Treg Cell Population Research Articles

Measuring CTLA-4-Dependent Suppressive Function in Regulatory T Cells.

Regulatory T cells (Treg) have a central role in controlling the activation of self-reactive T cells and maintaining peripheral tolerance in our body. Many effector mechanisms for Treg function have been described including a role for the protein CTLA-4 which is constitutively expressed by these cells. Despite its importance, there is currently little consensus in the methods and protocols for studying CTLA-4 function, which is partially due to debate over CTLA-4 function itself. In this chapter, we outline protocols used in our lab to study CTLA-4 function, which have been generated based on the observation that CTLA-4 acts to physically remove and degrade its ligands expressed by antigen presenting cells. Accordingly, we provide protocols for isolation of human monocytes and their differentiation into dendritic cells (DC), purification of conventional and regulatory T-cell populations, and the assembly of CTLA-4-dependent Treg suppression assays. We hope that this will offer a reliable platform for dissecting the biology of CTLA-4 on Treg and for testing reagents aimed at modulating CTLA-4 function. Such assays are increasingly vital for the study of immune function in both healthy individuals and patients with a variety of autoimmune and immune dysregulation syndromes.

Nicotine, as a novel tolerogenic adjuvant, enhances the efficacy of immunotherapy in a mouse model of allergic asthma

An increasing trend in the incidence of allergic diseases including asthma and related morbidity and mortality is observed worldwide during the last decades. Allergen-specific immunotherapy is suggested for the treatment of some allergic diseases; nevertheless, there is always a menace of uncommon, but life-treating reactions due to increasing the administration of allergen extract doses. Hence, improving its efficacy may reduce the required doses as well as the risk of such reactions. The current study aimed at examining the effects of nicotine (NIC), as a tolerogenic adjuvant, on the improvement of immunotherapy efficacy in a mouse model of allergic asthma. BALB/c mice were sensitized using alum and ovalbumin (OVA) on the days 0 and 7. Mice received OVA either alone or together with NIC (1 or 10 mg/kg) on the days 21, 23, and 25. Then, the mice were challenged with OVA 5% using a nebulizer on the days 35, 38, and 41 and sacrificed the next day. Co-administration of OVA and NIC decreased the inflammation of the lung tissue, eosinophils count in the bronchoalveolar lavage (BAL) fluid, the serum level of OVA-specific immunoglobulin E, as well as interleukin (IL)-4 production, while increasing the population of antigen-specific regulatory T-cells (Treg cells) and transforming growth factor-β/IL-4 (TGF-β/IL-4) ratio compared to the OVA and control groups in a dose-dependent manner. Collectively, the findings suggest that administration of NIC plus the allergen increased immunotherapy efficacy through decreasing allergic inflammation and allergic responses intensity, and increasing Treg cells population.

Helios but not CD226, TIGIT and Foxp3 is a Potential Marker for CD4+ Treg Cells in Patients with Rheumatoid Arthritis.

Background/Aims:Rheumatoid arthritis (RA) is a progressive, chronic, even disabling systemic autoimmune disease. Imbalance between pathogenic immune cells and immunosuppressive cells is associated with the pathogenesis and development of RA and other autoimmune diseases. As Foxp3 is also expressed on activated CD4+ cells in the presence of inflammation, the identification of Treg cells in patients with RA remains a challenge.Methods:Comprehensive analyses were carried out by Flow cytometry. Expression of Helios, CD226, T cell immunoreceptor with Ig and ITIM domains clinical samples and healthy controls.Results:We have systemically examined three potential markers, Helios, CD226 and TIGIT, that are possibly related to Treg identification, and found that Helios expression on CD4+Foxp3+ cells was decreased and negatively correlated with the disease activity of RA patients, while CD226 and TIGIT both showed elevated expression levels in CD4+Foxp3+ cells in RA patients and they were not associated with disease activity of RA patients.Conclusion:Taken together, our findings indicate that CD4+CD25hiCD127low/-Foxp3+Helios+ may represent the real Treg cell population in patients with RA.

CD150high CD4 T cells and CD150high regulatory T cells regulate hematopoietic stem cell quiescence via CD73.

Various extrinsic signals tightly control hematopoietic stem cell quiescence. Our recent study showed that hematopoietic stem cells are regulated by a special FoxP3+ regulatory T-cell population with high expression of a hematopoietic stem cell marker, CD150. Extracellular adenosine generated via a cell-surface ectoenzyme CD39 on CD150high regulatory T cells maintained hematopoietic stem cell quiescence. It remains unclear how conventional T cells and the other cell-surface ectoenzyme, CD73, contribute to regulation of hematopoietic stem cells. This work shows that CD150high regulatory T cells as well as unique CD150high CD4+ conventional T cells regulate hematopoietic stem cells via CD73. Global CD73 deletion increased the numbers of hematopoietic stem cells, cycling stem cell frequencies, and levels of reactive oxygen species in hematopoietic stem cells. In vivo antioxidant treatment inhibited the increase of hematopoietic stem cells in CD73 knockout mice, suggesting that CD73 maintains stem cell quiescence by preventing oxidative stress. High levels of CD73 expression were frequently found on CD150high regulatory T cells and CD150high FoxP3−CD4+ T cells within the bone marrow. Transfer of these CD150high regulatory T cells and CD150high CD4+ conventional T cells abolished the increase of hematopoietic stem cells in CD73 knockout mice. In addition, the increase of stem cells in CD73 knockout mice was also inhibited by pharmacological activation of adenosine receptor 2A which is highly expressed by hematopoietic stem cells. Taken together, these results suggest that CD73 of CD150high regulatory T cells and CD150high CD4+ conventional T cells protects hematopoietic stem cells from oxidative stress, maintaining stem cell quiescence via adenosine receptor 2A.

Combination peptide immunotherapy suppresses antibody and helper T-cell responses to the major human platelet autoantigen glycoprotein IIb/IIIa in HLA-transgenic mice.

Platelet destruction in immune thrombocytopenia is caused by autoreactive antibody and T-cell responses, most commonly directed against platelet glycoprotein IIb/IIIa. Loss of self-tolerance in the disease is also associated with deficient activity of regulatory T cells. Having previously mapped seven major epitopes on platelet glycoprotein IIIa that are recognized by helper T cells from patients with immune thrombocytopenia, the aim was to test whether peptide therapy with any of these sequences, alone or in combination, could inhibit responses to the antigen in humanized mice expressing HLA-DR15. None of the individual peptides, delivered by a putative tolerogenic regimen, consistently suppressed the antibody response to subsequent immunization with human platelet glycoprotein IIb/IIIa. However, the combination of glycoprotein IIIa peptides aa6-20 and aa711-725, which contain the predominant helper epitopes in patients and elicited the strongest trends to suppress when used individually, did abrogate this response. The peptide combination also blunted, but did not reverse, the ongoing antibody response when given after immunization. Suppression of antibody was associated with reduced splenocyte T-cell responsiveness to the antigen, and with the induction of a regulatory T-cell population that is more responsive to the peptides than to purified platelet glycoprotein IIb/IIIa. Overall, these data demonstrate that combinations of peptides containing helper epitopes, such as platelet glycoprotein IIIa aa6-20 and aa711-725, can promote in vivo suppression of responses to the major antigen implicated in immune thrombocytopenia. The approach offers a promising therapeutic option to boost T-cell regulation, which should be taken forward to clinical trials.

Recombinant adiponectin alleviates abortion in mice by regulating Th17/Treg imbalance via p38MAPK-STAT5 pathway

Recurrent spontaneous abortion is associated with abnormal maternal tolerance to the semi-allogenic fetus, wherein the Th17/Treg axis plays a crucial role. Adiponectin (APN) is an adipocytokine that is shown to be a novel negative T-cell regulator and induce immune tolerance. The CBA/J×DBA/2 mating was used as an abortion-prone model to investigate whether the addition of recombinant adiponectin (rAPN) improves the pregnancy outcome. Recombinant adiponectin therapy reduced the abortion rate in abortion-prone model. It skewed the ability of serum cytokine production toward a Treg bias and induced APN production. Flow cytometry revealed that rAPN administration expanded the splenic CD4+CD25+ regulatory T-cell (Treg) population and reduced the Th17 cell populations in CBA/J×DBA/2 matings. RT-PCR revealed that rAPN administration induced the expression of AdipoR1 and AdipoR2 mRNA at the maternofetal interface. Recombinant adiponectin administration induced FoxP3 and reduced RORγt expressions at the maternofetal interface. In vitro experiment also showed that rAPN treatment enhanced the FoxP3 mRNA and protein expression and decreased the RORγt expression in splenic lymphocytes of abortion-prone mice. Blocking the different signal transduction pathways downstream of APN, p38MAPK inhibitor (SB203580) and STAT5 inhibitor (Pimozide) could abrogate the regulatory effect of rAPN on FoxP3 and RORγt expression, while STAT3 inhibitor (Stattic) and AMPK inhibitor (p5499) did not exert any influence. Thus, the current results demonstrated that rAPN therapy improves pregnancy outcome in a murine model of abortion by expanding the Treg cell population and function and decreasing the Th17 cell population and function via a p38MAPK-STAT5 pathway.

B-cell and T-cell activation in South African HIV-1-positive non-Hodgkin's lymphoma patients.

BackgroundAltered immune mechanisms play a critical role in the pathogenesis of non-Hodgkin’s lymphoma (NHL). HIV-1 (HIV) infection is associated with a state of excessive T-cell activation, which can lead to increased T-cell turnover and lymph node fibrosis.ObjectivesThis study aimed to determine the serum levels of circulating B-cell activation markers, and the expression of T-cell activation and regulatory markers in HIV-positive NHL patients.MethodThe serum levels of circulating soluble(s) sCD20, sCD23, sCD27, sCD30 and sCD44 molecules, all of which are biomarkers of B-cell activation, were determined by enzyme-linked immunosorbent assays (ELISA), while biomarkers of T-cell activation (CD8+CD38+) and regulation (FoxP3) were determined by flow cytometry in 141 subjects who were divided into five groups: Combination antiretroviral therapy (ART)-naïve HIV-positive patients; ART-treated HIV-positive patients; HIV-negative NHL patients; HIV-positive NHL patients on ART; and healthy controls.ResultsHIV-positive NHL patients had significantly higher serum levels of sCD20, sCD23, sCD30 and sCD44 than HIV-negative NHL patients, while all five biomarkers were significantly elevated in HIV-positive NHL patients when compared with ART-treated HIV-positive patients. HIV-positive NHL patients had higher CD8+CD38+ and lower FoxP3 expression than HIV-negative NHL and ART-treated HIV-positive patients.ConclusionB-cell activation is increased in HIV-positive NHL patients and is associated with reduced regulatory T-cell populations and increased CD8+ T-cell activation.

Human retinoic acid-regulated CD161+ regulatory T cells support wound repair in intestinal mucosa.

Repair of tissue damaged during inflammatory processes is key to the return of local homeostasis and restoration of epithelial integrity. Here we describe CD161+ regulatory T (Treg) cells as a distinct, highly suppressive population of Treg cells that mediate wound healing. These Treg cells were enriched in intestinal lamina propria, particularly in Crohn's disease. CD161+ Treg cells had an all-trans retinoic acid (ATRA)-regulated gene signature, and CD161 expression on Treg cells was induced by ATRA, which directly regulated the CD161 gene. CD161 was co-stimulatory, and ligation with the T cell antigen receptor induced cytokines that accelerated the wound healing of intestinal epithelial cells. We identified a transcription-factor network, including BACH2, RORγt, FOSL2, AP-1 and RUNX1, that controlled expression of the wound-healing program, and found a CD161+ Treg cell signature in Crohn's disease mucosa associated with reduced inflammation. These findings identify CD161+ Treg cells as a population involved in controlling the balance between inflammation and epithelial barrier healing in the gut.

Limited Foxp3+ Regulatory T Cells Response During Acute Trypanosoma cruzi Infection Is Required to Allow the Emergence of Robust Parasite-Specific CD8+ T Cell Immunity.

While it is now acknowledged that CD4+ T cells expressing CD25 and Foxp3 (Treg cells) regulate immune responses and, consequently, influence the pathogenesis of infectious diseases, the regulatory response mediated by Treg cells upon infection by Trypanosoma cruzi was still poorly characterized. In order to understand the role of Treg cells during infection by this protozoan parasite, we determined in time and space the magnitude of the regulatory response and the phenotypic, functional and transcriptional features of the Treg cell population in infected mice. Contrary to the accumulation of Treg cells reported in most chronic infections in mice and humans, experimental T. cruzi infection was characterized by sustained numbers but decreased relative frequency of Treg cells. The reduction in Treg cell frequency resulted from a massive accumulation of effector immune cells, and inversely correlated with the magnitude of the effector immune response as well as with emergence of acute immunopathology. In order to understand the causes underlying the marked reduction in Treg cell frequency, we evaluated the dynamics of the Treg cell population and found a low proliferation rate and limited accrual of peripheral Treg cells during infection. We also observed that Treg cells became activated and acquired a phenotypic and transcriptional profile consistent with suppression of type 1 inflammatory responses. To assess the biological relevance of the relative reduction in Treg cells frequency observed during T. cruzi infection, we transferred in vitro differentiated Treg cells at early moments, when the deregulation of the ratio between regulatory and conventional T cells becomes significant. Intravenous injection of Treg cells dampened parasite-specific CD8+ T cell immunity and affected parasite control in blood and tissues. Altogether, our results show that limited Treg cell response during the acute phase of T. cruzi infection enables the emergence of protective anti-parasite CD8+ T cell immunity and critically influences host resistance.

Age Correlates with Response to Anti-PD1, Reflecting Age-Related Differences in Intratumoral Effector and Regulatory T-Cell Populations.

Purpose: We have shown that the aged microenvironment increases melanoma metastasis, and decreases response to targeted therapy, and here we queried response to anti-PD1.Experimental Design: We analyzed the relationship between age, response to anti-PD1, and prior therapy in 538 patients. We used mouse models of melanoma, to analyze the intratumoral immune microenvironment in young versus aged mice and confirmed our findings in human melanoma biopsies.Results: Patients over the age of 60 responded more efficiently to anti-PD-1, and likelihood of response to anti-PD-1 increased with age, even when we controlled for prior MAPKi therapy. Placing genetically identical tumors in aged mice (52 weeks) significantly increased their response to anti-PD1 as compared with the same tumors in young mice (8 weeks). These data suggest that this increased response in aged patients occurs even in the absence of a more complex mutational landscape. Next, we found that young mice had a significantly higher population of regulatory T cells (Tregs), skewing the CD8+:Treg ratio. FOXP3 staining of human melanoma biopsies revealed similar increases in Tregs in young patients. Depletion of Tregs using anti-CD25 increased the response to anti-PD1 in young mice.Conclusions: While there are obvious limitations to our study, including our inability to conduct a meta-analysis due to a lack of available data, and our inability to control for mutational burden, there is a remarkable consistency in these data from over 500 patients across 8 different institutes worldwide. These results stress the importance of considering age as a factor for immunotherapy response. Clin Cancer Res; 24(21); 5347-56. ©2018 AACR See related commentary by Pawelec, p. 5193.

The number of FoxP3 regulatory T cells in the circulation may be a predictive biomarker for kidney transplant recipients: A multistage systematic review

BackgroundThe kinetics of the FoxP3 regulatory T-cell (Treg) population in kidney transplant recipients (KTR) are related to the clinical effect of immunosuppression based on mammalian Target Of Rapamycin inhibitors (mTORi) with/without belatacept (predictive biomarker). MethodsA multistage systematic review of published and unpublished literature is presented [registration IDs in the International Prospective Register of Systematic Reviews (PROSPERO): CRD42017057570, CRD42018085019, CRD42018084941, CRD42018085186]. A multidisciplinary supervision mechanism for contextualizing of search findings was required. The peripheral blood immune cell phenotypes encompassing all regulatory cells in KTRs were assessed in order to suggest new markers of acute rejection-associated acute allograft dysfunction (AR/AAD) events in KTRs treated with mTORi alone or combined to belatacept. Quantitative estimates and evaluation of the body of evidence are provided. ResultsAn increase in Tregs and other regulatory cell types in the circulation in KTRs under mTORi with/without belatacept were observed. Patients with increased Tregs presented a low frequency of AR/AAD events compared to those in which the number of Tregs remained unchanged or even diminished [Odds Ratio (OR)/95% confidence interval (95% CI)/I2/number of studies (n): 0.31/0.10–0.93/0%/6]. Nevertheless, there are too few trials to consider Tregs in the circulation as a predictive biomarker. Inadequate reporting prevents appreciating clinical relevance in such studies. ConclusionsDespite advances, clinical qualification of potential predictive biomarkers continues to be difficult. Clinical evidence on Tregs in KTRs needs to be enlarged. Biomarkers should be able to evaluate the effect of medicines targeted to specific patient populations.

The Foxp3+ regulatory T-cell population requires IL-4Rα signaling to control inflammation during helminth infections.

Forkhead box P3 (Foxp3+) regulatory T (Treg)-cell function is controlled by environmental cues of which cytokine-mediated signaling is a dominant component. In vivo, interleukin-4 (IL-4)-mediated signaling via IL-4 receptor alpha (IL-4Rα) mediates Treg cell transdifferentiation into ex-Foxp3 T helper 2 (Th2) or T helper 17 (Th17) cells. However, IL-4-mediated signaling also reinforces the Foxp3 Treg compartment in vitro. We generated Foxp3-specific IL-4Rα-deficient mice and demonstrated differential efficiency of IL-4Rα deletion in male (approximately 90%) and female (approximately 40%) animals, because of cyclic recombinase (Cre)-mediated X-linked foxp3 inactivation. Irrespective of the degree of IL-4Rα deletion within the Foxp3+ Treg cell population, mice showed exacerbation of immune effector responses with aggravated tissue pathology in tissue-dwelling helminth infections (Schistosoma mansoni or Nippostrongylus brasiliensis). Mechanistically, IL-4Rα deletion in males and females led to a reduced expression of Foxp3 and subsequently an impaired accumulation of Foxp3+ Treg cells to inflamed tissues. In-depth cellular typing by flow cytometry revealed that the impairment of IL-4Rα-mediated signaling during helminth infections decreased the ability of central Treg cells to convert into effector Treg (eTreg) cells and caused a significant down-regulation of markers associated with Treg cell migration (C-X-C motif chemokine receptor 3 [CXCR3]) and accumulation in inflamed tissues (GATA binding protein 3 [GATA3]) as well as survival (B cell lymphoma 2 [Bcl-2]). These findings unprecedentedly, to our knowledge, uncover a role for IL-4Rα signaling in the positive regulation of Foxp3+ Treg cell function in vivo. Complementing our past knowledge on a widely reported role for IL-4Rα signaling in the negative regulation and transdifferentiation of Foxp3+ Treg cells in vivo, our present findings reveal the host requirement for an intact, but not reduced or potentiated, IL-4Rα-mediated signaling on Foxp3+ Treg cells to optimally control inflammation during helminth infections.

Frequency of Circulating CD4+Ki67+HLA-DR- T Regulatory Cells Prior to Treatment for Multidrug Resistant Tuberculosis Can Differentiate the Severity of Disease and Predict Time to Culture Conversion.

Identifying a blood circulating cellular biomarker that can be used to assess severity of disease and predict the time to culture conversion (TCC) in patients with multidrug resistant tuberculosis (MDR-TB) would facilitate monitoring response to treatment and may be of value in the design of future drug trials. We report on the frequency of blood Ki67+HLA-DR− CD4+ T regulatory (Treg) cells in predicting microbiological outcome before initiating second-line treatment for MDR-TB. Fifty-one patients with MDR-TB were enrolled and followed over 18 months; a subset of patients was sputum culture (SC) negative at baseline (n = 9). SC positive patients were divided into two groups, based on median TCC: rapid responders (≤71 days TCC; n = 21) and slow responders (>71 days TCC; n = 21). Whole blood at baseline, months 2 and 6 was stimulated with M tuberculosis (Mtb) antigens and Treg cells were then identified as CD3+CD4+CD25hiFoxP3+CD127−CD69− and further delineated as Ki67+HLA-DR− Treg. The frequency of these cells was significantly enlarged at baseline in SC positive relative to SC negative and smear positive relative to smear negative patients and in those with lung cavitation. This difference was further supported by unsupervised hierarchical clustering showing a significant grouping at baseline of total and early differentiated memory Treg cells in slow responders. Conversely, there was a clustering of a lower proportion of Treg cells and activated IFNγ-expressing T cells at baseline in the rapid responders. Examining changes over time revealed a more gradual reduction of Treg cells in slow responders relative to rapid responders to treatment. Receiver operating curve analysis showed that baseline Mtb-stimulated Ki67+HLA-DR− Treg cells could predict the TCC of MDR-TB treatment response with 81.2% sensitivity and 85% specificity (AUC of 0.87, p < 0.0001), but this was not the case after 2 months of treatment. In conclusion, our data show that the frequency of a highly defined Mtb-stimulated blood Treg cell population at baseline can discriminate MDR-TB disease severity and predict time to culture clearance.

Intravenous immunoglobulin G treatment increases live birth rate in women with recurrent miscarriage and modulates regulatory and exhausted regulatory T cells frequency and function.

Exhausted T cells and regulatory T (Treg) cells have been recently proposed to be new risk factors for recurrent miscarriage (RM). Intravenous immunoglobulin G (IVIG) treatment reported to modulate various immune cells. In this study, the effects of IVIG on the frequency and function of exhausted T cells, exhausted Tregs, and Treg cells, as well as pregnancy outcome in women with unexplained RM (URM), were investigated. Ninety-four pregnant women with RM were enrolled. At the time of positive pregnancy, blood samples were drawn. Forty-four patients with URM were included as IVIG receiving treated group and received 400 mg/kg of IVIG and the rest fifty patients were considered as a control group and received no IVIG administration. IVIG was given intravenously every 4 weeks during 32 weeks of gestation. Blood samples of patients were collected afterthe latest administration. Exhausted T cells, exhausted Tregs, and Treg cells were evaluated pre- and posttreatment in both groups. IVIG induced a significant decrease in the frequency of exhausted Tregs population and function as well as a significant increase in Treg cells population, however, IVIG failed to affect population and the function of exhausted T cells. Pregnancy outcome was successful in IVIG treated women (86.3%) and were significantly different (P = 0.0006) in compared with the untreated URM subjects (42%). Therefore, employing of IVIG increases Treg cells and diminishes exhausted Tregs responses in RM patients with cellular immune anomalies throughout the pregnancy. Immunemodulatory effects of IVIG are probably associated with successful pregnancy outcome.

Maintained thymic output of conventional and regulatory T cells during human pregnancy

Maintained thymic output of conventional and regulatory T cells during human pregnancy

Effect of corticosteroid and vitamin D3 as combined therapy on 25 (OH) vitamin D serum level and regulatory T (TReg) cells population in children with idiopathic nephrotic syndrome

Background: Nephrotic syndrome (NS) is a chronic disease in children that correlates with T lymphocyte dysregulation (imbalance of regulatory T cells (TReg)/ T-helper 17 (Th17) cells ratio). Vitamin D3 serum level was known decreased in children with nephrotic syndrome. Low vitamin D3 serum level can affect the outcome of nephrotic syndrome management with corticosteroid therapy. This study was aimed to investigate the effect of vitamin D as adjuvant therapy to 25 (OH) Vitamin D serum level and TReg population in children with idiopathic nephrotic syndrome.Method: This study was designed as a randomized clinical trial, double-blind, pre and post-test control group which involved 30 subjects that newly diagnosed as NS. Subjects were divided into two groups, prednisone and vitamin D treated group and prednisone only treated group. TReg population in peripheral blood mononuclear cells (PBMC) was analyzed using flow cytometry. Vitamin D serum level was measured by ELISA method.Results: Results showed that there was a significant elevation of  TReg (independent t-test, p=0.001) and 25 (OH) vitamin D serum level (independent t-test, p=0.001) in prednisone and vitamin D treated group as compared to prednisone only treated group. Pearson testing first group showed that vitamin D level was positively correlated with TReg(p=0.332, r = 0.183). The number of early remissions was higher in group treated with steroid and vitamin D3 as a combined therapy compared to group treated with steroid only (50 % vs 20%). Whereas the number of late remission was higher in steroid only group (23% vs 6%).Conclusions: We concluded that corticosteroid and vitamin D3 as a combined therapy increase both of TRegand 25 (OH) vitamin D level which affect glucocorticoid therapy response in subjects.The number of early remission was higher in group treated with corticosteroid and vitamin D3 as a combined therapy.

REGULATION OF IMMUNE RESPONSE AGAINST MYCOBACTERIUM TUBERCULOSIS BY THE POPULATION OF REGULATORY DENDRITIC CELLS

On the background of a high level of genetic susceptibility to tuberculosis infection (TB), granulomatous reactions in the lung tissue fail to effectively isolate infection foci and rather result in diffuse pathology, confluence of granulomata and formation of necrotic zones. Uncontrolled inflammation severely affect breathing function of the lung. Thus, effective disease control requires a good balance between protective and pathogenic immune responses. Immature regulatory dendritic cells (DCreg) and regulatory T lymphocytes (Treg) represent a pool of important cellular regulators of inflammation. Earlier we have demonstrated that stromal lung cells support development of CD11b+CD11clowCD103– DCreg from their bone marrowderived precursors in in vitro cultures. In addition, significantly larger population size and more rapid development of the lung CD4+Foxp3+ Treg cells characterize TB- resistant B6 mice compare to their TB-susceptible I/St counterparts. Here, we report that adoptive transfer of DCreg cells into TB-infected I/St mice is capable to enlarge the population of Treg cells in the lungs. This, in turn, attenuates lung pathology, decreases mycobacterial multiplication and diminishes lung infiltration with neutrophils, i.e., selectively restricts the population of cell largely responsible for TB pathogenesis. The key difference in lung pathology between DCreg recipients and control animals was the lack of tissue-destructive foci and necrotic zones in the former group. Meanwhile, the groups of mice did not differ in production of regulatory (IL-10 and TGF-β) and key inflammatory (IFNγ and IL-6) cytokines by lung cells. The latter result suggests that contact rather than secretory mechanisms underlie moderate attenuation of the TB process in the lungs of mice with an elevated lung Treg level, given that plethora of such mechanisms were described for Treg functioning. Although therapeutic effects were relatively weak, our results indicate that cell therapy approaches are applicable to regulation of lung tissue inflammation during TB course.

Regulation, Communication, and Functional Roles of Adipose Tissue-Resident CD4+ T Cells in the Control of Metabolic Homeostasis.

Evidence accumulated over the past few years has documented a critical role for adipose tissue (AT)-resident immune cells in the regulation of local and systemic metabolic homeostasis. In the lean state, visceral adipose tissue (VAT) is predominated by anti-inflammatory T-helper 2 (Th2) and regulatory T (Treg) cell subsets. As obesity progresses, the population of Th2 and Treg cells decreases while that of the T-helper 1 (Th1) and T-helper 17 (Th17) cells increases, leading to augmented inflammation and insulin resistance. Notably, recent studies also suggest a potential role of CD4+ T cells in the control of thermogenesis and energy homeostasis. In this review, we have summarized recent advances in understanding the characteristics and functional roles of AT CD4+ T cell subsets during obesity and energy expenditure. We have also discussed new findings on the crosstalk between CD4+ T cells and local antigen-presenting cells (APCs) including adipocytes, macrophages, and dendritic cells (DCs) to regulate AT function and metabolic homeostasis. Finally, we have highlighted the therapeutic potential of targeting CD4+ T cells as an effective strategy for the treatment of obesity and its associated metabolic diseases.

Extending Remission and Reversing New-Onset Type 1 Diabetes by Targeted Ablation of Autoreactive T Cells.

Preserving endogenous insulin production is clinically advantageous and remains a vital unmet challenge in the treatment and reversal of type 1 diabetes. Although broad immunosuppression has had limited success in prolonging the so-called remission period, it comes at the cost of compromising beneficial immunity. Here, we used a novel strategy to specifically deplete the activated diabetogenic T cells that drive pathogenesis while preserving not only endogenous insulin production but also protective immunity. Effector T (Teff) cells, such as diabetogenic T cells, are naturally poised on the edge of apoptosis because of activation-induced DNA damage that stresses the p53 regulation of the cell cycle. We have found that using small molecular inhibitors that further potentiate p53 while inhibiting the G2/M cell cycle checkpoint control drives apoptosis of activated T cells in vivo. When delivered at the onset of disease, these inhibitors significantly reduce diabetogenic Teff cells, prolong remission, preserve functional islets, and protect islet allografts while leaving naive, memory, and regulatory T-cell populations functionally untouched. Thus, the targeted manipulation of p53 and cell cycle checkpoints represents a new therapeutic modality for the preservation of islet β-cells in new-onset type 1 diabetes or after islet transplant.

Immunomodulatory effects of mesenchymal stem cell-derived exosomes on experimental type-1 autoimmune diabetes.

Exosomes derived from adipose tissue-derived mesenchymal stem cells (AD-MSCs) have immunomodulatory effects of T-cell inflammatory response and reduction of clinical symptoms on streptozotocin-induced of the type-1 diabetes mellitus (T1DM). Beside control group and untreated T1DM mice, a group of T1DM mice was treated with intraperitoneal injections of characterized exosomes derived from autologous AD-MSCs. Body weight and blood glucose levels were measured during the procedure. Histopathology and immunohistochemistry were used for evaluation of pancreatic islets using hemotoxylin and eosin (H&E) staining and anti-insulin antibody. Isolated splenic mononuclear cells (MNCs) were subjected to splenocytes proliferation assay using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, immunophenotyping of regulatory T cells and cytokines. A significant increase in the levels of interleukin-4 (IL-4), IL-10, and transforming growth factor-β, and a decrease in the levels of IL-17 and interferon-γ in concordance with the significant increase in the Treg cell ratio in splenic MNCs (P < 0.05) was shown in T1DM mice treated with AD-MSC's exosomes as compared to T1DM untreated mice. This amelioration of autoimmune reaction after treatment of T1DM mice with the AD-MSC exosomes was confirmed with a significant increase in islets using H&E staining and Immunohistochemistry analyses. As expected, body weight, blood glucose levels in a survival of T1DM mice treated with AD-MSC's exosomes were maintained stable in comparison to untreated T1DM mice. It can be concluded that AD-MSC's exosomes exert ameliorative effects on autoimmune T1DM through increasing regulatory T-cell population and their products without a change in the proliferation index of lymphocytes, which makes them more effective and practical candidates.