Arkadia-SKI/SnoN signaling differentially regulates TGF-β-induced iTreg and Th17 cell differentiation

Exosomal lncRNA TUG1 derived from BMSC ameliorate collagen-induced arthritis via BLIMP1-mediated Th17/Treg balance

BACKGROUND

Aberrant differentiation of Th17 cells has been identified as a critical factor in the development of rheumatoid arthritis (RA). BLIMP1 plays a key role in regulating plasma cell differentiation, T helper cell differentiation and Treg cell differentiation. Treatment with exosome injection or bone marrow mesenchymal stem cell (BMSC) transplantation reduce joint damage in RA. But the precise regulatory mechanisms remain unclear.

METHODS

We injected BMSC-derived exosomes into RA mice, and then performed histological analysis on mouse ankle joints. We cultured CD4+ T cells in vitro, then added exosomes with or without si-TUG1 and induced the differentiation of Th17 cells and Treg cells, and then we used flow cytometry to detect the ratio of Th17 cells and Treg cells. Furthermore, we injected exosomes into sh-NC or sh-BLIMP1-treated RA mice, and then performed histological analysis on the ankle joints.

RESULT

The results of our study demonstrate that exosome treatment decreased the proportion of differentiated Th17 cells, while increasing the proportion of Treg cells. And we observed that the Exo si-TUG1 group had an increased proportion of Th17 cells and a decreased proportion of Treg cells. We observed an increase in BLIMP1 expression in both the peripheral blood of mice and in CD4+ T cells cultured in vitro in the Exo group. Conversely, the Exo si-TUG1 group showed a decrease in BLIMP1 expression. Notably, inhibiting BLIMP1 expression led to the reversal of the therapeutic effects of exosomes.

CONCLUSION

Our findings suggest that BMSC-derived exosomes promote the expression of BLIMP1 through Lnc TUG1-carrying exosomes, which may modulate the balance between Th17 cells and Treg cells. This mechanism ultimately alleviates damage caused by RA, suggesting that BMSC-derived exosomes enriched in Lnc TUG1 hold promise as a potential therapeutic approach for treating RA.

SKI Regulates Medullary Thymic Epithelial Cell Differentiation to Control Peripheral T Cell Responses in Mice

The thymus is an important site for the establishment of an appropriate immune response through positive and negative selection of developing T cells. During selection, developing T cells interact with cortical and medullary thymic epithelial cells (TECs), termed cTECs and mTECs, respectively. Using a Foxn1Cre+/-SKIfl/fl mouse model, we found that TEC-specific deletion of SKI reduced the mTEC compartment in the thymus and that tissue-restricted Ag expression in mTECs was altered. This decrease in the medullary area led to a decrease in CD4 thymocyte cellularity; however, mature CD4 cellularity in the spleen remained normal. Interestingly, naive CD4 T cells purified from SKI-deleted mice showed a defect in proliferation in vitro after global TCR stimulation, and these mice were significantly protected from developing experimental autoimmune encephalomyelitis compared with the control mice. Overall, our findings suggest that SKI signaling in the thymus regulates mTEC differentiation and function as well as downstream peripheral T cell responses and provide evidence for targeting SKI in T cell-driven autoimmune diseases such as multiple sclerosis.

BET Inhibitor JQ1 Selectively Reduce Tregs by Upregulating STAT3 and Suppressing PD-1 Expression in Patients with Multiple Myeloma

Multiple myeloma (MM) stands as a prevalent hematological malignancy, primarily incurable, originating from plasma cell clones. MM's progression encompasses genetic abnormalities and disruptions in the bone marrow microenvironment, leading to tumor proliferation, immune dysfunction, and compromised treatment outcomes. Emerging evidence highlights the critical role of regulatory T cells (Tregs) in MM progression, suggesting that targeting Tregs could enhance immune functionality and treatment efficacy. In this study, a notable increase in Treg proportions within MM patients' bone marrow (BM) compared to healthy individuals is observed. Additionally, it is found that the bromodomain and extraterminal domain (BET) inhibitor JQ1 selectively diminishes Treg percentages in MM patients' BM and reduces TGF-β1-induced Tregs. This reduction occurs via inhibiting cell viability and promoting apoptosis. RNA sequencing further indicates that JQ1's inhibitory impact on Tregs likely involves upregulating STAT3 and suppressing PD-1 expression. Collectively, these findings suggest JQ1's potential to modulate Tregs, bolstering the immune response in MM and introducing a promising avenue for MM immunotherapy.

Receptor-activated transcription factors and beyond: multiple modes of Smad2/3-dependent transmission of TGF-β signaling

Transforming growth factor β (TGF-β) is a pleiotropic cytokine that is widely distributed throughout the body. Its receptor proteins, TGF-β type I and type II receptors, are also ubiquitously expressed. Therefore, the regulation of various signaling outputs in a context-dependent manner is a critical issue in this field. Smad proteins were originally identified as signal-activated transcription factors similar to signal transducer and activator of transcription proteins. Smads are activated by serine phosphorylation mediated by intrinsic receptor dual specificity kinases of the TGF-β family, indicating that Smads are receptor-restricted effector molecules downstream of ligands of the TGF-β family. Smad proteins have other functions in addition to transcriptional regulation, including post-transcriptional regulation of micro-RNA processing, pre-mRNA splicing, and m6A methylation. Recent technical advances have identified a novel landscape of Smad-dependent signal transduction, including regulation of mitochondrial function without involving regulation of gene expression. Therefore, Smad proteins are receptor-activated transcription factors and also act as intracellular signaling modulators with multiple modes of function. In this review, we discuss the role of Smad proteins as receptor-activated transcription factors and beyond. We also describe the functional differences between Smad2 and Smad3, two receptor-activated Smad proteins downstream of TGF-β, activin, myostatin, growth and differentiation factor (GDF) 11, and Nodal.

The dynamic shifts of IL-10-producing Th17 and IL-17-producing Treg in health and disease: a crosstalk between ancient "Yin-Yang" theory and modern immunology

The changes in T regulatory cell (Treg) and T helper cell (Th) 17 ratios holds paramount importance in ensuring internal homeostasis and disease progression. Recently, novel subsets of Treg and Th17, namely IL-17-producing Treg and IL-10-producing Th17 have been identified. IL-17-producing Treg and IL-10-producing Th17 are widely considered as the intermediates during Treg/Th17 transformation. These "bi-functional" cells exhibit plasticity and have been demonstrated with important roles in multiple physiological functions and disease processes. Yin and Yang represent opposing aspects of phenomena according to the ancient Chinese philosophy "Yin-Yang" theory. Furthermore, Yin can transform into Yang, and vice versa, under specific conditions. This theory has been widely used to describe the contrasting functions of immune cells and molecules. Therefore, immune-activating populations (Th17, M1 macrophage, etc.) and immune overreaction (inflammation, autoimmunity) can be considered Yang, while immunosuppressive populations (Treg, M2 macrophage, etc.) and immunosuppression (tumor, immunodeficiency) can be considered Yin. However, another important connotation of "Yin-Yang" theory, the conversion between Yin and Yang, has been rarely documented in immune studies. The discovery of IL-17-producing Treg and IL-10-producing Th17 enriches the meaning of "Yin-Yang" theory and further promotes the relationship between ancient "Yin-Yang" theory and modern immunology. Besides, illustrating the functions of IL-17-producing Treg and IL-10-producing Th17 and mechanisms governing their differentiation provides valuable insights into the mechanisms underlying the dynamically changing statement of immune statement in health and diseases.

Microbiota-dependent activation of CD4+ T cells induces CTLA-4 blockade-associated colitis via Fcγ receptors

Immune checkpoint inhibitors can stimulate antitumor immunity but can also induce toxicities termed immune-related adverse events (irAEs). Colitis is a common and severe irAE that can lead to treatment discontinuation. Mechanistic understanding of gut irAEs has been hampered because robust colitis is not observed in laboratory mice treated with checkpoint inhibitors. We report here that this limitation can be overcome by using mice harboring the microbiota of wild-caught mice, which develop overt colitis following treatment with anti-CTLA-4 antibodies. Intestinal inflammation is driven by unrestrained activation of IFNγ-producing CD4+ T cells and depletion of peripherally induced regulatory T cells through Fcγ receptor signaling. Accordingly, anti-CTLA-4 nanobodies that lack an Fc domain can promote antitumor responses without triggering colitis. This work suggests a strategy for mitigating gut irAEs while preserving antitumor stimulating effects of CTLA-4 blockade.

Yiqi Jiedu Xiaoying Decoction Improves Experimental Autoimmune Thyroiditis in Rats by Regulating Th17/Treg Cell Balance

BACKGROUND

Experimental autoimmune thyroiditis (EAT) is a widely used animal model to study the pathogenesis and treatment of autoimmune thyroid diseases. Yiqi Jiedu Xiaoying Decoction (YJXD) is a traditional Chinese medicine formula with potential immunomodulatory effects. In this study, we investigated the therapeutic effects of YJXD on EAT in rats and explored its underlying mechanisms.

METHODS

Female Wistar rats were induced to develop EAT by immunization with thyroglobulin (Tg) and taken sodium iodide water (0.05%) and then treated with YJXD or sodium selenite. HE staining was used to observe the pathological changes of thyroid tissue in EAT rats. Th17 and Treg cell frequencies were analyzed by flow cytometry, and the expression levels of Th17- and Treg-related cytokines and thyroid autoantibody were determined by enzyme-linked immunosorbent assay (ELISA). The expression of Th17- and Treg-related transcriptional factors was detected by real-time polymerase chain reaction (RT-PCR) and Immunohistochemistry (IHC).

RESULTS

Our results demonstrated that treatment with YJXD significantly attenuated the severity of EAT, as evidenced by reduced thyroid gland inflammatory infiltration and decreased serum thyroglobulin autoantibody levels. Importantly, YJXD treatment effectively modulated the Th17/Treg cell balance by suppressing Th17 cell differentiation and promoting Treg cell expansion. Moreover, YJXD was also found to regulate the expression levels of Th17- and Treg-related cytokines and transcriptional factors, further supporting its immunomodulatory effects in EAT.

CONCLUSION

YJXD exerted therapeutic effects on EAT by regulating the Th17/Treg cell balance, modulating the production of Th17- and Treg-related cytokines and the expression of transcriptional factors.

Dexamethasone alleviates pulmonary sarcoidosis by regulating the TGF-β/Smad3 signaling to promote Th17/Treg cell rebalance

Pulmonary sarcoidosis is an immune-mediated disorder closely related to Th17/Treg cell imbalance. Dexamethasone has been shown to regulate inflammation and immune responses in sarcoidosis patients. However, the underlying mechanisms of dexamethasone regulating Th17/Treg balance in sarcoidosis remain elusive. Herein, we elucidated the function role of TGF-β/Smad3 signaling in pulmonary sarcoidosis development and explored the underlying mechanism of dexamethasone in treating pulmonary sarcoidosis. We found that the TGF-β/Smad3 pathway was inactivated in pulmonary sarcoidosis patients. Propionibacterium acnes (PA) induced mouse model was generated to investigate the function of TGF-β/Smad3 signaling in vivo. Data indicated that IL17A inhibition with neutralizing antibody and activation of TGF-β/Smad3 signaling with SRI-011381 alleviated granuloma formation in the sarcoidosis mouse model. Moreover, we revealed that the Th17/Treg cell ratio was increased with PA treatment in mouse bronchoalveolar lavage fluid (BALF) and peripheral blood. The concentration of cytokines produced by Th17 cells (IL-17A, IL-23) was up-regulated in the BALF of PA-treated mice, while those produced by Tregs (IL-10, TGF-β1) presented significant reduction. The treatment of IL-17A neutralizing antibody or SRI-011381 was demonstrated to rescue the PA-induced changes in the concentration of IL-17A, IL-23, IL-10, and TGF-β1. Additionally, we demonstrated that dexamethasone treatment activated the TGF-β/Smad3 signaling in the lung tissues of pulmonary sarcoidosis mice. Dexamethasone was also revealed to promote the rebalancing of the Th17/Treg ratio and attenuated the granuloma formation in pulmonary sarcoidosis. In conclusion, dexamethasone activates the TGF-β/Smad3 signaling and induces Th17/Treg rebalance, alleviating pulmonary sarcoidosis, which suggests the potential of dexamethasone in treating pulmonary sarcoidosis.

Preserving genome integrity: The vital role of SUMO-targeted ubiquitin ligases

Various post-translational modifications (PTMs) collaboratively fine-tune protein activities. SUMO-targeted ubiquitin E3 ligases (STUbLs) emerge as specialized enzymes that recognize SUMO-modified substrates through SUMO-interaction motifs and subsequently ubiquitinate them via the RING domain, thereby bridging the SUMO and ubiquitin signaling pathways. STUbLs participate in a wide array of molecular processes, including cell cycle regulation, DNA repair, replication, and mitosis, operating under both normal conditions and in response to challenges such as genotoxic stress. Their ability to catalyze various types of ubiquitin chains results in diverse proteolytic and non-proteolytic outcomes for target substrates. Importantly, STUbLs are strategically positioned in close proximity to SUMO proteases and deubiquitinases (DUBs), ensuring precise and dynamic control over their target proteins. In this review, we provide insights into the unique properties and indispensable roles of STUbLs, with a particular emphasis on their significance in preserving genome integrity in humans.

Shaoyao decoction alleviates TNBS-induced ulcerative colitis by decreasing inflammation and balancing the homeostasis of Th17/Treg cells

BACKGROUND

Ulcerative colitis (UC) is a persistent and non-specific inflammatory condition that mainly affects the bowels and has challenging treatment. UC has a growing incidence and significantly affects the well-being of patients. Many medications used to treat UC can disrupt the metabolism and immune system homeostasis, frequently leading to significant adverse effects. Hence, exploring alternative therapies, such as traditional Chinese medicine and probiotics, has recently emerged as a primary research hotspot owing to their safety. Although the therapeutic mechanism of Shaoyao decoction has not been clarified, it has demonstrated a beneficial clinical effect on UC.

AIM

This study aimed to assess the effect of Shaoyao decoction on a rat model of UC and investigate its underlying mechanisms.

METHODS

The rat model of UC was induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS). The extent of damage to the intestines was assessed using the disease activity index (DAI), colonic mucosa damage index (CMDI), and histological scores. Immunohistochemistry was employed to detect the tissue levels of interleukin (IL)-17, transforming growth factor (TGF)-β1, and IL-10. Additionally, the proportion of Th17 and Treg cells was detected using flow cytometry. In colon tissue, the levels of forkhead box (Fox)p3, RAR-related orphan receptor (ROR)γt, IL-6, p-STAT3, and STAT3 proteins were quantified by Western blotting.

RESULTS

Treatment with Shaoyao decoction enhanced the overall health of rats and reduced colonic damage. Additionally, Shaoyao decoction significantly alleviated the severity of DAI, CMDI, and HS. The proportion of Th17 cells was reduced, and the proportion of Treg cells was increased by Shaoyao decoction. The expression of IL-17 and RORγt was suppressed by Shaoyao decoction, while the expression of IL-10, TGF-β1, and Foxp3 was increased. The expression of IL-6, p-STAT3, and STAT3 was decreased by Shaoyao decoction.

CONCLUSION

The Shaoyao decoction alleviates the symptoms of TNBS-induced UC by decreasing inflammation and mitigating intestinal damage while preserving the balance between Th17 and Treg. Shaoyao decoction modulates the IL-6/STAT3 axis, thereby regulating the balance between Th17 and Treg cells.

Bifidobacterium longum subsp. infantis B6MNI Alleviates Collagen-Induced Arthritis in Rats via Regulating 5-HIAA and Pim-1/JAK/STAT3 Inflammation Pathways

The immunomodulatory potential of certain bacterial strains suggests that they could be beneficial in the treatment of rheumatoid arthritis (RA). In this study, we investigated the effects of Bifidobacterium longum subsp. infantis B6MNI on the progression of collagen-induced arthritis (CIA) in rats as well as its influence on the gut microbiota and fecal metabolites. Forty-eight female Wistar rats were divided into six groups that included a B6MNI group with CIA and intragastrically administered B. longum subsp. infantis B6MNI (109 CFU/day/rat), a control group (CON), and a CIA group, both of which were intracardiacally administered the same volume of saline. Rats were sacrificed after short-term (ST, 4 weeks) or long-term (LT, 6 weeks) administration. The results indicate that B. longum subsp. infantis B6MNI can modulate the gut microbiota and fecal metabolites, including 5-hydroxyindole-3-acetic acid (5-HIAA), which in turn impacts the expression of Pim-1 and immune cell differentiation, then through the JAK-STAT3 pathway affects joint inflammation, regulates osteoclast differentiation factors, and delays the progression of RA. Our results also suggest that B. longum subsp. infantis B6MNI is most efficacious for the early or middle stages of RA.

Regulatory T cells in the face of the intestinal microbiota

Regulatory T cells (Treg cells) are key players in ensuring a peaceful coexistence with microorganisms and food antigens at intestinal borders. Startling new information has appeared in recent years on their diversity, the importance of the transcription factor FOXP3, how T cell receptors influence their fate and the unexpected and varied cellular partners that influence Treg cell homeostatic setpoints. We also revisit some tenets, maintained by the echo chambers of Reviews, that rest on uncertain foundations or are a subject of debate.

Intricacies of TGF-β signaling in Treg and Th17 cell biology

Balanced immunity is pivotal for health and homeostasis. CD4+ helper T (Th) cells are central to the balance between immune tolerance and immune rejection. Th cells adopt distinct functions to maintain tolerance and clear pathogens. Dysregulation of Th cell function often leads to maladies, including autoimmunity, inflammatory disease, cancer, and infection. Regulatory T (Treg) and Th17 cells are critical Th cell types involved in immune tolerance, homeostasis, pathogenicity, and pathogen clearance. It is therefore critical to understand how Treg and Th17 cells are regulated in health and disease. Cytokines are instrumental in directing Treg and Th17 cell function. The evolutionarily conserved TGF-β (transforming growth factor-β) cytokine superfamily is of particular interest because it is central to the biology of both Treg cells that are predominantly immunosuppressive and Th17 cells that can be proinflammatory, pathogenic, and immune regulatory. How TGF-β superfamily members and their intricate signaling pathways regulate Treg and Th17 cell function is a question that has been intensely investigated for two decades. Here, we introduce the fundamental biology of TGF-β superfamily signaling, Treg cells, and Th17 cells and discuss in detail how the TGF-β superfamily contributes to Treg and Th17 cell biology through complex yet ordered and cooperative signaling networks.

Biologic Mechanisms of Macrophage Phenotypes Responding to Infection and the Novel Therapies to Moderate Inflammation

Pro-inflammatory and anti-inflammatory types are the main phenotypes of the macrophage, which are commonly notified as M1 and M2, respectively. The alteration of macrophage phenotypes and the progression of inflammation are intimately associated; both phenotypes usually coexist throughout the whole inflammation stage, involving the transduction of intracellular signals and the secretion of extracellular cytokines. This paper aims to address the interaction of macrophages and surrounding cells and tissues with inflammation-related diseases and clarify the crosstalk of signal pathways relevant to the phenotypic metamorphosis of macrophages. On these bases, some novel therapeutic methods are proposed for regulating inflammation through monitoring the transition of macrophage phenotypes so as to prevent the negative effects of antibiotic drugs utilized in the long term in the clinic. This information will be quite beneficial for the diagnosis and treatment of inflammation-related diseases like pneumonia and other disorders involving macrophages.

Induced regulatory T cells modified by knocking down T-bet in combination with ectopic expression of inhibitory cytokines effectively protect Graft-versus-Host Disease

Induced regulatory T (iT_reg) cells play a vital role in immune tolerance and in controlling chronic inflammation. Generated in the periphery, iT_reg cells are suitable for responding to alloantigens and preventing transplant rejection. Nevertheless, their clinical application has been impeded by the plasticity and instability attributed to the loss of Foxp3 expression, raising concerns that iT_reg may be converted to T_eff cells and even exert a pathogenic effect. Herein, second-generation short hairpin RNAs (shRNAs) loaded with three pairs of small interfering RNAs (siRNAs) were utilized to target the transcription factor T-bet. In addition, two immunosuppressive cytokines, namely transforming growth factor beta (TGF-β) and interleukin-10 (IL-10), were constitutively expressed. This novel engineering strategy allowed the generation of stably-induced iT_reg cells (SI T_reg), which maintained the expression of Foxp3 even in an unfavorable environment and exerted potent immunosuppressive functions in vitro. Furthermore, SI T_reg cells demonstrated an effector transcriptional profile. Finally, SI T_reg showed a significant protective effect against G_VHD-related deaths in a xenotransplantation model. Collectively, these results signify that SI T_reg cells hold great promise for future clinical application and offer a rational therapeutic approach for transplant rejection.

N-butyldeoxynojirimycin (miglustat) ameliorates pulmonary fibrosis through inhibition of nuclear translocation of Smad2/3

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease. The disease involves excessive accumulation of fibroblasts and myofibroblasts, and myofibroblasts differentiated by pro-fibrotic factors promote the deposition of extracellular matrix proteins such as collagen and fibronectin. Transforming growth factor-β1 is a pro-fibrotic factor that promotes fibroblast-to-myofibroblast differentiation (FMD). Therefore, inhibition of FMD may be an effective strategy for IPF treatment. In this study, we screened the anti-FMD effects of various iminosugars and showed that some compounds, including N-butyldeoxynojirimycin (NB-DNJ, miglustat, an inhibitor of glucosylceramide synthase (GCS)), a clinically approved drug for treating Niemann-Pick disease type C and Gaucher disease type 1, inhibited TGF-β1-induced FMD by inhibiting the nuclear translocation of Smad2/3. N-butyldeoxygalactonojirimycin having GCS inhibitory effect did not attenuate the TGF-β1-induced FMD, suggesting that NB-DNJ exerts the anti-FMD effects by GCS inhibitory effect independent manner. N-butyldeoxynojirimycin did not inhibit TGF-β1-induced Smad2/3 phosphorylation. In a mouse model of bleomycin (BLM)-induced pulmonary fibrosis, intratracheal or oral administration of NB-DNJ at an early fibrotic stage markedly ameliorated lung injury and deterioration of respiratory functions, such as specific airway resistance, tidal volume, and peak expiratory flow. Furthermore, the anti-fibrotic effects of NB-DNJ in the BLM-induced lung injury model were similar to those of pirfenidone and nintedanib, which are clinically approved drugs for the treatment of IPF. These results suggest that NB-DNJ may be effective for IPF treatment.

Assessment of the Potential Role of Selected Single Nucleotide Polymorphisms (SNPs) of Genes Related to the Functioning of Regulatory T Cells in the Pathogenesis of Psoriasis

Recent studies have indicated a key role of the impaired suppressive capacity of regulatory T cells (Tregs) in psoriasis (PsO) pathogenesis. However, the genetic background of Treg dysfunctions remains unknown. The aim of this study was to evaluate the association of PsO development with selected single nucleotide polymorphisms (SNPs) of genes in which protein products play a significant role in the regulation of differentiation and function of Tregs. There were three study groups in our research and each consisted of different unrelated patients and controls: 192 PsO patients and 5605 healthy volunteers in the microarray genotyping group, 150 PsO patients and 173 controls in the ARMS-PCR method group, and 6 PsO patients and 6 healthy volunteers in the expression analysis group. The DNA microarrays analysis (283 SNPs of 57 genes) and ARMS-PCR method (8 SNPs in 7 genes) were used to determine the frequency of occurrence of SNPs in selected genes. The mRNA expression of selected genes was determined in skin samples. There were statistically significant differences in the allele frequencies of four SNPs in three genes (TNF, IL12RB2, and IL12B) between early-onset PsO patients and controls. The lowest p-value was observed for rs3093662 (TNF), and the G allele carriers had a 2.73 times higher risk of developing early-onset PsO. Moreover, the study revealed significant differences in the frequency of SNPs and their influence on PsO development between early- and late-onset PsO. Based on the ARMS-PCR method, the association between some polymorphisms of four genes (IL4, IL10, TGFB1, and STAT3) and the risk of developing PsO was noticed. Psoriatic lesions were characterized with a lower mRNA expression of FOXP3, CTLA4, and IL2, and a higher expression of TNF and IL1A in comparison with unaffected skin. In conclusion, the genetic background associated with properly functioning Tregs seems to play a significant role in PsO pathogenesis and could have diagnostic value.

Regulation of T Cell Activation and Metabolism by Transforming Growth Factor-Beta

Transforming growth factor beta (TGFβ) receptor signalling regulates T cell development, differentiation and effector function. Expression of the immune-associated isoform of this cytokine, TGFβ1, is absolutely required for the maintenance of immunological tolerance in both mice and humans, whilst context-dependent TGFβ1 signalling regulates the differentiation of both anti- and pro-inflammatory T cell effector populations. Thus, distinct TGFβ-dependent T cell responses are implicated in the suppression or initiation of inflammatory and autoimmune diseases. In cancer settings, TGFβ signals contribute to the blockade of anti-tumour immune responses and disease progression. Given the key functions of TGFβ in the regulation of immune responses and the potential for therapeutic targeting of TGFβ-dependent pathways, the mechanisms underpinning these pleiotropic effects have been the subject of much investigation. This review focuses on accumulating evidence suggesting that modulation of T cell metabolism represents a major mechanism by which TGFβ influences T cell immunity.

MicroRNA-181a regulates Treg functions via TGF-β1/Smad axis in the spleen of mice with acute gouty arthritis induced by MSU crystals

Regulatory T cells (Tregs) play critical roles in restricting inflammatory pathogenesis and limiting undesirable Th2 response to environmental allergens. However, the role of miR-181a in regulating acute gouty arthritis (AGA) and Treg function remains unclear. This study aimed to investigate the potential roles of miR-181a in Treg immunity and the associated signaling pathway in the AGA mouse model. A solution with monosodium urate (MSU) crystals was injected into the joint tissue of mice to induce AGA. ELISA was used to examine inflammatory factors in blood samples, and flow cytometry was used to analyze Treg profile in mice with MSU-induced AGA. Cell proliferation and viability were assessed by CCK-8 assay. TGF-β1/Smad signaling activation was detected by western blot. We found that miR-181a expression showed a positive correlation with the changes of splenic Tregs percentage in AGA mice. miR-181a regulated the TGF-β1/Smad axis, since the transfection of miR-181a mimic increased the level of TGF-β1 and the phosphorylation of Smad2/3 in Tregs in AGA mice. Additionally, miR-181a mimic also promoted responses of Tregs via TGF-β1 in vitro and in vivo. Our work uncovered a vital role of miR-181a in the immune function of Treg cells by mediating the activity of the TGF-β1/Smad pathway in the AGA mouse model induced by MSU.

Proteomics reveals unique identities of human TGF-β-induced and thymus-derived CD4+ regulatory T cells

The CD4+ regulatory T (Treg) cell lineage, defined by FOXP3 expression, comprises thymus-derived (t)Treg cells and peripherally induced (p)Treg cells. As a model for Treg cells, studies employ TGF-β-induced (i)Treg cells generated from CD4+ conventional T (Tconv) cells in vitro. Here, we describe how human iTreg cells relate to human blood-derived tTreg and Tconv cells according to proteomic analysis. Each of these cell populations had a unique protein expression pattern. iTreg cells had very limited overlap in protein expression with tTreg cells, regardless of cell activation status and instead shared signaling and metabolic proteins with Tconv cells. tTreg cells had a uniquely modest response to CD3/CD28-mediated stimulation. As a benchmark, we used a previously defined proteomic signature that discerns ex vivo naïve and effector Treg cells from Tconv cells and includes conserved Treg cell properties. iTreg cells largely lacked this Treg cell core signature and highly expressed e.g. STAT4 and NFATC2, which may contribute to inflammatory responses. We also used a proteomic signature that distinguishes ex vivo effector Treg cells from Tconv cells and naïve Treg cells. iTreg cells contained part of this effector Treg cell signature, suggesting acquisition of pTreg cell features. In conclusion, iTreg cells are distinct from tTreg cells and share limited features with ex vivo Treg cells at the proteomic level.

Effects of oral administration and intravenous injection of polygalacturonic acid on the immunomodulation and gut microbiota in UC mice

This study aimed to compare the differences between oral administration and intravenous injection of polygalacturonic acid (PGA) in the regulation of immune and intestinal microflora in ulcerative colitis (UC) mice. PGA was administered orally or intravenously. PGA in the high-dose ig group was the most effective in treating UC by increasing colon length and downregulating disease activity index, histopathological score and proinflammatory cytokine levels. In spleen, the efficacy of PGA on restoring Th17/Treg balance in the high-dose iv group was better than that in the high-dose ig group, the opposite was observed in the lamina propria. The level of colonic IL-17A in the high-dose ig group was lower than that in the high-dose iv group, the opposite was observed for that of colonic IL-10. Western blot and immunohistochemistry analysis revealed that PGA in the high-dose ig group decreased the protein expression of RORγt, and increased that of FOXP3. Furthermore, PGA in the high-dose ig group was more effective than that in the high-dose iv group in improving the intestinal microflora structure. Our results suggest that in immune regulation, oral PGA is more effective in the lamina propria and gut microbiota while intravenous PGA is more effective in the spleen.

Regulatory T Cells: Regulation of Identity and Function

T regulatory cells suppress a variety of immune responses to self-antigens and play a role in peripheral tolerance maintenance by limiting autoimmune disorders, and other pathological immune responses such as limiting immune reactivity to oncoprotein encoded antigens. Forkhead box P3 (FOXP3) expression is required for Treg stability and affects functional activity. Mutations in the master regulator FOXP3 and related components have been linked to autoimmune diseases in humans, such as IPEX, and a scurfy-like phenotype in mice. Several lines of evidence indicate that Treg use a variety of immunosuppressive mechanisms to limit an immune response by targeting effector cells, including secretion of immunoregulatory cytokines, granzyme/perforin-mediated cell cytolysis, metabolic perturbation, directing the maturation and function of antigen-presenting cells (APC) and secretion of extracellular vesicles for the development of immunological tolerance. In this review, several regulatory mechanisms have been highlighted and discussed.