IL-21 is produced by Th17 cells and drives IL-17 production in a STAT3-dependent manner

Roles of Menin in T cell differentiation and function: Current knowledge and perspectives

The commitment to specific T lymphocytes (T cell) lineages is governed by distinct transcription factors, whose expression is modulated through epigenetic mechanisms. Unravelling these epigenetic mechanisms that regulate T cell differentiation and function holds significant importance for understanding T cells. Menin, a multifunctional scaffolding protein, is implicated in various cellular processes, such as cell proliferation, cell cycle control, DNA repair and transcriptional regulation, primarily through epigenetic mechanisms. Existing research indicates Menin's impact on T cell differentiation and function, while a comprehensive and systematic review is currently lacking to consolidate these findings. In the current review, we have highlighted recent studies on the role of Menin in T cell differentiation and function, focusing mainly on its impact on the memory Th2 maintenance, Th17 differentiation and maintenance, CD4+ T cell senescence, and effector CD8+ T cell survival. Considering Menin's crucial function in maintaining effector T cell function, the potential of inhibiting Menin activity in mitigating inflammatory diseases associated with excessive T cell activation has also been emphasised.

Machine learning unveils an immune-related DNA methylation profile in germline DNA from breast cancer patients

BACKGROUND

There is an unmet need for precise biomarkers for early non-invasive breast cancer detection. Here, we aimed to identify blood-based DNA methylation biomarkers that are associated with breast cancer.

METHODS

DNA methylation profiling was performed for 524 Asian Chinese individuals, comprising 256 breast cancer patients and 268 age-matched healthy controls, using the Infinium MethylationEPIC array. Feature selection was applied to 649,688 CpG sites in the training set. Predictive models were built by training three machine learning models, with performance evaluated on an independent test set. Enrichment analysis to identify transcription factors binding to regions associated with the selected CpG sites and pathway analysis for genes located nearby were conducted.

RESULTS

A methylation profile comprising 51 CpGs was identified that effectively distinguishes breast cancer patients from healthy controls achieving an AUC of 0.823 on an independent test set. Notably, it outperformed all four previously reported breast cancer-associated methylation profiles. Enrichment analysis revealed enrichment of genomic loci associated with the binding of immune modulating AP-1 transcription factors, while pathway analysis of nearby genes showed an overrepresentation of immune-related pathways.

CONCLUSION

This study has identified a breast cancer-associated methylation profile that is immune-related to potential for early cancer detection.

CD4+T and CD8+T Cells in Uterus Exhibit Both Selective Dysfunction and Residency Signatures

Unlike T cells in other tissues, uterine T cells must balance strong immune defense against pathogens with tolerance to semiallogeneic fetus. Our previous study fully elucidated the characteristics of γδT cells in nonpregnant uterus and the mechanism modulated by estrogen. However, comprehensive knowledge of the immunological properties of αβT (including CD4+T cells and CD8+T) cells in nonpregnancy uterus has not been acquired. In this study, we fully compared the immunological properties of αβT cells between uterus and blood using mouse and human sample. It showed that most of CD4+T cells and CD8+T cells in murine uterus and human endometrium were tissue resident memory T cells which highly expressed tissue residence markers CD69 and/or CD103. In addition, both CD4+T cells and CD8+T cells in uterus highly expressed inhibitory molecular PD-1 and cytokine IFN-γ. Uterine CD4+T cells highly expressed IL-17 and modulated by transcription factor pSTAT3. Moreover, we compared the similarities and differences between human and murine uterine T cell phenotype. Together, uterine CD4+T cells and CD8+ cells exhibited a unique mixed signature of T cell dysfunction, activation, and effector function which enabled them to balance strong immune defense against pathogens with tolerance to fetus. Our study fully elucidated the unique immunologic properties of uterine CD4+T and CD8+T cells and provided a base for further investigation of functions.

RORγt inverse agonist TF-S14 inhibits Th17 cytokines and prolongs skin allograft survival in sensitized mice

Chronic antibody mediated rejection (AMR) is the major cause of solid organ graft rejection. Th17 contributes to AMR through the secretion of IL17A, IL21 and IL22. These cytokines promote neutrophilic infiltration, B cell proliferation and donor specific antibodies (DSAs) production. In the current study we investigated the role of Th17 in transplant sensitization. Additionally, we investigated the therapeutic potential of novel inverse agonists of the retinoic acid receptor-related orphan receptor gamma t (RORγt) in the treatment of skin allograft rejection in sensitized mice. Our results show that RORγt inverse agonists reduce cytokine production in human Th17 cells in vitro. In mice, we demonstrate that the RORγt inverse agonist TF-S14 reduces Th17 signature cytokines in vitro and in vivo and leads to blocking neutrophilic infiltration to skin allografts, inhibition of the B-cell differentiation, and the reduction of de novo IgG3 DSAs production. Finally, we show that TF-S14 prolongs the survival of a total mismatch grafts in sensitized mice. In conclusion, RORγt inverse agonists offer a therapeutic intervention through a novel mechanism to treat rejection in highly sensitized patients.

Control of adaptive immunity by pattern recognition receptors

One of the most significant conceptual advances in immunology in recent history is the recognition that signals from the innate immune system are required for induction of adaptive immune responses. Two breakthroughs were critical in establishing this paradigm: the identification of dendritic cells (DCs) as the cellular link between innate and adaptive immunity and the discovery of pattern recognition receptors (PRRs) as a molecular link that controls innate immune activation as well as DC function. Here, we recount the key events leading to these discoveries and discuss our current understanding of how PRRs shape adaptive immune responses, both indirectly through control of DC function and directly through control of lymphocyte function. In this context, we provide a conceptual framework for how variation in the signals generated by PRR activation, in DCs or other cell types, can influence T cell differentiation and shape the ensuing adaptive immune response.

The Immunology of Psoriasis-Current Concepts in Pathogenesis

Psoriasis is one of the most common inflammatory skin diseases with a chronic, relapsing-remitting course. The last decades of intense research uncovered a pathological network of interactions between immune cells and other types of cells in the pathogenesis of psoriasis. Emerging evidence indicates that dendritic cells, TH17 cells, and keratinocytes constitute a pathogenic triad in psoriasis. Dendritic cells produce TNF-α and IL-23 to promote T cell differentiation toward TH17 cells that produce key psoriatic cytokines IL-17, IFN-γ, and IL-22. Their activity results in skin inflammation and activation and hyperproliferation of keratinocytes. In addition, other cells and signaling pathways are implicated in the pathogenesis of psoriasis, including TH9 cells, TH22 cells, CD8+ cytotoxic cells, neutrophils, γδ T cells, and cytokines and chemokines secreted by them. New insights from high-throughput analysis of lesional skin identified novel signaling pathways and cell populations involved in the pathogenesis. These studies not only expanded our knowledge about the mechanisms of immune response and the pathogenesis of psoriasis but also resulted in a revolution in the clinical management of patients with psoriasis. Thus, understanding the mechanisms of immune response in psoriatic inflammation is crucial for further studies, the development of novel therapeutic strategies, and the clinical management of psoriasis patients. The aim of the review was to comprehensively present the dysregulation of immune response in psoriasis with an emphasis on recent findings. Here, we described the role of immune cells, including T cells, B cells, dendritic cells, neutrophils, monocytes, mast cells, and innate lymphoid cells (ILCs), as well as non-immune cells, including keratinocytes, fibroblasts, endothelial cells, and platelets in the initiation, development, and progression of psoriasis.

Anti-aquaporin-4 immune complex stimulates complement-dependent Th17 cytokine release in neuromyelitis optica spectrum disorders

Proinflammatory cytokines, such as (IL: interleukin) IL-6 and IL-17A, and complement fixation are critical in the immunopathogenesis of neuromyelitis optica spectrum disorders (NMOSD). Blocking the IL-6 receptor or the C5 complement pathway reduces relapse risk. However, the role of interleukin (IL)-6 and complement in aquaporin-4 (AQP4) autoimmunity remains unclear. To investigate the role of the anti-AQP4 immunoglobulin (AQP4-IgG)/AQP4 immunocomplex on the induction and profile of ex vivo cytokine and surface marker expression in peripheral blood mononuclear cells (PBMC) culture. Isolated PBMCs obtained from 18 patients with AQP4-IgG-seropositive-NMOSD (8 treatment-naive, 10 rituximab-treated) or ten healthy controls were cultured with AQP4-immunocomplex with or without complement. Changes in PBMC surface markers and cytokine expression were profiled using flow cytometry and ELISA. PBMCs derived from treatment-naive NMOSD patients stimulated with a complex mixture of serum complement proteins produced significant elevations of IL-17A and IL-6. Rituximab-treated patients also exhibited higher IL-6 but not IL-17A release. IL-6 and IL-17A elevations are not observed without complement. Co-stimulation of PBMCs with AQP4-IgG/AQP4 immunocomplex and complement prompts a Th17-biased response consistent with the inflammatory paradigm observed in NMOSD. A possible inflammation model is proposed via antigen-specific autoreactive peripheral blood cells, including NK/NKT cells.

IL-17 and IL-21: Their Immunobiology and Therapeutic Potentials

Studies over the last 2 decades have identified IL-17 and IL-21 as key cytokines in the modulation of a wide range of immune responses. IL-17 serves as a critical defender against bacterial and fungal pathogens, while maintaining symbiotic relationships with commensal microbiota. However, alterations in its levels can lead to chronic inflammation and autoimmunity. IL-21, on the other hand, bridges the adaptive and innate immune responses, and its imbalance is implicated in autoimmune diseases and cancer, highlighting its important role in both health and disease. Delving into the intricacies of these cytokines not only opens new avenues for understanding the immune system, but also promises innovative advances in the development of therapeutic strategies for numerous diseases. In this review, we will discuss an updated view of the immunobiology and therapeutic potential of IL-17 and IL-21.

The identification and expression of an interleukin-21 receptor in large yellow croaker (Larimichthys crocea)

BACKGROUND

We identified a homologue of IL-21R (LcIL-21R) in large yellow croaker (Larimichthys crocea, Lc). Our investigation focused on understanding the molecular structural features and immune function of LcIL-21R.

METHODS

We cloned the LcIL-21R gene from the genome of Larimichthys crocea by RT‒PCR, and the molecular and structural characteristics of LcIL-21R were analyzed by a series of protein analysis tools. We used real-time PCR to investigate the tissue distribution of LcIL-21R, and LcIL-21R gene expression regulation was also measured in head kidney leukocytes under trivalent bacterial vaccine or poly (I:C) stimulation.

RESULTS

The open reading frame (ORF) of the LcIL-21R gene is 1629 bp long and encodes a precursor protein of 542 amino acids (aa), with a 23-aa signal peptide and a 519-aa mature peptide containing four putative N-glycosylation sites. LcIL-21R has two fibronectin type III (FNIII)-like domains (D1 and D2), a transmembrane domain, and a cytoplasmic region. A conserved WSXWS motif was also found in the D2 domain. The predicted structure of the extracellular region of LcIL-21R (LcIL-21R-Ex) is highly similar to that of human IL-21R. LcIL-21R was constitutively expressed in all tissues examined, and LcIL-21R mRNA levels were increased in the head kidney and spleen upon inactivated trivalent bacterial vaccine or poly(I:C) stimulation.

CONCLUSIONS

Our results suggest that LcIL-21R shares structural and functional properties with IL-21Rs found in other vertebrates, indicating its potential involvement in the IL-21-mediated immune response to pathogenic infections. These findings contribute to our understanding of the evolutionary conservation of IL-21 signaling and its role in the immune system.

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.

High-Density IgG4+ Plasma Cells Infiltration Is Associated With Fibroplasia in Fibrostenotic Crohn's Disease

Transmural fibrosis and stricture formation are key pathogenic processes for Crohn's disease that underlies clinical refractoriness, resulting in severe morbidity. The mechanisms for fibroplasia in Crohn's are not fully elucidated. In this study, we identified a cohort of refractory Crohn's disease with surgically resected bowel specimens including cases with bowel stricture and age-/sex-matched refractory disease without bowel stricture. Via immunohistochemistry, density and distribution of IgG4+ plasma cells in resected cases were analyzed. The histologic severity of fibrosis and association with gross evidence of stricture formation and IgG4+ plasma cells were comprehensively analyzed. Our results showed that density of IgG4+ plasma cells/high-power field (IgG4+ PCs/HPF) was significantly associated with increasing histologic fibrosis score (15 IgG4+ PCs/HPF in specimens with fibrosis score 0 vs 31 IgG4+ PC/HPF in fibrosis score 2 and 3, P = .039). Patients with gross evidence of stricture had significantly higher fibrosis scores compared to those without gross evidence of stricture (P = .044). There was a trend that mean IgG4+ plasma cell count was higher in Crohn's disease with gross stricture formation (P = .26), although it did not reach statistical significance (likely due to multiple pathogenesis events involved in bowel stricture formation besides IgG4+ plasma cells; such as transmural fibrosis, muscular hypertrophy, transmural ulcer/scar formation, and muscular-neural dysfunction). Our findings indicate IgG4+ plasma cells are associated with increasing histologic fibrosis in Crohn's. Further research is needed to establish a role for IgG4+ plasma cells in fibroplasia with an eye toward potential medical therapies targeting IgG4+ plasma cells to prevent transmural fibrosis.

IL-6 and IL-27 play both distinct and redundant roles in regulating CD4 T-cell responses during chronic viral infection

The IL-6 cytokine family signals through the common signal transduction molecule gp130 combined with a cytokine-specific receptor. Gp130 signaling on CD4 T cells is vital in controlling chronic infection of mice with lymphocytic choriomeningitis virus clone 13 (LCMV Cl13), but the precise role of individual members of the IL-6 cytokine family is not fully understood. Transcriptional analysis highlighted the importance of gp130 signaling in promoting key processes in CD4 T cells after LCMV Cl13 infection, particularly genes associated with T follicular helper (Tfh) cell differentiation and IL-21 production. Further, Il27r-/-Il6ra-/- mice failed to generate antibody or CD8 T-cell immunity and to control LCMV Cl13. Transcriptomics and phenotypic analyses of Il27r-/-Il6ra-/- Tfh cells revealed that IL-6R and IL-27R signaling was required to activate key pathways within CD4 T cells. IL-6 and IL-27 signaling has distinct and overlapping roles, with IL-6 regulating Tfh differentiation, IL-27 regulating CD4 T cell survival, and both redundantly promoting IL-21.

Recent Thymic Emigrants Require RBPJ-Dependent Notch Signaling to Transition into Functionally Mature Naive T Cells

Recent thymic emigrant (RTE) cells are nascent T cells that continue their post-thymic maturation in the periphery and dominate T cell immune responses in early life and in adults having undergone lymphodepletion regimens. However, the events that govern their maturation and their functionality as they transition to mature naive T cells have not been clearly defined. Using RBPJind mice, we were able to identify different stages of RTE maturation and interrogate their immune function using a T cell transfer model of colitis. As CD45RBlo RTE cells mature, they transition through a CD45RBint immature naive T (INT) cell population that is more immunocompetent but shows a bias toward IL-17 production at the expense of IFN-γ. Additionally, the levels of IFN-γ and IL-17 produced in INT cells are highly dependent on whether Notch signals are received during INT cell maturation or during their effector function. IL-17 production by INT cells showed a total requirement for Notch signaling. Loss of Notch signaling at any stage of INT cells resulted in an impaired colitogenic effect of INT cells. RNA sequencing of INT cells that had matured in the absence of Notch signals showed a reduced inflammatory profile compared with Notch-responsive INT cells. Overall, we have elucidated a previously unknown INT cell stage, revealed its intrinsic bias toward IL-17 production, and demonstrated a role for Notch signaling in INT cell peripheral maturation and effector function in the context of a T cell transfer model of colitis.

A structural blueprint for interleukin-21 signal modulation

Interleukin-21 (IL-21) plays a critical role in generating immunological memory by promoting the germinal center reaction, yet clinical use of IL-21 remains challenging because of its pleiotropy and association with autoimmune disease. To better understand the structural basis of IL-21 signaling, we determine the structure of the IL-21-IL-21R-γc ternary signaling complex by X-ray crystallography and a structure of a dimer of trimeric complexes using cryo-electron microscopy. Guided by the structure, we design analogs of IL-21 by introducing substitutions to the IL-21-γc interface. These IL-21 analogs act as partial agonists that modulate downstream activation of pS6, pSTAT3, and pSTAT1. These analogs exhibit differential activity on T and B cell subsets and modulate antibody production in human tonsil organoids. These results clarify the structural basis of IL-21 signaling and offer a potential strategy for tunable manipulation of humoral immunity.

Release from persistent T cell receptor engagement and blockade of aryl hydrocarbon receptor activity enhance IL-6-dependent mouse follicular helper T-like cell differentiation in vitro

Follicular helper T (Tfh) cells are crucial for humoral immunity. Dysregulation of Tfh cell differentiation can cause infectious, allergic, and autoimmune diseases. To elucidate the molecular mechanisms underlying Tfh cell differentiation, we attempted to establish an in vitro mouse model of Tfh cell differentiation in the absence of other cell types. Various cytokines and cell surface molecules are suggested to contribute to the differentiation. We found that stimulating naïve CD4+ T cells with immobilized antibodies to CD3, ICOS, and LFA-1 in the presence of soluble anti-CD28 antibody, IL-6, and antibodies that block IL-2 signaling for 3 days induced the expression of Bcl6 and Rorc(γt), master regulator genes of Tfh and Th17 cells, respectively. TGF-β significantly enhanced cell proliferation and Bcl6 and Rorc(γt) expression. An additional 2 days of culture without immobilized antibodies selectively downregulated Rorc(γt) expression. These cells produced IL-21 and promoted B cells to produce IgG antibodies. Adding the aryl hydrocarbon receptor (AhR) antagonist CH-223191 to the T cell culture further downregulated Rorc(γt) expression without significantly affecting Bcl6 expression, and upregulated expression of a key Tfh marker, CXCR5. Although their CXCR5 expression levels were still not high, the CH-223191-treated cells showed chemotactic activity towards the CXCR5 ligand CXCL13. On the other hand, AhR agonists upregulated Rorc(γt) expression and downregulated CXCR5 expression. These findings suggest that AhR activity and the duration of T cell receptor stimulation contribute to regulating the balance between Tfh and Th17 cell differentiation. Although this in vitro system needs to be further improved, it may be useful for elucidating the mechanisms of Tfh cell differentiation as well as for screening physiological or pharmacological factors that affect Tfh cell differentiation including CXCR5 expression.

The development and benefits of metformin in various diseases

Metformin has been used for the treatment of type II diabetes mellitus for decades due to its safety, low cost, and outstanding hypoglycemic effect clinically. The mechanisms underlying these benefits are complex and still not fully understood. Inhibition of mitochondrial respiratory-chain complex I is the most described downstream mechanism of metformin, leading to reduced ATP production and activation of AMP-activated protein kinase (AMPK). Meanwhile, many novel targets of metformin have been gradually discovered. In recent years, multiple pre-clinical and clinical studies are committed to extend the indications of metformin in addition to diabetes. Herein, we summarized the benefits of metformin in four types of diseases, including metabolic associated diseases, cancer, aging and age-related diseases, neurological disorders. We comprehensively discussed the pharmacokinetic properties and the mechanisms of action, treatment strategies, the clinical application, the potential risk of metformin in various diseases. This review provides a brief summary of the benefits and concerns of metformin, aiming to interest scientists to consider and explore the common and specific mechanisms and guiding for the further research. Although there have been countless studies of metformin, longitudinal research in each field is still much warranted.

Detection of Anti-ZIKV NS1 IgA, IgM, and Combined IgA/IgM and Identification of IL-4 and IL-10 as Potential Biomarkers for Early ZIKV and DENV Infections in Hyperendemic Regions, Thailand

The frequency of Zika virus (ZIKV)-specific IgA and IgM and the cytokine expression profile of ZIKV-infected patients in hyperendemic areas remain unclear. This study investigated the rates of ZIKV non-structural protein 1 (NS1)-specific IgA and IgM and evaluated serum cytokine levels of ZIKV and Dengue virus (DENV) cases in Thailand to identify potential diagnostic biomarkers, elucidate the immunity against ZIKV and DENV, and investigate the association between cytokine levels and ZIKV symptoms. Low rates of positivity for ZIKV NS1-specific IgA and IgM were detected in our study. ZIKV NS1 IgA/M (11%, 11/101) in combination was more frequently detected than ZIKV NS1 IgM (2%, 2/101) or ZIKV NS1 IgA (4%, 4/96) alone, especially in acute ZIKV cases with previous DENV exposure (14%, 10/72). Cytokine analysis showed that both ZIKV and DENV infections induced polyfunctional immunity, and the latter triggered more prolonged responses. The existence of significant differences in IL-4 and IL-10 levels between acute ZIKV and acute DENV cases suggested that IL-4 (p = 0.0176) and IL-10 (p = 0.0003) may represent biomarkers for acute ZIKV and acute DENV infections, respectively. Analysis of the association between increased cytokine levels and ZIKV symptoms indicated that CXCL10 (p = 0.0029) was associated with exanthema, while IL-5 (p = 0.0496) was linked to headache. The detection of ZIKV NS1 IgA and IgM in combination may enhance the diagnosis of early ZIKV infection, particularly when levels of IgM or IgA alone are low or undetectable. IL-4 and IL-10 may serve as targets for the development of diagnostic tools to detect ZIKV and DENV infections early, respectively, in flavivirus-endemic regions.

Recent Development in the Understanding of Molecular and Cellular Mechanisms Underlying the Etiopathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that leads to dementia and patient death. AD is characterized by intracellular neurofibrillary tangles, extracellular amyloid beta (Aβ) plaque deposition, and neurodegeneration. Diverse alterations have been associated with AD progression, including genetic mutations, neuroinflammation, blood-brain barrier (BBB) impairment, mitochondrial dysfunction, oxidative stress, and metal ion imbalance.Additionally, recent studies have shown an association between altered heme metabolism and AD. Unfortunately, decades of research and drug development have not produced any effective treatments for AD. Therefore, understanding the cellular and molecular mechanisms underlying AD pathology and identifying potential therapeutic targets are crucial for AD drug development. This review discusses the most common alterations associated with AD and promising therapeutic targets for AD drug discovery. Furthermore, it highlights the role of heme in AD development and summarizes mathematical models of AD, including a stochastic mathematical model of AD and mathematical models of the effect of Aβ on AD. We also summarize the potential treatment strategies that these models can offer in clinical trials.

Regulatory factors involved in Th17/Treg cell balance of immune thrombocytopenia

Immune thrombocytopenia is a common heterogeneous autoimmune disease that is characterized by decreasing peripheral blood platelet counts and increasing risk of bleeding. Studies have shown that an imbalance between T helper 17 (Th17) and Regulatory T (Treg) cells differentiated from CD4+T-cells is a key factor influencing the development and pathogenesis of immune thrombocytopenia. Th17 cells promote the development of chronic inflammatory disorders and induce autoimmune diseases, whereas Treg cells regulate immune homeostasis and prevent autoimmune diseases. Several regulators affecting the production and maintenance of these cells are also essential for proper regulation of Th17/Treg balance; these regulatory factors include cell surface proteins, miRNAs, and cytokine signaling. In this review, we focus on the function and role of balance between Th17 and Treg cells in immune thrombocytopenia, the regulatory factors, and therapeutic goals of this balance in immune thrombocytopenia.

The transcriptional regulator Sin3A balances IL-17A and Foxp3 expression in primary CD4 T cells

The Sin3 transcriptional regulator homolog A (Sin3A) is the core member of a multiprotein chromatin-modifying complex. Its inactivation at the CD4/CD8 double-negative stage halts further thymocyte development. Among various functions, Sin3A regulates STAT3 transcriptional activity, central to the differentiation of Th17 cells active in inflammatory disorders and opportunistic infections. To further investigate the consequences of conditional Sin3A inactivation in more mature precursors and post-thymic T cell, we have generated CD4-Cre and CD4-CreER^T2 Sin3A^F/F mice. Sin3A inactivation in vivo hinders both thymocyte development and peripheral T-cell survival. In vitro, in Th17 skewing conditions, Sin3A-deficient cells proliferate and acquire memory markers and yet fail to properly upregulate Il17a, Il23r, and Il22. Instead, IL-2⁺ and FOXP3⁺ are mostly enriched for, and their inhibition partially rescues IL-17A⁺ T cells. Notably, Sin3A deletion also causes an enrichment of genes implicated in the mTORC1 signaling pathway, overt STAT3 activation, and aberrant cytoplasmic RORγt accumulation. Thus, together our data unveil a previously unappreciated role for Sin3A in shaping critical signaling events central to the acquisition of immunoregulatory T-cell phenotypes.

Gut microbiota dysbiosis associated with different types of demyelinating optic neuritis in patients

BACKGROUND

Demyelinating optic neuritis (DON) causes rapid vision loss in young and middle-aged people. The limited efficacy of treatment and the toxic side effects of drugs significantly affect the quality of life of patients with DON. Therefore, DON pathogenesis has always been a research hotspot in terms of prevention and treatment. Studies have suggested that gut microbiota imbalances may be involved in autoimmune disease development via the modulation of multiple inflammatory cytokines and anti-inflammatory metabolites. Therefore, this study aims to explore gut microbiota differences between healthy controls (HCs) and patients with DON.

METHODS

A total of 54 patients with DON and 41 HCs were recruited. Fecal and blood samples were collected before and after intravenous methylprednisolone pulse (IVMP) treatment. The Shannon index, gut microbiota structure, and differential bacteria were evaluated and compared.

RESULTS

The Shannon diversity index was decreased in patients with DON (p < 0.001) but was higher after IVMP treatment (p < 0.05). In patients with DON, Blautia, Escherichia-Shigella, and Ruminococcus showed higher abundances, whereas Bacteroides, Faecalibacterium, Roseburia, Parabacteroides, Romboutsia, and Alistipes showed lower abundances compared to that in the HCs. After IVMP treatment, the Shannon index of the myelin oligodendrocyte glycoprotein-immunoglobulin G (+) (MOG-IgG (+)) and both aquaporin-4 (AQP4)-IgG (-) and MOG-IgG (-) groups increased (p < 0.05). Bacteroides was negatively correlated with interleukin (IL)-21, IL-17E, and tumor necrosis factor-α levels (p < 0.05, r = -0.54; p < 0.05, r= -0.50; p < 0.05, r =-0.55, respectively). Escherichia was positively correlated with macrophage inflammatory protein-3α (p < 0.05, r = 0.51). Alistipes was negatively correlated with soluble CD40 ligand (p < 0.05, r = -0.52).

CONCLUSION

The gut microbiota differed significantly between patients with DON and HCs; however, IVMP treatment may restore gut microbiota diversity and structure in patients with DON. Moreover, gut microbiota changes may play a role in DON pathogenesis.

Role of Th17 cells, Treg cells, and Th17/Treg imbalance in immune homeostasis disorders in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide, following strokes and cardiovascular diseases. Chronic lung inflammation is believed to play a role in the development of COPD. In addition, accumulating evidence shows that the immune system plays a crucial role in the pathogenesis of COPD. Significant advancements have been made in research on the pathogenesis of immune diseases and chronic inflammation in recent years, and T helper 17 (Th17) cells and regulatory T (Treg) cells have been found to play a crucial role in the autoimmune response. Th17 cells are a proinflammatory subpopulation that causes autoimmune disease and tissue damage. Treg cells, on the other hand, have a negative effect but can contribute to the occurrence of the same disease when their antagonism fails. This review mainly summarizes the biological characteristics of Th17 cells and Treg cells, their roles in chronic inflammatory diseases of COPD, and the role of the Th17/Treg ratio in the onset, development, and outcome of inflammatory disorders, as well as recent advancements in immunomodulatory treatment targeting Th17/Treg cells in COPD.

Wuweixiaoduyin regulates TAZ-mediated immunoregulatory properties of Treg/TH17 cells in chronic osteomyelitis

Wuwei xiaoduyin (WWXDY) is a prescription for Chronic osteomyelitis (COM) in traditional Chinese medicine (TCM). However, its specific mechanism remains unclear. The objective of this study was to investigate the mechanism of WWXDY in COM treatment. To clarify the potential role of TAZ in the treatment of COM by WWXDY via regulatory CD4+ T cells differentiation. The expressions of TAZ, RORγt and Foxp3 were determined by Quantitative Real-time PCR and Western blot. Besides, levels of IL-21, IL-17 and IL-10 in peripheral blood were detected by using ELISA. Molecular dynamics simulations and docking were further utilized to explore the binding mechanism. COM resulted in abnormal cell differentiation and an imbalance of Treg/Th17. In comparison with the control group, the percentage of Treg cells, Foxp3 expression and secretion of IL-17 and -21 cytokines decreased (P < 0.001), while the proportion of Th17 cells, the levels of TAZ and RORγt and concentration of IL-10 in PBMCs increased in the COM group (P < 0.001). Furthermore, the above abnormal differentiation and function of Treg/Th17 cells in COM were suppressed after treatment with WWXDY in vivo and in vitro. In addition, TEAD1 inhibited the therapeutic effect of WWXDY in terms of Treg/Th17 cells with COM. it was found that the main active ingredients were cichoric acid and isocarlinoside. WWXDY regulates immunoregulatory properties of Treg/Th17 cells in COM mainly by mediating TAZ expression. By inhibiting the chronic inflammation in COM, WWXDY is potentially used to inhibit the progression of COM into bone tumors.

Differential regulation of lineage-determining transcription factor expression in innate lymphoid cell and adaptive T helper cell subsets

CD4 T helper (Th) cell subsets, including Th1, Th2 and Th17 cells, and their innate counterparts innate lymphoid cell (ILC) subsets consisting of ILC1s, ILC2s and ILC3s, display similar effector cytokine-producing capabilities during pro-inflammatory immune responses. These lymphoid cell subsets utilize the same set of lineage-determining transcription factors (LDTFs) for their differentiation, development and functions. The distinct ontogeny and developmental niches between Th cells and ILCs indicate that they may adopt different external signals for the induction of LDTF during lineage commitment. Increasing evidence demonstrates that many conserved cis-regulatory elements at the gene loci of LDTFs are often preferentially utilized for the induction of LDTF expression during Th cell differentiation and ILC development at different stages. In this review, we discuss the functions of lineage-related cis-regulatory elements in inducing T-bet, GATA3 or RORγt expression based on the genetic evidence provided in recent publications. We also review and compare the upstream signals involved in LDTF induction in Th cells and ILCs both in vitro and in vivo. Finally, we discuss the possible mechanisms and physiological importance of regulating LDTF dynamic expression during ILC development and activation.

Association of cytokine profile with prior treatment failure and revision surgery in chronic rhinosinusitis

BACKGROUND

Inflammatory patterns in chronic rhinosinusitis (CRS) may predict disease severity, need for multiple sinus surgeries, and treatment response. This study analyzes nasal mucus inflammatory cytokine patterns in patients with (CRSwNP) and without (CRSsNP) nasal polyposis and their association with revision sinus surgery.

METHODS

A total of 319 CRS patients who underwent sinus surgery were included. Cytokines were quantified in intraoperative mucus specimens using a multiplex flow cytometric bead assay. Cytokine expression patterns in patients with 0, 1, and ≥2 previous surgeries were analyzed using Kruskal-Wallis and principal component (PC) regression analyses.

RESULTS

There were 122 (38%) patients with CRSsNP and 197 (62%) with CRSwNP. On univariate analysis, interleukin (IL)-1β, IL-6, IL-8, and IL-21 were associated with increasing number of sinus surgeries in CRSsNP, as were IL-2, IL-4, IL-5, IL-6, IL-9, IL-17A, and tumor necrosis factor (TNF)-α in CRSwNP. PC analysis with continuous Poisson regression in CRSwNP demonstrated that high IL-5 and IL-13 and low IL-1β, IL-12, and IL-21 were associated with more prior surgeries. In CRSsNP low IL-13 and high IL-5 and regulated-on-activation, normal T-cell-expressed and secreted (RANTES) were associated with more prior surgeries. Age remained a significant covariate in the full regression model for CRSsNP, but was nonsignificant in CRSwNP.

CONCLUSION

In CRSwNP, elevated IL-5 and IL-13 levels were higher at time of surgery in patients with more prior surgeries. Type 2 cytokines in CRSsNP demonstrated mixed associations with revision surgery. For both phenotypes, IL-10, IL-12, and IL-21 were consistently lower as number of prior surgeries increased, suggesting that treatment-resistant disease may be modulated by impairment in these signaling pathways.

Th17 Cell-Derived Amphiregulin Promotes Colitis-Associated Intestinal Fibrosis Through Activation of mTOR and MEK in Intestinal Myofibroblasts

BACKGROUND & AIMS

Intestinal fibrosis is a significant complication of Crohn's disease (CD). Gut microbiota reactive Th17 cells are crucial in the pathogenesis of CD; however, how Th17 cells induce intestinal fibrosis is still not completely understood.

METHODS

In this study, T-cell transfer model with wild-type (WT) and Areg-/- Th17 cells and dextran sulfate sodium (DSS)-induced chronic colitis model in WT and Areg-/- mice were used. CD4+ T-cell expression of AREG was determined by quantitative reverse-transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay. The effect of AREG on proliferation/migration/collagen expression in human intestinal myofibroblasts was determined. AREG expression was assessed in healthy controls and patients with CD with or without intestinal fibrosis.

RESULTS

Although Th1 and Th17 cells induced intestinal inflammation at similar levels when transferred into Tcrβxδ-/- mice, Th17 cells induced more severe intestinal fibrosis. Th17 cells expressed higher levels of AREG than Th1 cells. Areg-/- mice developed less severe intestinal fibrosis compared with WT mice on DSS insults. Transfer of Areg-/- Th17 cells induced less severe fibrosis in Tcrβxδ-/- mice compared with WT Th17 cells. Interleukin (IL)6 and IL21 promoted AREG expression in Th17 cells by activating Stat3. Stat3 inhibitor suppressed Th17-induced intestinal fibrosis. AREG promoted human intestinal myofibroblast proliferation, motility, and collagen I expression, which was mediated by activating mammalian target of rapamycin and MEK. AREG expression was increased in intestinal CD4+ T cells in fibrotic sites compared with nonfibrotic sites from patients with CD.

CONCLUSIONS

These findings reveal that Th17-derived AREG promotes intestinal fibrotic responses in experimental colitis and human patients with CD. Thereby, AREG might serve as a potential therapeutic target for fibrosis in CD.

Selenoprotein I deficiency in T cells promotes differentiation into tolerant phenotypes while decreasing Th17 pathology

Selenoprotein I (SELENOI) is an ethanolamine phospholipid transferase contributing to cellular metabolism and the synthesis of glycosylphosphatidylinositol (GPI) anchors. SELENOI knockout (KO) in T cells has been shown to impair metabolic reprogramming during T cell activation and reduce GPI-anchored Thy-1 levels, which are both crucial for Th17 differentiation. This suggests SELENOI may be important for Th17 differentiation, and we found that SELENOI was indeed up-regulated early during the activation of naïve CD4+ T cells in Th17 conditions. SELENOI KO reduced RORγt mRNA levels by decreasing SOX5 and STAT3 binding to promoter and enhancer regions in the RORC gene encoding this master regulator of Th17 cell differentiation. Differentiation of naïve CD4+ T cells into inflammatory versus tolerogenic Th cell subsets was analyzed and results showed that SELENOI deficiency skewed differentiation away from pathogenic Th17 cells (RORγt+ and IL-17A+ ) while promoting tolerogenic phenotypes (Foxp3+ and IL-10+ ). Wild-type and T cell-specific SELENOI KO mice were subjected to experimental autoimmune encephalitis (EAE), with KO mice exhibiting diminished clinical symptoms, reduced CNS pathology and decreased T cell infiltration. Flow cytometry showed that SELENOI T cell KO mice exhibited lower CD4+ RORγt+ and CD4+ IL-17A+ T cells and higher CD4+ CD25+ FoxP3+ T cells in CNS tissues of mice subjected to EAE. Thus, the metabolic enzyme SELENOI is up-regulated to promote RORγt transcription that drives Th17 differentiation, and SELENOI deficiency shifts differentiation toward tolerogenic phenotypes while protecting against pathogenic Th17 responses.

Research progress on Th17 and T regulatory cells and their cytokines in regulating atherosclerosis

Background

Coronary heart disease due to atherosclerosis is the leading cause of death worldwide. Atherosclerosis is considered a chronic inflammatory state in the arterial wall that promotes disease progression and outcome, and immune cells play an important role in the inflammatory process.

Purpose

We review the mechanisms of CD4+ T subsets, i.e., helper T17 (Th17) cells and regulatory T cells (Tregs), in regulating atherosclerosis, focusing on the role of interleukin (IL)-17, IL-10, and other cytokines in this disease and the factors influencing the effects of these cytokines.

Results

IL-17 secreted by Th17 cells can promote atherosclerosis, but few studies have reported that IL-17 can also stabilize atherosclerotic plaques. Tregs play a protective role in atherosclerosis, and Th17/Treg imbalance also plays an important role in atherosclerosis.

Conclusion

The immune response is important in regulating atherosclerosis, and studying the mechanism of action of each immune cell on atherosclerosis presents directions for the treatment of atherosclerosis. Nevertheless, the current studies are insufficient for elucidating the mechanism of action, and further in-depth studies are needed to provide a theoretical basis for clinical drug development.

Therapeutic Effect of IL-21 Blockage by Gene Therapy in Experimental Autoimmune Encephalomyelitis

The pathogenic role of the interleukin 21 (IL-21) in different autoimmune diseases, such as multiple sclerosis (MS), has been extensively studied. However, its pleiotropic nature makes it a cytokine that may exhibit different activity depending on the immunological stage of the disease. In this study, we developed a gene therapy strategy to block the interaction between IL-21 and its receptor (IL-21R) by using adeno-associated vectors (AAV) encoding a new soluble cytokine receptor (sIL21R) protein. We tested this strategy in a murine model of experimental autoimmune encephalomyelitis (EAE), obtaining different clinical effects depending on the time at which the treatment was applied. Although the administration of the treatment during the development of the immune response was counterproductive, the preventive administration of the therapeutic vectors showed a protective effect by reducing the number of animals that developed the disease, as well as an improvement at the histopathological level and a modification of the immunological profile of the animals treated with the AAV8.sIL21R. The beneficial effect of the treatment was also observed when inducing the expression of the therapeutic molecule once the first neurological signs were established in a therapeutic approach with a doxycyline (Dox)-inducible expression system. All these clinical results highlight the pleiotropicity of this cytokine in the different clinical stages and its key role in the EAE immunopathogenesis.

IL-23 in axial spondyloarthritis and psoriatic arthritis: a good fit for biological treatment?

INTRODUCTION

Interleukin 23 (IL-23) is a pro-inflammatory cytokine that plays a protective role against bacterial and fungal infections. However, the dysregulation of the IL-23/IL-17 axis provides a solid substrate for the development of various inflammatory diseases, such as psoriatic arthritis (PsA) and ankylosing spondylitis (AS).

AREAS COVERED

In different clinical trials, several drugs against IL-23 have shown efficacy and safety towards PsA, with excellent results on skin and joint scores. However, the same drugs did not show the same efficacy in AS, suggesting that IL-23 may not be a relevant driver of the pathobiology and clinical symptoms of active axial spondyloarthritis (axSpA).

EXPERT OPINION

These drugs have shown an excellent efficacy and a good safety profile towards PsA, while in AS the efficacy of the IL-23 blockade is lacking for reasons not yet known. Several hypotheses have been reported, but further studies will be needed for a greater understanding. This suggests the involvement of pathways or mechanisms for the development of SpA that remain unknown. In order to allow a wide use of IL-23 inhibitors, further clinical trials and long-term prospective studies are necessary.

Abnormal Epigenetic Regulations in the Immunocytes of Sjögren’s Syndrome Patients and Therapeutic Potentials

Sjögren’s syndrome (SjS), characterized by keratoconjunctivitis sicca and dry mouth, is a common autoimmune disease, especially in middle-aged women. The immunopathogenesis of SjS is caused by the sequential infiltration of T and B cells into exocrine glands, including salivary and lacrimal glands. Effector cytokines produced by these immunocytes, such as interferons (IFNs), IL-17, IL-22, IL-21, IL-4, TNF-α, BAFF and APRIL, play critical roles in promoting autoimmune responses and inducing tissue damages. Epigenetic regulations, including DNA methylation, histone modification and non-coding RNAs, have recently been comprehensively studied during the activation of various immunocytes. The deficiency of key epigenetic enzymes usually leads to aberrant immune activation. Epigenetic modifications in T and B cells are usually found to be altered during the immunopathogenesis of SjS, and they are closely correlated with autoimmune responses. In particular, the important role of methylation in activating IFN pathways during SjS progression has been revealed. Thus, according to the involvement of epigenetic regulations in SjS, target therapies to reverse the altered epigenetic modifications in auto-responsive T and B cells are worthy of being considered as a potential therapeutic strategy for SjS.

T Cell Specific BOB.1/OBF.1 Expression Promotes Germinal Center Response and T Helper Cell Differentiation

The transcriptional co-activator BOB.1/OBF.1 is expressed in both B and T cells. The main characteristic of conventional BOB.1/OBF.1 deficient mice is the complete absence of germinal centers (GCs). This defect was mainly attributed to the defective B cell compartment. However, it is unknown whether and how BOB.1/OBF.1 expression in T cells contributes to the GC reaction. To finally clarify this question, we studied the in vivo function of BOB.1/OBF.1 in CD4⁺ T and follicular T helper (TFH) cell subpopulations by conditional mutagenesis, in the presence of immunocompetent B lymphocytes. BOB.1/OBF.1 deletion in CD4⁺ T as well as TFH cells resulted in impaired GC formation demonstrating that the impaired GC reaction described for conventional BOB.1/OBF.1-deficient mice cannot exclusively be traced back to the B cell compartment. Furthermore, we show a requirement of BOB.1/OBF.1 for T helper (TH) cell subsets, particularly for TFH cell differentiation.

Proximal and Distal Regions of Pathogenic Th17 Related Chromatin Loci Are Sequentially Accessible During Pathogenicity of Th17

Pathogenic Th17, featured by their production of pro-inflammatory cytokines, are considered as a key player in most autoimmune diseases. The transcriptome of them is obviously distinct from that of conventional regulatory Th17. However, chromatin accessibility of the two Th17 groups have not been comprehensively compared yet. Here, we found that their chromatin-accessible regions(ChARs) significantly correlated with the expression of related genes, indicating that they might engage in the regulation of these genes. Indeed, pathogenic Th17 specific ChARs (patho-ChARs) exhibited a significant distribution preference in TSS-proximal region. We further filtered the patho-ChARs based on their conservation among mammalians or their concordance with the expression of their related genes. In either situation, the filtered patho-ChARs also showed a preference for TSS-proximal region. Enrichment of expression concordant patho-ChARs related genes suggested that they might involve in the pathogenicity of Th17. Thus, we also examined all ChARs of patho-ChARs related genes, and defined an opening ChAR set according to their changes in the Th17 to Th1 conversion. Interestingly, these opening ChARs displayed a sequential accessibility change from TSS-proximal region to TSS-distal region. Meanwhile, a group of patho-TFs (transcription factors) were identified based on the appearance of their binding motifs in the opening ChARs. Consistently, some of them also displayed a similar preference for binding the TSS-proximal region. Single-cell transcriptome analysis further confirmed that these patho-TFs were involved in the generation of pathogenic Th17. Therefore, our results shed light on a new regulatory mechanism underlying the generation of pathogenic Th17, which is worth to be considered for autoimmune disease therapy.

A systematic comparison of FOSL1, FOSL2 and BATF-mediated transcriptional regulation during early human Th17 differentiation

Th17 cells are essential for protection against extracellular pathogens, but their aberrant activity can cause autoimmunity. Molecular mechanisms that dictate Th17 cell-differentiation have been extensively studied using mouse models. However, species-specific differences underscore the need to validate these findings in human. Here, we characterized the human-specific roles of three AP-1 transcription factors, FOSL1, FOSL2 and BATF, during early stages of Th17 differentiation. Our results demonstrate that FOSL1 and FOSL2 co-repress Th17 fate-specification, whereas BATF promotes the Th17 lineage. Strikingly, FOSL1 was found to play different roles in human and mouse. Genome-wide binding analysis indicated that FOSL1, FOSL2 and BATF share occupancy over regulatory regions of genes involved in Th17 lineage commitment. These AP-1 factors also share their protein interacting partners, which suggests mechanisms for their functional interplay. Our study further reveals that the genomic binding sites of FOSL1, FOSL2 and BATF harbour hundreds of autoimmune disease-linked SNPs. We show that many of these SNPs alter the ability of these transcription factors to bind DNA. Our findings thus provide critical insights into AP-1-mediated regulation of human Th17-fate and associated pathologies.

Activation pathways that drive CD4+ T cells to break tolerance in autoimmune diseases. Immunol Rev 2022;307:161-190. [PMID: 35142369 PMCID: PMC9255211 DOI: 10.1111/imr.13071]

Autoimmune diseases are characterized by dysfunctional immune systems that misrecognize self as non-self and cause tissue destruction. Several cell types have been implicated in triggering and sustaining disease. Due to a strong association of major histocompatibility complex II (MHC-II) proteins with various autoimmune diseases, CD4+ T lymphocytes have been thoroughly investigated for their roles in dictating disease course. CD4+ T cell activation is a coordinated process that requires three distinct signals: Signal 1, which is mediated by antigen recognition on MHC-II molecules; Signal 2, which boosts signal 1 in a costimulatory manner; and Signal 3, which helps to differentiate the activated cells into functionally relevant subsets. These signals are disrupted during autoimmunity and prompt CD4+ T cells to break tolerance. Herein, we review our current understanding of how each of the three signals plays a role in three different autoimmune diseases and highlight the genetic polymorphisms that predispose individuals to autoimmunity. We also discuss the drawbacks of existing therapies and how they can be addressed to achieve lasting tolerance in patients.

T peripheral helper cells in autoimmune diseases

Pathologic T cell-B cell interactions underlie many autoimmune diseases. The T cells that help B cells in autoimmune diseases vary in phenotype and include T cells that lack typical features of T follicular helper cells, such as expression of CXCR5 and BCL6. A population of PD-1hi CXCR5- T peripheral helper (Tph) cells has now been recognized in multiple autoantibody-associated diseases. Tph cells display a distinctive set of features, merging the ability to provide B cell help with the capacity to migrate to inflamed peripheral tissues. Here, we review the scope of immune-related conditions in which Tph cells have been implicated and provide a perspective on their potential contributions to pathologic B cell activation in autoimmune diseases. We discuss Tph cells as a promising therapeutic strategy in autoimmunity and consider the utility of tracking Tph cells in blood as a biomarker to quantify aberrant T cell-B cell activation in patients with autoimmune diseases.

Immune Inhibitory Properties and Therapeutic Prospects of Transforming Growth Factor-Beta and Interleukin 10 in Autoimmune Hepatitis

Transforming growth factor-beta and interleukin 10 have diverse immune inhibitory properties that have restored homeostatic defense mechanisms in experimental models of autoimmune disease. The goals of this review are to describe the actions of each cytokine, review their investigational use in animal models and patients, and indicate their prospects as interventions in autoimmune hepatitis. English abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed. Transforming growth factor-beta expands the natural and inducible populations of regulatory T cells, limits the proliferation of natural killer cells, suppresses the activation of naïve CD8⁺ T cells, decreases the production of interferon-gamma, and stimulates fibrotic repair. Interleukin 10 selectively inhibits the CD28 co-stimulatory signal for antigen recognition and impairs antigen-specific activation of uncommitted CD4⁺ and CD8⁺ T cells. It also inhibits maturation of dendritic cells, suppresses Th17 cells, supports regulatory T cells, and limits production of diverse pro-inflammatory cytokines. Contradictory immune stimulatory effects have been associated with each cytokine and may relate to the dose and accompanying cytokine milieu. Experimental findings have not translated into successful early clinical trials. The recombinant preparation of each agent in low dosage has been safe in human studies. In conclusion, transforming growth factor-beta and interleukin 10 have powerful immune inhibitory actions of potential therapeutic value in autoimmune hepatitis. The keys to their therapeutic application will be to match their predominant non-redundant function with the pivotal pathogenic mechanism or cytokine deficiency and to avoid contradictory immune stimulatory actions.

Hepatitis B Flare in Hepatitis B e Antigen-Negative Patients: A Complicated Cascade of Innate and Adaptive Immune Responses

Chronic hepatitis B virus (HBV) infection is a dynamic process involving interactions among HBV, hepatocytes, and the host immune system. The natural course of chronic hepatitis B (CHB) is divided into four chronological phases, including the hepatitis B e antigen (HBeAg)-positive and HBeAg-negative phases. During HBV flare, alanine aminotransferase (ALT) levels abruptly rise to >5× the upper limit of normal; this is thought to occur due to the immune response against an upsurge in serum HBV DNA and antigen levels. Hepatitis flares may occur spontaneously, during or after antiviral therapy, or upon immunosuppression or chemotherapy in both HBeAg-positive and HBeAg-negative patients. The clinical spectrum of HBV flares varies from asymptomatic to hepatic decompensation or failure. HBeAg seroconversion with ≥ 1 year of consolidation therapy is accepted as an endpoint of oral antiviral therapy in HBeAg-positive patients, but recommendations for treating HBeAg-negative patients differ. Thus, the management of HBeAg-negative patients has attracted increasing interest. In the current review, we summarize various types of HBV flares and the associated complex cascade of innate and adaptive immune responses, with a focus on HBeAg-negative CHB patients. Hopefully, this review will provide insight into immunopathogenesis to improve the management of HBV flares in HBeAg-negative CHB patients.

The Possible Pathogenic Role of IgG4-Producing Plasmablasts in Stricturing Crohn's Disease

BACKGROUND

Crohn's disease (CD) is a condition on the spectrum of inflammatory bowel disease that affects up to 20 people per 100,000 in the US annually, and with incidence increasing. One of the most significant sources of morbidity in CD is the formation of strictures, with resultant intestinal blockage a common indication for hospitalization and surgical intervention in these patients. The pathophysiology of stricture formation is not fully understood. However, the fibroplasia that leads to fibrostenotic stricture formation may have shared pathophysiology with IgG4-related fibrosis.

SUMMARY

Initial intestinal inflammation recruits innate immune cells, such as neutrophils, that secrete IL-1β and IL-23, which induces a type 17 CD4+ T-helper T-cell (Th17)-mediated adaptive immune response. These CD4+ Th17 T cells also contribute to inflammation by secreting proinflammatory cytokines such as IL-17 and IL-21. IL-21 recruits and stimulates CD4+ T follicular helper (Tfh) cells, which secrete more IL-21. This causes ectopic germinal center formation, recruiting and stimulating naïve B cells. The IL-17 and IL-21 produced by Th17 cells and Tfh cells also induce IgG4 plasmablast differentiation. Finally, these IgG4-producing plasmablasts secrete platelet-derived growth factor (PDGF), which activates local PDGF-receptor expressing fibroblasts and myofibroblasts, resulting in uncontrolled fibroplasia.

Neoantigen-driven B cell and CD4 T follicular helper cell collaboration promotes anti-tumor CD8 T cell responses

CD4 T follicular helper (TFH) cells support B cells, which are critical for germinal center (GC) formation, but the importance of TFH-B cell interactions in cancer is unclear. We found enrichment of TFH cell transcriptional signature correlates with GC B cell signature and with prolonged survival in individuals with lung adenocarcinoma (LUAD). We further developed a murine LUAD model in which tumor cells express B cell- and T cell-recognized neoantigens. Interactions between tumor-specific TFH and GC B cells, as well as interleukin (IL)-21 primarily produced by TFH cells, are necessary for tumor control and effector CD8 T cell function. Development of TFH cells requires B cells and B cell-recognized neoantigens. Thus, tumor neoantigens can regulate the fate of tumor-specific CD4 T cells by facilitating their interactions with tumor-specific B cells, which in turn promote anti-tumor immunity by enhancing CD8 T cell effector functions.

New Insights into Epigenetic Regulation of T Cell Differentiation

Immature CD4⁻ CD8⁻ thymocytes progress through several developmental steps in the thymus, ultimately emerging as mature CD4⁺ (helper) or CD8⁺ (cytotoxic) T cells. Activation of naïve CD4⁺ and CD8⁺ T cells in the presence of specific cytokines results in the induction of transcriptional programs that result in their differentiation into effector or memory cells and in the case of CD4⁺ T cells, the adoption of distinct T-helper fates. Previous studies have shown that histone modification and DNA methylation play important roles in each of these events. More recently, the roles of specific epigenetic regulators in T cell differentiation have been clarified. The identification of the epigenetic modifications and modifiers that control mature T cell differentiation and specification has also provided further insights into how dysregulation of these processes can lead to cancer or autoimmune diseases. In this review, we summarize recent findings that have provided new insights into epigenetic regulation of T cell differentiation in both mice and humans.

Interleukin-17 in Liver Disease Pathogenesis

Interleukin 17A (IL-17A)-producing T helper 17 (Th17) cells were identified as a subset of T helper cells that play a critical role in host defense against bacterial and fungal pathogens. Th17 cells differentiate from Th0 naïve T-cells in response to transforming growth factor β1 (TGF-β1) and IL-6, the cytokines which also drive development of liver fibrosis, require activation of transcription factor retinoic acid receptor-related orphan nuclear receptor gamma t (RORγt). IL-17A signals through the ubiquitously expressed receptor IL-17RA. Expression of IL-17RA is upregulated in patients with hepatitis B virus/hepatitis C virus (HBV/HCV) infections, nonalcoholic steatohepatitis (NASH), alcohol-associated liver disease (AALD), hepatocellular carcinoma (HCC), and experimental models of chronic toxic liver injury. The role of IL-17 signaling in the pathogenesis of NASH- and AALD-induced metabolic liver injury and HCC will be the focus of this review. The role of IL-17A-IL-17RA axis in mediation of the cross-talk between metabolically injured hepatic macrophages, hepatocytes, and fibrogenic myofibroblasts will be discussed.

Effects of combination treatment with durvalumab plus tremelimumab on the tumor microenvironment in non-small-cell lung carcinoma

The rapid development of immune checkpoint blockade (ICB) therapies has revolutionized the cancer treatment landscape and brightened the long-term forecast for many cancer patients. However, the specific genomic and proteomic changes in tumors treated with different ICB treatments have yet to be fully characterized. We treated four non-small-cell lung carcinoma (NSCLC) tumor digests ex vivo with the anti-PD-L1 antibody durvalumab (D) alone or in combination with the anti-CTLA-4 antibody tremelimumab (T) to explore changes in gene and protein expression associated with these ICB therapies. All four tumors showed a robust increase in interferon gamma (IFN-γ) production (100–300% higher than isotype control) in both D- and D + T-treated tumors. Three of the four tumors showed additional increases in IFN-γ production with D + T compared with D (40–70%). A substantial reduction in interleukin 10 (IL-10) was also found in three of the four tumors (reduced to 4–8%) in response to D and D + T. Conventional CD4 + /CD8 + populations and T cell activation markers increased after D and D + T treatment. D and D + T upregulated multiple IPA pathways involving T cell activation. D + T resulted in additional upregulation of Th1/Th2 pathways through a different set of genes, as well as greater reduction in genes involved in epithelial-mesenchymal transition (EMT), angiogenesis, and cancer stemness. Our results demonstrated that D + T augmented the effects of D in the microenvironment of this set of NSCLC tumors. The specific impact of D + T on the regulation of EMT, angiogenesis, and cancer stemness warrants further evaluation in a larger set of tumors.

The Potential Roles of T Cells in Periapical Lesions

INTRODUCTION

Periapical lesions are inflammatory diseases mainly caused by microbial infection from the root canal system, affecting the integrity of alveolar bone, periapical cementum, and periodontal ligament. The invasion of pathogenic microorganisms activates local inflammation and host immune response, especially the recruitment and differentiation of T cells. Many studies have discussed the fundamental roles of T cell-related immunological regulation and the possible clinical significance of cytokine disorders in periapical lesions. However, oral pathogen-mediated T cell immune response is far more clarified. Therefore, the aim of this study was to discuss the research status of T cell-related immunology involved in the progression of periapical lesions and potential future directions.

METHODS

We conducted a literature review focusing on T cell-related immunology in periapical lesions by searching PubMed, Web of Science, Scopus and ScienceDirect online databases.

RESULTS

In total 108 articles were involved in this narrative review. During the development of periapical lesions, the infiltrated number of different types of T cells and the secretion of T cell-related cytokines in root apex region reflected the inflammatory status of periapical lesions. In addition, it was also highly correlated with the periapical bone destruction. Future study could attempt to provide a wider and deeper study on the expression profile and regulatory function of T cells in the development of periapical lesions.

CONCLUSION

This review would help us understand the essence of the T cell-related pathology of periapical lesions and raise the potential therapeutic targets for the treatment of apical periodontitis.

Targeting cytokines and immune checkpoints in atherosclerosis with monoclonal antibodies

Over the past fifteen years, treatments using monoclonal antibodies specifically targeting cytokines have been developed to treat chronic inflammatory diseases, including rheumatoid arthritis or psoriasis, both associated with increased cardiovascular risk. The cardiovascular impact of these therapies allows us to validate the clinical relevance of the knowledge acquired from experimental studies about the role of cytokines in atherosclerosis. Several clinical studies have confirmed the protective effects of anti-TNFα and anti-IL-6R monoclonal antibodies against athero-thrombotic cardiovascular risk in patients with chronic inflammatory diseases. Yet, caution is needed since anti-TNFα treatment can aggravate chronic heart failure. More recently, the CANTOS study showed for the first time that an anti-inflammatory treatment using anti-IL-1β monoclonal antibody in coronary artery disease patients significantly reduced cardiovascular events. The effects of IL-23/IL-17 axis blockade on cardiovascular risk in patients with psoriasis or arthritis remain controversial. Several monoclonal antibodies targeting costimulatory molecules have also been developed, a direct way to confirm their involvement in atherothrombotic cardiovascular diseases. Blocking the CD28^-CD80/86 axis with Abatacept has been shown to reduce cardiovascular risk. In contrast, the treatment of cancer patients with antibodies blocking immune checkpoint inhibitory receptors, such as CTLA-4, PD1, or PDL1, could worsen the risk of atherothrombotic events. In the future, cardiologists will be increasingly solicited to assess the cardiovascular risk of patients suffering from chronic inflammatory diseases or cancer and participate in choosing the most appropriate treatment. At the same time, immunomodulatory approaches directly targeting cardiovascular diseases will be developed as a complement to the usual treatment strategies.

Immunobiology of T Cells in Sjögren's Syndrome

Sjögren's syndrome (SjS) is a systemic autoimmune disease marked by xerostomia (dry mouth), keratoconjunctivitis sicca (eye dryness), and other systematic disorders. Its pathogenesis involves an inflammatory process that is characterized by lymphocytic infiltration into exocrine glands and other tissues. Although the development of ectopic lymphoid tissue and overproduction of autoantibodies by hyperactive B cells suggest that they may promote SjS development, treatment directed towards them fails to induce significant laboratory or clinical improvement. T cells are overwhelming infiltrators in most phases of the disease, and the involvement of multiple T cell subsets of suggests the extraordinary complexity of SjS pathogenesis. The factors, including various cellular subtypes and molecules, regulate the activation and suppression of T cells. T cell activation induces inflammatory cell infiltration, B cell activation, tissue damage, and metabolic changes in SjS. Knowledge of the pathways that link these T cell subtypes and regulation of their activities are not completely understood. This review comprehensively summarizes the research progress and our understanding of T cells in SjS, including CD4⁺ T cells, CD8⁺ T_RM cells, and innate T cells, to provide insights into for clinical treatment.

Interleukin-21 in Viral Infections

Interleukin (IL)-21 is a cytokine that affects the differentiation and function of lymphoid and myeloid cells and regulates both innate and adaptive immune responses. In addition to regulating the immune response to tumor and viral infections, IL-21 also has a profound effect on the development of autoimmune and inflammatory diseases. IL-21 is produced mainly from CD4⁺ T cells-in particular, follicular helper T (Tfh) cells-which have a great influence on the regulation of antibody production. It is also an important cytokine for the activation of CD8⁺ T cells, and its role in recovering the function of CD8⁺ T cells exhausted by chronic microbial infections and cancer has been clarified. Thus, IL-21 plays an extremely important role in viral infections, especially chronic viral infections. In this review, I will introduce the findings to date on how IL-21 is involved in some typical viral infections and the potential of treating viral diseases with IL-21.

Th17-Related Cytokines as Potential Discriminatory Markers between Neuromyelitis Optica (Devic's Disease) and Multiple Sclerosis-A Review

Multiple sclerosis (MS) and Devic’s disease (NMO; neuromyelitis optica) are autoimmune, inflammatory diseases of the central nervous system (CNS), the etiology of which remains unclear. It is a serious limitation in the treatment of these diseases. The resemblance of the clinical pictures of these two conditions generates a partial possibility of introducing similar treatment, but on the other hand, a high risk of misdiagnosis. Therefore, a better understanding and comparative characterization of the immunopathogenic mechanisms of each of these diseases are essential to improve their discriminatory diagnosis and more effective treatment. In this review, special attention is given to Th17 cells and Th17-related cytokines in the context of their potential usefulness as discriminatory markers for MS and NMO. The discussed results emphasize the role of Th17 immune response in both MS and NMO pathogenesis, which, however, cannot be considered without taking into account the broader perspective of immune response mechanisms.

TLR2 deficiency promotes IgE and inhibits IgG1 class-switching following ovalbumin sensitization

BACKGROUND

To explore the roles of Toll-like receptor (TLR)2 in Th2 cytokine production and immunoglobulin (Ig) class switching following ovalbumin (OVA) sensitization.

METHODS

TLR2-/- and wild-type C57BL/6 mice were sensitized by intraperitoneal injection with OVA. Lung pathology was assessed by hematoxylin and eosin staining. Abundance of interleukin (IL)4, IL5, IL13, and IL21 transcripts in the lungs was quantified by RT-PCR. OVA-specific IgG1, IgG2a, IgG2b, IgE and IgM were quantified by enzyme-linked immunosorbent assay. Phosphorylated signal transducer and activator of transcription (STAT)3 in lung tissue was detected by immunohistochemistry staining and nuclear factor (NF) κB activation was measured by immunofluorescence staining. STAT3 activation was inhibited using cryptotanshinone (CPT) treatment. Germline transcripts (Iμ-Cμ, Iγ-Cγ, Iα-Cα or Iε-Cε), post-recombination transcripts (Iμ-Cγ, Iμ-Cα or Iμ- Cε) and mature transcripts (VHDJH-Cγ, VHDJH-Cα or VHDJH-Cε) were analyzed from splenic B cells of OVA-sensitized wild-type mice (with or without CPT treatment) and TLR2-/- mice (with or without IL21 treatment).

RESULTS

The lungs of TLR2-/- mice showed a lesser degree of inflammation than wild-type mice after OVA sensitization. Following OVA sensitization, levels of IL4, IL13, and IL21, but not IL5, were significantly lower in TLR2-/- compared with wild-type mice. Moreover, OVA-specific IgG1 and IgE titers were markedly lower and higher, respectively, in TLR2-/- mice. TLR2 deficiency inhibited STAT3 activation but not NF-κB p65 activation. CPT treatment reduced IgG1 titers via inhibition of Stat3 phosphorylation. Both TLR2 knockout and CPT treatment reduced the frequencies of Iγ1-Cγ1, Iγ3-Cγ3 and Iα-Cα transcripts, but IL21 treatment compensated for the effects of TLR2 deficiency.

CONCLUSION

These results suggest a role of TLR2 in restricting OVA-sensitized lung inflammation via promotion of IgG1 and inhibition of IgE class switching regulated by IL21 and STAT3.