Systemic Immunological changes in patients with distinct clinical outcomes during Mycobacterium tuberculosis infection

Analysis of T-lymphocyte subsets and risk factors in children with tuberculosis

BACKGROUND

Tuberculosis (TB) is not only related to infection but also involves immune factors. This study explores the changes in T-lymphocyte subsets in children with TB who are human immunodeficiency virus (HIV)-negative and examines their relationship using chest computed tomography (CT) scans. Additionally, the study identifies risk factors for severe TB (STB) in children and establishes relevant risk prediction models.

METHODS

We recruited 235 participants between 2018 and 2022, comprising 176 paediatric patients with TB who were HIV-negative and 59 age-matched children with bacterial community-acquired pneumonia (CAP). We quantitatively analysed and compared T-lymphocyte subsets between the two groups and among different types of TB infection. Both univariate and multivariate analyses of clinical and laboratory characteristics were conducted to identify independent risk factors for STB in children and to establish a risk prediction model.

RESULTS

The absolute counts of CD3, CD4 and CD8 T-cells in children with TB infection decreased significantly compared with bacterial CAP. The percentage of CD8 T-cells increased, whereas the percentage of CD4 T-cells did not change significantly. The absolute count of CD3, CD4 and CD8 T-cells in extrapulmonary TB (EPTB) was significantly higher than in extra-respiratory TB, with unchanged subset percentages. According to chest CT lesion classification, CD4 T-cell counts decreased significantly in S3 compared with S1 or S2, with no significant change in CD3 and CD8 T-cell counts and percentages. No significant differences were observed in lymphocyte subset counts and percentages between S1 and S2. Univariate analyses indicated that factors such as age, symptom duration, white blood cell count, platelet count, neutrophil-to-lymphocyte ratio (NLR), erythrocyte sedimentation rate, prealbumin level, albumin level, globulin level, albumin/globulin (A/G) ratio, high-sensitivity C-reactive protein (Hs-CRP) level and CD4 and CD8 T-cell counts are associated with STB. Multivariate logistic regression analysis revealed that age, Hs-CRP level, NLR, symptom duration and A/G ratio are independent risk factors for STB in children. Increased age, Hs-CRP levels and NLR, along with decreased A/G, correlate with increased susceptibility to STB. A nomogram model, based on these independent risk factors, demonstrated an area under the receiver operating characteristics curve of 0.867 (95% CI: 0.813-0.921). Internal verification confirmed the model's accuracy, with the calibration curve approaching the ideal and the Hosmer-Lemeshow goodness-of-fit test showing consistent results (χ2 = 12.212, p = 0.142).

CONCLUSION

In paediatric patients with TB, the absolute counts of all lymphocyte subsets were considerably reduced compared with those in patients with bacterial CAP. Clinicians should consider the possibility of EPTB infection in addition to respiratory infections in children with TB who have higher CD3, CD4 and CD8 T-cell counts than the ERTB group. Furthermore, CD4 T-cell counts correlated closely with the severity of chest CT lesions. Age, symptom duration, A/G ratio, Hs-CRP level and NLR were established as independent risk factors for STB. The nomogram model, based on these factors, offers effective discrimination and calibration in predicting STB in children.

The changes and its significance of peripheral blood NK cells in patients with tuberculous meningitis

Objective

Tuberculous meningitis (TBM) is the most severe form of tuberculosis (TB). The purpose of this study was to explore the relationship between the number of natural killer (NK) cells and adaptive immune status, and disease severity in TBM patients.

Methods

We conducted a retrospective study on 244 TB patients and 146 healthy control subjects in the 8th Medical Center of the PLA General Hospital from March 2018 and August 2023.

Results

The absolute count of NK cells in the peripheral blood of TBM patients was significantly lower than that in normal controls (NC), latent tuberculosis infection (LTBI), and non-severe TB (NSTB) patients (p < 0.05). The proportion of TBM patients (48.7%) with a lower absolute count of NK cells than the normal reference value was significantly higher than that in NC (5.2%) and LTBI groups (4.0%) (p < 0.05), and slightly higher than that in NSTB group (36.0%) (p > 0.05). The absolute counts of lymphocyte subsets in TBM combined with other active TB group, etiology (+) group, IGRA (-) group, and antibody (+) group were lower than that in simple TBM group, etiology (-) group, IGRA (+) group, and antibody (-) group, respectively. The CD3+ T, NK, and B cells in BMRC-stage III TBM patients were significantly lower than those in stage I and stage II patients (p < 0.05). The counts of CD3+ T, CD4+ T, and B cells in the etiology (+) group were significantly lower than those in the etiology (-) group (p < 0.05).

Conclusion

The absolute counts of lymphocyte subsets in the peripheral blood of TBM patients were significantly decreased, especially in NK cells. The reduction of these immune cells was closely related to the disease severity and had a certain correlation with cellular and humoral immune responses. This study helps to better understand the immune mechanism of TBM and provides reliable indicators for evaluating the immune status of TBM patients in clinical practice.

Building a model for the differential diagnosis of non-tuberculous mycobacterial lung disease and pulmonary tuberculosis: A case-control study based on immunological and radiological features

BACKGROUND

Although the incidence of non-tuberculous mycobacterial pulmonary disease (NTM-PD) is increasing annually, it is easily misdiagnosed as pulmonary tuberculosis (PTB). This study aimed to screen and identify the immunological and radiological characteristics that differentiate NTM-PD from PTB and to construct a discriminatory diagnostic model for NTM-PD, providing new tools for its differential diagnosis.

METHODS

Hospitalised patients diagnosed with NTM-PD or PTB between January 2019 and June 2023 were included in the study. Immunological and radiological characteristics were compared between the two groups. Based on the selected differential features, a logistic regression algorithm was used to construct a discriminatory diagnostic model for NTM-PD, and its diagnostic performance was preliminarily analysed.

RESULTS

Patients with NTM-PD were significantly older than those with PTB and the tuberculosis-specific interferon-gamma release assay (TB-IGRA) positivity rate was significantly lower in the NTM-PD group. Moreover, the absolute counts of total T lymphocytes, CD4+ T lymphocytes, CD8+ T lymphocytes, NK cells, and B lymphocytes were significantly lower in patients with NTM-PD and PTB than in healthy controls. Additionally, patients with NTM-PD had a significantly lower absolute count of B lymphocytes than the PTB group. Radiological analysis revealed significant differences between patients with NTM-PD and PTB in terms of cavity wall thickness, bronchial dilation, lung consolidation, pulmonary nodule size, pulmonary emphysema, lung bullae, lymph node calcification, pleural effusion, mediastinal and hilar lymphadenopathy, and the tree-in-bud sign. Bronchial dilation was identified as the predominant risk factor of NTM-PD, whereas TB-IGRA positivity, lymph node calcification, pleural effusion, and mediastinal and hilar lymphadenopathies were protective factors. Based on this, we constructed a discriminatory diagnostic model for NTM-PD. Its receiver operating characteristic curve demonstrated good diagnostic performance, with an area under the curve of 0.938. At the maximum Youden index of 0.746, the sensitivity and specificity were 0.835 and 0.911, respectively.

CONCLUSIONS

Patients with NTM-PD and PTB exhibited impaired humoral and cellular immune functions as well as significant differences in radiological features. The constructed NTM-PD diagnostic model demonstrated good diagnostic performance. This study provides a new tool for the differential diagnosis of NTM-PD.

A Key Role of CD8+ T Cells in Controlling of Tuberculosis Infection

The main role in the control of tuberculosis infection is played by macrophages and Th1 and CD8+ T cells. The study aimed to identify the most diagnostically significant CD8+ T cell subsets in tuberculosis patients.

METHODS

Peripheral blood samples from patients with clinical, radiological, and bacteriologically confirmed pulmonary tuberculosis (TB, n = 32) and healthy subjects (HC, n = 31) were collected and analyzed using 10-color flow cytometry.

RESULTS

The frequency of the EM4 CD3+CD8+ cells was reduced in the peripheral blood of patients with pulmonary tuberculosis, while the relative and absolute number of EM1 CD3+CD8+ cells increased compared to the control group. CD57 expression was reduced in patients with pulmonary tuberculosis on EM1, EM2, and pE1 CD3+CD8+ cells, whereas the EM3 cells had a high level of CD57 expression. The relative and absolute number of Tc2 (CCR6-CXCR3-) cells in peripheral blood in patients with pulmonary tuberculosis was increased, while the frequency of Tc1 (CCR6-CXCR3+) was decreased, compared to healthy donors.

CONCLUSIONS

Patients with pulmonary tuberculosis have an abnormal CD3+CD8+ cell profile and demonstrate their impaired maturation and functional activity.

The CD56-CD16+ NK cell subset in chronic infections

Long-term human diseases can shape the immune system, and natural killer (NK) cells have been documented to differentiate into distinct subsets specifically associated with chronic virus infections. One of these subsets found in large frequencies in HIV-1 are the CD56-CD16+ NK cells, and this population's association with chronic virus infections is the subject of this review. Human NK cells are classically defined by CD56 expression, yet increasing evidence supports the NK cell status of the CD56-CD16+ subset which we discuss herein. We then discuss the evidence linking CD56-CD16+ NK cells to chronic virus infections, and the potential immunological pathways that are altered by long-term infection that could be inducing the population's differentiation. An important aspect of NK cell regulation is their interaction with human leukocyte antigen (HLA) class-I molecules, and we highlight work that indicates both virus and genetic-mediated variations in HLA expression that have been linked to CD56-CD16+ NK cell frequencies. Finally, we offer a perspective on CD56-CD16+ NK cell function, taking into account recent work that implies the subset is comparable to CD56+CD16+ NK cell functionality in antibody-dependent cell cytotoxicity response, and the definition of CD56-CD16+ NK cell subpopulations with varying degranulation capacity against target cells.

Mechanisms of ag85a/b DNA vaccine conferred immunotherapy and recovery from Mycobacterium tuberculosis-induced injury

Our previous research developed a novel tuberculosis (TB) DNA vaccine ag85a/b that showed a significant therapeutic effect on the mouse tuberculosis model by intramuscular injection (IM) and electroporation (EP). However, the action mechanisms between these two vaccine immunization methods remain unclear. In a previous study, 96 Mycobacterium tuberculosis (MTB) H₃₇ Rv-infected BALB/c mice were treated with phosphate-buffered saline, 10, 50, 100, and 200 μg ag85a/b DNA vaccine delivered by IM and EP three times at 2-week intervals, respectively. In this study, peripheral blood mononuclear cells (PBMCs) from three mice in each group were isolated to extract total RNA. The gene expression profiles were analyzed using gene microarray technology to obtain differentially expressed (DE) genes. Finally, DE genes were validated by real-time reverse transcription-quantitive polymerase chain reaction and the GEO database. After MTB infection, most of the upregulated DE genes were related to the digestion and absorption of nutrients or neuroendocrine (such as Iapp, Scg2, Chga, Amy2a5), and most of the downregulated DE genes were related to cellular structural and functional proteins, especially the structure and function proteins of the alveolar epithelial cell (such as Sftpc, Sftpd, Pdpn). Most of the abnormally upregulated or downregulated DE genes in the TB model group were recovered in the 100 and 200 μg ag85a/b DNA IM groups and four DNA EP groups. The pancreatic secretion pathway downregulated and the Rap1 signal pathway upregulated had particularly significant changes during the immunotherapy of the ag85a/b DNA vaccine on the mouse TB model. The action targets and mechanisms of IM and EP are highly consistent. Tuberculosis infection causes rapid catabolism and slow anabolism in mice. For the first time, we found that the effective dose of the ag85a/b DNA vaccine immunized whether by IM or EP could significantly up-regulate immune-related pathways and recover the metabolic disorder and the injury caused by MTB.

Beyond the Clinic: The Activation of Diverse Cellular and Humoral Factors Shapes the Immunological Status of Patients with Active Tuberculosis

Mycobacterium tuberculosis (Mtb), the etiologic agent of tuberculosis (TB), has killed nearly one billion people in the last two centuries. Nowadays, TB remains a major global health problem, ranking among the thirteen leading causes of death worldwide. Human TB infection spans different levels of stages: incipient, subclinical, latent and active TB, all of them with varying symptoms, microbiological characteristics, immune responses and pathologies profiles. After infection, Mtb interacts with diverse cells of both innate and adaptive immune compartments, playing a crucial role in the modulation and development of the pathology. Underlying TB clinical manifestations, individual immunological profiles can be identified in patients with active TB according to the strength of their immune responses to Mtb infection, defining diverse endotypes. Those different endotypes are regulated by a complex interaction of the patient's cellular metabolism, genetic background, epigenetics, and gene transcriptional regulation. Here, we review immunological categorizations of TB patients based on the activation of different cellular populations (both myeloid and lymphocytic subsets) and humoral mediators (such as cytokines and lipid mediators). The analysis of the participating factors that operate during active Mtb infection shaping the immunological status or immune endotypes of TB patients could contribute to the development of Host Directed Therapy.

The relationship between absolute counts of lymphocyte subsets and clinical features in patients with pulmonary tuberculosis

Background

The aim of the present study is to investigate the clinical value and characteristics of peripheral blood lymphocyte subsets in patients with pulmonary tuberculosis (PTB) using flow cytometry.

Methods

The absolute counts of T, CD4⁺T, CD8⁺T, natural killer (NK), NKT and B lymphocytes in 217 cases of PTB were detected, and the variations in lymphocyte subset counts between different ages and genders and between aetiological detection results and chest radiography results were analysed.

Results

In 75.3% of the patients with PTB, six subset counts were lower than the normal reference range, and 44% showed lower‐than‐normal CD4⁺T lymphocyte levels. The counts of T, CD4⁺T, CD8⁺T and B lymphocytes were significantly lower in patients aged >60 years, and the NKT cell counts were significantly lower in female patients than in male patients. Among the patients with positive aetiological results, 40.8% had reduced CD8⁺T counts; these were significantly lower than those in patients with negative aetiological results (P = 0.0295). The cell counts of T, CD4⁺T, CD8⁺T and B lymphocytes reduced as lesion lobe numbers increased. The counts of T, CD4⁺T and CD8⁺T lymphocytes were significantly higher in the group with lesions affecting one lobe than in the groups with two to three lobes or four to five lobes, and the counts of B lymphocytes were significantly higher in the group with one lobe and the group with two to three lobes than in the group with four to five lobes. The counts of CD4⁺T and CD8⁺T lymphocytes were highest in the no cavity group and showed a downward trend with the increase in cavities; the T lymphocyte count was significantly higher in the no cavity group than in the group with five or more cavities (P = 0.014), and the CD8⁺T lymphocyte count was significantly higher in the no cavity group than in the group with one to two cavities and the group with five or more cavities (P = 0.001 and 0.01, respectively).

Conclusions

In most patients with tuberculosis, immune function is impaired. The absolute counts of peripheral blood lymphocyte subsets are closely related to the aetiological results and lesion severity in patients with PTB; this could be used as evidence for immune intervention and monitoring curative effects.

Decreased classical monocytes and CD163 expression in TB patients: an indicator of drug resistance

Tuberculosis (TB) is a disease instigated by Mycobacterium tuberculosis. Peripheral blood monocytes represent highly efficient effector cells of innate immunity against TB. Little is known about monocyte subsets and their potential involvement in the development of M. tuberculosis drug resistance in patients with TB. This study was conducted to investigate alterations in monocyte subsets, CD163 expression on monocytes, and its serum level in patients without and with rifampicin resistance TB (RR-TB) and healthy controls. A total of 164 patients with TB (84 without RR-TB and 80 patients with RR-TB) and 85 healthy controls were enrolled in this study. The percentages of various monocyte subsets and surface expression of CD163 on monocytes were quantitatively determined using flow cytometry. The serum level of CD163 was determined by commercially available ELISA kits. Decreased frequency of classical monocytes was detected in patients with RR-TB. Non-classical monocytes were decreased in patients without RR-TB; however, intermediate monocytes were raised in patients with RR-TB. The serum level of CD163 was decreased in patients of RR-TB that showsed a positive correlation with the frequency of CD14++CD16-CD163+ and CD14++CD16+CD163+ monocytes. It is concluded that decreased classical monocytes and sCD163 in patients with RR-TB could be an indicator of drug resistance.

Precision medicine in the clinical management of respiratory tract infections including multidrug-resistant tuberculosis: learning from innovations in immuno-oncology

PURPOSE OF REVIEW

In the light of poor management outcomes of antibiotic-resistant respiratory tract infection (RTI)-associated sepsis syndrome and multidrug-resistant tuberculosis (MDR-TB), new management interventions based on host-directed therapies (HDTs) are warranted to improve morbidity, mortality and long-term functional outcomes. We review developments in potential HDTs based on precision cancer therapy concepts applicable to RTIs including MDR-TB.

RECENT FINDINGS

Immune reactivity, tissue destruction and repair processes identified during studies of cancer immunotherapy share common pathogenetic mechanisms with RTI-associated sepsis syndrome and MDR-TB. T-cell receptors (TCRs) and chimeric antigen receptors targeting pathogen-specific or host-derived mutated molecules (major histocompatibility class-dependent/ major histocompatibility class-independent) can be engineered for recognition by TCR γδ and natural killer (NK) cells. T-cell subsets and, more recently, NK cells are shown to be host-protective. These cells can also be activated by immune checkpoint inhibitor (ICI) or derived from allogeneic sources and serve as potential for improving clinical outcomes in RTIs and MDR-TB.

SUMMARY

Recent developments of immunotherapy in cancer reveal common pathways in immune reactivity, tissue destruction and repair. RTIs-related sepsis syndrome exhibits mixed immune reactions, making cytokine or ICI therapy guided by robust biomarker analyses, viable treatment options.

Platelet-monocyte interaction in Mycobacterium tuberculosis infection

The immune effects of platelets and platelet-leukocyte aggregation are increasingly recognized. We studied the occurrence of platelet-monocyte aggregation (PMA) in patients with pulmonary tuberculosis (TB), the processes underlying PMA and consequences for cytokine responses. In a cross-sectional study involving 65 Tanzanian TB patients in different phases of treatment and 29 healthy controls, TB patients had a significantly higher PMA. This increased PMA in TB patients was associated with increased monocyte CCR5, CD16 expression and PF4, but not with increased membrane-expressed or soluble P-selectin expression. These findings were confirmed in vitro: whereas incubation of whole blood with Mycobacterium tuberculosis (Mtb) did not activate platelets, monocytes became activated with higher CD11b, CD16 and CCR5 expression, but this was independent of platelet-monocyte interaction. Still, platelets had an anti-inflammatory effect on cytokine responses as peripheral blood mononuclear cells (PBMC) incubated with Mtb in the presence of platelets produced less interleukin (IL)-1β, tumor necrosis factor-α, IL-6 and interferon-γ and more IL-10. In conclusion, increased PMA during TB infection is caused by monocyte and not platelet activation. By counteracting the Mtb-induced pro-inflammatory leukocyte response, platelets may protect against excessive tissue damage, but may also compromise the production of protective cytokines, such as IFNƴ and TNFα.