Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis (M.tb), primarily affecting lung cells and characterized by granuloma formation (1,2). It has historically been the leading cause of mortality from a single pathogen (3). The World Health Organization (WHO) reported 10.80 million cases and 1.25 million mortalities from tuberculosis in 2023 (4). A total of 30 countries with a high tuberculosis burden account for 87% of the global cases in 2023, including India, Indonesia and China, accounting for 26.0, 10.0 and 6.8% respectively (4,5). Furthermore, the 2019 coronavirus disease pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, makes the global tuberculosis mortality toll in 2020 exceed that observed in 2015 and even 2012 (6–8). The End Tuberculosis Strategy composed by the WHO aims to reduce the incidence of tuberculosis by 90%, to <10 cases per 100,000 individuals within the global population annually by 2035 (9). This would require an annual decline in tuberculosis incidence to accelerate from the current decline of 2% per year to 20% per year (10,11). A total of three key areas of tuberculosis research are important to reducing incidence: i) Vaccine development; ii) improved diagnostic tools and iii) improved treatment options (11,12).

Traditional mice, as valuable experimental models, are widely used in M.tb research, including studies on pathogenesis, drug development and vaccine assessment (13–15). Although traditional mice share some genomic and physiological traits with humans (2), marked differences in immune responses and pathogenesis following M.tb infections, such as collagen destruction, limit the utility of these models (16,17), hindering progress in M.tb research (18). A key difference in pathogenesis between mice and humans is that human tuberculosis forms organized, caseous necrotizing granulomas with a macrophage core and a peripheral rim of lymphocytes (19), whereas M.tb-infected mice form loose granulomata-like structures without giant cells (20). These differences highlight the notable need for a novel animal model that accurately mimics the pathogenesis of M.tb infections in humans.

Humanized mice, which are immunodeficient recipients engrafted with human cells or tissues or that express human gene products, emphasize the evolutionary specificity and diversity of human genotype and phenotype (21,22). Currently, common humanized mouse models of M.tb infection are created by grafting human hematopoietic cells and bone marrow-liver-thymus (BLT) tissues, and by transferring human leukocyte antigen (HLA) genes and receptor genes, such as T cell receptor (TCR), toll-like receptor (TLR) and Fcγ receptor (FcγR), to immunodeficient mice (Fig. S1, Fig. S2, Fig. S3, Fig. S4, Fig. S5, Fig. S6, Fig. S7, Fig. S8, Fig. S9, Fig. S10, Fig. S11). The humanized mouse model has become an appealing alternative for studying human infectious diseases, including tuberculosis, as it closely mimics the human immune system (23,24) and is increasingly used to study host responses and immunopathology (17,25–27). These models are also being used with increasing frequency as preclinical tools to assess the efficacy of novel drugs and vaccines and to investigate underlying mechanisms in M.tb infections (2,28). The present review systematically searched for studies on humanized mice and tuberculosis in the Web of Science (https://www.webofscience.com) and PubMed (https://pubmed.ncbi.nlm.nih.gov/) databases, using the keywords ‘humanized’, ‘mice’ or ‘mouse’ and ‘tuberculosis’. The present review summarizes advances in the application of humanized mice for studying immune responses, therapy development and vaccine assessment in M.tb infections and M.tb-human immunodeficiency virus (HIV) co-infections.

An incomplete understanding of the human immune response to M.tb infections and its associated protections has hindered the development of tuberculosis vaccines and therapies. Further exploration of the immune response and pathogenesis induced by M.tb infections is important (Table I and Fig. 1) (17,24–27,29–34). Several humanized mouse models have been developed to investigate this issue (24,29,30).

A total of five research groups have utilized humanized mice to analyze the immune response induced by M.tb and its antigens (25,26,29,31–33). A research group successfully developed humanized non-obese diabetic (NOD).Cg-Prkdc^scidIl2rg^tm1sug/JicTac (NOG) mice by injecting human CD34⁺ hematopoietic progenitor cells (HPCs) into mice, resulting in the generation of human CD45⁺ cells (Fig. S1) (31). The researchers observed a multi-subpopulation human T-cell response (CD4⁺ CD45RA⁻ CD45RO⁺ subpopulation) and the expression of cytokines and chemokines, such as interleukin (IL)-2, tumor necrosis factor-α (TNF-α), interferon-γ, perforin and granulysin, following M.tb infection (31). In HLA transgenic mice injected with the class III human genes, HLA DQ and/or DR genes (Fig. S1), the variable T-helper (Th) response to the M.tb antigen early secreted antigenic target (ESAT)-6-31-45 depended on the HLA haplotype of transgenic mice rather than a single DR or DQ HLA molecule (25).

A team created human CD1 transgenic mice and M.tb antigen mycolic acid (MA)-specific TCR (DN1)/CD1 transgenic mice by transferring human CD1 and CD1b-restricted MA-specific TCR genes into mouse models, resulting in successful expression of human CD1 and DN1 TCRs in transgenic mice (Fig. S2) (26,29). The authors found that intranasal inoculation of MA-loaded micellar nanocarriers activated and proliferated adoptively transferred DN1 T cells, eliciting MA-specific T cell responses in humanized mice infected with the M.tb antigen MA. Additionally, active DN1 T cells congregated in pulmonary granulomas and provided protection against M.tb infection (26,29). A group built humanized NOD.Cg-Prkdc^scid Il2rg^tm1Wjl Tg [cytomegalovirus-IL-3, granulocyte-macrophage colony-stimulating factor, KIT ligand (KITLG)]1Eav/MloySzJ (NSG-SGM3) mice by engrafting human CD34⁺ hematopoietic stem cells (HSCs), which differentiate into human CD45⁺ cells (Fig. S3) (32). M.tb infection increases colony-forming units (CFUs) and the CD4⁺/CD8⁺ T cell ratio, leading to immune cell infiltration around a necrotic nucleus. The immune response to tuberculosis is complex and requires further investigation.

Several researchers have investigated the role of TNF in humanized mice infected with M.tb (Fig. S3). Humanized TNF knock-in mice can survive and control M.tb load during infection, while TNF knock-out mice die rapidly. Administration of TNF blockers, such as infliximab, etanercept or adalimumab, subsequently increases M.tb levels and hyperinflammation in M.tb-infected humanized TNF knock-in mice (33). Therefore, TNF may carry out an important role in controlling M.tb infection.

Some researchers have examined M.tb-induced pathology and clarified that damage to the pulmonary extracellular matrix via collagen destruction may initiate caseous necrosis, as seen in humans, rather than be a result of necrosis in humanized C57BL6 mice. This mouse model generates human matrix metalloproteinase 1 (MMP-1) and forms human giant cells following M.tb infection (Fig. S4) (17).

Organized granulomas are a characteristic pathological feature of human tuberculosis, preventing the spread of M.tb (24). A total of four research teams have developed humanized mouse models for granuloma formation. The first team developed a humanized BLT mouse model by grafting human fetal liver-thymus tissues and CD34⁺ fetal liver cells. The human immune system was well-reconstructed, as evidenced by the generation of human CD45⁺ cells (Fig. S4). Organized granulomatous lesions with an acellular center, M.tb periphery, caseous necrosis and cholesterol crystal similar to human tuberculosis granulomas were observed in the humanized mice infected with M.tb but not in traditional mice (24). The second team developed humanized NOD.Cg-Rag1^tm1MoMIl2rg^tm1Wjl (NRG-A2) mice with transgenes for human HLA-A2.1/A*02:01 (A2) and humanized HLA I/II-transgenic mice with transgenes for human HLA-DR4/DRB1*04:01 (DRAG) and A2. Both mouse models expressed human CD45⁺ leukocytes (Fig. S5). These two mouse models showed similar bacillus loads and dissemination potential. However, the DRAG-A2 mice developed more classical, well-organized granulomas following M.tb infection than the NRG-A2 mice (34).

The third team created humanized human immune system (HIS)-NOD.Cg-Prkdc^scidIl2rg^tm1Wjl (HIS-NSG) mice by injecting human CD34⁺ HSCs and HPCs, which resulted in the generation of human CD45⁺ cells (Fig. S6). After M.tb infection, the mice developed caseous necrotic granulomas resembling human tuberculosis, with a core of necrotic debris and a peripheral cell layer (30). The fourth team generated humanized NSG mice by injecting human CD34⁺ HSCs into mice, resulting in the production of human CD45⁺ cells (Fig. S6). Compared with non-humanized mice, the humanized mice developed irregular or circular granulomas, characterized by numerous human giant cells and bacilli in the core, surrounded by CD3⁺ T cells or a collagen layer and increased necrosis following M.tb infection (27). Among these models, the humanized BLT, DRAG-A2 and HIS-NSG mice exhibited characteristics of human tuberculosis granulomas, making them suitable for further research. Overall, the observations made in these humanized mouse models provide valuable insights for developing protective biomarkers of tuberculosis and identifying precise host-pathogen interactions.

Humanized mice have markedly enhanced the current understanding of the immune responses and pathological processes induced by M.tb (28). The aforementioned models have enabled detailed investigations of human-specific immune cell interactions, cytokine profiles and granuloma formation. However, current models still have limitations in fully recapitulating the complexity and heterogeneity of human immune responses. Furthermore, several questions remain to be addressed. This includes: i) The proportion of human immune cells in the peripheral blood of humanized mice that is suitable for use in further research; and ii) any changes that have occurred in the body weight, survival rate, M.tb burdens, lesions and the expressions of antibodies, CD4⁺ T cells, CD8⁺ T cells, cytokines and chemokines in humanized mice compared with humans, traditional mice and negative controls (24). The degree to which these indices increase or decrease may indicate whether the humanized mice are a suitable M.tb infection model. A ‘gold standard’ humanized mouse model could then be generated based on these indices and possibly utilized for future research on vaccines and therapies.

Vaccination generates long-lasting host immunity, an important component in global tuberculosis control and eventual eradication. The Mycobacterium bovis bacillus Calmette-Guerin (BCG) vaccine has been used for >100 years (35). BCG is the only licensed tuberculosis vaccine, but its efficacy against pulmonary tuberculosis is limited, providing protection for only 10–15 years (35–38). Therefore, new tuberculosis vaccines are needed to create a protective environment in the lungs (37,39). Previous research has employed humanized mouse models to develop more effective vaccines (Table II) (3,31,40–43). The protective efficacy of four new vaccines against M.tb infection was tested via subcutaneous injection, similar to BCG administration, using transgenic mice. The peptide-based vaccine ACP, containing Th1 the immunodominant peptides antigen Ag85B_12-26, CFP21_12-26 and PPE18_149-163 derived from M.tb antigens, has the following effects: i) It reduces lung pathological lesions; ii) increases levels of interferon (IFN)-γ⁺ T lymphocytes, Th1-type cytokines, such as IFN-γ and TNF-α, and antibodies, resulting in an immunoglobulin ratio of IgG2a/IgG1>1; and iii) stimulates a stronger cellular immune response. However, the ACP vaccine does not enhance the protective efficacy of BCG following M.tb infection in humanized C57BL/6 (HLA-A11^+/+ downregulator of transcription 1^+/+H-2-β2 microglobulin^−/−/ intracellular amyloid β^−/−) mice expressing human HLA genes (Fig. S7) (3).

The MP3RT peptide-based vaccine, containing the mycobacterial antigens Mpt51, Mpt63, Mpt64, Mtb8.4, PPE18, PPE44, PPE68, resuscitation promoting factor RpfA, RpfB, RpfE and TB10.4, reduces M.tb load, pulmonary lesions and inflammatory cell numbers, and increases IFN-γ⁺ and CD3⁺IFN-γ⁺ T lymphocytes, IFN-γ cytokine and MP3RT-specific IgG antibodies. However, the MP3RT vaccine does not restore animal weight as with BCG in humanized C57BL/6 mice expressing human HLA genes after M.tb infection (Fig. S3) (40). Similarly, the Ag85A/B chimeric DNA vaccine also fails to provide improved protection compared with BCG in restoring animal weight, reducing M.tb load and alleviating lung lesions and inflammatory cell infiltration in humanized C57BL/6 mice challenged with M.tb (40). The CL075:antigen 85B peptide 25 (Ag85Bp25)-PS vaccine, a combination of a polymer nanocarrier encapsulating the TLR agonist CL075-PS with M.tb Ag85Bp25, primes Ag85B-specific CD4⁺ adaptive immune responses similar to BCG in humanized TLR8 neonatal mice expressing human TLR genes (Fig. S7) (41).

Unlike traditional subcutaneous BCG inoculation, some researchers have explored the efficacy of the respiratory mucosal route for vaccine delivery, mimicking the M.tb infection pathway. In humanized NRG mice, engrafted with human CD34⁺ HSCs and expressing human CD45⁺ cells (Fig. S8), BCG is injected subcutaneously to protect against M.tb infection, similar to its effect in humans. The respiratory mucosal vaccination pathway using virus-vectored M.tb Ag85A (AdHu5Ag85A) induces a more robust CD4⁺ and CD8⁺ T cell response, reduces M.tb burdens and decreases granulomatous lesions in humanized NRG mice compared with control mice after M.tb infection (42). Intranasal inoculation with a trivalent adenoviral-vectored (Tri:ChAd:TB) vaccine, containing the M.tb antigens, Ag85A, TB10.4 and RpfB, targeting antigens expressed during the acute, chronic and dormant phases of M.tb provides robust protection against pulmonary M.tb challenge in humanized NRG mice, engrafted with human HSCs and reconstituting human CD45⁺ leukocytes (Fig. S8). The treated mice maintain stable weight, with reduced M.tb burden, fewer pathological changes and less granulomatous lesions compared with unvaccinated mice (43). In humanized NOG mice, the M.tb antigen ESAT-6 vaccine, administered via intranasal immunization, fails to effectively stimulate granzyme⁺ perforin⁺ CD8⁺ T cells or control bacillus CFUs, unlike BCG after M.tb infection (31).

Humanized mouse models hold potential as tools for preclinical evaluation of tuberculosis vaccines (31). These models enable the testing of human-specific immune responses, such as T-cell priming and memory formation, following vaccination (31). These models bridge the gap between basic research and clinical application (44), however, challenges persist. To the best of our knowledge, the humanized mice used to evaluate these vaccines have not undergone comprehensive immune and pathological assessments. Additionally, the similarity between mice and humans in terms of immunity and pathology remains to be fully elucidated, which may raise questions regarding the validity of vaccine evaluation data generated using these models. Furthermore, the ACP, MP3RT, Ag85B/p25, ESAT-6 and Ag85A/B DNA vaccines did not demonstrate superior efficacy compared with the traditional BCG vaccine and the efficacy of the AdHu5Ag85A and Tri:ChAd:TB vaccines was not directly compared with BCG (3,31,40–43). To the best of our knowledge, the method of administering vaccines via the respiratory mucosa has not identified a vaccine superior to BCG. Therefore, further consideration is needed for the development and clinical application of subsequent vaccines.

Researchers have tested and developed several therapeutic strategies for tuberculosis using humanized mice models (Table III) (30,45–48). To eliminate species differences in drug metabolism, researchers developed the humanized 8HUM mouse model by replacing 33 mouse cytochrome P450 (CYP) genes, pregnane X receptor (PXR) and constitutive androstane receptor (CAR) with 8 human genes, including human CYP genes (CYP1A1, CYP1A2, CYP2C9, CYP2D6, CYP3A4 and CYP3A7), as well as human PXR and CAR (Fig. S9), which are the CYPs responsible for the majority of drug metabolism in humans (49). Both the humanized 8HUM mice and C57BL/6J mice exhibit similar CFU counts and maintain comparable body weight following M.tb infection. In humanized 8HUM mice, the efficacy of three anti-tuberculosis drugs was tested, revealing that moxifloxacin reduces M.tb CFU counts compared with the untreated group. However, pretomanid and bedaquiline do not eliminate the bacillus load when compared with C57BL/6J mice. Efavirenz, a CYP3A4 inducer, has no effect on the pharmacokinetics or efficacy of bedaquiline. However, its combination with bedaquiline reduces M.tb load in humanized 8HUM mice compared with C57BL/6J mice (45). In addition, the drug disposition pathways and drug-drug interactions of several substances, such as rifampicin, the herbal medicine St. John's Wort and S-acenocoumarol, in humanized 8HUM mice are similar to those in humans (50). This suggests that the 8HUM model can facilitate the clinical development of drugs and serve as an appropriate tool for drug development. Notably, the researchers observed changes in bacillus load and weight in humanized 8HUM mice after M.tb infection (45). However, they did not compare the reduction in M.tb CFU by pretomanid and bedaquiline with the untreated group or investigate immune responses and pathological changes (45). Therefore, the viability of humanized 8HUM mice for studying M.tb infection requires further investigation.

Moxifloxacin has been proposed as an addition to the standard tuberculosis chemotherapy regimen, which comprises rifampicin, isoniazid and pyrazinamide, to enhance therapeutic efficacy. Some studies support this approach (51–53), while others contradict it (54,55). Researchers tested this hypothesis using humanized HIS-NSG mice (Fig. S6) and found that adding moxifloxacin did not reduce M.tb CFUs in organs compared with mice denied the addition (30). Therefore, further investigation is needed to determine whether moxifloxacin should be added to the standard chemotherapy regimen.

Due to the inevitable drug resistance associated with traditional antibiotics, novel therapies, such as necrosis inhibitors, monoclonal antibodies and phage therapy, must be developed to address this issue. Previous report indicate that macrophage apoptosis promotes microbial escape and propagation (56). The effect of necrosis inhibition on the dissemination of M.tb in humanized NSG mice was examined. M.tb loads in mice treated with the necrosis inhibitor necrostatin-1s were comparable with those in control mice, as observed in humanized NSG mice, which produce human CD45⁺ cells and are engrafted with human CD34⁺ cord blood stem cells (Fig. S9) (46). Therefore, necroptosis inhibition does not reduce M.tb dissemination, contradicting a previous finding (56).

A research team evaluated the protective efficacy of human monoclonal antibodies targeting M.tb surface glycans, which FcγR mediates (57). In humanized FcγR mice expressing human FcγR I/II/IIB/IIIA/IIIB genes (Fig. S10), IgG1 P1AM25, a monoclonal antibody with a high affinity for the M.tb surface glycan arabinomannan, reduces pulmonary M.tb CFUs following infection (47).

In addition to the aforementioned therapies, researchers have identified the potential benefits of phage therapy. Humanized NSG-SGM3 mice, engineered with HSCs and the human cytokine/chemokine genes IL-3, granulocyte-macrophage colony-stimulating factor and KITLG, generate human immune cells (Fig. S10). Following aerosolized M.tb infection, phage DS6A-treated mice gain weight, and display improved lung function, reduced lung inflammation and clearance of M.tb from the spleen compared with untreated mice (48).

Humanized mice have proven valuable in evaluating the efficacy of anti-tuberculosis drugs and host-directed therapies (48). These models provide insight into the effects of drugs on human immune cells and facilitate the assessment of potential immune-modulatory treatments. New therapies for tuberculosis, such as IgG1 P1AM25 and phage DS6A, have shown promising efficacy in humanized mice and warrant further investigation (47,48). However, current humanized mouse models often fail to accurately replicate the pharmacokinetics and pharmacodynamics of drugs in humans, limiting their predictive value (50,51). Additionally, as the aforementioned studies have shown, variability in immune cell reconstitution across different humanized mouse strains leads to inconsistencies in therapeutic outcomes. To address these challenges, future research should focus on enhancing the physiological relevance of drug metabolism and improving the consistency of human immune cell engraftment.

Since the mid-1980s, the HIV epidemic has contributed to an increase in tuberculosis cases (58). Co-infection with M.tb and HIV has become a notable obstacle in the treatment of tuberculosis (38). HIV infection leads to a decline in CD4⁺ T cells, creating an opportunity for latent tuberculosis infection (LTBI) to reactivate into active tuberculosis (38,59). HIV-infected individuals are 16–27 times more likely to develop tuberculosis compared with healthy individuals. Co-infection with HIV and LTBI increases the risk of progression to active tuberculosis from 10% over a lifetime to 10% per year (60). The public health impact of HIV and M.tb co-infection underscores the need to investigate the interaction between these pathogens and develop novel prophylactics and therapeutics. This requires reliable animal models for evaluation (Table IV) (32,34,61–63).

The BLT, HLA transgenic and NSG-SGM3 mouse models were developed to study the immune responses triggered by M.tb and HIV co-infection. In BLT humanized mice, transplanted with human fetal liver-thymus tissues and CD34⁺ HSCs expressing human CD45⁺ leukocytes (Fig. S4), HIV infection increases production of the pro-inflammatory cytokines, IL-1β and IL-6, resulting in poorly organized granulomas, worse pulmonary lesions, increased neutrophils and higher M.tb load and propagation. These effects are more severe following intravenous HIV infection followed by intranasal M.tb infection compared with M.tb infection alone. Furthermore, pulmonary pneumonia and vascular occlusions with endothelialitis develop in HIV/M.tb co-infected mice (61). Following co-infection with HIV and M.tb, humanized NRG-A2 mice with human A2 transgenes express human CD45⁺ leukocytes (Fig. S5) and develop granulomatous lesions similar to those in mice infected with M.tb alone (34), which is inconsistent with previous finding (61). After M.tb and HIV co-infection, humanized NSG-SGM3 mice (Figs. S3 and S11) exhibit a similar infection pattern to humans, with a decrease in CD4⁺ T cells and an increase in HIV burden compared with uninfected mice (32,62).

Additionally, humanized NSG-SGM3 mice have been used to evaluate the role of sirtinol in controlling M.tb following HIV and M.tb co-infection. The authors of the study found that sirtinol reduces CFU counts in the lung and spleen and decreases lung lesions (Fig. S11) (62).

Additionally, a humanized mouse model of M.tb relapse was created in the context of HIV. In humanized BLT mice, injected with human BLT tissues and generating human CD45⁺ cells (Fig. S4), rifampin and isoniazid treatment reduces M.tb loads and facilitates granuloma resolution following M.tb infection. However, subsequent HIV infection increases M.tb CFU counts (63). Studies on M.tb and HIV co-infection in humanized mice are limited, making it difficult to draw definitive conclusions. However, they provide valuable insights for future research.

Analysis of the data of patients with pulmonary tuberculosis in China from 2005 to 2021 revealed that the total recurrence rate was 0.47 per 100 person-years (64). Thus, it is important to establish latent M.tb infection and control reactivation under immunocompromised conditions, particularly in the context of HIV co-infection, as HIV markedly increases the risk of tuberculosis reactivation (65). A strategy to achieve this is to use low-dose M.tb inoculation in humanized mice, which can induce a dormant state similar to latent tuberculosis. The depletion of CD4⁺ T cells can be used to create an immunocompromised environment, facilitating latency (66). In HIV co-infection models, where HIV-induced immune dysfunction is present, M.tb can establish latency and reactivation can be triggered by immune reconstitution or withdrawal of immunosuppressive treatments (65). The aforementioned immunocompromised-latent M.tb models will allow for the study of tuberculosis relapse and provide valuable insights into therapeutic strategies for preventing reactivation in immunocompromised individuals.

Humanized mice can model M.tb and HIV co-infection, a complex clinical scenario with important public health implications. These models enable the investigation of the mutual impact of both pathogens on immune function and allow for testing combined therapeutic strategies. Despite these advantages, current models have limitations in fully capturing the dynamic interplay between HIV and M.tb in humans. Limitations include incomplete immune cell development, poor lymphoid tissue organization and the short lifespan of some models (67). Advancing humanized mouse models to support long-term studies and more comprehensive immune reconstruction is a notable priority.

Since the discovery of M.tb in 1882, numerous vaccines and treatments against M.tb infection have been developed; however, tuberculosis incidence and mortality have not decreased as expected (68). The humanized mouse model holds promise for studying tuberculosis, but several aspects need improvement.

Compared with traditional mice, humanized mice generate immune responses that resemble those in humans during M.tb infection more closely (31). NSG or NRG humanized mice, transplanted with human HSCs, are primarily used for short-term studies of tuberculosis immune responses (27,30,32,34). By contrast, humanized BLT mice, transplanted with human BLT, are used for long-term studies, such as co-infection with M.tb and HIV (61,63). For specific purposes, researchers have developed unique humanized mouse models. For instance, humanized TNF knock-in mice were developed to study the role of TNF in tuberculosis (33).

Of the humanized mice infected with M.tb discussed in 23 studies, 11 were generated by injecting human CD34⁺ cells. The frequency of human CD45⁺ cells in the peripheral blood of humanized mice ranged from 1 to 55%. Typically, human CD45⁺ T cells make up >25% of the peripheral blood in successfully constructed humanized mice (69). This variability in frequency limits comparisons between humanized mouse models. Incomplete replication of the human immune system and variability in human immune cell frequencies across humanized mice led to inconsistent results, limiting the interpretation of human immune responses to M.tb. Furthermore, treating M.tb requires the collaboration of multiple systems, not just the immune system (70). Therefore, no animal model can fully replicate human M.tb infection. The results of M.tb infection and treatment in humanized mice suggest the need for caution in their interpretation.

Of the 23 humanized mouse models for tuberculosis, three were engrafted with human BLT tissues and four were transgenic for human HLA. These differences in transplantation methods highlight the need to select the optimal mouse model for experiments based on specific research requirements (2). Additionally, these studies of M.tb infection using humanized mice are varied, emphasizing the need for relevant institutions to establish protocols that standardize the use of humanized mice. This will enable the comparison of results across laboratories and facilitate the development of effective vaccines and therapeutic regimens.

Mice remain the primary animal model for tuberculosis research, accounting for 61% of all tuberculosis-infected models, due to their ease of use, low cost and ability to rapidly evaluate vaccine and drug efficacy (71,72). Non-human primates (NHPs) are considered ideal models for studying tuberculosis due to their similar pathogenesis to humans. However, NHP models make up only 1% of all tuberculosis animal models and are limited by ethical and economic constraints (72).

There remain ambiguities in M.tb research using humanized mice, including inadequate replication of the human lung microenvironment and strain-specific differences. Future research should focus on developing advanced models with improved engraftment protocols, enhanced lung-specific humanization and greater diversity in M.tb strains to address these issues.

The use of humanized mouse models in M.tb infection research has substantial practical and medical value. Compared with traditional mice, humanized models provide a more accurate representation of human immune responses, improving current understanding of tuberculosis pathogenesis in humans and aiding in the development of effective interventions (27,31,48).

The present review summarizes the following two key contributions to medical progress: i) The investigation of co-infections. Humanized mouse models are important for studying co-infections, such as HIV and M.tb, which are common in human populations (61). These models replicate the immunopathological effects of co-infection, including CD4⁺ T cell depletion and granulomatous lesion formation, providing insights into disease progression and potential therapeutic targets (61); and ii) preclinical evaluations of therapeutics. Humanized mouse models serve as valuable platforms for testing new anti-tuberculosis drugs and vaccines (3,48). Their ability to replicate human immune responses allows for the evaluation of therapeutic efficacy and safety prior to clinical trials, potentially speeding up the development of effective treatments (48).

The utilization of humanized mouse models in tuberculosis research is of notable practical and medical importance. These models bridge the gap between animal studies and human clinical applications, facilitating a deeper understanding of disease mechanisms and the development of effective interventions. Their role in advancing tuberculosis research is notable, particularly in the face of challenges such as drug resistance and co-infections.

Co-infection with other pathogens, such as HIV and SARS-CoV-2, continues to exacerbate the challenges of treating tuberculosis, with limited strategies available (32,34,61–63). Although several vaccines and therapeutic agents are undergoing clinical trials, there is a substantial need to identify safe and effective vaccines and drugs to prevent and treat M.tb infection (3,30,31,40–43,45–48), especially in cases of HIV-M.tb co-infection. To address this, a number of humanized mouse models have been developed to study the immune response and pathogenesis of tuberculosis, as well as the interactions between HIV and M.tb, to accelerate the screening process. However, greater efforts are required to implement the End Tuberculosis Strategy.