, but the strength of evidence varies between its components. Some links are supported by genetic or pharmacological manipulation of Piezo1, whereas others are inferred mainly from general Ca²⁺ signaling and cell stress mechanisms and require direct validation (13,15,16,25) (Fig. 1).

Piezo1 activation does not necessarily cause injury. Pulmonary endothelial studies show Piezo1 activation maintains adherens junctions or contributes to junction disruption in experimental models, indicating that the direction of its effects cannot be determined solely by whether the channel is activated or by the intensity of mechanical stimulation (13,17,23). Understanding these differences requires further examination of the Ca²⁺ signals generated by mechanical input and the downstream responses they engage in specific cells. A functional switch provides a framework for analyzing these differences but is not an established unified mechanism. How signaling changes within the same cell, opposing effects between different cell populations and stress adaptation each influence the final outcome requires validation in specific disease models.

Membrane tension is a key determinant of Piezo1 mechanosensitivity, suggesting that the same external load may not elicit the same channel response in different cell environments (45). When discussing a functional switch, the threshold for channel opening should be distinguished from the threshold for cell injury. Channel opening reflects the detection of mechanical signals, whereas injury should be assessed in relation to Ca²⁺ signaling, downstream stress response and cell functional outcomes. Comparisons between models should therefore examine stimulation amplitude, duration and frequency separately rather than classify stimuli simply as physiological or excessive. The ability of pulmonary endothelial Piezo1 to protect the barrier during high-volume mechanical ventilation indicates that greater mechanical loading does not necessarily shift its effects toward injury (13).

The intracellular signaling environment influences the functional output of Piezo1 activation. Pulmonary endothelial studies show that Ca²⁺-dependent calpain signaling produces opposing effects on barrier function (13,17,23). Calpain cleaves and inactivates Src, thereby decreasing Src-dependent VE-cadherin phosphorylation and maintaining adherens junctions (13), whereas Piezo1/Ca²⁺/calpain signaling contributes to junctional protein degradation and barrier disruption in other experimental models (17,23). These findings suggest downstream substrates and their modes of action may explain differences between models, but whether regulated changes in substrate selection occur requires direct validation. Inflammatory receptors alter the signaling networks involving Piezo1. For example, bacterial infection or lipopolysaccharide stimulation induces a TLR4-Piezo1 complex in macrophages, enhancing phagocytosis and bacterial killing through Ca²⁺/CaMKII/Mst1/2/Rac signaling (25). This supports coupling between pathogen recognition signals and Piezo1 but does not establish that an inflammatory context shifts its effects toward tissue injury.

Cell adaptation to mechanical stress also involves nuclear and chromatin changes. In epithelial cells, Nava et al (46) found that stretch-induced nuclear deformation triggers Piezo1-dependent endoplasmic reticulum Ca²⁺ release, decreases H3K9me3-marked heterochromatin and reduces nuclear stiffness, thereby increasing nuclear deformability and limiting mechanical stress-induced DNA damage. The study also suggested that early chromatin softening and longer-term cytoskeletal and cell population rearrangements represent distinct levels of adaptation that contribute to genome protection (46). These findings support a role for Piezo1-associated Ca²⁺ signaling in adaptation to mechanical stress but do not establish a universal temporal boundary for a shift from protective to detrimental effects.

A study of lung injury induced by acid aspiration combined with mechanical ventilation found that changes in the nuclear lamina and chromatin, together with DNA damage, are accompanied by activation of the p53/p21 pathway (47). Loss of p21 attenuates senescence but increases apoptosis and worsens lung injury (47). This study provides background evidence on the association between cellular stress, survival and senescence in mechanical lung injury but did not directly investigate Piezo1. Therefore, the aforementioned studies cannot be combined into a causal sequence in which Piezo1 shifts from protective to detrimental effects as stimulation is prolonged. This requires validation within the same cell type and disease model through Piezo1 manipulation and continuous functional assessment.

Evidence involving ataxia telangiectasia and Rad3-related protein (ATR), a kinase involved in DNA damage responses and cellular responses to mechanical stress, also highlights the importance of considering the experimental context when interpreting nuclear responses to mechanical deformation. In a neural regeneration study, Li et al (48) found Piezo-dependent mechanosensing can activate the ATR/checkpoint kinase 1 (Chk1) pathway through nitric oxide signaling and inhibit axon regeneration independently of DNA damage. The aforementioned study provides mechanistic evidence linking mechanosensing with checkpoint signaling but does not directly establish the same pathway in pulmonary endothelial or alveolar epithelial cells, nor can ATR activation be regarded as direct evidence of Piezo1-induced DNA damage. Whether nuclear lamina structure, chromatin adaptation and ATR signaling regulate the protective or detrimental effects of Piezo1 in acute and critical illness requires causal validation in cells and disease models.

Overall, mechanical inputs, downstream signaling context and cellular adaptive capacity provide clues to understanding the divergent protective and detrimental effects of Piezo1, but whether these factors jointly determine a transition between protective and detrimental effects within a single experimental model under different conditions remains to be validated. Future studies should examine stimulation amplitude, duration and frequency separately in defined cell types and disease models, combine manipulation of Piezo1 and candidate downstream molecules with continuous monitoring of Ca²⁺ dynamics and assess barrier function, DNA damage and cell fate. Distinguishing differences in effects across models from a functional switch within a single model may identify its molecular determinants and potential intervention windows that preserve protective signaling while limiting injurious responses.

Sepsis is one of the most extensively studied critical illnesses in the context of Piezo1, although direct disease-specific evidence is limited (15,49). Sepsis-associated organ dysfunction involves infection-induced immune dysregulation, inflammation, endothelial injury and microcirculatory impairment (50,51). Hemodynamic instability, glycocalyx degradation, edema and ECM remodeling alter shear stress, tissue tension and matrix mechanics (52,53). These changes provide a plausible mechanical context in which Piezo1 may influence inflammatory, barrier and microvascular responses.

Yan et al (15) found increased Piezo1 expression in intestinal tissue from mice with cecal ligation and puncture-induced sepsis. Intestinal epithelial-specific Piezo1 deletion attenuates the increase in intestinal permeability, preserves expression of the tight junction proteins zonula occludens-1 and occludin and decreases intestinal epithelial TUNEL positivity, suggesting decreased apoptosis. Deletion also improves 7-day survival (15). In TNF-α-treated Caco-2 cells, the mechanosensitive channel inhibitor GsMTx4 attenuates the increase in Ca²⁺, mitochondrial reactive oxygen species accumulation, loss of membrane potential and junctional protein abnormality (15). The mitochondria-targeted superoxide scavenger MitoTEMPO improves tight junction protein expression (15). These findings support links between intestinal epithelial Piezo1-related Ca²⁺ signaling, mitochondrial stress and barrier injury (15). A strength of the aforementioned study is its combination of intestinal epithelial-specific genetic manipulation and cell mechanistic experiments, although its conclusions are limited in scope. First, Caco-2 cells are tumor-derived, and TNF-α stimulation reproduces only selected aspects of the inflammatory environment in sepsis, particularly TNF-α-mediated inflammatory signaling, epithelial barrier dysfunction and associated cellular stress responses. Second, GsMTx4 is not a Piezo1-specific inhibitor, so the in vitro pharmacological findings must be interpreted alongside the genetic evidence. Furthermore, the study did not directly quantify or manipulate local mechanical loading during sepsis, leaving the specific mechanical stimulus that activates intestinal epithelial Piezo1 unresolved. The findings do not establish how its effects vary across disease stages or predict therapeutic benefit in patients. Thus, the study supports Piezo1 involvement in intestinal barrier injury during experimental sepsis but does not demonstrate that systemic Piezo1 inhibition would benefit all organs (15).

In addition to intestinal epithelial cells, endothelial and immune cells are key subjects of Piezo1 research. Studies of pulmonary microvascular pressure and infection-associated models provide evidence for Piezo1 involvement in endothelial barrier regulation, neutrophil bacterial killing and macrophage antibacterial responses (17,24,25). However, these findings do not constitute direct evidence in sepsis and their relevance to specific stages and organs in sepsis requires validation.

Endothelial Piezo1 participates in flow-related mechanosensing and the regulation of vascular function, but its effects on barrier function are model-dependent. Models of elevated pulmonary microvascular pressure and ARDS-associated stretch show that Piezo1 contributes to endothelial junction disruption and increased permeability (17,23), whereas a high-volume mechanical ventilation model shows that endothelial Piezo1 helps maintain adherens junctions and the vascular barrier (13). These findings provide a basis for investigating endothelial mechanosensing but do not establish the direction of Piezo1 effects in the vascular endothelium during sepsis. Its specific effects across organs and disease stages require validation through endothelial-specific manipulation of Piezo1, measurement of local mechanical loading and assessment of barrier function.

Immune cell studies also provide a basis for investigating the role of Piezo1 in sepsis (14,25). Piezo1 participates in macrophage sensing of matrix stiffness and the regulation of polarization (14). Other studies have implicated Piezo1 in myeloid cell responses to cyclical mechanical force (54) and CD11b-dependent macrophage responses to mechanical cues (55). In neutrophils, mechanical constraints during transendothelial migration activate Ca²⁺ signaling through Piezo1 and enhance bactericidal function (24). The aforementioned studies provide evidence linking mechanosensing with immune function but do not establish the roles of Piezo1 across stages of sepsis. Its effects on pathogen clearance and immune dysregulation require validation in disease models.

Existing studies address macrophage stiffness sensing and polarization (14), myeloid cell response to cyclical mechanical force (54) and neutrophil bactericidal function following transendothelial migration (24). Their experimental conditions and functional endpoints differ, so findings cannot be directly interpreted as evidence of a uniform immune effect (14,24,54).

Reported effects are not uniformly pro- or anti-inflammatory, potentially because they depend on cell type, mechanical stimulus, experimental model, inflammatory stage and the local tissue environment (13,17,25).

Infection-associated studies support a role for Piezo1 in regulating host immune responses but do not establish it as an independent initiator of infection-induced inflammation (14,25). In macrophages, TLR4-Piezo1 coupling can enhance phagocytosis and bacterial killing (25), whereas in neutrophils, mechanical signals generated during transendothelial migration enhance bactericidal activity through Piezo1 (24). These findings indicate that Piezo1 participates in the regulation of antibacterial function by pathogen recognition signals and mechanosensing but enhanced host defense is not equivalent to increased inflammatory injury. The specific effects of these mechanisms on pathogen clearance and tissue injury in sepsis require direct validation in relation to cell type, infection status and disease stage, and cannot be inferred from general infection models.

Evidence on Piezo1 in sepsis is largely based on experimental cell and animal models, while its clinical relevance requires further investigation (15,25). Changes in Piezo1 expression and activity across disease stage and their relationships with severity, organ function and outcome remain unknown. Piezo1 in different organs and cell types may exert divergent effects; sustained activation may be injurious in certain contexts but compensatory in others.

ARDS is a key cause of respiratory failure in critically ill patients and a prototypical disorder in which mechanical forces contribute to organ injury (56-58). Repeated alveolar collapse and reopening, decreased lung compliance, inflammation-associated ECM remodeling and mechanical ventilation expose lung tissue to abnormal stretch, compression and shear stress (56,57). Alveolar epithelial and pulmonary microvascular endothelial cells are continuously subjected to altered mechanics that may be sensed through Piezo1 (56,57,59).

Research has focused primarily on Piezo1 in alveolar epithelial and pulmonary microvascular endothelial cells (23,59,60). Experimental studies involving Piezo1 manipulation provide direct evidence for its involvement in pulmonary endothelial barrier injury (17,23). Friedrich et al (17) found that endothelial-specific Piezo1 deletion attenuates vascular leakage caused by elevated pulmonary microvascular pressure, while Jiang et al (23) found that Piezo1 knockdown decreases endothelial junction disruption in ARDS-associated mechanical stretch. These findings support detrimental effects of Piezo1 in these models but cannot be generalized to all mechanical loading conditions.

In lung epithelial cells, mechanical stimulation activates a disintegrin and metalloproteinase 10 (ADAM10) and ADAM17 through Piezo1, promoting the proteolytic release of the growth factor amphiregulin and junctional adhesion molecule A (JAM-A) (61). JAM-A shedding is accompanied by decreased intercellular contact (61).

Piezo1 knockdown attenuates mechanical stretch-induced apoptosis in A549 lung epithelial cells, an in vitro model used to investigate ARDS-associated alveolar epithelial injury (62). These findings concern growth factor release, changes in cell junctions and apoptosis and cannot collectively be described as decreased repair capacity. Pulmonary vascular endothelial Piezo1 exerts detrimental or protective effects on barrier function in different models (13,17,23). Epithelial and endothelial findings should be discussed separately to avoid combining them into a uniform mechanism of pulmonary barrier injury. Comparisons between studies need to account for the mode of mechanical loading, inflammatory context and intervention. Friedrich et al (17) increased pulmonary microvascular pressure in mice by elevating left atrial pressure or constricting the aorta and found that endothelial-specific Piezo1 deletion attenuates vascular leakage and pulmonary edema. Mechanistic experiments show that Piezo1-mediated Ca²⁺ signaling activates calpain, promoting VE-cadherin internalization and adherens junction protein degradation (17). Jiang et al (23) used short hairpin RNA in vivo and small interfering RNA in vitro to knock down Piezo1 in ARDS rats and lipopolysaccharide-treated pulmonary endothelial cells subjected to 20% cyclic stretch, respectively. Knockdown attenuates junction disruption and the increase in permeability, supporting a role for Piezo1/Ca²⁺/calpain signaling in barrier injury in these models. These studies examined vascular pressure loading and mechanical stretch in an inflammatory context, respectively, and their findings should be interpreted within their experimental conditions.

By contrast, Zhong et al (13) found that endothelial-specific Piezo1 deletion in mice undergoing high-volume mechanical ventilation and Piezo1 depletion in human pulmonary endothelial cells exposed to cyclic stretch exacerbate the increase in permeability.

Piezo1-mediated Ca²⁺ influx activates calpain, which cleaved and inactivated Src kinase, decreasing Src-dependent VE-cadherin phosphorylation and thereby maintaining adherens junction stability (13). Increasing intracellular Ca²⁺ and promoting calpain activity using the calcium ionophore A23187 attenuates pulmonary microvascular leakage in Piezo1-deficient mice, further supporting this protective pathway (13). These findings demonstrate that endothelial Piezo1 serves a barrier-protective role in this high-volume mechanical ventilation model. Its protective effects cannot be attributed exclusively to physiological or low-intensity stretch.

Although the aforementioned studies concern endothelial Piezo1, they differ in the mode of mechanical loading, inflammatory context and intervention. Friedrich et al (17) examined barrier injury caused by elevated vascular pressure, Jiang et al (23) investigated mechanical ventilation and cyclic stretch in an inflammatory context and Zhong et al (13) combined endothelial-specific deletion, cell Piezo1 depletion and downstream rescue experiments to identify a stretch-related barrier-protective pathway. Although all involve calpain, their downstream effects differ: Adherens junction protein degradation is associated with barrier disruption, whereas Src cleavage and inactivation maintain junctional stability (13,17,23). These findings suggest that the net effects of Piezo1 cannot be determined solely by stimulation intensity and duration, but should also be interpreted in association with loading mode, cellular state and downstream signaling. Whether differences in calpain substrate selection or other regulatory mechanisms account for these divergent effects remains to be directly tested under comparable experimental conditions. Piezo1 inhibition strategies in ARDS should consider the possibility of weakening endothelial barrier protection, with benefits and risks assessed in defined cell types and disease contexts.

Studies of mechanical ventilation indicate that assessment of Piezo1 effects should consider both ventilatory loading and the response of different cell types, including epithelial and endothelial cells (13,23,62).

Lung-protective mechanical ventilation is a key component of ARDS management (56-58). Larger tidal volume, higher plateau pressure and repeated alveolar opening and closure can increase mechanical stress in lung tissue (56-58). However, these ventilatory parameters are not equivalent to the local loads experienced by specific cells and do not directly reflect the extent of Piezo1 activation (13,17,23). Experimental studies show Piezo1 can contribute to junction disruption or protect the endothelial barrier in ventilation or stretch models (13,23). Ventilation-related lung injury therefore cannot uniformly be attributed to Piezo1, nor can the benefits of lung-protective ventilation be directly interpreted as resulting from Piezo1 inhibition. Its specific effects must be assessed in association with cell type, local mechanical loading and downstream signaling.

Piezo1 participates in ADAM10/17-mediated growth factor and adhesion molecule release (61), as well as mechanical stretch-induced apoptosis in A549 lung epithelial cells (62). These findings concern distinct cell responses and should be interpreted within their experimental conditions. They do not establish a unified causal sequence in which Piezo1 links inflammation, microcirculatory dysfunction and mitochondrial stress.

Most studies remain based on experimental models, and the specific effects of Piezo1 across ARDS etiology, ventilator settings and disease stages are not fully resolved (13,23,62).

AKI is a frequent form of organ dysfunction in critically ill patients, affecting 57.3% of patients during the first week of ICU admission in a multinational study (63), and involves altered renal hemodynamics, inflammation, microcirculatory impairment, metabolic stress and tubular epithelial injury (64-66). The kidney has a distinctive mechanical environment created by high perfusion, continuous filtration, tubular flow, fluid shear stress, intraluminal pressure and ECM mechanics (67-69). Under physiological conditions, tubular epithelial cells sense urine flow and use mechanical cues to regulate tubular structure and transport (69,70).

Sepsis, ischemia-reperfusion, shock and nephrotoxic injury alter renal blood flow, tubular patency, interstitial pressure and edema, thereby changing local shear stress and tissue tension (64,65). These changes may alter the mechanical environments of renal cells, but whether they influence AKI progression through Piezo1 requires direct validation. Studies of myeloid Piezo1 have demonstrated its involvement in macrophage immune responses (25) and ischemia-reperfusion-induced renal injury (16). However, the principal mechanical inputs responsible for these effects remain unclear, and the available evidence does not establish that changes in renal blood flow or tubular fluid flow directly cause injury through tubular epithelial Piezo1. Assessment of Piezo1 in AKI should distinguish its roles in myeloid cells, tubular epithelial cells and other cell types, and define the mechanical load, downstream signaling and their specific contributions to injury in models.

Direct mechanistic evidence in ischemia-reperfusion-associated AKI demonstrates the involvement of myeloid cell Piezo1 (16). In mice subjected to bilateral renal vascular clamping and bone marrow-derived macrophages exposed to hypoxia, Chen et al (16) found that Piezo1 upregulates HIF-1α via Ca²⁺-dependent calpain signaling and modulates the Notch and CCL2/CCR2 pathways, promoting inflammatory macrophage polarization. Myeloid-specific Piezo1 deletion attenuates renal injury (16). The aforementioned study supports the involvement of myeloid cell and macrophage Piezo1 in ischemia-reperfusion injury but does not establish these pathways as intrinsic Piezo1 mechanisms in tubular epithelial cells.

Tubular epithelial cell stress and organelle injury are key pathological processes in AKI, but studies of these processes do not establish that they are directly mediated by Piezo1 (71,72). Whether renal vascular endothelial Piezo1 influences local blood flow and microcirculation in AKI requires validation through cell-specific manipulation in the corresponding models.

It is not clear whether renal Piezo1 in AKI responds predominantly to vascular shear stress, tubular shear stress, luminal pressure or a combination of forces. Ischemia-reperfusion, sepsis-associated and drug-induced AKI have distinct hemodynamic and tissue injury profiles and may engage Piezo1 differently. Their effects should not be reduced to a single unified mechanism.

Chen et al (16) support a role for myeloid cell Piezo1 in inflammatory injury during experimental ischemia-reperfusion-associated AKI, but this mechanism cannot yet be generalized to AKI of other etiologies (16). Because myeloid-specific Piezo1 deletion is not restricted to macrophages, more precise cell-specific interventions are needed to identify the cell sources of the protective effects observed in vivo. The relative contributions of Piezo1 in tubular epithelial and vascular endothelial cells, podocytes and different immune cell populations, as well as possible cooperative or opposing effects between these cells, also require validation. Future studies should define the principal responding cells, sources of mechanical stimulation and downstream effects in association with AKI etiology and disease stage.

Severe trauma and hemorrhagic shock are notable causes of MODS and typically coexist, creating a complex mechanical stress environment (73,74). Trauma directly deforms tissue and disrupts the ECM, whereas hemorrhage and resuscitation produce marked hemodynamic fluctuations and ischemia-reperfusion injury. Hemodynamic changes during hemorrhage and resuscitation, together with trauma-associated glycocalyx injury and tissue edema, may alter the local mechanical environment (74,75). The coexistence of mechanical perturbations distinguishes trauma/hemorrhagic shock from other types of critical illness.

Direct experimental evidence for the role of Piezo1 in trauma and hemorrhagic shock remains limited; its potential involvement is inferred primarily from studies of endothelial mechanobiology (8,21,29) and established trauma pathophysiology (73,74). Endothelial Piezo1 senses shear stress and vascular tension and regulates endothelial structure and function through Ca²⁺-dependent signaling (18,21,29,76,77). Post-traumatic hypoperfusion and hemodynamic changes during resuscitation, together with glycocalyx injury and tissue edema, may alter the mechanical environment of endothelial cells (74,75).

Pulmonary vascular pressure and mechanical stretch models show that endothelial Piezo1 can contribute to adherens junction disruption and vascular leakage through Ca²⁺-dependent calpain signaling (17,23). However, whether this mechanism operates in trauma or hemorrhagic shock requires direct validation.

Vascular leakage and tissue edema may exacerbate microcirculatory dysfunction and tissue hypoxia, thereby contributing to organ injury (28,52,78).

Piezo1 may participate in post-traumatic immune responses (14). Studies have shown that macrophage Piezo1 participates in matrix stiffness sensing and the regulation of cell polarization (14), whereas neutrophil Piezo1 senses mechanical constraints during transendothelial migration and enhances bactericidal function (24). These findings provide a mechanistic basis for the link between mechanosensing and immune responses but do not directly establish the role of Piezo1 in trauma or hemorrhagic shock. Based on the available evidence, Piezo1 may modulate and amplify inflammatory responses following initiation by tissue injury rather than act as an independent initiator of post-traumatic inflammation (14,25). Its effects may vary with injury type, severity and resuscitation strategy.

Addressing these gaps requires characterization of Piezo1 expression and activity across trauma models, injury stages and resuscitation conditions, together with comparisons between endothelial, immune and parenchymal cells. Single-cell and spatial omics may define cellular sources and spatiotemporal patterns. Establishing causality between Piezo1 signaling and post-traumatic organ injury, however, requires cell-specific intervention.

In summary, Piezo1 operates within distinct mechanical environments across acute and critical illness. Sepsis involves mechanical alterations associated with inflammation and circulatory disturbance (12,15,25); ARDS is characterized by abnormal lung stretch (13,17,23); AKI involves changes in renal blood and tubular flow (64-66,70); and trauma/hemorrhagic shock combines tissue deformation, hemodynamic fluctuation and ischemia-reperfusion (73,74). The principal responding cells and proposed pathological consequences differ among these conditions. The proposed Piezo1-associated signaling mechanisms and their potential contributions to organ dysfunction are summarized in Fig. 2. Table I summarizes representative experimental models, intervention approaches, the direction of Piezo1 effects and the limitations of the available evidence (13,17,23-25).

As the contribution of Piezo1 to organ injury has attracted increasing attention, modulation of Piezo1-mediated mechanotransduction is a potential therapeutic strategy (10,13).

Piezo1-dependent Ca²⁺ signaling intersects with inflammation, barrier function, vascular homeostasis and cellular stress (10,25). Targeting the channel could therefore influence several pathological processes simultaneously. However, Piezo1 is also integral to normal physiology, and therapeutic development remains at a preclinical stage (10,18).

Direct pharmacological modulation is a widely used experimental strategy (79-82). Available tools include the Piezo1 agonist Yoda1, Dooku1, which antagonizes Yoda1-induced effects, and GsMTx4, a non-selective peptide inhibitor of mechanosensitive ion channels (79-82). These compounds are valuable for investigating channel biology, but limitations in selectivity, in vivo stability, pharmacokinetics and long-term safety preclude their current use as established therapeutics.

Beyond direct modulation of Piezo1 activity, downstream signaling in specific cell types may offer candidate targets for intervention. Pulmonary endothelial studies show that Piezo1-associated calpain signaling can contribute to adherens junction protein degradation and barrier injury (17,23) or maintain junctional stability by cleaving and inactivating Src (13).

Sepsis-associated intestinal epithelial injury provides experimental evidence linking Piezo1-mediated Ca²⁺ signaling, mitochondrial stress and barrier injury (15). Selection of downstream targets should be guided by their effects in specific models and interventions should be assessed for their potential to weaken protective signaling. Whether the benefits of modulating Ca²⁺, reactive oxygen species or cell death depend on Piezo1 requires validation through genetic manipulation of Piezo1 and downstream rescue experiments. These candidate targets should not be regarded as established therapeutic strategies.

Lung-protective ventilation, circulatory support and resuscitation are important components of care for acute and critical illness, but their clinical benefits cannot be directly attributed to Piezo1. Lung-protective ventilation aims to limit ventilation-associated mechanical stress and reduce ventilator-induced lung injury (57), while treatment of sepsis and major traumatic hemorrhage emphasizes circulatory support and resuscitation tailored to the patient condition (83,84). These measures may alter the mechanical environment of cells, but whether they influence Piezo1 activity and the direction of effects requires direct validation. Improved perfusion cannot be assumed to decrease Piezo1 activity. In AKI, the association between improved renal perfusion and changes in Piezo1 signaling is unclear. Combining modulation of the mechanical environment with cell-specific intervention targeting Piezo1 or its downstream pathways requires validation and does not provide a basis for clinical treatment recommendations.

Despite its potential therapeutic value, the clinical translation of Piezo1 targeting faces limitations (9,10,18). The foremost challenge is that Piezo1 participates in both physiological mechanical adaptation and pathological mechanotransduction. Piezo1 contributes to flow-associated mechanosensing and vascular regulation (21,29). In a high-volume mechanical ventilation model, endothelial Piezo1 was shown to maintain pulmonary vascular barrier stability (13). In infection-associated models, neutrophil Piezo1 senses mechanical constraints during transendothelial migration and enhances bactericidal function (24), while macrophage Piezo1 enhances phagocytosis and bacterial killing (25).

In models of elevated pulmonary microvascular pressure and mechanical stretch in an inflammatory context, Piezo1 contributes to endothelial junction disruption and increased vascular permeability (17,23), whereas endothelial Piezo1 maintains adherens junctions and barrier stability during high-volume mechanical ventilation (13). These opposing findings indicate that inhibition or activation strategies cannot be selected solely on the basis of stimulation intensity or duration. The direction of intervention should be assessed in association with loading mode, inflammatory context and downstream signaling.

Prolonged systemic Piezo1 inhibition may attenuate pathological signaling while interfering with normal mechanosensing and tissue homeostasis (10).

Zhong et al (13) suggest that Piezo1 inhibition may weaken barrier-protective responses to mechanical stress in pulmonary endothelial cells. Endothelial-specific Piezo1 deletion exacerbates pulmonary vascular leakage induced by high-volume mechanical ventilation, indicating a protective role for endothelial Piezo1 (13). This suggests that broad Piezo1 inhibition may also weaken protective endothelial signaling, although its net effects on overall lung injury require validation. Piezo1-targeted strategies in ARDS should define the target cells and downstream pathways and assess potential benefits and risks, without assuming that channel inhibition produces consistent therapeutic effects.

The functional output of Piezo1 depends on cell type and experimental context. For example, pulmonary vascular endothelial Piezo1 protects or disrupts the barrier in different mechanical loading models (13,17); macrophage Piezo1 enhances infection-related phagocytosis and bacterial killing (25) and epithelial Piezo1 can participate in mechanical stretch-induced cell proliferation (26). Systemic treatment lacking cell specificity may suppress both harmful and beneficial responses. Achieving organ- or cell-targeted delivery while minimizing interference with mechanosensing in normal tissue is therefore an important challenge in the development of Piezo1-directed therapy.

The timing of Piezo1 intervention should be assessed in relation to disease stage, the inflammatory and metabolic status of the affected cells, the extent of cellular injury, and downstream signaling responses. Existing evidence is insufficient to define a universal intervention window across acute and critical illness (13,23). Early disease cannot be equated with a protective phase, nor can sustained mechanical stimulation be assumed to cause injury (13,17,23). Future studies should apply interventions at defined times in specific disease models, combining measurements of Piezo1 function with serial assessment of protective and injurious outcomes to identify potential intervention windows. Evidence remains insufficient to define the appropriate timing, duration, dose or intensity of intervention.

Mechanical environments in acute and critical illness are highly dynamic and disease-specific. The predominant mechanical stimuli differ among diseases, and a single disease may progress through successive changes involving hypoperfusion, tissue edema, increased pressure or reperfusion. A uniform Piezo1-directed regimen based solely on diagnosis may fail to produce consistent benefit. Clinical translation requires measures that reflect the local mechanical environment and Piezo1 activity to identify patients who may benefit and the appropriate timing of intervention.

A priority is to map Piezo1 expression and activity across diseases, organs, cell types and disease stages. Cell-specific genetic manipulation, single-cell transcriptomics and spatial transcriptomics may identify Piezo1-expressing populations and their distribution. These descriptive data should be integrated with functional experiments to establish causal relationships between Piezo1 signaling and organ injury.

More selective, tissue-targeted and temporally controllable Piezo1 modulators are also needed. Alternatives to direct channel modulation include targeting downstream signaling in defined cell types and decreasing abnormal mechanical stimulation through optimized ventilation, resuscitation and organ perfusion. Whether these strategies can act synergistically with anti-inflammatory treatment, organ support and other standards of care requires further evaluation in disease models and clinical studies.

Future Piezo1-targeted strategies should account for cell type and disease context, prioritize injury-associated pathways supported by direct mechanistic evidence and assess whether interventions decrease injury while preserving normal mechanosensing, barrier maintenance and host defense. This goal requires defining the conditions under which Piezo1 shifts from adaptive to detrimental effects and identifying biomarkers that reflect the mechanical environment, channel activity and treatment response. Until sufficient human evidence is available, Piezo1 is better regarded as a research target for understanding the mechanobiology of acute and critical illness and its therapeutic value should be assessed.