Implication of regulatory T cells' telomere shortening in pathogenesis of generalized vitiligo

Generalized vitiligo(GV) is a skin depigmenting condition due to loss of melanocytes. Regulatory T cells(Tregs), responsible for peripheral tolerance, show altered numbers and functions in GV patients, likely influenced by the aging process. Therefore, the present study was focused on measuring the relative telomere length of Tregs in 96 GV patients and 90 controls by qPCR, along with correlation of relative telomere length with in vitro Treg suppressive capacity. Interestingly, we found significantly decreased relative telomere length in Tregs of GV patients as compared to controls(p = 0.0001). Additionally, age based-analysis suggested significant decrease in relative telomere length in elderly GV patients(>40 years) in comparison to young GV patients(0-20 years; p = 0.0027). Furthermore, age of onset analysis suggested for reduced relative telomere length in early onset GV patients (0-20 years) in comparison to late onset GV patients(>40 years; p = 0.0036). The correlation analysis suggested positive correlation for relative telomere length with in vitro Tregs suppressive capacity(r = 0.68 & r = 0.45; p < 0.0001). Additionally, the in vitro Tregs suppressive capacity was significantly reduced in elderly GV patients(p = 0.003) and early onset GV patients(p = 0.0074). Overall, our study for the first time demonstrated that, the Tregs ageing due to telomere shortening may be responsible for altered Treg functions and number.

Progranulin promotes regulatory T cells plasticity by mitochondrial metabolism through AMPK/PGC-1α pathway in ARDS

As the aging population increases, the focus on elderly patients with acute respiratory distress syndrome (ARDS) is also increasing. In this article, we found progranulin (PGRN) differential expression in ARDS patients and healthy controls, even in young and old ARDS patients. Its expression strongly correlates with several cytokines in both young and elderly ARDS patients. PGRN has comparable therapeutic effects in young and elderly mice with lipopolysaccharide-induced acute lung injury, manifesting as lung injury, apoptosis, inflammation, and regulatory T cells (Tregs) differentiation. Considering that Tregs differentiation relies on metabolic reprogramming, we discovered that Tregs differentiation was mediated by mitochondrial function, especially in the aged population. Furthermore, we demonstrated that PGRN alleviated the mitochondrial damage during Tregs differentiation through the AMPK/PGC-1α pathway in T cells. Collectively, PGRN may regulate mitochondria function to promote Tregs differentiation through the AMPK/PGC-1α pathway to improve ARDS.

Altered regulatory T cell-mediated Natural Killer cells suppression may lead to generalized vitiligo

Generalized vitiligo (GV) is characterized by white patches due to autoimmune loss of melanocytes. Regulatory T cells (Tregs) maintain immune homeostasis, while NK cells eliminate pathogens and tumors. Increased NK cell frequency and reduced Treg frequency and suppressive capacity are observed in vitiligo patients. However, studies assessing Treg-mediated suppression of NK cell functions in GV are lacking. Therefore, our study aimed to assess in vitro Treg-mediated suppression of NK cells function over K562 and SK-Mel-28 cells in 31 GV patients and 30 controls using the BrdU-cell proliferation assay. We found decreased Treg-mediated suppression of NK cell function in GV patients (p = 0.0289). Moreover, increased NK cell-mediated K562 and SK-Mel-28 cells' suppression was observed in GV patients (p = 0.0207,p = 0.0419). Disease activity-based analysis, suggested reduced Treg-mediated suppression of NK cell function and increased NK cell function in active vitiligo patients (p = 0.03,p = 0.0436). Interestingly, age-based analysis suggested decreased Treg-mediated suppression of NK cell function in 1-20 and 21-40 years age groups compared to 41-60 years age group of GV patients (p = 0.005,p = 0.0380). Overall, our study, for the first time, suggests that decreased Treg-mediated suppression of NK cells may lead to increased destruction of melanocytes in GV, and this knowledge may help in developing effective therapeutics based on Tregs and NK cells for GV.

Harmine and Kaempferol treatment enhances NFATC1 and FOXP3 mediated regulatory T-cells' suppressive capacity in generalized vitiligo

BACKGROUND

Generalized vitiligo (GV) is an autoimmune disease characterized by the progressive loss of melanocytes.

OBJECTIVES

Current study was undertaken to assess in-vitro therapeutic potential of Harmine and Kaempferol for GV.

METHODS

Calcium, calcineurin, NFATC1 levels, cell proliferation were assessed by various kits and ORAI1, PEIZO1, Calcineurin, GSK3B, DYRK1A transcripts and IFN-γ,IL-10,TGF-β protein levels were assessed by qPCR and ELISA in blood and skin biopsy samples from Tregs of 52 patients and 50 controls.

RESULTS

Harmine and Kaempferol treatment enhances Treg suppressive capacity, NFATs and FOXP3 expression in blood and skin Tregs of GV patients (p < 0.05). Furthermore, Harmine and Kaempferol treatment in Tregs increased calcineurin and NFATC1 activity and decreased DYRK1A transcripts in blood and skin Tregs of GV patients(p < 0.05). In-silico analysis revealed that Harmine and Kaempferol might boost Treg suppressive capacity by increasing calcineurin dephosphorylation activity leading to increase NFATs activation and also increase nuclear retention of NFATs by inhibiting DYRK1a phosphorylation activity. Moreover, calcineurin and NFATC1 activity in Tregs were positively correlated with Treg suppressive capacity, NFATC1 and FOXP3 expression (p < 0.05), whereas, DYRK1A transcripts were negatively correlated with Treg suppressive capacity, NFATC1 and FOXP3 expression (p < 0.05). These compounds significantly increased melanocytes' survival and proliferation in Treg:CD4+/CD8+:SK-Mel-28 cell line co-culture system from GV patients (p < 0.0001).

CONCLUSIONS

For the first time the study suggests that Harmine and Kaempferol treated Tregs could control the CD8+ and CD4+T-cells' proliferation and IFN-γ production, leading to melanocytes' survival and proliferation. These compounds may serve as novel Treg-based therapeutics for GV; however, in vivo studies are warranted to assess the safety and efficacy of these compounds.

Regulatory T cells in skin regeneration and wound healing

As the body's integumentary system, the skin is vulnerable to injuries. The subsequent wound healing processes aim to restore dermal and epidermal integrity and functionality. To this end, multiple tissue-resident cells and recruited immune cells cooperate to efficiently repair the injured tissue. Such temporally- and spatially-coordinated interplay necessitates tight regulation to prevent collateral damage such as overshooting immune responses and excessive inflammation. In this context, regulatory T cells (Tregs) hold a key role in balancing immune homeostasis and mediating cutaneous wound healing. A comprehensive understanding of Tregs' multifaceted field of activity may help decipher wound pathologies and, ultimately, establish new treatment modalities. Herein, we review the role of Tregs in orchestrating the regeneration of skin adnexa and catalyzing healthy wound repair. Further, we discuss how Tregs operate during fibrosis, keloidosis, and scarring.

Targeting ACC1 in T cells ameliorates psoriatic skin inflammation

Psoriasis is a chronic inflammatory skin disease driven by the IL-23/IL-17 axis. It results from excessive activation of effector T cells, including T helper (Th) and cytotoxic T (Tc) cells, and is associated with dysfunctional regulatory T cells (Tregs). Acetyl-CoA carboxylase 1 (ACC1), a rate-limiting enzyme of fatty acid synthesis (FAS), directs cell fate decisions between Th17 and Tregs and thus could be a promising therapeutic target for psoriasis treatment. Here, we demonstrate that targeting ACC1 in T cells by genetic ablation ameliorates skin inflammation in an experimental model of psoriasis by limiting Th17, Tc17, Th1, and Tc1 cells in skin lesions and increasing the frequency of effector Tregs in skin-draining lymph nodes (LNs). KEY MESSAGES : ACC1 deficiency in T cells ameliorates psoriatic skin inflammation in mice. ACC1 deficiency in T cells reduces IL-17A-producing Th17/Tc17/dysfunctional Treg populations in psoriatic lesions. ACC1 deficiency in T cells restrains IFN-γ-producing Th1/Tc1 populations in psoriatic skin lesions and skin-draining LNs. ACC1 deficiency promotes activated CD44+CD25+ Tregs and effector CD62L-CD44+ Tregs under homeostasis and psoriatic conditions.

Murine regulatory T cells utilize granzyme B to promote tumor metastasis

Regulatory T cells (Tregs) possess a wide range of mechanisms for immune suppression. Among them, Granzyme B (GzmB) and perforin expressed by Tregs were shown to inhibit tumor clearance in previous reports, which contradicted the canonical roles of these cytotoxic molecules expressed by cytotoxic T cells and NK cells in antitumor immune responses. Given the ability of the tumor to manipulate the microenvironment, Treg-derived GzmB function may represent an important approach to aid in tumor growth as well as facilitating tumor metastasis. In this study, we utilized Treg-specific GzmB knockout (Foxp3creGzmBfl/fl) mice to test whether Treg-derived GzmB can aid in tumor progression and metastasis. Using an IL-2 complex to activate GzmB expression in the non-immunogenic B16-F10 tumor model, we provide evidence to show that GzmB produced by Tregs is important for spontaneous metastasis to the lungs. In addition, we depleted CD8 + T cells to selectively measure the impact of Treg-derived GzmB in an experimental lung metastasis model by intravenous injection of B16-F10 tumor cells; our results demonstrate that Treg-derived GzmB plays an important role in increasing the metastatic burden to the lungs.

Peripheral MC1R activation modulates immune responses and is neuroprotective in a mouse model of Parkinson's disease

Background

Melanocortin 1 receptor (MC1R) is a key pigmentation gene, and loss-of-function of MC1R variants that produce red hair may be associated with Parkinson's disease (PD). We previously reported compromised dopaminergic neuron survival in Mc1r mutant mice and dopaminergic neuroprotective effects of local injection of a MC1R agonist to the brain or a systemically administered MC1R agonist with appreciable CNS permeability. Beyond melanocytes and dopaminergic neurons, MC1R is expressed in other peripheral tissues and cell types, including immune cells. The present study investigates the impact of NDP-MSH, a synthetic melanocortin receptor (MCR) agonist that does not cross BBB, on the immune system and the nigrostriatal dopaminergic system in mouse model of PD.

Methods

C57BL/6 mice were treated systemically with MPTP.HCl (20 mg/kg) and LPS (1 mg/kg) from day 1 to day 4 and NDP-MSH (400 μg/kg) or vehicle from day 1 to day 12 following which the mice were sacrificed. Peripheral and CNS immune cells were phenotyped and inflammatory markers were measured. The nigrostriatal dopaminergic system was assessed behaviorally, chemically, immunologically, and pathologically. To understand the role of regulatory T cells (Tregs) in this model, CD25 monoclonal antibody was used to deplete CD25+ Tregs.

Results

Systemic NDP-MSH administration significantly attenuated striatal dopamine depletion and nigral dopaminergic neuron loss induced by MPTP+LPS. It improved the behavioral outcomes in the pole test. Mc1r mutant mice injected with NDP-MSH in the MPTP and LPS paradigm showed no changes in striatal dopamine levels suggesting that the NDP-MSH acts through the MC1R pathway. Although no NDP-MSH was detected in the brain, peripheral, NDP-MSH attenuated neuroinflammation as observed by diminished microglial activation in the nigral region, along with reduced TNF-α and IL1β levels in the ventral midbrain. Depletion of Tregs limited the neuroprotective effects of NDP-MSH.

Conclusions

Our study demonstrates that peripherally acting NDP-MSH confers protection on dopaminergic nigrostriatal neurons and reduces hyperactivated microglia. NDP-MSH modulates peripheral immune responses, and Tregs may be involved in the neuroprotective effect of NDP-MSH.

Regulatory T cells in peripheral tissue tolerance and diseases

Maintenance of peripheral tolerance by CD4+Foxp3+ regulatory T cells (Tregs) is essential for regulating autoreactive T cells. The loss of function of Foxp3 leads to autoimmune disease in both animals and humans. An example is the rare, X-linked recessive disorder known as IPEX (Immune Dysregulation, Polyendocrinopathy, Enteropathy X-linked) syndrome. In more common human autoimmune diseases, defects in Treg function are accompanied with aberrant effector cytokines such as IFNγ. It has recently become appreciated that Tregs plays an important role in not only maintaining immune homeostasis but also in establishing the tissue microenvironment and homeostasis of non-lymphoid tissues. Tissue resident Tregs show profiles that are unique to their local environments which are composed of both immune and non-immune cells. Core tissue-residence gene signatures are shared across different tissue Tregs and are crucial to homeostatic regulation and maintaining the tissue Treg pool in a steady state. Through interaction with immunocytes and non-immunocytes, tissue Tregs exert a suppressive function via conventional ways involving contact dependent and independent processes. In addition, tissue resident Tregs communicate with other tissue resident cells which allows Tregs to adopt to their local microenvironment. These bidirectional interactions are dependent on the specific tissue environment. Here, we summarize the recent advancements of tissue Treg studies in both human and mice, and discuss the molecular mechanisms that maintain tissue homeostasis and prevent pathogenesis.

Aberrant pro-inflammatory responses of CD20+ T cells in experimental arthritis

CD20+ T cells comprise a highly inflammatory subset implicated in autoimmunity, including rheumatoid arthritis (RA). We sought to characterize the CD20+ T cell subset in the murine collagen-induced arthritis (CIA) model of RA and investigate the phenotype and functional relevance of CD3+CD20+ T cells in the lymph nodes and arthritic joints using flow cytometry and immunohistochemistry. We demonstrate that CD3+CD4+CD20+ and CD3+CD8+CD20+ T cells are expanded in the draining lymph nodes of CIA mice, produce increased levels of pro-inflammatory cytokines and are less susceptible to regulation by regulatory T cells. Notably, CD3+CD4+CD20+ and CD3+CD8+CD20+ T cells are enriched with CXCR5+PD-1+ T follicular helper cells and CXCR5-PD-1+ peripheral T helper cells, subsets of T cells implicated in promoting B-cell responses and antibody production within pathologically inflamed non-lymphoid tissues in RA. Our findings suggest CD20+ T cells are associated with inflammatory responses and may exacerbate pathology by promoting inflammatory B-cell responses.

Localization and movement of Tregs in gastrointestinal tract: a systematic review

BACKGROUND

The intestine is rich in food-derived and microbe-derived antigens. Regulatory T cells (Tregs) are an essential T-cell population that prevents systemic autoimmune diseases and inhibits inflammation by encountering antigens. Previously, it was reported that the functional loss of Tregs induces systemic inflammation, including inflammatory bowel disease and graft-versus-host disease in human and murine models. However, there is a dearth of information about how Tregs localize in different tissues and suppress effector cells.

MAIN BODY

The development of Tregs and their molecular mechanism in the digestive tract have been elucidated earlier using murine genetic models, infectious models, and human samples. Tregs suppress immune and other nonimmune cells through direct effect and cytokine production. The recent development of in vivo imaging technology allows us to visualize how Tregs localize and move in the settings of inflammation and homeostasis. This is important because, according to a recent report, Treg characterization and function are regulated by their location. Tregs located in the proximal intestine and its draining lymph nodes induce tolerance against food antigens, and those located in the distal intestine suppress the inflammation induced by microbial antigens. Taken together, various Tregs are induced in a location-specific manner in the gastrointestinal tract and influence the homeostasis of the gut.

CONCLUSION

In this review, we summarize how Tregs are induced in the digestive tract and the application of in vivo Treg imaging to elucidate immune homeostasis in the digestive tract.

The interactions of paclitaxel with tumour microenvironment

Today, it is well-known that the interactions and secretion within the tumour are crucial to consider for cancer therapy. Some novel cancer therapy modalities such as immunotherapy or tumour vaccination therapy work based on the control of interactions within the tumour microenvironment (TME). It has been revealed that anti-cancer drugs or radiotherapy can modulate some interactions in favour of cancer therapy. However, they may induce some mechanisms to increase the resistance of cancer cells to therapy. Paclitaxel is known as the first approved herbal derived chemotherapy drug. Although the main known anti-cancer effect of paclitaxel is the inhibition of the cell cycle, today, it has been well known that paclitaxel may suppress the tumour via modulating several interactions in TME. Furthermore, paclitaxel may increase the expression of some tumour resistance drivers. This review aims to discuss the interactions within TME following treatment with paclitaxel. The effects of paclitaxel on the anti-tumour immunity, immunosuppressive cells, hypoxia, and also angiogenesis will be discussed. The targeting of these interactions may be interesting to increase therapy efficiency using the combination modalities.

Effects of Local Nasal Immunotherapy with FIP-fve Peptide and Denatured Tyrophagus putrescentiae for Storage Mite-Induced Airway Inflammation

Allergic diseases are affecting public health and have increased over the last decade. Sensitization to mite allergens is a considerable trigger for allergy development. Storage mite-Tyrophagus putrescentiae shows great significance of allergenic potential and clinical relevance. The fungal immunomodulatory peptide FIP-fve has been reported to possess immunomodulatory activity. We aimed to determine whether T. putrescentiae-induced sensitization and airway inflammation in mice could be downregulated by FIP-fve in conjunction with denatured T. putrescentiae (FIP-fve and DN-Tp). Immune responses and physiologic variations in immunoglobulins, leukocyte subpopulations, cytokine productions, pulmonary function, lung pathology, cytokines in CD4⁺ and Treg cells were evaluated after local nasal immunotherapy (LNIT). After the LNIT with FIP-fve and DN-Tp, levels of specific IgE, IgG1, and IgG2a in the sera and IgA in the bronchoalveolar lavage fluid (BALF) were significantly reduced. Infiltrations of inflammatory leukocytes (eosinophils, neutrophils, and lymphocytes) in the airway decreased significantly. Production of proinflammatory cytokines (IL-5, IL-13, IL-17F and IL-23) and chemokine (IL-8) were significantly reduced, and Th1-cytokine (IL-12) increased in the airway BALF after LNIT. Pulmonary functions of Penh values were significantly decreased after the methacholine challenge, which resulted in a reduction of airway hypersensitivity after LNIT. Bronchus pathology showed a reduction of inflammatory cell infiltration and epithelium damage after LNIT. The IL-4⁺/CD4⁺ T cells could be downregulated and the IFN-γ⁺/CD4⁺ T cells upregulated. The Treg-related immunity of IL-10 and Foxp3 expressions in CD4⁺CD25⁺ cells were both upregulated after LNIT. In conclusion, LNIT with FIP-fve and DN-Tp had an anti-inflammatory effect on mite-induced airway inflammations and possesses potential as an immunomodulatory therapy agent for allergic airway diseases.

CD4+FoxP3+CD73+ regulatory T cell promotes cardiac healing post-myocardial infarction

Rationale: Despite recent studies indicating a crucial role of ecto-5′-nucleotidase (CD73) on T cells in cardiac injury after ischemia/reperfusion, the involvement of CD73⁺ regulatory T cells (Tregs) in cardiac repair post-myocardial infarction (MI) remains unclear. We sought to investigate the contribution of CD73 on Tregs to the resolution of cardiac inflammation and remodeling after MI.

Methods: Cardiac function, tissue injury, Tregs percentage in injured hearts, and purinergic signaling changes in cardiac FoxP3⁺ Tregs were analyzed after permanent descending coronary artery ligation. CD73 knockout Tregs were used to determine the function of CD73 on Tregs. Peripheral blood mononuclear cells (PBMCs) from acute myocardial infarction (AMI) patients and matched non-MI subjects were assessed via flow cytometry.

Results: Cardiac Tregs exhibited distinction of purinergic signaling post MI with dramatically high level of CD73 compared to the sham Tregs. CD73 deficiency decreased the tissue tropism, and impaired the immunosuppressive and protective function of Tregs in cardiac healing. Administration of low-dose of IL-2/anti-IL-2 complex resulted in FoxP3⁺CD73⁺Tregs expansion in the heart and contributed to the recovery of cardiac function. CD73 derived from FoxP3⁺Tregs could bind to FoxP3^- effector T-cells and inhibit the production of multiple inflammatory cytokines. In AMI patients, CD73 expressions on both CD4⁺ cells and FoxP3⁺Tregs decreased in PBMCs. Moreover, CD73 expressions on CD4⁺ T cells were negatively correlated with the levels of NT pro-BNP and myocardial zymogram in serum.

Conclusions: Our findings indicated the importance of FoxP3⁺CD73⁺Tregs in inflammation resolution and cardiac healing post-MI.

CAR Treg: A new approach in the treatment of autoimmune diseases

Regulatory T cells (Tregs) have the role of regulating self-tolerance, and suppressing immune responses. Defects in Treg function and number can lead to in loss of tolerance or autoimmune disease. To treat or control autoimmune diseases, one of the options is to develop immune tolerance for Tregs cell therapy, which includes promotion and activation. Recently, cell-based treatment as a promising approach to increase cells function and number has been developed. Cell therapy by chimeric T antigen receptor (CAR-T) cells has shown significant efficacy in the treatment of leukemia, which has led researchers to use CAR-T cells in other diseases like autoimmune diseases. Here, we describe the existing treatments for autoimmune diseases and the available treatments based on Treg, their benefits and restrictions for implementation in clinical trials. We also discussed potential solutions to overcome these limitations. It seems novel designs of CARs to be new hope for autoimmune diseases and expected to be a potential cure option in a wide array of disease in the future. Therefore, it is very important to address this issue and increase information about it.

Impact of Graft-Resident Leucocytes on Treg Mediated Skin Graft Survival

The importance and exact role of graft-resident leucocytes (also referred to as passenger leucocytes) in transplantation is controversial as these cells have been reported to either initiate or retard graft rejection. T cell activation to allografts is mediated via recognition of intact or processed donor MHC molecules on antigen-presenting cells (APC) as well as through interaction with donor-derived extracellular vesicles. Reduction of graft-resident leucocytes before transplantation is a well-known approach for prolonging organ survival without interfering with the recipient's immune system. As previously shown by our group, injecting mice with IL-2/anti-IL-2 complexes (IL-2cplx) to augment expansion of CD4 T regulatory cells (Tregs) induces tolerance towards islet allografts, and also to skin allografts when IL-2cplx treatment is supplemented with rapamycin and a short-term treatment of anti-IL-6. In this study, we investigated the mechanisms by which graft-resident leucocytes impact graft survival by studying the combined effects of IL-2cplx-mediated Treg expansion and passenger leucocyte depletion. For the latter, effective depletion of APC and T cells within the graft was induced by prior total body irradiation (TBI) of the graft donor. Surprisingly, substantial depletion of donor-derived leucocytes by TBI did not prolong graft survival in naïve mice, although it did result in augmented recipient leucocyte graft infiltration, presumably through irradiation-induced nonspecific inflammation. Notably, treatment with the IL-2cplx protocol prevented early inflammation of irradiated grafts, which correlated with an influx of Tregs into the grafts. This finding suggested there might be a synergistic effect of Treg expansion and graft-resident leucocyte depletion. In support of this idea, significant prolongation of skin graft survival was achieved if we combined graft-resident leucocyte depletion with the IL-2cplx protocol; this finding correlated along with a progressive shift in the composition of T cells subsets in the grafts towards a more tolerogenic environment. Donor-specific humoral responses remained unchanged, indicating minor importance of graft-resident leucocytes in anti-donor antibody development. These results demonstrate the importance of donor-derived leucocytes as well as Tregs in allograft survival, which might give rise to new clinical approaches.

Study on the preparation and function of regulatory T cells from human peripheral blood

Background

Regulatory T cells (Tregs) are an important cell subgroup of CD4⁺ T cells. Treg cells are critically involved in inducing immune tolerance, maintaining immune environment homeostasis, and preventing the occurrence of autoimmune diseases. Under normal conditions, the number of Tregs in the body is very small. This research was designed to establish an effective method to expand human peripheral blood Tregs in vitro and to analyze phenotype, purity, and function of Treg cells post-expansion.

Methods

Peripheral blood was obtained from healthy donors. CD4⁺CD25⁺CD127^dim/− Treg cells were isolated from peripheral blood mononuclear cells (PBMCs) by magnetic-activated cell sorting (MACS), and an optimized culture system was used for amplification. The in vitro amplification ability of Treg cells was evaluated to determine the expression and purity of Treg cell-specific surface markers in different culture cycles. The suppressive function of Treg was determined by in vitro lymphocyte proliferation assay.

Results

Treg cells could be successfully isolated by magnetic activated cell sorting (MACS). After 21 days of in vitro culture, the mean expansion fold was 2,009±452.2 in ≤60 years, and there was a significant difference between the younger group and the older than 60 years group (1,238±330.0). Flow cytometry analysis revealed that the percentages of CD4⁺CD25⁺ cells and FOXP3⁺ cells were (93.25±3.05)% and (94.19±4.21)% on day 14, and (92.86±4.36)% and (91.55±5.62)% on day 21, respectively. In addition, the proportions of CD8⁺ T, CD19⁺ B, CD3⁻CD56⁺ natural killer cell (NK), and CD3⁺ CD56⁺ natural killer T cell (NKT) were extremely low. Lymphocyte proliferation assay demonstrated that Tregs could inhibit the proliferation of CD8⁺ T cells more effectively than that of CD4⁺ T cells. Furthermore, the suppressive capacity of Tregs was correlated with Treg-to-PBMCs ratios.

Conclusions

We successfully established a technical protocol for manufacturing a large quantity of Tregs with high efficiency in vitro. The expanded Tregs have a steady FOXP3 expression and exhibited a potent immune suppression, which might have great significance in adoptive Treg therapy for treating graft-versus-host disease and autoimmune diseases.

2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin potential impacts on peripheral blood mononuclear cells of endometriosis women

Endometriosis happens following the implantation of endometrial-derived tissues outside the uterine cavity. It has been suggested that 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin (TCDD) is involved in endometriosis development. Furthermore, aryl hydrocarbon receptor (AHR), as a TCDD receptor, has been demonstrated to regulate immune responses. Nonetheless, data regarding the mechanisms, through which TCDD influences the immune system in endometriosis, are still inconclusive. Therefore, frequency of regulatory T cells (Tregs) and the expression of FOXP3, AHR and indoleamine 2, 3-dioxygenase 1 (IDO1) from endometriosis and non-endometriosis individuals were investigated in the absence and presence of TCDD; also, the concentration of IL-6 and kynurenine in the supernatant of cultures was assessed. The impact of TCDD-treated PBMCs on the migration capacity of menstrual blood-derived stromal stem cells (MenSCs) and monocyte chemoattractant protein-1 (MCP-1) and IL-6 production was determined. Here, we found that AHR and IDO1 expression levels were lower in endometriosis PBMCs; however, TCDD treatment increased AHR, FOXP3, IDO1, IL-6, and Treg levels in the endometriosis group (P ≤ 0.05-0.0001). TCDD-treated PBMCs increased the migration capacity of MenSCs and up-regulated MCP-1 and IL-6 levels in the PBMCs/MenSCs co-culture (P ≤ 0.01-0.0001). In conclusion, these results shed light on the probable mechanisms, through which AHR activation by chemical toxicants can impact inflammatory immune mediators involved in the development of endometriosis; also, these data support the idea that TCDD could promote endometriosis progression.

Expression of the immune checkpoint receptors CTLA-4, LAG-3, and TIM-3 in β-thalassemia major patients: correlation with alloantibody production and regulatory T cells (Tregs) phenotype

Alloimmunization is a serious complication in β-thalassemia major patients as a result of repeated blood transfusion. The immune checkpoint receptors play an important role in regulating immune system homeostasis and the function of the immune cells. This study aimed to evaluate the expression of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), lymphocyte activation gene 3 (LAG-3), and T-cell immunoglobulin and mucin domain-containing protein-3 (TIM-3) immune checkpoint molecules in β-thalassemia major patients with and without alloantibody. For this purpose, 68 β-thalassemia major patients with (34 patients) and without (34 patients) alloantibody as well as 20 healthy controls were enrolled. The expression of these genes was evaluated in different groups of patients by SYBR Green real-time PCR method. Our results showed that the mean expression of LAG-3 was significantly increased in thalassemia patients compared to the control group (*P < 0.001). However, there was no significant difference in expression of the CTLA-4 and TIM-3 as well as LAG-3 genes between patients with and without alloantibody (P > 0.05). A positive correlation was observed between the level of LAG-3 expression with markers associated with Treg function including FOXP3 and GDF-15 genes in β-thalassemia major patients. Taken together, the LAG-3 molecule might have a more prominent role in the abnormality of the immune system in thalassemia patients especially the function of regulatory T cells (Tregs), prior to the CTLA-4 and TIM-3 genes.

Modulation of the tumor microenvironment (TME) by melatonin

The tumor microenvironment (TME) includes a number of non-cancerous cells that affect cancer cell survival. Although CD8⁺ T lymphocytes and natural killer (NK) cells suppress tumor growth through induction of cell death in cancer cells, there are various immunosuppressive cells such as regulatory T cells (Tregs), tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), etc., which drive cancer cell proliferation. These cells may also support tumor growth and metastasis by stimulating angiogenesis, epithelial-mesenchymal transition (EMT), and resistance to apoptosis. Interactions between cancer cells and other cells, as well as molecules released into EMT, play a key role in tumor growth and suppression of antitumoral immunity. Melatonin is a natural hormone that may be found in certain foods and is also available as a drug. Melatonin has been demonstrated to modulate cell activity and the release of cytokines and growth factors in TME. The purpose of this review is to explain the cellular and molecular mechanisms of cancer cell resistance as a result of interactions with TME. Next, we explain how melatonin affects cells and interactions within the TME.

The impact of selenium on regulatory T cell frequency and immune checkpoint receptor expression in patients with diffuse large B cell lymphoma (DLBCL)

For many decades, selenium (Se) has been known as a potential anti-cancer agent that can also improve the function of immune cells in a variety of solid tumors. However, there is no report on the role of Se on CD4⁺ T cell subsets like CD4⁺CD25⁺FOXP3⁺ regulatory T cells (Tregs) in lymphoma patients. In this randomized clinical trial, we investigated the effect of 3-month Se consumption on the frequency of CD4⁺CD25⁺FOXP3⁺ Tregs and the expression of immune checkpoint receptors in thirty-two non-Hodgkin lymphoma (NHL) patients (16 patients with Se (Se+) and 16 without Se (Se-) consumption) with diffuse large B-cell lymphoma (DLBCL) subtype at stable remission. The change in the frequency of Tregs and expression of immune checkpoint receptors including CTLA-4, LAG-3, TIM-3, and PD-L1 genes were evaluated after 3 months in both groups using flow cytometry and SYBR Green Real-time PCR method, respectively. The results showed that the frequency of CD4⁺CD25⁺FOXP3⁺ Tregs and expression of immune checkpoint receptors did not significantly change after 3-month Se consumption in DLBCL patients. However, alteration in the frequency of CD4⁺CD25^-FOXP3⁺ Treg subsets was positively correlated with change in CTLA-4, LAG-3, and TIM-3 expression in the Se+ group. Three-month Se supplementation did not prevent relapse in Se+ group. Taken together, Se supplementation alone did not affect the frequency of CD4⁺CD25⁺FOXP3⁺ Tregs, expression of checkpoint receptors, and prevention of relapse in DLBCL patients at stable remission phase but might influence the functional properties of other Treg subsets like CD4⁺CD25^-FOXP3⁺ Tregs.

Auto-antigen and Immunomodulatory Agent-Based Approaches for Antigen-Specific Tolerance in NOD Mice

PURPOSE OF REVIEW

Type 1 diabetes (T1D) can be managed by insulin replacement, but it is still associated with an increased risk of microvascular/cardiovascular complications. There is considerable interest in antigen-specific approaches for treating T1D due to their potential for a favorable risk-benefit ratio relative to non-specific immune-based treatments. Here we review recent antigen-specific tolerance approaches using auto-antigen and/or immunomodulatory agents in NOD mice and provide insight into seemingly contradictory findings.

RECENT FINDINGS

Although delivery of auto-antigen alone can prevent T1D in NOD mice, this approach may be prone to inconsistent results and has not demonstrated an ability to reverse established T1D. Conversely, several approaches that promote presentation of auto-antigen in a tolerogenic context through cell/tissue targeting, delivery system properties, or the delivery of immunomodulatory agents have had success in reversing recent-onset T1D in NOD mice. While initial auto-antigen based approaches were unable to substantially influence T1D progression clinically, recent antigen-specific approaches have promising potential.

Immune system in cancer radiotherapy: Resistance mechanisms and therapy perspectives

Radiotherapy is a common modality for more than half of cancer patients. Classically, radiation is known as a strategy to kill cancer cells via direct interaction with DNA or generation of free radicals. Nowadays, we know that modulation of immune system has a key role in the outcome of radiotherapy. Selecting an appropriate dose per fraction is important for stimulation of anti-tumor immunity. Unfortunately, cancer cells and other cells within tumor microenvironment (TME) promote some mechanisms implicated in the attenuation of anti-tumor immunity via exhaustion of CD8 + T lymphocytes and natural killer (NK) cells. Immunotherapy with immune checkpoint inhibitors (ICIs) has shown to be an interesting adjuvant for induction of more effective anti-tumor immunity. Clinical trial studies are ongoing for uncovering more knowledge about the efficacy of ICI combination with radiotherapy. Some newer pre-clinical studies show more effective therapeutic window for targeting PD-1 and some other targets in combination with hypofractionated radiotherapy. In this review, we explain cellular and molecular consequences in the TME following radiotherapy and promising immune targets to enhance anti-tumor immunity.

Recent advances in studies of molecular hydrogen in the treatment of pancreatitis

Pancreatitis is an inflammatory disease of the pancreas characterized by acinar cell injury and is associated with the abnormal release of trypsin, which results in high mortality due to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). The inflammatory response, impaired autophagic flux, endoplasmic reticulum stress (ERS) and their interactions are involved in the development of pancreatitis. Molecular hydrogen (H₂) is a novel antioxidant that possesses the features of selective scavenging of oxygen free radicals and nontoxic metabolites and has been shown to be efficacious for treating infection, injury, tumors, ischemia-reperfusion organ injury, metabolic disease and several other diseases. Recent studies have found that H₂ is also useful in the treatment of pancreatitis, which may be related to the mechanism of antioxidative stress, anti-inflammation, anti-apoptosis, regulation of immunity and regulation of molecular pathways. This review focuses on the pathogenesis of pancreatitis and the research progress and potential mechanisms of H₂ against pancreatitis to provide theoretical bases for future research and clinical application of H₂ therapy for pancreatitis.

Programmed death-1 expression and regulatory T cells increase in the Intestinal mucosa of cytomegalovirus colitis in patients with HIV/AIDS

BACKGROUND

Cytomegalovirus (CMV) is among the most common opportunistic infections identified in patients with HIV/AIDS. CMV often targets the colon in such patients. However, the role of regulatory T cells (T_regs) and Programmed death-1 (PD-1) in intestinal CMV infection is unclear. In this study, we evaluate the expression of programmed death -1 (PD-1) and its association with regulatory T cells (T_regs) in patients with HIV/AIDS having CMV colitis.

METHODS

CMV was detected in the intestinal mucosal biopsy samples via nucleic acid in situ hybridization. PD-1, CD4, CD8, and T_reg-specific marker as well as the winged-helix transcription factor and forkhead box P3 (FoxP3) were detected by immunohistochemical methods.

RESULTS

Intestinal CMV diease was identified in 20 out of 195 patients with HIV/AIDS enrolled in our study. CMV was diagnosed microscopically by the presence of giant cell inclusion bodies in epithelial cells, histiocytes, and fibroblasts. Levels of immunoreactive PD-1 detected in mucosal biopsies from patients with HIV/AIDS having CMV colitis were significantly higher than CMV-negative control group (p = 0.023). FoxP3⁺ cells were detected in the CMV colitis group slight more than that in the control group. CD4⁺ T lymphocyte counts in the peripheral blood and intestinal mucosal biopsies from CMV colitis group were all notably decreased compared with those with control group (p < 0.001 for both). PD-1 had a significant negative correlation with CD4 counts in intestinal mucosa (p = 0.016). CD8⁺T lymphocyte counts in peripheral blood and intestinal mucosa were slightly lower than those in the control group, although the differences were not statistically significant.

CONCLUSIONS

CMV colitis with HIV/AIDS is associated with significant changes in T lymphocyte populations. These findings may have important implications for disease pathogenesis and progression.

Discovery of CD80 and CD86 as recent activation markers on regulatory T cells by protein-RNA single-cell analysis

BACKGROUND

Traditionally, the transcriptomic and proteomic characterisation of CD4+ T cells at the single-cell level has been performed by two largely exclusive types of technologies: single-cell RNA sequencing (scRNA-seq) and antibody-based cytometry. Here, we present a multi-omics approach allowing the simultaneous targeted quantification of mRNA and protein expression in single cells and investigate its performance to dissect the heterogeneity of human immune cell populations.

METHODS

We have quantified the single-cell expression of 397 genes at the mRNA level and up to 68 proteins using oligo-conjugated antibodies (AbSeq) in 43,656 primary CD4+ T cells isolated from the blood and 31,907 CD45+ cells isolated from the blood and matched duodenal biopsies. We explored the sensitivity of this targeted scRNA-seq approach to dissect the heterogeneity of human immune cell populations and identify trajectories of functional T cell differentiation.

RESULTS

We provide a high-resolution map of human primary CD4+ T cells and identify precise trajectories of Th1, Th17 and regulatory T cell (Treg) differentiation in the blood and tissue. The sensitivity provided by this multi-omics approach identified the expression of the B7 molecules CD80 and CD86 on the surface of CD4+ Tregs, and we further demonstrated that B7 expression has the potential to identify recently activated T cells in circulation. Moreover, we identified a rare subset of CCR9+ T cells in the blood with tissue-homing properties and expression of several immune checkpoint molecules, suggestive of a regulatory function.

CONCLUSIONS

The transcriptomic and proteomic hybrid technology described in this study provides a cost-effective solution to dissect the heterogeneity of immune cell populations at extremely high resolution. Unexpectedly, CD80 and CD86, normally expressed on antigen-presenting cells, were detected on a subset of activated Tregs, indicating a role for these co-stimulatory molecules in regulating the dynamics of CD4+ T cell responses.

Harnessing regulatory T cell neuroprotective activities for treatment of neurodegenerative disorders

Emerging evidence demonstrates that adaptive immunity influences the pathobiology of neurodegenerative disorders. Misfolded aggregated self-proteins can break immune tolerance leading to the induction of autoreactive effector T cells (Teffs) with associated decreases in anti-inflammatory neuroprotective regulatory T cells (Tregs). An imbalance between Teffs and Tregs leads to microglial activation, inflammation and neuronal injury. The cascade of such a disordered immunity includes the drainage of the aggregated protein antigens into cervical lymph nodes serving to amplify effector immune responses. Both preclinical and clinical studies demonstrate transformation of this altered immunity for therapeutic gain. We posit that the signs and symptoms of common neurodegenerative disorders such as Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, and stroke can be attenuated by boosting Treg activities.

Aberrant peripheral blood CD4+ CD25+ FOXP3+ regulatory T cells/T helper-17 number is associated with the outcome of patients with lymphoma

Little is known about the clinical significance of the peripheral blood CD4⁺ CD25⁺ FOXP3⁺ regulatory T cells (Tregs) and T helper-17 (Th17) cells in lymphoma patients. In this study, the prognostic and clinical significance of peripheral blood Tregs and Th17 cells were evaluated in lymphoma patients during different phases. The frequency of Tregs and Th17 lymphocytes was measured by flow cytometry method in 47 classical Hodgkin's lymphoma (cHL) and 48 diffuse large B cell lymphoma (DLBCL) patients. Our results showed that the frequency of Tregs and absolute Treg count was significantly reduced in relapsed patients compared to patients at the remission phase, as well as with newly diagnosed untreated patients in both groups. Patients who reached complete remission had elevated frequency of CD4⁺ FOXP3⁺ lymphocytes, Tregs, absolute Treg count, Treg/CD4 and Treg/Th17 ratio in the cHL group and CD4⁺ CD25⁺ cells in DLBCL group. The frequency of Tregs, absolute Treg count and Treg/Th17 ratio in cHL patients and CD4⁺ FOXP3⁺ and CD4⁺ CD25⁺ cells in DLBCL patients positively associated with survival rate. Moreover, the percentage of Tregs and absolute Treg count positively correlated with white blood cell, platelet count and ESR level in cHL patients and with white blood cell count in DLBCL patients. The initial number of Tregs/Th17 cells and also the Treg/Th17 ratio was not associated with changes in disease-free survival (DFS) in both groups. Therefore, higher frequency of peripheral blood Tregs and Treg/Th17 ratio might be associated with a favorable outcome in lymphoma patients, better response to chemotherapy and lower rate of relapse.

Reduction of FoxP3+ Tregs by an immunosuppressive protocol of rapamycin plus Thymalfasin and Huaier extract predicts positive survival benefits in a rat model of hepatocellular carcinoma

Background

Investigate immunoregulation and anti-tumor immunity of FoxP3⁺Tregs after treatment with rapamycin (RAPA/SRL) plus thymalfasin (Zadaxin) and Huaier extract (PS-T) in a hepatocellular carcinoma (HCC) rat model simulating HCC relapse after liver transplant (LT).

Methods

We successfully established a rat model simulating HCC relapse after LT using an optimized chemical induction method with TACROLIMUS, methylprednisolone, and diethylnitrosamine as identified by visible liver nodules and hematoxylin-eosin staining. The model rats were then treated with RAPA, Zadaxin, and PS-T. Immune status changes were analyzed by flow cytometry, and protein expression of Akt and mTOR was determined by western blotting. Cytokines were measured by ELISAs.

Results

Combined therapy by RAPA plus Zadaxin and PS-T obviously alleviated hepatic pathological changes and significantly decreased the levels of FoxP3⁺Tregs in peripheral blood, the spleen, and the liver (P<0.05) and expression of mTOR protein (P<0.01) in the liver, obviously improved survival time (P=0.02). Moreover, the levels of CD8⁺T cells were increased significantly to almost normal levels (P<0.05) in comparison with no SRL monotherapy protocols. Inhibitory cytokines were also decreased in accordance with FoxP3⁺Tregs. Significant decreases of IL-10 and TGF-β were observed after SRL-based therapy (P<0.01) in comparison with the other groups. Serum alpha fetoprotein (AFP) and vascular endothelial growth factor (VEGF) levels were also decreased significantly (P<0.05). FoxP3⁺Tregs showed a negative correlation with CD8⁺ and CD4⁺/CD8⁺T cells and a positive correlation with AFP, and VEGF (P<0.05).

Conclusions

SRL-based therapy reduces FoxP3⁺Tregs to decrease secreted inhibitory cytokines which may enhancement the viability and number of CD8⁺T cells to exert anti-tumor effects that are mainly mediated through the AKT-mTOR signaling pathway.

CD200-CD200R Pathway in the Regulation of Tumor Immune Microenvironment and Immunotherapy

Tumor-associated inflammation and immune responses are key components in the tumor microenvironment (TME) which regulate tumor growth, progression, and metastasis. Tumor-associated myeloid cells (TAMCs) are a group of cells that play multiple key roles including induction of tumor-associated inflammation/angiogenesis and regulation of tumor-specific T-cell responses. Thus, identification and characterization of key pathways that can regulate TAMCs are of critical importance for developing cancer immunotherapy. Recent studies suggest that CD200-CD200 receptor (CD200R) interaction may be important in regulating the TME via affecting TAMCs. In this chapter, we will give a brief overview of the CD200-CD200R axis, including the biology behind CD200-CD200R interaction and the role(s) it plays in tumor microenvironment and tumor growth, and activation/effector functions of T cells. We will also discuss CD200-CD200R's role as potential checkpoint molecules for cancer immunotherapy. Further investigation of the CD200-CD200R pathway will not only advance our understanding of tumor pathogenesis and immunity but also provide the rationale for CD200-CD200R-targeted immunotherapy of human cancer.

The Impact of Estrogen in the Tumor Microenvironment

Tumor immune escape is now a hallmark of cancer development, and therapies targeting these pathways have emerged as standard of care. Specifically, immune checkpoint signal blockade offers durable responses and increased overall survival. However, the majority of cancer patients still do not respond to checkpoint blockade immune therapy leading to an unmet need in tumor immunology research. Sex-based differences have been noted in the use of cancer immunotherapy suggesting that sex hormones such as estrogen may play an important role in tumor immune regulation. Estrogen signaling already has a known role in autoimmunity, and the estrogen receptor can be expressed across multiple immune cell populations and effect their regulation. While it has been well established that tumor cells such as ovarian carcinoma, breast carcinoma, and even lung carcinoma can be regulated by estrogen, research into the role of estrogen in the regulation of tumor-associated immune cells is still emerging. In this chapter, we discuss the role of estrogen in the tumor immune microenvironment and the possible immunotherapeutic implications of targeting estrogen in cancer patients.

CCL20 Signaling in the Tumor Microenvironment

CCL20, as a chemokine, plays an important role in rheumatoid arthritis, psoriasis, and other diseases by binding to its receptor CCR6. Recent 10 years' research has demonstrated that CCL20 also contributes to the progression of many cancers, such as liver cancer, colon cancer, breast cancer, pancreatic cancer, and gastric cancer. This article reviews and discusses the previous studies on CCL20 roles in cancers from the aspects of its specific effects on various cancers, its remodeling on tumor microenvironment (TME), its synergistic effects with other cytokines in tumor microenvironment, and the specific mechanisms of CCL20 signal activation, illustrating CCL20 signaling in TME from multiple directions.

An immune gate of depression - Early neuroimmune development in the formation of the underlying depressive disorder

The prevalence of depression worldwide is increasing from year to year and constitutes a serious medical, economic and social problem. Currently, despite multifactorial risk factors and pathways contributing to depression development, a significant aspect is attributed to the inflammatory process. Cytokines are considered a factor activating the kynurenine pathway, which leads to the exhaustion of tryptophan in the tryptophan catabolite (TRYCAT) pathway. This results in the activation of potentially neuroprogressive processes and also affects the metabolism of many neurotransmitters. The immune system plays a coordinating role in mediating inflammatory process. Beginning from foetal life, dendritic cells have the ability to react to bacterial and viral antigens, stimulating T lymphocytes in a similar way to adult cells. Cytotoxicity in the prenatal period shapes the predisposition to the development of depression in adult life. Allostasis, i.e. the ability to maintain the body's balance in the face of environmental adversity through changes in its behaviour or physiology, allows the organism to survive but its consequences may be unfavourable if it lasts too long. As a result, Th lymphocytes, in particular T helper 17 cells, which play a central role in the immunity of the whole body, contribute to the development of both autoimmune diseases and psychiatric disorders including depression, as well as have an impact on the differentiation of T CD4+ cells into Th17 cells in the later development of the child's organism, which confirms the importance of the foetal period for the progression of depressive disorders.

The predictive and prognostic value of Foxp3+/CD25+ regulatory T cells and PD-L1 expression in triple negative breast cancer

Recent significant developments in cancer immunotherapy have led to important breakthroughs and paradigm shifts in the treatment of malignancy. Although breast cancer traditionally has been considered less immunogenic, triple-negative breast cancer (TNBC) is the most immunogenic subtype with more stromal tumor-infiltrating lymphocytes (TILs) and higher programmed death-ligand 1 (PD-L1) expression. The goal of this study is to evaluate regulatory T cells (Tregs) and PD-L1 expression in TNBC, as well as their associations with clinicopathologic features and the outcomes. Tissue microarrays (TMA) of biopsy and resection specimens of 43 TNBC patients who underwent breast biopsy, neoadjuvant chemotherapy, and mastectomy were prepared. The number of Foxp3+ Tregs, Foxp3+/CD25+ Tregs, and expression of PD-L1 in tumor cells (PD-L1 TCs) and TILs (PD-L1 TILs) were assessed by immunohistochemistry. PD-L1 expression combined positive score (PD-L1 CPS) was calculated according to the manufacturer's guidelines. PD-L1 expression was detected in 72% of the cases, and it expressed in a higher percentage and higher intensity in TILs than TCs in TNBC (p = 0.006 and 0.0005, respectively). PD-L1 TCs, PD-L1 TILs, and PD-L1 CPS were all positively associated with pathologic complete response (pCR) (p = 0.04, 0.03, and 0.02, respectively). PD-L1 TILs and PD-L1 CPS also correlated with TILs and tumor infiltrating lymphocyte volume (TILV). Foxp3+ Tregs and Foxp3+/CD25+ Tregs had strong positive correlation (r = 0.89), and they were positively associated with TILs, TILV, and PD-L1 expression. Foxp3+/CD25+ Tregs, PD-L1 TCs, and PD-L1 CPS were positively correlated with better overall survival (p = 0.04, 0.04 and 0.01, respectively).

The role of dietary sodium in autoimmune diseases: The salty truth

Autoimmune diseases are a group of heterogeneous condition that occur secondary to the intrinsic loss of tolerance to self- antigens. In genetically susceptible individuals, the complex interplay of environmental factors and epigenetic deregulations have been proposed to drive disease etiopathogenesis. Various environmental variables have been identified including viral infections, exposure to pollutants, stress and dietary factors. Sodium, a major constituent of salt is essential for mammalian physiology. However, high salt intake may play a role in the development of autoimmune diseases. Several lines of evidence point toward the role of high sodium intake in reversing the suppressive effects of Regulatory T cells (Tregs) and instead promoting cellular shift toward T-helper (Th)-1 and Th17 pro-inflammatory phenotypes. These effects have been attributed to cascade of events that ultimately results in downstream activation of serum glucocorticoid kinase 1 (Sgk1). In vivo, various autoimmune animal models have confirmed the role of high sodium diet in the emergence and the exacerbation of autoimmune conditions including for instance Experimental Autoimmune Encephalomyelitis model for multiple sclerosis, MRL/lpr mouse model for lupus nephritis, collagen induced arthritis model for rheumatoid arthritis, and dextran sulfate sodium induced colitis, and TNBS-induced colitis models for Crohn's disease. Clinical epidemiological studies are scarce. High sodium intake was associated with increased risk of rheumatoid arthritis disease emergence. In multiple sclerosis, some studies suggest a relation to clinical exacerbation rates however other studies did not corroborate these results. Taken together, high dietary salt intake plays a role in the spectrum of autoimmune disease etiology. Further research is warranted to better characterize such relationship and assist in identifying individuals that would benefit from dietary salt restriction.

Sunitinib and Sorafenib Modulating Antitumor Immunity in Hepatocellular Cancer

Sorafenib and sunitinib are multiple tyrosine kinase inhibitors. Both of them have been approved by the US FDA in the treatment of patients with malignancies. In order to develop an effective and clinically useful chemoimmunotherapy modality against hepatocellular cancer (HCC), we investigate their tumoricidal and immune modulatory effect in the setting of HCC. In vitro experiments suggested that sunitinib and sorafenib both induced HCC cell apoptosis at an equivalent level, but stronger suppressive function to cell proliferation was detected in sorafenib. Correspondingly, treatment of tumor-bearing mice with sorafenib led to the suppression of tumor growth to a larger extent than sunitinib. Flow cytometry showed that treatment with sunitinib, not sorafenib, significantly reduced the frequency of regulatory T cells (Tregs) and myeloid-derived suppressive cells (MDSCs) in tumor-bearing mice; and allowed splenic lymphocytes to produce equivalent levels of IFN-γ and TNF-α in response to vaccination as that in wild type mice. This activation was not detected in control and sorafenib-treated tumor mice. In addition, treatment of tumor-bearing mice with sunitinib followed by adoptive transfer of tumor antigen-specific CD8⁺ T cells and immunization resulted in the additional suppression to tumor growth compared to sunitinib monotherapy. These results imply treatment with sunitinib, not sorafenib, is able to prevent tumor-induced immunotolerance and activate antitumorimmunity. Our data suggest that sunitinib may be a preferable chemotherapeutic agent to use in combination with immunotherapy for the treatment of HCC.

Very Low Numbers of CD4+ FoxP3+ Tregs Expanded in Donors via TL1A-Ig and Low-Dose IL-2 Exhibit a Distinct Activation/Functional Profile and Suppress GVHD in a Preclinical Model

Regulatory T cells (Tregs) are essential for the maintenance of tolerance and immune homeostasis. In allogeneic hematopoietic stem cell transplantation (aHSCT), transfer of appropriate Treg numbers is a promising therapy for the prevention of graft-versus-host disease (GVHD). We have recently reported a novel approach that induces the marked expansion and selective activation of Tregs in vivo by targeting tumor necrosis factor receptor superfamily 25 (TNFRSF25) and CD25. A potential advance to promote clinical application of Tregs to ameliorate GVHD and other disorders would be the generation of more potent Treg populations. Here we wanted to determine if very low doses of Tregs generated using the "2-pathway" stimulation protocol via TL1A-Ig fusion protein and low-dose IL-2 (targeting TNFRSF25 and CD25, respectively) could be used to regulate preclinical GVHD. Analysis of such 2-pathway expanded Tregs identified higher levels of activation and functional molecules (CD103, ICOS-1, Nrp-1, CD39, CD73, il-10, and tgfb1) versus unexpanded Tregs. Additionally, in vitro assessment of 2-pathway stimulated Tregs indicated enhanced suppressor activity. Notably, transplant of extremely low numbers of these Tregs (1:6 expanded Tregs/conventional T cells) suppressed GVHD after an MHC-mismatched aHSCT. Overall, these results demonstrate that 2-pathway stimulated CD4⁺ FoxP3⁺ Tregs were quantitatively and qualitatively more functionally effective than unexpanded Tregs. In total, the findings in this study support the notion that such 2-pathway stimulated Tregs may be useful for prevention of GVHD and ultimately promote more widespread application of aHSCT in the clinic.

Adipose-tissue regulatory T cells: Critical players in adipose-immune crosstalk

Obesity and type-2 diabetes (T2D) are associated with metabolic defects and inflammatory processes in fat depots. FoxP3⁺ regulatory T cells (Tregs) control immune tolerance, and have an important role in controlling tissue-specific inflammation. In this mini-review we will discuss current insights into how cross-talk between T cells and adipose tissue shapes the inflammatory environment in obesity-associated metabolic diseases, focusing on the role of CD4⁺ T cells and Tregs. We will also highlight potential opportunities for how the immunoregulatory properties of Tregs could be harnessed to control inflammation in obesity and T2D and emphasize the critical need for more research on humans to establish mechanisms that are conserved in both mice and humans.

Cells with Treg-specific FOXP3 demethylation but low CD25 are prevalent in autoimmunity

Identification of alterations in the cellular composition of the human immune system is key to understanding the autoimmune process. Recently, a subset of FOXP3⁺ cells with low CD25 expression was found to be increased in peripheral blood from systemic lupus erythematosus (SLE) patients, although its functional significance remains controversial. Here we find in comparisons with healthy donors that the frequency of FOXP3⁺ cells within CD127^lowCD25^low CD4⁺ T cells (here defined as CD25^lowFOXP3⁺ T cells) is increased in patients affected by autoimmune disease of varying severity, from combined immunodeficiency with active autoimmunity, SLE to type 1 diabetes. We show that CD25^lowFOXP3⁺ T cells share phenotypic features resembling conventional CD127^lowCD25^highFOXP3⁺ Tregs, including demethylation of the Treg-specific epigenetic control region in FOXP3, HELIOS expression, and lack of IL-2 production. As compared to conventional Tregs, more CD25^lowFOXP3⁺HELIOS⁺ T cells are in cell cycle (33.0% vs 20.7% Ki-67⁺; P = 1.3 × 10⁻⁹) and express the late-stage inhibitory receptor PD-1 (67.2% vs 35.5%; P = 4.0 × 10⁻¹⁸), while having reduced expression of the early-stage inhibitory receptor CTLA-4, as well as other Treg markers, such as FOXP3 and CD15s. The number of CD25^lowFOXP3⁺ T cells is correlated (P = 3.1 × 10⁻⁷) with the proportion of CD25^highFOXP3⁺ T cells in cell cycle (Ki-67⁺). These findings suggest that CD25^lowFOXP3⁺ T cells represent a subset of Tregs that are derived from CD25^highFOXP3⁺ T cells, and are a peripheral marker of recent Treg expansion in response to an autoimmune reaction in tissues.

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FOXP3⁺ compartment within CD127^lowCD25^low T cells is expanded in autoimmune patients.

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Increased numbers of CD25^lowFOXP3⁺ T cells are a circulating marker of autoimmunity.

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CD25^lowFOXP3⁺ HELIOS⁺ T cells are fully demethylated at the FOXP3 TSDR.

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CD25^lowFOXP3⁺ T cells could represent a terminal differentiation stage of regulatory T cells.

Role of intestinal microbiota and metabolites on gut homeostasis and human diseases

Background

A vast diversity of microbes colonizes in the human gastrointestinal tract, referred to intestinal microbiota. Microbiota and products thereof are indispensable for shaping the development and function of host innate immune system, thereby exerting multifaceted impacts in gut health.

Methods

This paper reviews the effects on immunity of gut microbe-derived nucleic acids, and gut microbial metabolites, as well as the involvement of commensals in the gut homeostasis. We focus on the recent findings with an intention to illuminate the mechanisms by which the microbiota and products thereof are interacting with host immunity, as well as to scrutinize imbalanced gut microbiota (dysbiosis) which lead to autoimmune disorders including inflammatory bowel disease (IBD), Type 1 diabetes (T1D) and systemic immune syndromes such as rheumatoid arthritis (RA).

Results

In addition to their well-recognized benefits in the gut such as occupation of ecological niches and competition with pathogens, commensal bacteria have been shown to strengthen the gut barrier and to exert immunomodulatory actions within the gut and beyond. It has been realized that impaired intestinal microbiota not only contribute to gut diseases but also are inextricably linked to metabolic disorders and even brain dysfunction.

Conclusions

A better understanding of the mutual interactions of the microbiota and host immune system, would shed light on our endeavors of disease prevention and broaden the path to our discovery of immune intervention targets for disease treatment.

Successful chemoimmunotherapy against hepatocellular cancer in a novel murine model

BACKGROUND & AIMS

We have established a clinically relevant animal model of hepatocellular cancer (HCC) in immune competent mice to elucidate the complex dialog between host immunity and tumors during HCC initiation and progression. Mechanistic findings have been leveraged to develop a clinically feasible anti-tumor chemoimmunotherapeutic strategy.

METHODS

Intraperitoneal injection of carbon tetrachloride and intrasplenic inoculation of oncogenic hepatocytes were combined to induce progressive HCCs in fibrotic livers of immunocompetent mice. Immunization and adoptive cell transfer (ACT) were used to dissect the tumor antigen-specific immune response. The ability of the tyrosine kinase inhibitor sunitinib to enhance immunotherapy in the setting of HCC was evaluated.

RESULTS

This new mouse model mimics human HCC and reflects its typical features. Tumor-antigen-specific CD8⁺ T cells maintained a naïve phenotype and remained responsive during early-stage tumor progression. Late tumor progression produced circulating tumor cells, tumor migration into draining lymph nodes, and profound exhaustion of tumor-antigen-specific CD8⁺ T cells associated with accumulation of programmed cell death protein 1 (PD-1)^hi CD8⁺ T cells and regulatory T cells (Tregs). Sunitinib-mediated tumoricidal effect and Treg suppression synergized with antibody-mediated blockade of PD-1 to powerfully suppress tumor growth and activate anti-tumor immunity.

CONCLUSION

Treg accumulation and upregulation of PD-1 provide two independent mechanisms to induce profound immune tolerance in HCC. Chemoimmunotherapy using Food and Drug Administration-approved sunitinib with anti-PD-1 antibodies achieved significant tumor control, supporting translation of this approach for the treatment of HCC patients.

LAY SUMMARY

In the current study, we have established a clinically relevant mouse model which mimics human liver cancer. Using this unique model, we studied the response of the immune system to this aggressive cancer. Findings from this trial have led to the development of an innovative and clinically feasible chemoimmunotherapeutic strategy.

Restoring Regulatory T Cells in Type 1 Diabetes

Genetic and cellular studies of type 1 diabetes in patients and in the nonobese diabetic mouse model of type 1 diabetes point to an imbalance between effector T cells and regulatory T cells (Tregs) as a driver of the disease. The imbalance may arise as a consequence of genetically encoded defects in thymic deletion of islet antigen-specific T cells, induction of islet antigen-specific thymic Tregs, unfavorable tissue environment for peripheral Treg induction, and failure of islet antigen-specific Tregs to survive in the inflamed islets secondary to insufficient IL-2 signals. These understandings are the foundation for rationalized design of new therapeutic interventions to restore the balance by selectively targeting effector T cells and boosting Tregs.

The combination of systemic inflammation-based marker NLR and circulating regulatory T cells predicts the prognosis of resectable pancreatic cancer patients

BACKGROUND

The systemic inflammation response and immune impairment are closely related to the development and progression of various tumours, such as pancreatic cancer. In this study, we evaluated circulating inflammation factors and circulating regulatory T cells (Tregs) as markers of immunosuppression in a cohort of Chinese patients with resectable pancreatic cancer.

METHODS

Samples were retrospectively collected from a series of 195 pathological stage I/II pancreatic cancer patients who underwent potentially curative surgery between June 2010 and April 2014. To examine the prognostic factors, circulating systemic inflammation-based markers and Tregs, detected by flow cytometry, were analysed.

RESULTS

Univariate analyses revealed that the neutrophil-lymphocyte ratio (NLR), TNM stage, differentiation, chemotherapy, CA19-9 levels and presence of Tregs are significantly associated with overall survival in patients with resectable pancreatic cancers. NLR (p = 0.001, HR = 0.538), TNM stage (p = 0.004, HR = 0.593), differentiation (p = 0.011, HR = 0.46), chemotherapy (p = 0.006, HR = 0.516) and Tregs (p = 0.001, HR = 0.558) are identified as independent prognostic markers by multivariate analyses. Interestingly, we also found that high NLR levels combined with a high proportion of Tregs (p < 0.001, HR = 3.521) correlate strongly with worse survival, with a greater than 3.5-fold increased risk of death compared with those with concurrent low levels of NLR and Tregs.

CONCLUSIONS

The preoperative NLR and circulating regulatory T cells are potentially independent prognostic factors for overall survival in resectable pancreatic cancer patients. High NLR levels combined with poor immune state before surgery, as measured by Tregs, are associated with an extremely poor prognosis.

Circulating T cell subsets are altered in individuals with chronic spinal cord injury

Traumatic spinal cord injury (SCI) induces changes in the immune system, both acutely and chronically. To better understand changes in the chronic phase of SCI, we performed a prospective, observational study in a research institute and Department of Physical Medicine and Rehabilitation of an academic medical center to examine immune system parameters, including peripheral immune cell populations, in individuals with chronic SCI as compared to uninjured individuals. Here, we describe the relative frequencies of T cell populations in individuals with chronic SCI as compared to uninjured individuals. We show that the frequency of CD3+ and CD3+ CD4+ T cells are decreased in individuals with chronic SCI, although activated (HLA-DR+) CD4+ T cells are elevated in chronic SCI. We also examined regulatory T cells (T_regs), defined as CD3+ CD4+ CD25+ CD127lo and CCR4+, HLA-DR+ or CCR4+ HLA-DR+. To our knowledge, we provide the first evidence that CCR4+, HLA-DR+ or CCR4+ HLA-DR+ T_regs are expanded in individuals with SCI. These data support additional functional studies of T cells isolated from individuals with chronic SCI, where alterations in T cell homeostasis may contribute to immune dysfunction, such as immunity against infections or the persistence of chronic inflammation.

Regulatory and Effector Helper T-Cell Profile after Nerve Xenografting in the Toll-Like Receptor-Deficient Mice

INTRODUCTION

The balance between regulatory T cells (Tregs) and effector T help cells (Th cells) is critical for the control of adaptive immune response during nerve transplantation. However, whether the homeostasis of immune regulation between Tregs and Th cells requires toll-like receptor (TLR) signaling is unclear. The aim of this study is to profile the distribution of spleen Tregs and Th cells in a mouse model of nerve xenografting in the TLR2 and NF-κB gene knockout mice.

METHODS

The sciatic nerve was taken from a SD rat or an allogeneic mouse and transplanted to a right back leg of recipient C57BL/6, TLR2(-/-), or NF-κB(-/-) mice by subcutaneous transplantation. After 7 days, the T lymphocytes were then isolated from spleen, stained with phenotyping kits, and analyzed by flow cytometry.

RESULTS

The results showed that Tregs were decreased after nerve xenografting in the recipient C57BL/6 mouse. In addition, nerve xenografting also increased the Th1 and Th17 but not the Th2 cell populations. In contrast, amelioration of the Tregs elimination was found in TLR2(-/-) and NF-κB(-/-) mice after transplantation of the nerve xenograft. Moreover, the mice lacking TLR2 or NF-κB showed attenuation of the increase in Th1 and Th17 cells after nerve xenografting.

CONCLUSIONS

TLR signaling is involved in T cell population regulation during tissue transplantation. Knock-out of TLR2 and NF-κB prevented Tregs elimination and inhibited Th1- and Th17-driven immune response after nerve xenografting. This study highlighted the potential of inhibiting TLR signaling to modulate T cell-mediated immune regulation to facilitate tolerance to nerve transplantation.