Evaluation of CD4+ CD25+ FoxP3+ Regulatory T cells and FoxP3 and CTLA-4 gene Expression in Patients wwith Newly Diagnosed Tuberculosis in Northeast of Iran

Raised circulatory T regulatory cells in paediatric tuberculosis - An environment for bacterial persistence?

OBJECTIVES

T-regulatory cells (Tregs) restrain the Th1-mediated immune response and thus may help in persistence and dissemination of childhood Tuberculosis. This study compared the percentage of Tregs in peripheral blood of paediatric TB patients (severe and non severe) with healthy individuals by flow cytometry.

METHODS

Study enrolled 40 subjects, less than 12 years along with 20 age matched healthy controls. Cases were further classified as severe TB and non severe TB. Haematological work-up and flow-cytometry for Tregs was done. Tregs were quantified as CD4CD25 high and CD4FoxP3 cells and compared in different groups using the Mann-Whitney U test.

RESULTS

In cases, CD4CD25 high Tregs (%) ranged from 0.55 to 12.8 with a Mean ± SD of 3.61 ± 2.98 and CD4FoxP3 Tregs (%) ranged from 0.02 to 13.44 with a Mean ± SD of 3.56 ± 2.76. In controls, CD4CD25 high Tregs (%) ranged from 0.3 to 6.5 with a Mean ± SD of 1.29 ± 1.4 and CD4FoxP3 Tregs (%) ranged from 0.33 to 2.59 with a Mean ± SD of 1.57 ± 0.58. Thus the percentage of both CD4CD25 high and CD4FoxP3 Tregs were significantly higher in cases as compared to controls (p value, 0.001 and 0.001 respectively), however the difference was not significant between severe versus non-severe TB (p value, 0.827 and 0.880 respectively).

CONCLUSION

Children with TB (both pulmonary and extra-pulmonary) demonstrate increased number of T regulatory cells as compared to healthy controls. However, the number of Tregs are not significantly different between cases with severe versus non severe TB.

SMAD4 Suppresses Colitis-associated Carcinoma Through Inhibition of CCL20/CCR6-mediated Inflammation

BACKGROUND & AIMS

We previously reported that colon epithelial cell silencing of Smad4 increased epithelial expression of inflammatory genes, including the chemokine c-c motif chemokine ligand 20 (CCL20), and increased susceptibility to colitis-associated cancer. Here, we examine the role of the chemokine/receptor pair CCL20/c-c motif chemokine receptor 6 (CCR6) in mediating colitis-associated colon carcinogenesis induced by SMAD4 loss.

METHODS

In silico analysis of SMAD4, CCL20, and CCR6 messenger RNA expression was performed on published transcriptomic data from human ulcerative colitis (UC), and colon and rectal cancer samples. Immunohistochemistry for CCL20 and CCR6 was performed on human tissue microarrays comprising human UC-associated cancer specimens, Mice with conditional, epithelial-specific Smad4 loss with and without germline deletion of the Ccr6 gene were subjected to colitis and followed for up to 3 months. Tumors were quantified histologically, and immune cell populations were analyzed by flow cytometry and immunostaining.

RESULTS

In human UC-associated cancers, loss of epithelial SMAD4 was associated with increased CCL20 expression and CCR6+ cells. SMAD4 loss in mouse colon epithelium led to enlarged gut-associated lymphoid tissues and recruitment of immune cells to the mouse colon epithelium and stroma, particularly T regulatory, Th17, and dendritic cells. Loss of CCR6 abrogated these immune responses and significantly reduced the incidence of colitis-associated tumors observed with loss of SMAD4 alone.

CONCLUSIONS

Regulation of mucosal inflammation is central to SMAD4 tumor suppressor function in the colon. A key downstream node in this regulation is suppression of epithelial CCL20 signaling to CCR6 in immune cells. Loss of SMAD4 in the colon epithelium increases CCL20 expression and chemoattraction of CCR6+ immune cells, contributing to greater susceptibility to colon cancer.

Emerging patterns of regulatory T cell function in tuberculosis

Tuberculosis (TB) is one of the top 10 causes of mortality worldwide from a single infectious agent and has significant implications for global health. A major hurdle in the development of effective TB vaccines and therapies is the absence of defined immune‐correlates of protection. In this context, the role of regulatory T cells (T_reg), which are essential for maintaining immune homeostasis, is even less understood. This review aims to address this knowledge gap by providing an overview of the emerging patterns of T_reg function in TB. Increasing evidence from studies, both in animal models of infection and TB patients, points to the fact the role of T_regs in TB is dependent on disease stage. While T_regs might expand and delay the appearance of protective responses in the early stages of infection, their role in the chronic phase perhaps is to counter‐regulate excessive inflammation. New data highlight that this important homeostatic role of T_regs in the chronic phase of TB may be compromised by the expansion of activated human leucocyte antigen D‐related (HLA‐DR)⁺CD4⁺ suppression‐resistant effector T cells. This review provides a comprehensive and critical analysis of the key features of T_reg cells in TB; highlights the importance of a balanced immune response as being important in TB and discusses the importance of probing not just T_reg frequency but also qualitative aspects of T_reg function as part of a comprehensive search for novel TB treatments.

Circulating HLA-DR+CD4+ effector memory T cells resistant to CCR5 and PD-L1 mediated suppression compromise regulatory T cell function in tuberculosis

Chronic T cell activation is a hallmark of pulmonary tuberculosis (PTB). The mechanisms underpinning this important phenomenon are however, poorly elucidated, though known to rely on control of T effector cells (Teff) by regulatory T cells (Treg). Our studies show that circulating natural Treg cells in adults with PTB preserve their suppressive potential but Teff cells from such subjects are resistant to Treg-mediated suppression. We found this to be due to expansion of an activated Teff subset identified by Human Leukocyte Antigen (HLA)-DR expression. Sensitivity to suppression was restored to control levels by depletion of this subset. Comparative transcriptome analysis of Teff cells that contain HLA-DR⁺ cells versus the fraction depleted of this population identified putative resistance mechanisms linked to IFNG, IL17A, IL22, PD-L1 and β-chemokines CCL3L3, CCL4 expression. Antibody blocking experiments confirmed HLA-DR⁺ Teff cells, but not the fraction depleted of HLA-DR⁺ effectors, to be resistant to Treg suppression mediated via CCR5 and PD-L1 associated pathways. In the presence of HLA-DR⁺ Teff cells, activation of NFκB downstream of CCR5 and PD-L1 was perturbed. In addition, HLA-DR⁺ Teff cells expressed significantly higher levels of Th1/Th17 cytokines that may regulate Treg function through a reciprocal counter-balancing relationship. Taken together, our study provides novel insight on how activated HLA-DR⁺CD4⁺ T cells may contribute to disease associated inflammation by compromising Treg-mediated suppression in PTB.

An important marker of progression to PTB following Mycobacterium tuberculosis (Mtb) infection in humans is elevated frequencies of HLA-DR⁺CD4⁺ T cells, reflecting chronic T cell activation. However, the mechanisms by which activated HLA-DR⁺CD4⁺ T cells contribute to disease process is not known. We show that CD25^- HLA-DR⁺CD4⁺ memory Teff from PTB patients are resistant to suppression mediated by Treg cells. An unbiased transcriptome analysis identified several key pathways that contribute to this resistance. Specifically, presence of HLA-DR⁺CD4⁺ T cells renders the effector population resistant to CCR5 and PD-L1 mediated suppression by Treg cells. In addition, the HLA-DR⁺CD4⁺ memory Teff cells express elevated levels of Th1/Th17 cytokines known to counter-regulate and dampen Treg suppression. These findings provide fresh insight to disease process in TB and identify HLA-DR⁺ Teff resistant to Treg suppression as a potential functional marker of disease.

Assay of Peripheral Regulatory Vδ1 T Cells in Ankylosing Spondylitis and its Significance

BACKGROUND Ankylosing spondylitis (AS) involves inflammation at the sacroiliac joint and spine attachment site. This study aimed to observe the ratio and function of peripheral regulatory Vδ1 T cells in AS patients to investigate their roles in AS pathogenesis. MATERIAL AND METHODS Peripheral blood mononuclear cells (PBMC) were separated by density-gradient centrifugation from AS patients and healthy controls. Flow cytometry was used to determine the ratio between Vδ1 and CD4 T cells of PBMC in AS patients and controls. Flow cytometry sorting (FCS) was used to obtain Vδ1 and naïve CD4 T cells with purity higher than 90%. CFSE staining method was used to detect the effect of Vδ1 T cells on proliferation of naïve CD4 T cells. The effect of Vδ1 T cells on secretion of IFN-γ from naïve CD4 T cells and the ability to secrete IL-10 from Vδ1 T cells were determined by flow cytometry. RESULTS AS patients had significantly lower Vδ1 T cell ratio in PBMC compared to controls (p<0.05), but their CD4 T cell ratio was significantly elevated (p<0.05). Functional assay showed suppression of naïve CD4 T cell proliferation and IFN-γ secretion by peripheral Vδ1 T cells in AS patients (p<0.01). AS patients also had lower IL-10 secreting level from peripheral derived Vδ1 T cells (p<0.01). CONCLUSIONS The immune suppression of peripheral Vδ1 T cell in AS patient increases the ratio of peripheral CD4 T cells and IFN-γ level, leading to AS pathogenesis. This immune suppression is mainly due to suppressed IL-10 secretion.

Evaluation of Interleukin17and Interleukin 23 expression in patients with active and latent tuberculosis infection

OBJECTIVES

Tuberculosis is one of the most important infectious diseases with high mortality rates worldwide, especially in developing countries. Interleukin17 (IL-17) is an important acquired immunity cytokine, which is mainly produced by CD4+TH17 cells. It can recruit neutrophils and macrophages to the infected site in the lungs. IL-23 is one of the most important inducers of IL-17. In the present study, the expressions of IL-23 and IL-17 were examined in the pathogenesis of tuberculosis.

MATERIALS AND METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from subjects with latent tuberculosis infection (LTB) and newly diagnosed active tuberculosis patients (ATB). PBMCs were activated with purified protein derivative (PPD) for 72 hr. Activated cells were harvested, RNA was extracted, and cDNA was synthesized. IL-17 and IL-23 mRNA expressions were evaluated by real-time PCR. The frequency of Th17 cells was examined by flowcytometry.

RESULTS

The expressions of IL-17 and IL-23 mRNA were lower in patients than subjects with LTB (P<0.05). The frequency of IL-17 producing CD4+ T cells in patients with active TB was lower than LTB subjects (P<0.05).

CONCLUSION

The results of the present study might suggest that IL-17 and IL-23 play critical roles in the immune response against TB.