Phenotypic and functional features of human Th17 cells

N-ethyl-N-nitrosourea (ENU)-induced C-terminal truncation of Runx3 results in autoimmune colitis associated with Th17/Treg imbalance

Inflammatory bowel disease (IBD) is a chronic and progressive inflammatory intestinal disease that affects people around the world. The primary cause of IBD is an imbalance in the host immune response to intestinal flora. Several human genes, including IL10, STAT3, IRGM, ATG16L1, NOD2 and RUNX3, are associated with inappropriate immune responses in IBD. It has been reported that homozygous Runx3-knockout (ko) mice spontaneously develop colitis. However, the high mortality rate in these mice within the first two weeks makes it challenging to study the role of Runx3 in colitis. To address this issue, a spontaneous colitis (SC) mouse model carrying a C-terminal truncated form of Runx3 with Tyr319stop point mutation has been generated. After weaning, SC mice developed spontaneous diarrhea and exhibited prominent enlargement of the colon, accompanied by severe inflammatory cell infiltration. Results of immunofluorescence staining showed massive CD4+ T cell infiltration in the inflammatory colon of SC mice. Colonic IL-17A mRNA expression and serum IL-17A level were increased in SC mice. CD4+ T cells from SC mice produced stronger IL-17A than those from wildtype mice in Th17-skewing conditions in vitro. In addition, the percentages of Foxp3+ Treg cells as well as the RORγt+Foxp3+ Treg subset, known for its role in suppressing Th17 response in the gut, were notably lower in colon lamina propria of SC mice than those in WT mice. Furthermore, transfer of total CD4+ T cells from SC mice, but not from wildtype mice, into Rag1-ko host mice resulted in severe autoimmune colitis. In conclusion, the C-terminal truncated Runx3 caused autoimmune colitis associated with Th17/Treg imbalance. The SC mouse model is a feasible approach to investigate the effect of immune response on spontaneous colitis.

Integrating clinical data mining, network analysis and experimental validation reveal the anti-inflammatory mechanism of Huangqin Qingre Chubi Capsule in rheumatoid arthritis treatment

ETHNOPHARMACOLOGICAL RELEVANCE

Huangqin Qingre Chubi Capsule (HQC) is a Chinese medicinal compound used for the treatment of damp-heat pattern rheumatism, guided by the traditional Chinese medicine syndrome differentiation practice. HQC has been used in the clinical treatment of rheumatic diseases for more than 20 years with remarkable efficacy. HQC has been experimentally shown to exert anti-arthritic effects via the Wnt signaling pathway.

AIM OF THE STUDY

This study used clinical data mining, network analysis, and in vitro and in vivo tests to investigate the anti-arthritic and possible anti-inflammatory mechanism of HQC. Specifically, emphasis was placed on the function of the hsa_circ_0091,685/EIF4A3/IL-17 axis in the anti-inflammatory process.

MATERIALS AND METHODS

A random walk model was used to evaluate the effects of HQC on clinical immune inflammatory marker function in patients with RA. Network analysis was used to predict the potential target genes and pathways of HQC. Hematoxylin & eosin, safranin O-fast green and toluidine blue staining, immunohistochemistry, and transmission electron microscopy were performed to evaluate the anti-arthritic effects of HQC in rat models. Cell Counting Kit-8 assay, quantitative real-time polymerase chain reaction, western blotting, enzyme-linked immunosorbent assay, and RNA pull-down were used to study the anti-proliferation and anti-inflammatory mechanisms of HQC.

RESULTS

Patients with RA who underwent HQC treatment showed a significant reduction in inflammatory response levels, according to retrospective clinical study. Network analysis revealed that HQC potentially targeted genes and pathways related to inflammation, especially IL-6, IL-17, TNF-α, IL-23, and IL-17 signaling pathway. Animal experiments showed that HQC inhibits inflammation through the IL-17 signaling pathway in rat models. Cellular experiments showed that HQC-containing serum inhibited the inflammatory response in patients with RA-FLS or RA by blocking hsa_circ_0091,685 and EIF4A3 expression.

CONCLUSION

In RA patients, HQC reduces the inflammatory response. The antiproliferative and anti-inflammatory qualities of HQC are responsible for its therapeutic impact. The suppression of the hsa_circ_0091,685/EIF4A3/IL-17 axis was linked to these favorable outcomes.

Reconstruction of Sjögren's syndrome-like sialadenitis by a defined disease specific gut-reactive single TCR and an autoantibody

Lymphocytes such as CD4+ T cells and B cells mainly infiltrate the salivary glands; however, the precise roles and targets of autoreactive T cells and autoantibodies in the pathogenesis of Sjögren's Syndrome (SS) remain unclear. This study was designed to clarify the role of autoreactive T cells and autoantibodies at the single-cell level involved in the development of sialadenitis. Infiltrated CD4+ T and B cells in the salivary glands of a mouse model resembling SS were single-cell-sorted, and their T cell receptor (TCR) and B cell receptor (BCR) sequences were analyzed. The predominant TCR and BCR clonotypes were reconstituted in vitro, and their pathogenicity was evaluated by transferring reconstituted TCR-expressing CD4+ T cells into Rag2-/- mice and administering recombinant IgG in vivo. The reconstitution of Th17 cells expressing TCR (#G) in Rag2-/- mice resulted in the infiltration of T cells into the salivary glands and development of sialadenitis, while an autoantibody (IgGr22) was observed to promote the proliferation of pathogenic T cells. IgGr22 specifically recognizes double-stranded RNA (dsRNA) and induces the activation of dendritic cells, thereby enhancing the expression of IFN signature and inflammatory genes. TCR#G recognizes antigens related to the gut microbiota. Antibiotic treatment severely reduces the activation of TCR#G-expressing Th17 cells and suppresses sialadenitis development. These data suggest that the anti-dsRNA antibodies and, TCR recognizing the gut microbiota involved in the development of sialadenitis like SS. Thus, our model provides a novel strategy for defining the roles of autoreactive TCR and autoantibodies in the development and pathogenesis of SS.

Anti-psoriasis effect of 18β-glycyrrhetinic acid by breaking CCL20/CCR6 axis through its vital active group targeting GUSB/ATF2 signaling

BACKGROUND

Psoriasis is an immune-mediated chronic inflammatory skin disease. Current research suggests that the long-term persistence and recurrence of psoriasis are closely related to the feedback loop formed between keratinocytes and immune cells, especially in Th 17 or DC cells expressing CCR6. CCL20 is the ligand of CCR6. Therefore, drugs that block the expression of CCL20 or CCR6 may have a certain therapeutic effect on psoriasis. Glycyrrhetinic acid (GA) is the main active ingredient of the plant drug licorice and is often used to treat autoimmune diseases, including psoriasis. However, its mechanism of action is still unclear.

METHODS

Psoriasis like skin lesion model was established by continuously applying imiquimod on the back skin of normal mice and CCR6-/- mice for 7 days. The therapeutic and preventive effects of glycyrrhetinic acid (GA) on the model were observed and compared. The severity of skin injury is estimated through clinical PASI scores and histopathological examination. qRT-PCR and multiple cytoline assay were explored to detect the expression levels of cytokines in animal dorsal skin lesions and keratinocyte line HaCaT cells, respectively. The dermis and epidermis of the mouse back were separated for the detection of CCL20 expression. Transcription factor assay was applied to screen, and luciferase activity assay to validate transcription factors regulated by GA. Technology of surface plasmon laser resonance with LC-MS (SPR-MS), molecular docking, and enzyme activity assay were used to identified the target proteins for GA. Finally, we synthesized different derivatives of 18beta-GA and compared their effects, as well as glycyrrhetinic acid (GL), on the skin lesion of imiquimod-induced mice to evaluate the active groups of 18beta-GA.

RESULTS

18β-glycyrrhetinic acid (GA) improved IMQ-induced psoriatic lesions, and could specifically reduce the chemokine CCL20 level of the epidermis in lesion area, especially in therapeutic administration manner. The process was mainly regulated by transcription factor ATF2 in the keratinocytes. In addition, GUSB was identified as the primary target of 18βGA. Our findings indicated that the subject on molecular target research of glycyrrhizin should be glycyrrhetinic acid (GA) instead of glycyrrhizic acid (GL), because GL showed little activity in vitro or in vivo. Apart from that, α, β, -unsaturated carbonyl in C11/12 positions was crucial or unchangeable to its activity of 18βGA, while proper modification of C3 or C30 position of 18βGA may vastly increase its activity.

CONCLUSION

Our research indicates that 18βGA exerted its anti-psoriasis effect mainly by suppressing ATF2 and downstream molecule CCL20 predominately through α, β, -unsaturated carbonyl at C11/12 position binding to GUSB in the keratinocytes, and then broke the feedback loop between keratinocytes and CCR6-expressing immune cells. GA has more advantages than GL in the external treatment of psoriasis. A highlight of this study is to investigate the influence of special active groups on the pharmacological action of a natural product, inspired by the molecular docking result.

Correlation between the dynamic changes of γδT cells, Th17 cells, CD4+CD25+ regulatory T cells in peripheral blood and pharmacological interventions against bleomycin-induced pulmonary fibrosis progression in mice

The involvement of γδT cells, Th17 cells, and CD4+CD25+ regulatory T cells (Tregs) is crucial in the progression of pulmonary fibrosis (PF), particularly in maintaining immune tolerance and homeostasis. However, the dynamics of these cells in relation to PF progression, especially under pharmacological interventions, remains poorly understood. This study aims to unravel the interplay between the dynamic changes of these cells and the effect of pharmacological agents in a mouse model of PF induced by intratracheal instillation of bleomycin. We analyzed changes in lung histology, lung index, hydroxyproline levels, and the proportions of γδT cells, Th17 cells, and Tregs on the 3rd, 14th, and 28th days following treatment with Neferine, Isoliensinine, Pirfenidone, and Prednisolone. Our results demonstrate that these drugs can partially or dynamically reverse weight loss, decrease lung index and hydroxyproline levels, and ameliorate lung histopathological damage. Additionally, they significantly modulated the abnormal changes in γδT, Th17, and Treg cell proportions. Notably, on day 3, the proportion of γδT cells increased in the Neferine and Prednisolone groups but decreased in the Isoliensinine and Pirfenidone groups, while the proportion of Th17 cells decreased across all treated groups. On day 14, the Neferine group showed an increase in all three cell types, whereas the Pirfenidone group exhibited a decrease. In the Isoliensinine group, γδT and Th17 cells increased, and in the Prednisolone group, only Tregs increased. By day 28, an increase in Th17 cell proportion was observed in all treatment groups, with a decrease in γδT cells noted in the Neferine group. These shifts in cell proportions are consistent with the pathogenesis changes induced by these anti-PF drugs, suggesting a correlation between cellular dynamics and pharmacological interventions in PF progression. Our findings imply potential strategies for assessing the efficacy and timing of anti-PF treatments based on these cellular changes.

Activated HLA-DR+CD38+ Effector Th1/17 Cells Distinguish Crohn's Disease-associated Perianal Fistulas from Cryptoglandular Fistulas

BACKGROUND

Perianal fistulas are a debilitating complication of Crohn's disease (CD). Due to unknown reasons, CD-associated fistulas are in general more difficult to treat than cryptoglandular fistulas (non-CD-associated). Understanding the immune cell landscape is a first step towards the development of more effective therapies for CD-associated fistulas. In this work, we characterized the composition and spatial localization of disease-associated immune cells in both types of perianal fistulas by high-dimensional analyses.

METHODS

We applied single-cell mass cytometry (scMC), spectral flow cytometry (SFC), and imaging mass cytometry (IMC) to profile the immune compartment in CD-associated perianal fistulas and cryptoglandular fistulas. An exploratory cohort (CD fistula, n = 10; non-CD fistula, n = 5) was analyzed by scMC to unravel disease-associated immune cell types. SFC was performed on a second fistula cohort (CD, n = 10; non-CD, n = 11) to comprehensively phenotype disease-associated T helper (Th) cells. IMC was used on a third cohort (CD, n = 5) to investigate the spatial distribution/interaction of relevant immune cell subsets.

RESULTS

Our analyses revealed that activated HLA-DR+CD38+ effector CD4+ T cells with a Th1/17 phenotype were significantly enriched in CD-associated compared with cryptoglandular fistulas. These cells, displaying features of proliferation, regulation, and differentiation, were also present in blood, and colocalized with other CD4+ T cells, CCR6+ B cells, and macrophages in the fistula tracts.

CONCLUSIONS

Overall, proliferating activated HLA-DR+CD38+ effector Th1/17 cells distinguish CD-associated from cryptoglandular perianal fistulas and are a promising biomarker in blood to discriminate between these 2 fistula types. Targeting HLA-DR and CD38-expressing CD4+ T cells may offer a potential new therapeutic strategy for CD-related fistulas.

Allosteric inhibition of CXCR1 and CXCR2 abrogates Th2/Th17-associated Allergic Lung Inflammation in Mice

Background

IL4, IL5, IL13, and IL17-producing CD4 T helper 2 (Th2)-cells and IL17-producing CD4 T helper 17 (Th17)-cells contribute to chronic eosinophilic and neutrophilic airway inflammation in asthma and allergic airway inflammation. Chemokines and their receptors are upregulated in Th2/Th17-mediated inflammation. However, the ability of CXCR1 and CXCR2 modulate Th2 and Th17-cell-mediated allergic lung inflammation has not been reported.

Methods

Mice sensitized and challenged with cat dander extract (CDE) mount a vigorous Th2-Th17-mediated allergic lung inflammation. Allosteric inhibitor of CXCR1 and CXCR2, ladarixin was orally administered in this model. The ability of ladarixin to modulate allergen-challenge induced recruitment of CXCR1 and CXCR2-expressing Th2 and Th17-cells and allergic lung inflammation were examined.

Results

Allergen challenge in sensitized mice increased mRNA expression levels of Il4, Il5, Il13, Il6, Il1β, Tgfβ1, Il17, Il23, Gata3, and Rorc , and induced allergic lung inflammation characterized by recruitment of CXCR1- and CXCR2-expressing Th2-cells, Th17-cells, neutrophils, and eosinophils. Allosteric inhibition of CXCR1 and CXCR2 vigorously blocked each of these pro-inflammatory effects of allergen challenge. CXCL chemokines induced a CXCR1 and CXCR2-dependent proliferation of IL4, IL5, IL13, and IL17 expressing T-cells.

Conclusion

Allosteric inhibition of CXCR1 and CXCR2 abrogates blocks recruitment of CXCR1- and CXCR2-expressing Th2-cells, Th17-cells, neutrophils, and eosinophils in this mouse model of allergic lung inflammation. We suggest that the ability of allosteric inhibition of CXCR1 and CXCR2 to abrogate Th2 and Th17-mediated allergic inflammation should be investigated in humans.

Thymic gene expression analysis reveals a potential link between HIF-1A and Th17/Treg imbalance in thymoma associated myasthenia gravis

Myasthenia gravis (MG) is an immune-mediated disease frequently associated with thymic changes. Increased T helper 17 (Th17) cell activity and dysfunctional regulatory T (Treg) cells have been demonstrated in subgroups of MG. On the other hand, hypoxia-inducible factor 1 (HIF-1) has been shown to regulate the Th17/Treg balance by inducing Th17 differentiation while attenuating Treg development. To identify the underlying mechanisms of different thymic pathologies in MG development, we evaluated thymic samples from thymoma-associated myasthenia gravis (TAMG), MG with hyperplasia (TFH-MG) and thymoma without MG (TOMA) patients. Differential gene expression analysis revealed that TAMG and TFH-MG cells are associated with different functional pathways. A higher RORC/FOXP3 ratio provided evidence for Th17/Treg imbalance in TAMG potentially related to increased HIF1A. The hypoxic microenvironment in thymoma may be a driver of TAMG by increasing HIF1A. These findings may lead to new therapeutic approaches targeting HIF1A in the development of TAMG.

Unraveling CCL20's role by regulating Th17 cell chemotaxis in experimental autoimmune prostatitis

Chronic prostatitis and chronic pelvic pain syndrome (CP/CPPS), a prevalent urological ailment, exerts a profound influence upon the well-being of the males. Autoimmunity driven by Th17 cells has been postulated as a potential factor in CP/CPPS pathogenesis. Nonetheless, elucidating the precise mechanisms governing Th17 cell recruitment to the prostate, triggering inflammation, remained an urgent inquiry. This study illuminated that CCL20 played a pivotal role in attracting Th17 cells to the prostate, thereby contributing to prostatitis development. Furthermore, it identified prostate stromal cells and immune cells as likely sources of CCL20. Additionally, this research unveiled that IL-17A, released by Th17 cells, could stimulate macrophages to produce CCL20 through the NF-κB/MAPK/PI3K pathway. The interplay between IL-17A and CCL20 establishes a positive feedback loop, which might serve as a critical mechanism underpinning the development of chronic prostatitis, thus adding complexity to its treatment challenges.

High-parameter phenotypic characterization reveals a subset of human Th17 cells that preferentially produce IL-17 against M. tuberculosis antigen

Background

Interleukin-17-producing CD4 T cells contribute to the control of Mycobacterium tuberculosis (Mtb) infection in humans; whether infection with human immunodeficiency virus (HIV) disproportionately affects distinct Th17-cell subsets that respond to Mtb is incompletely defined.

Methods

We performed high-definition characterization of circulating Mtb-specific Th17 cells by spectral flow cytometry in people with latent TB and treated HIV (HIV-ART). We also measured kynurenine pathway activity by liquid chromatography-mass spectrometry (LC/MS) on plasma and tested the hypothesis that tryptophan catabolism influences Th17-cell frequencies in this context.

Results

We identified two subsets of Th17 cells: subset 1 defined as CD4+Vα7.2-CD161+CD26+and subset 2 defined as CD4+Vα7.2-CCR6+CXCR3-cells of which subset 1 was significantly reduced in latent tuberculosis infection (LTBI) with HIV-ART, yet Mtb-responsive IL-17-producing CD4 T cells were preserved; we found that IL-17-producing CD4 T cells dominate the response to Mtb antigen but not cytomegalovirus (CMV) antigen or staphylococcal enterotoxin B (SEB), and tryptophan catabolism negatively correlates with both subset 1 and subset 2 Th17-cell frequencies.

Conclusions

We found differential effects of ART-suppressed HIV on distinct subsets of Th17 cells, that IL-17-producing CD4 T cells dominate responses to Mtb but not CMV antigen or SEB, and that kynurenine pathway activity is associated with decreases of circulating Th17 cells that may contribute to tuberculosis immunity.

The Effects of Endosomal Toll-like Receptor Inhibitors in an EBV DNA-Exacerbated Inflammatory Bowel Disease Mouse Model

Epstein-Barr virus (EBV), a Herpesviridae family member, is associated with an increased risk of autoimmune disease development in the host. We previously demonstrated that EBV DNA elevates levels of the pro-inflammatory cytokine IL-17A and that inhibiting Toll-like receptor (TLR) 3, 7, or 9 reduces its levels. Moreover, this DNA exacerbated colitis in a mouse model of inflammatory bowel disease (IBD). In the study at hand, we examined whether inhibition of TLR3, 7, or 9 alleviates this exacerbation. Mice were fed 1.5% dextran sulfate sodium (DSS) water and administered EBV DNA. Then, they were treated with a TLR3, 7, or 9 inhibitor or left untreated. We also assessed the additive impact of combined inhibition of all three receptors. Mice that received DSS, EBV DNA, and each inhibitor alone, or a combination of inhibitors, showed significant improvement. They also had a decrease in the numbers of the pathogenic colonic IL-17A+IFN-γ+ foci. Inhibition of all three endosomal TLR receptors offered no additive benefit over administering a single inhibitor. Therefore, inhibition of endosomal TLRs reduces EBV DNA exacerbation of mouse colitis, offering a potential approach for managing IBD patients infected with EBV.

Immune response induced by standard and fractional doses of 17DD yellow fever vaccine

The re-emergence of yellow fever (YF) urged new mass vaccination campaigns and, in 2017, the World Health Organization approved the use of the fractional dose (FD) of the YF vaccine due to stock shortage. In an observational cross-sectional investigation, we have assessed viremia, antibodies, soluble mediators and effector and memory T and B-cells induced by primary vaccination of volunteers with FD and standard dose (SD). Similar viremia and levels of antibodies and soluble markers were induced early after immunization. However, a faster decrease in the latter was observed after SD. The FD led to a sustained expansion of helper T-cells and an increased expression of activation markers on T-cells early after vaccination. Although with different kinetics, expansion of plasma cells was induced upon SD and FD immunization. Integrative analysis reveals that FD induces a more complex network involving follicular helper T cells and B-cells than SD. Our findings substantiate that FD can replace SD inducing robust correlates of protective immune response against YF.

Integrating circulating T follicular memory cells and autoantibody repertoires for characterization of autoimmune disorders

Introduction

Autoimmune diseases are heterogeneous and often lack specific or sensitive diagnostic tests. Increased percentages of CD4+CXCR5+PD1+ circulating T follicular helper (cTfh) cells and skewed distributions of cTfh subtypes have been associated with autoimmunity. However, cTfh cell percentages can normalize with immunomodulatory treatment despite persistent disease activity, indicating the need for identifying additional cellular and/or serologic features correlating with autoimmunity.

Methods

The cohort included 50 controls and 56 patients with autoimmune cytopenias, gastrointestinal, pulmonary, and/or neurologic autoimmune disease. Flow cytometry was used to measure CD4+CXCR5+ T cell subsets expressing the chemokine receptors CXCR3 and/or CCR6: CXCR3+CCR6- Type 1, CXCR3-CCR6- Type 2, CXCR3+CCR6+ Type 1/17, and CXCR3- CCR6+ Type 17 T cells. IgG and IgA autoantibodies were quantified using a microarray featuring 1616 full-length, conformationally intact protein antigens. The 97.5th percentile in the control cohort defined normal limits for T cell subset percentages and total number (burden) of autoantibodies.

Results

This study focused on CD4+CXCR5+ T cells because CXCR5 upregulation occurs after cognate T-B cell interactions characteristic of autoimmune diseases. We refer to these cells as circulating T follicular memory (cTfm) cells to acknowledge the dynamic nature of antigen-experienced CXCR5+ T cells, which encompass progenitors of cTfh or Tfh cells as well as early effector memory T cells that have not yet lost CXCR5. Compared to controls, 57.1% of patients had increased CXCR5+CXCR3+CCR6+ cTfm1/17 and 25% had increased CXCR5+CXCR3-CCR6+ cTfm17 cell percentages. Patients had significantly more diverse IgG and IgA autoantibodies than controls and 44.6% had an increased burden of autoantibodies of either isotype. Unsupervised autoantibody clustering identified three clusters of patients with IgG autoantibody profiles distinct from those of controls, enriched for patients with active autoimmunity and monogenic diseases. An increased percentage of cTfm17 cells was most closely associated with an increased burden of high-titer IgG and IgA autoantibodies. A composite measure integrating increased cTfm1/17, cTfm17, and high-titer IgG and/or IgA autoantibodies had 91.1% sensitivity and 90.9% specificity for identifying patients with autoimmunity. Percentages of cTfm1/17 and cTfm17 percentages and numbers of high-titer autoantibodies in patients receiving immunomodulatory treatment did not differ from those in untreated patients, thus suggesting that measurements of cTfm can complement measurements of other cellular markers affected by treatment.

Conclusions

This study highlights two new approaches for assessing autoimmunity: measuring CD4+CXCR5+ cTfm subsets as well as total burden of autoantibodies. Our findings suggest that these approaches are particularly relevant to patients with rare autoimmune disorders for whom target antigens and prognosis are often unknown.

High-parameter phenotypic characterization reveals a subset of human Th17 cells that preferentially produce IL17 against M. tuberculosis antigen

Background

Interleukin 17 producing CD4 T cells contribute to the control of Mycobacterium tuberculosis (Mtb) infection in humans; whether infection with Human Immunodeficiency Virus (HIV) disproportionately affects distinct Th17 cell subsets that respond to Mtb is incompletely defined.

Methods

We performed high-definition characterization of circulating Mtb-specific Th17 cells by spectral flow cytometry in people with latent TB and treated HIV (HIV-ART). We also measured kynurenine pathway activity by LC/MS on plasma and tested the hypothesis that tryptophan catabolism influences Th17 cell frequencies in this context.

Results

We identified two subsets of Th17 cells: subset 1 defined as CD4+Vα7.2-CD161+CD26+ and subset 2 defined as CD4+Vα7.2-CCR6+CXCR3- cells of which subset 1 was significantly reduced in LTBI with HIV-ART, yet Mtb-responsive IL17-producing CD4 T cells were preserved; we found that IL17-producing CD4 T cells dominate the response to Mtb antigen but not CMV antigen or staphylococcal enterotoxin B (SEB); and tryptophan catabolism negatively correlates with both subset 1 and subset 2 Th17 cell frequencies.

Conclusions

We found differential effects of ART-suppressed HIV on distinct subsets of Th17 cells, that IL17-producing CD4 T cells dominate responses to Mtb but not CMV antigen or SEB, and that kynurenine pathway activity is associated with decreases of circulating Th17 cells that may contribute to tuberculosis immunity.

Single-cell RNA sequencing in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is one of the most common chronic inflammatory rheumatic diseases in children, with onset before age 16 and lasting for more than 6 weeks. JIA is a highly heterogeneous condition with various consequences for health and quality of life. For some JIA patients, early detection and intervention remain challenging. As a result, further investigation of the complex and unknown mechanisms underlying JIA is required. Advances in technology now allow us to describe the biological heterogeneity and function of individual cell populations in JIA. Through this review, we hope to provide novel ideas and potential targets for the diagnosis and treatment of JIA by summarizing the current findings of single-cell RNA sequencing studies and understanding how the major cell subsets drive JIA pathogenesis.

Immune mapping of human tuberculosis and sarcoidosis lung granulomas

Tuberculosis (TB) and sarcoidosis are both granulomatous diseases. Here, we compared the immunological microenvironments of granulomas from TB and sarcoidosis patients using in situ sequencing (ISS) transcriptomic analysis and multiplexed immunolabeling of tissue sections. TB lesions consisted of large necrotic and cellular granulomas, whereas "multifocal" granulomas with macrophages or epitheloid cell core and a T-cell rim were observed in sarcoidosis samples. The necrotic core in TB lesions was surrounded by macrophages and encircled by a dense T-cell layer. Within the T-cell layer, compact B-cell aggregates were observed in most TB samples. These B-cell clusters were vascularized and could contain defined B-/T-cell and macrophage-rich areas. The ISS of 40-60 immune transcripts revealed the enriched expression of transcripts involved in homing or migration to lymph nodes, which formed networks at single-cell distances in lymphoid areas of the TB lesions. Instead, myeloid-annotated regions were enriched in CD68, CD14, ITGAM, ITGAX, and CD4 mRNA. CXCL8 and IL1B mRNA were observed in granulocytic areas in which M. tuberculosis was also detected. In line with ISS data indicating tertiary lymphoid structures, immune labeling of TB sections expressed markers of high endothelial venules, follicular dendritic cells, follicular helper T cells, and lymph-node homing receptors on T cells. Neither ISS nor immunolabeling showed evidence of tertiary lymphoid aggregates in sarcoidosis samples. Together, our finding suggests that despite their heterogeneity, the formation of tertiary immune structures is a common feature in granulomas from TB patients.

Chemokine Receptor Profile of T Cells and Progression Rate of Geographic Atrophy Secondary to Age-related Macular Degeneration

Purpose

Geographic atrophy (GA) secondary to age-related macular degeneration is a progressive retinal degenerative disease. Systemic chemokine receptors and known risk-associated single-nucleotide polymorphisms have been associated with GA pathogenesis. Because halting progression is pivotal for patients, we investigated the association of candidate chemokine receptors and progression rate (PR) of atrophic lesions in patients with GA.

Methods

This prospective observational study conducted at a single center included 85 patients with GA and 45 healthy controls. Patients were followed up after 13 months on average. Serial fundus autofluorescence images were used to determine the PR of atrophic lesions. The proportion of chemokine receptors on peripheral lymphocytes were determined by flow cytometric analysis.

Results

Patients with GA had a lower proportion of CCR6 on CD8+T cells compared to healthy controls. Importantly, the proportion of CCR6 on CD4+T cells was lower in patients with fast GA progression compared to patients with slow progression of disease, suggesting that dysregulation of CCR6 could be involved in progression of GA. We also found that GA patients had a markedly higher percentage of CCR5 on CD4+ and CD8+T cells compared to healthy controls. After stratification according to ARMS2 polymorphism, we found a significantly lower level of CCR5 on CD8+T cells among patients with high-risk genotypes compared with patients with the low-risk genotype.

Conclusions

Our study finds that chemokine receptors are dysregulated in patients with GA and that CCR6 might be involved in GA progression, making it a potential target for intervention.

Immune mechanisms of granuloma formation in sarcoidosis and tuberculosis

Sarcoidosis is a complex immune-mediated disease characterized by clusters of immune cells called granulomas. Despite major steps in understanding the cause of this disease, many questions remain. In this Review, we perform a mechanistic interrogation of the immune activities that contribute to granuloma formation in sarcoidosis and compare these processes with its closest mimic, tuberculosis, highlighting shared and divergent immune activities. We examine how Mycobacterium tuberculosis is sensed by the immune system; how the granuloma is initiated, formed, and perpetuated in tuberculosis compared with sarcoidosis; and the role of major innate and adaptive immune cells in shaping these processes. Finally, we draw these findings together around several recent high-resolution studies of the granuloma in situ that utilized the latest advances in single-cell technology combined with spatial methods to analyze plausible disease mechanisms. We conclude with an overall view of granuloma formation in sarcoidosis.

Viral Persistence in the Gut-Associated Lymphoid Tissue and Barriers to HIV Cure

More than 40 years after the first reported cases of what then became known as acquired immunodeficiency syndrome (AIDS), tremendous progress has been achieved in transforming the disease from almost universally fatal to a chronic manageable condition. Nonetheless, the efforts to find a preventative vaccine or a cure for the underlying infection with Human Immunodeficiency Virus (HIV) remain largely unsuccessful. Many challenges intrinsic to the virus characteristics and host response need to be overcome for either goal to be achieved. This article will review the obstacles to an effective HIV cure, specifically the steps involved in the generation of HIV latency, focusing on the role of the gut-associated lymphoid tissue, which has received less attention compared with the peripheral blood, despite being the largest repository of lymphoid tissue in the human body, and a large site for HIV persistence.

CD70-induced differentiation of proinflammatory Th1/17/22/GM lymphocytes associated with disease progression and immune reconstitution during HIV infection

Immune overactivation is a hallmark of chronic HIV infection, which is critical to HIV pathogenesis and disease progression. The imbalance of helper T cell (Th) differentiation and subsequent cytokine dysregulation are generally considered to be the major drivers of excessive activation and inflammatory disorders in HIV infection. However, the accurate factors driving HIV-associated Th changes remained to be established. CD70, which was a costimulatory molecule, was found to increase on CD4+ T cells during HIV infection. Overexpression of CD70 on CD4+ T cells was recently reported to associate with highly pathogenic proinflammatory Th1/Th17 polarization in multiple sclerosis. Thus, the role of CD70 in the imbalance of Th polarization and immune overactivation during HIV infection needs to be investigated. Here, we found that the elevated frequency of CD70 + CD4+ T cells was negatively correlated with CD4 count and positively associated with immune activation in treatment-naïve people living with HIV (PLWH). More importantly, CD70 expression defined a population of proinflammatory Th1/17/22/GM subsets in PLWH. Blocking CD70 decreased the mRNA expression of subset-specific markers during Th1/17/22/GM polarization. Furthermore, we demonstrated that CD70 influenced the differentiation of these Th cells through STAT pathway. Finally, it was revealed that patients with a high baseline level of CD70 on CD4+ T cells exhibited a greater risk of poor immune reconstitution after antiretroviral therapy (ART) than those with low CD70. In general, our data highlighted the role of CD70 in Th1/17/22/GM differentiation during HIV infection and provided evidence for CD70 as a potential biomarker for predicting immune recovery.

Lactobacillus johnsonii N6.2 phospholipids induce immature-like dendritic cells with a migratory-regulatory-like transcriptional signature

Shifts in the gut microbiota composition, called dysbiosis, have been directly associated with acute and chronic diseases. However, the underlying biological systems connecting gut dysbiosis to systemic inflammatory pathologies are not well understood. Phospholipids (PLs) act as precursors of both, bioactive inflammatory and resolving mediators. Their dysregulation is associated with chronic diseases including cancer. Gut microbial-derived lipids are structurally unique and capable of modulating host's immunity. Lactobacillus johnsonii N6.2 is a Gram-positive gut symbiont with probiotic characteristics. L. johnsonii N6.2 reduces the incidence of autoimmunity in animal models of Type 1 Diabetes and improves general wellness in healthy volunteers by promoting, in part, local and systemic anti-inflammatory responses. By utilizing bioassay-guided fractionation methods with bone marrow-derived dendritic cells (BMDCs), we report here that L. johnsonii N6.2 purified lipids induce a transcriptional signature that resembles that of migratory (mig) DCs. RNAseq-based analysis showed that BMDCs stimulated with L. johnsonii N6.2 total lipids upregulate maturation-mig related genes Cd86, Cd40, Ccr7, Icam1 along with immunoregulatory genes including Itgb8, Nfkbiz, Jag1, Adora2a, IL2ra, Arg1, and Cd274. Quantitative reverse transcription (qRT)-PCR analysis indicated that PLs are the bioactive lipids triggering the BMDCs response. Antibody-blocking of surface Toll-like receptor (TLR)2 resulted in boosted PL-mediated upregulation of pro-inflammatory Il6. Chemical inhibition of the IKKα kinase from the non-canonical NF-κB pathway specifically restricted upregulation of Il6 and Tnf. Phenotypically, PL-stimulated BMDCs displayed an immature like-phenotype with significantly increased surface ICAM-1. This study provides insight into the immunoregulatory capacity of Gram-positive, gut microbial-derived phospholipids on innate immune responses.

Mass cytometric analysis unveils a disease-specific immune cell network in the bone marrow in acquired aplastic anemia

Idiopathic acquired aplastic anemia (AA) is considered an immune-mediated syndrome of bone marrow failure since approximately 70% of patients respond to immunosuppressive therapy (IST) consisting of a course of anti-thymocyte globulin (ATG) followed by long-term use of ciclosporin. However, the immune response that underlies the pathogenesis of AA remains poorly understood. In this study, we applied high-dimensional mass cytometry on bone marrow aspirates of AA patients pre-ATG, AA patients post-ATG and healthy donors to decipher which immune cells may be implicated in the pathogenesis of AA. We show that the bone marrow of AA patients features an immune cell composition distinct from healthy donors, with significant differences in the myeloid, B-cell, CD4+ and CD8+ T-cells lineages. Specifically, we discovered that AA pre-ATG is characterized by a disease-specific immune cell network with high frequencies of CD16+ myeloid cells, CCR6++ B-cells, Th17-like CCR6+ memory CD4+ T-cells, CD45RA+CCR7+CD38+ CD8+ T-cells and KLRG1+ terminally differentiated effector memory (EMRA) CD8+ T-cells, compatible with a state of chronic inflammation. Successful treatment with IST strongly reduced the levels of CD16+ myeloid cells and showed a trend toward normalization of the frequencies of CCR6++ B-cells, CCR6+ memory CD4+ T-cells and KLRG1+EMRA CD8+ T-cells. Altogether, our study provides a unique overview of the immune landscape in bone marrow in AA at a single-cell level and proposes CCR6 as a potential new therapeutic target in AA.

Critical Roles of SRC-3 in the Development and Progression of Breast Cancer, Rendering It a Prospective Clinical Target

Breast cancer (BCa) is the most frequently diagnosed malignant tumor in women and is also one of the leading causes of cancer-related death. Most breast tumors are hormone-dependent and estrogen signaling plays a critical role in promoting the survival and malignant behaviors of these cells. Estrogen signaling involves ligand-activated cytoplasmic estrogen receptors that translocate to the nucleus with various co-regulators, such as steroid receptor co-activator (SRC) family members, and bind to the promoters of target genes and regulate their expression. SRC-3 is a member of this family that interacts with, and enhances, the transcriptional activity of the ligand activated estrogen receptor. Although SRC-3 has important roles in normal homeostasis and developmental processes, it has been shown to be amplified and overexpressed in breast cancer and to promote malignancy. The malignancy-promoting potential of SRC-3 is diverse and involves both promoting malignant behavior of tumor cells and creating a tumor microenvironment that has an immunosuppressive phenotype. SRC-3 also inhibits the recruitment of tumor-infiltrating lymphocytes with effector function and promotes stemness. Furthermore, SRC-3 is also involved in the development of resistance to hormone therapy and immunotherapy during breast cancer treatment. The versatility of SRC-3 in promoting breast cancer malignancy in this way makes it a good target, and methodical targeting of SRC-3 probably will be important for the success of breast cancer treatment.

Pathogenic Th17 cells in autoimmunity with regard to rheumatoid arthritis

Th17 cells contribute the pathobiology of autoimmune diseases, including rheumatoid arthritis (RA). However, it was shown that differentiated Th17 cells display a high degree of plasticity under the influence of inflammatory conditions. In some autoimmune diseases, the majority of Th17 cells, especially at sites of inflammation, have a phenotype that is intermediate between Th17 and Th1. These cells, which are described as Th17.1 or exTh17 cells, are hypothesized to be more pathogenic than classical Th17 cells. In this review, the involvement of Th17.1 lymphocytes in RA, and potential features that might render these cells to be more pathogenic are discussed.

A permutation-based approach using a rank-based statistic to identify sex differences in epigenetics

Epigenetic sex differences and their resulting implications for human health have been studied for about a decade. The objective of this paper is to use permutation-based inference and a new ranked-based test statistic to identify sex-based epigenetic differences in the human DNA methylome. In particular, we examine whether we could identify separations between the female and male distributions of DNA methylation across hundred of thousands CpG sites in two independent cohorts, the Swedish Adoption Twin study and the Lamarck study. Based on Fisherian p-values, we set a threshold for methylation differences "worth further scrutiny". At this threshold, we were able to confirm previously-found CpG sites that stratify with respect to sex. These CpG sites with sex differences in DNA methylation should be further investigated for their possible contribution to various physiological and pathological functions in the human body. We followed-up our statistical analyses with a literature review in order to inform the proposed disease implications for the loci we uncovered.

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.

Proteomics profiling of CD4 + T-cell-derived exosomes from patients with rheumatoid arthritis

OBJECTIVES

Our study profiled the CD4 + T-cell-derived exosomes from patients with rheumatoid arthritis (RA) using proteomics.

METHODS

Proteomic analysis of CD4 + T-cell-derived exosomes was performed by tandem mass tags (TMT) combined with LC-MS/MS. We validated the most significantly upregulated and downregulated proteins using ELISA and WB.

RESULTS

The proteomic results showed that there were 3 upregulated differentially expressed proteins and 31 downregulated differentially expressed proteins in the RA group. The results indicated that dihydropyrimidinase-related protein 3 (DPYSL3) was significantly upregulated in CD4 + T-cell-derived exosomes, whereas proteasome activator complex subunit 1 (PSME1) was significantly downregulated in the RA group. Bioinformatics analysis showed that proteins were enriched in "positive regulation of gene expression", "antigen processing and presentation", "acute-phase response" and "PI3K-AKT signaling" pathways. ELISA verified that compared to the control group, the RA group showed significant upregulation of DPYSL3, and downregulation of PSME1 in CD4 + T-cell-derived exosomes.

CONCLUSIONS

The proteomic analysis results of CD4 + T-cell-derived exosomes from patients with RA suggest that these differentially expressed proteins may be involved in RA pathogenesis. DPYSL3 and PSME1 may become useful biomarkers for RA.

Baseline innate and T cell populations are correlates of protection against symptomatic influenza virus infection independent of serology

Evidence suggests that innate and adaptive cellular responses mediate resistance to the influenza virus and confer protection after vaccination. However, few studies have resolved the contribution of cellular responses within the context of preexisting antibody titers. Here, we measured the peripheral immune profiles of 206 vaccinated or unvaccinated adults to determine how baseline variations in the cellular and humoral immune compartments contribute independently or synergistically to the risk of developing symptomatic influenza. Protection correlated with diverse and polyfunctional CD4+ and CD8+ T, circulating T follicular helper, T helper type 17, myeloid dendritic and CD16+ natural killer (NK) cell subsets. Conversely, increased susceptibility was predominantly attributed to nonspecific inflammatory populations, including γδ T cells and activated CD16- NK cells, as well as TNFα+ single-cytokine-producing CD8+ T cells. Multivariate and predictive modeling indicated that cellular subsets (1) work synergistically with humoral immunity to confer protection, (2) improve model performance over demographic and serologic factors alone and (3) comprise the most important predictive covariates. Together, these results demonstrate that preinfection peripheral cell composition improves the prediction of symptomatic influenza susceptibility over vaccination, demographics or serology alone.

The interplay between Epstein-Barr virus DNA and gut microbiota in the development of arthritis in a mouse model

Epstein-Barr virus (EBV) DNA may influence the development of autoimmune diseases by increasing the production of proinflammatory cytokines. Such cytokines have been associated with inducing the dysbiosis of colonic microbiota, which, in turn, is a risk factor for autoimmune diseases such as rheumatoid arthritis (RA). Therefore, we investigated the role that EBV DNA may play in modulating the intestinal microbiota and consequent exacerbation of arthritis in a mouse model. Mice were treated with collagen (arthritis-inducing agent), EBV DNA and collagen, EBV DNA, or water. Fecal samples were collected from arthritic and control mice, and 16S rRNA sequencing was performed to determine the effect of EBV DNA on the composition of colonic microbiota. EBV DNA causes a change in the alpha diversity of the microbiota resulting in an increased Chao1 microbial richness and decreased Shannon diversity index in the RA mouse model. In addition, the abundance of particular genera/genus clusters was significantly altered among the various groups, with the EBV DNA-exacerbated arthritic group having the highest number of altered genera/genus cluster abundances. This group also had the highest number of cells co-expressing IL-17A, FOXP3, and IFNγ in the colons. Antimicrobial-cleared mice transplanted with fecal samples from EBV DNA-exacerbated arthritic mice showed a higher incidence and enhanced severity of RA compared to those transplanted with fecal samples from water or collagen-treated mice. IMPORTANCE Epstein-Barr virus (EBV) DNA alters the composition and diversity of the gut microbiota in a rheumatoid arthritis (RA) mouse model. These induced changes are associated with enhanced severity of symptoms. This better understanding of the various factors involved in the development of RA will possibly help in creating individualized treatments for RA patients including target mediators triggered by viral DNA. Given that a large swathe of the population harbors EBV, a significant proportion of subjects with arthritis may benefit from possible approaches that target EBV or mediators triggered by this virus.

Dynamics of circulating lymphocytes responding to human experimental enterotoxigenic Escherichia coli infection

Enterotoxigenic Escherichia coli (ETEC) is an important cause of children's and travelers' diarrhea, with no licensed vaccine. This study aimed to explore the role of cellular immunity in protection against human ETEC infection. Nine volunteers were experimentally infected with ETEC, of which six developed diarrhea. Lymphocytes were collected from peripheral blood buffy coats, before and 3, 5, 6, 7, 10, and 28 days after dose ingestion, and 34 phenotypic and functional markers were examined by mass cytometry. Thirty-three cell populations, derived by manually merging 139 cell clusters from the X-shift unsupervised clustering algorithm, were analyzed. Initially, the diarrhea group responded with increased CD56dim CD16+ natural killer cells, dendritic cells tended to rise, and mucosal-associated invariant T cells decreased. On day 5-7, an increase in plasmablasts was paralleled by a consistent rise in CD4+ Th17-like effector memory and regulatory cell subsets. CD4+ Th17-like central memory cells peaked on day 10. All Th17-like cell populations showed increased expression of activation, gut-homing, and proliferation markers. Interestingly, in the nondiarrhea group, these same CD4+ Th17-like cell populations expanded earlier, normalizing around day 7. Earlier development of these CD4+ Th17-like cell populations in the nondiarrhea group may suggest a recall response and a potential role in controlling ETEC infections.

Dysbiosis and primary B-cell immunodeficiencies: current knowledge and future perspective

According to Elie Metchnikoff, an originator of modern immunology, several pivotal functions for disease and health are provided by indigenous microbiota. Nonetheless, important mechanistic insights have been elucidated more recently, owing to the growing availability of DNA sequencing technology. There are 10 to 100 trillion symbiotic microbes (such as viruses, bacteria, and yeast) in each human gut microbiota. Both locally and systemically, the gut microbiota has been demonstrated to impact immune homeostasis. Primary B-cell immunodeficiencies (PBIDs) are a group of primary immunodeficiency diseases (PIDs) referring to the dysregulated antibody production due to either intrinsic genetic defects or failures in functions of B cells. Recent studies have found that PBIDs cause disruptions in the gut's typical homeostatic systems, resulting in inadequate immune surveillance in the gastrointestinal (GI) tract, which is linked to increased dysbiosis, which is characterized by a disruption in the microbial homeostasis. This study aimed to review the published articles in this field to provide a comprehensive view of the existing knowledge about the crosstalk between the gut microbiome and PBID, the factors shaping the gut microbiota in PBID, as well as the potential clinical approaches for restoring a normal microbial community.

Inflammation, Autoinflammation and Autoimmunity in Inflammatory Bowel Diseases

In this review, the role of innate and adaptive immunity in the pathogenesis of inflammatory bowel diseases (IBD) is reported. In IBD, an altered innate immunity is often found, with increased Th17 and decreased Treg cells infiltrating the intestinal mucosa. An associated increase in inflammatory cytokines, such as IL-1 and TNF-α, and a decrease in anti-inflammatory cytokines, such as IL-10, concur in favoring the persistent inflammation of the gut mucosa. Autoinflammation is highlighted with insights in the role of inflammasomes, which activation by exogenous or endogenous triggers might be favored by mutations of NOD and NLRP proteins. Autoimmunity mechanisms also take place in IBD pathogenesis and in this context of a persistent immune stimulation by bacterial antigens and antigens derived from intestinal cells degradation, the adaptive immune response takes place and results in antibodies and autoantibodies production, a frequent finding in these diseases. Inflammation, autoinflammation and autoimmunity concur in altering the mucus layer and enhancing intestinal permeability, which sustains the vicious cycle of further mucosal inflammation.

The protective and pathogenic role of Th17 cell plasticity and function in the tumor microenvironment

At the turn of the century, researchers discovered a unique subtype of T helper cells that secretes IL-17 and defined it as Th17. The latest study found that Th17 cells play both positive and negative definitive roles in the regulation of antitumor immune responses. Although the function of Th17 in the tumor microenvironment remains poorly understood, more and more studies have shown that this paradoxical dual role is closely related to the plasticity of Th17 cells in recent decades. Further understanding of the characteristics of Th17 cells in the tumor microenvironment could yield novel and useful therapeutic approaches to treat cancer. In this review, we further present the high plasticity of Th17 cells and the function of Th17-producing IL-17 in tumor immunity.

Development and therapeutic potential of allosteric retinoic acid receptor-related orphan receptor γt (RORγt) inverse agonists for autoimmune diseases

The transcription factor retinoic acid receptor-related orphan receptor γt (RORγt) is an attractive drug target for some autoimmune diseases owing to its roles in the differentiation of human T helper 17 (Th17) cells which produce pro-inflammatory cytokine interleukin (IL)-17. RORγt agonists and inverse agonists are classically targeted to the hydrophobic and highly conserved orthosteric binding pocket of RORγt ligand binding domain (LBD). Although successful, this approach also brings some challenges, including off-target effects due to lack of selectivity over other nuclear receptors (NRs). Allosteric regulation of RORγt by synthetic small molecules has recently emerged as novel research interests for its interesting modes of action (MOA), satisfying bioactivity profile and improved selectivity. In this review, we delineated the discovery and identification of the allosteric pocket of RORγt. Subsequently, we focused on examples of small molecules that allosterically inhibit RORγt, with a central attention on structural-activity-relationship (SAR) information, biological activity, pharmacokinetic (PK) property, and the ligand binding mode of these compounds. We also discussed the potential role of RORγt allosteric inverse agonists as small molecule therapeutics for autoimmune diseases.

Human CCR6+ Th Cells Show Both an Extended Stable Gradient of Th17 Activity and Imprinted Plasticity

Th17 cells have been investigated in mice primarily for their contributions to autoimmune diseases. However, the pathways of differentiation of Th17 and related Th cells (type 17 cells) and the structure of the type 17 memory population in humans are not well understood; such understanding is critical for manipulating these cells in vivo. By exploiting differences in levels of surface CCR6, we found that human type 17 memory cells, including individual T cell clonotypes, form an elongated continuum of type 17 character along which cells can be driven by increasing RORγt. This continuum includes cells preserved within the memory pool with potentials that reflect the early preferential activation of multiple over single lineages. The phenotypes and epigenomes of CCR6+ cells are stable across cell divisions under noninflammatory conditions. Nonetheless, activation in polarizing and nonpolarizing conditions can yield additional functionalities, revealing, respectively, both environmentally induced and imprinted mechanisms that contribute differentially across the type 17 continuum to yield the unusual plasticity ascribed to type 17 cells.

Intestinal endothelial cells increase HIV infection and latency in resting and activated CD4 + T cells, particularly affecting CCR6 + CD4 + T cells

BACKGROUND

With suppressive antiretroviral therapy, HIV infection is well-managed in most patients. However, eradication and cure are still beyond reach due to latent viral reservoirs in CD4 + T cells, particularly in lymphoid tissue environments including the gut associated lymphatic tissues. In HIV patients, there is extensive depletion of T helper cells, particularly T helper 17 cells from the intestinal mucosal area, and the gut is one of the largest viral reservoir sites. Endothelial cells line lymphatic and blood vessels and were found to promote HIV infection and latency in previous studies. In this study, we examined endothelial cells specific to the gut mucosal area-intestinal endothelial cells-for their impact on HIV infection and latency in T helper cells.

RESULTS

We found that intestinal endothelial cells dramatically increased productive and latent HIV infection in resting CD4 + T helper cells. In activated CD4 + T cells, endothelial cells enabled the formation of latent infection in addition to the increase of productive infection. Endothelial-cell-mediated HIV infection was more prominent in memory T cells than naïve T cells, and it involved the cytokine IL-6 but did not involve the co-stimulatory molecule CD2. The CCR6 + T helper 17 subpopulation was particularly susceptible to such endothelial-cell-promoted infection.

CONCLUSION

Endothelial cells, which are widely present in lymphoid tissues including the intestinal mucosal area and interact regularly with T cells physiologically, significantly increase HIV infection and latent reservoir formation in CD4 + T cells, particularly in CCR6 + T helper 17 cells. Our study highlighted the importance of endothelial cells and the lymphoid tissue environment in HIV pathology and persistence.

Tocilizumab increases regulatory T cells, reduces natural killer cells and delays graft-versus-host disease development in humanized mice treated with post-transplant cyclophosphamide

Graft-versus-host disease (GVHD) is a life-threatening complication following donor hematopoietic stem cell transplantation, where donor T cells damage host tissues. This study investigated the effect of tocilizumab (TOC) combined with post-transplant cyclophosphamide (PTCy) on immune cell engraftment and GVHD development in a humanized mouse model. NOD-scid-IL2Rγ^null (NSG) mice were injected intraperitoneally with 2 × 10⁷ human (h) peripheral blood mononuclear cells and cyclophosphamide (33 mg kg^-1 ) or saline on days 3 and 4, then TOC or control antibody (0.5 mg mouse^-1 ) twice weekly for 28 days. Mice were monitored for clinical signs of GVHD for either 28 or 70 days. Spleens and livers were assessed for human leukocyte subsets, and serum cytokines and tissue histology were analyzed. In the short-term model (day 28), liver and lung damage were reduced in PTCy + TOC compared with control mice. All groups showed similar splenic hCD45⁺ leukocyte engraftment (55-60%); however, PTCy + TOC mice demonstrated significantly increased (1.5-2-fold) splenic regulatory T cells. Serum human interferon gamma was significantly reduced in PTCy + TOC compared with control mice. Long-term (day 70), prolonged survival was similar in PTCy + TOC (median survival time, > 70 days) and PTCy mice (median survival time, 56 days). GVHD onset was significantly delayed in PTCy + TOC, compared with TOC or control mice. Notably, natural killer cells were reduced (77.5%) in TOC and PTCy + TOC mice. Overall, combining PTCy with TOC increases regulatory T cells and reduces clinical signs of early GVHD, but does not improve long-term survival compared with PTCy alone.

The Epigenetic Reader Protein SP140 Regulates Dendritic Cell Activation, Maturation and Tolerogenic Potential

SP140 is an epigenetic reader protein expressed predominantly in immune cells. GWAS studies have shown an association between SP140 single nucleotide polymorphisms (SNPs) and diverse autoimmune and inflammatory diseases, suggesting a possible pathogenic role for SP140 in immune-mediated diseases. We previously demonstrated that treatment of human macrophages with the novel selective inhibitor of the SP140 protein (GSK761) reduced the expression of endotoxin-induced cytokines, implicating a role of SP140 in the function of inflammatory macrophages. In this study, we investigated the effects of GSK761 on in vitro human dendritic cell (DC) differentiation and maturation, assessing the expression of cytokines and co-stimulatory molecules and their capacity to stimulate T-cell activation and induce phenotypic changes. In DCs, lipopolysaccharide (LPS) stimulation induced an increase in SP140 expression and its recruitment to transcription start sites (TSS) of pro-inflammatory cytokine genes. Moreover, LPS-induced cytokines such as TNF, IL-6, and IL-1β were reduced in GSK761- or SP140 siRNA- treated DCs. Although GSK761 did not significantly affect the expression of surface markers that define the differentiation of CD14⁺ monocytes into immature DCs (iDCs), subsequent maturation of iDCs to mature DCs was significantly inhibited. GSK761 strongly reduced expression of the maturation marker CD83, the co-stimulatory molecules CD80 and CD86, and the lipid-antigen presentation molecule CD1b. Finally, when the ability of DCs to stimulate recall T-cell responses by vaccine-specific T cells was assessed, T cells stimulated by GSK761-treated DCs showed reduced TBX21 and RORA expression and increased FOXP3 expression, indicating a preferential generation of regulatory T cells. Overall, this study suggests that SP140 inhibition enhances the tolerogenic properties of DCs, supporting the rationale of targeting SP140 in autoimmune and inflammatory diseases where DC-mediated inflammatory responses contribute to disease pathogenesis.

Identification of the Binding Epitope of an Anti-Mouse CCR6 Monoclonal Antibody (C6Mab-13) Using 1× Alanine Scanning

CC chemokine receptor 6 (CCR6) is one of the members of the G-protein-coupled receptor (GPCR) family that is upregulated in many immune-related cells, such as B lymphocytes, effector and memory T cells, regulatory T cells, and immature dendritic cells. The coordination between CCR6 and its ligand CC motif chemokine ligand 20 (CCL20) is deeply involved in the pathogenesis of various diseases, such as cancer, psoriasis, and autoimmune diseases. Thus, CCR6 is an attractive target for therapy and is being investigated as a diagnostic marker for various diseases. In a previous study, we developed an anti-mouse CCR6 (mCCR6) monoclonal antibody (mAb), C₆Mab-13 (rat IgG₁, kappa), that was applicable for flow cytometry by immunizing a rat with the N-terminal peptide of mCCR6. In this study, we investigated the binding epitope of C₆Mab-13 using an enzyme-linked immunosorbent assay (ELISA) and the surface plasmon resonance (SPR) method, which were conducted with respect to the synthesized point-mutated-peptides within the 1-20 amino acid region of mCCR6. In the ELISA results, C₆Mab-13 lost its ability to react to the alanine-substituted peptide of mCCR6 at Asp11, thereby identifying Asp11 as the epitope of C₆Mab-13. In our SPR analysis, the dissociation constants (K_D) could not be calculated for the G9A and D11A mutants due to the lack of binding. The SPR analysis demonstrated that the C₆Mab-13 epitope comprises Gly9 and Asp11. Taken together, the key binding epitope of C₆Mab-13 was determined to be located around Asp11 on mCCR6. Based on the epitope information, C₆Mab-13 could be useful for further functional analysis of mCCR6 in future studies.

Manual cell selection in single cell transcriptomics using scSELpy supports the analysis of immune cell subsets

Introduction

Single cell RNA sequencing plays an increasing and indispensable role in immunological research such as in the field of inflammatory bowel diseases (IBD). Professional pipelines are complex, but tools for the manual selection and further downstream analysis of single cell populations are missing so far.

Methods

We developed a tool called scSELpy, which can easily be integrated into Scanpy-based pipelines, allowing the manual selection of cells on single cell transcriptomic datasets by drawing polygons on various data representations. The tool further supports the downstream analysis of the selected cells and the plotting of results.

Results

Taking advantage of two previously published single cell RNA sequencing datasets we show that this tool is useful for the positive and negative selection of T cell subsets implicated in IBD beyond standard clustering. We further demonstrate the feasibility for subphenotyping T cell subsets and use scSELpy to corroborate earlier conclusions drawn from the dataset. Moreover, we also show its usefulness in the context of T cell receptor sequencing.

Discussion

Collectively, scSELpy is a promising additive tool fulfilling a so far unmet need in the field of single cell transcriptomic analysis that might support future immunological research.

SMURF1 inhibits the Th17 and Th17.1 polarization and improves the Treg/Th17 imbalance in systemic lupus erythematosus through the ubiquitination of RORγt

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease. This study aimed to investigate the role of SMAD specific E3 ubiquitin protein ligase 1 (SMURF1) in the Th17 and Th17.1 differentiation and Treg/Th17 imbalance, which are major factors contributing to the pathogenesis of SLE. SLE patients and healthy individuals were recruited to detect the SMURF1 levels in naïve CD4⁺ cells from peripheral blood. Purified and expanded naïve CD4⁺ T cells were employed to evaluate the effects of SMURF1 on Th17 and Th17.1 polarization in vitro. MRL/lpr lupus model was employed to explore the disease phenotype as well as Treg/Th17 balance in vivo. The results showed that SMURF1 was down-regulated in naïve CD4⁺ T cells in peripheral blood of patients with SLE and in spleen of MRL/lpr mice. SMURF1 overexpression suppressed the polarization of naïve CD4⁺ T cells toward Th17 and Th17.1 phenotype and down-regulated the expression of retinoid-related orphan receptor-gammat (RORγt). Subsequently, SMURF1 down-regulation aggravated the disease phenotype, inflammation, and the Treg/Th17 imbalance in MRL/lpr mice. Furthermore, we found that SMURF overexpression promoted the ubiquitination and decreases the stability of RORγt. In conclusion, SMURF1 inhibited the polarization of Th17 and Th17.1 cells and improved the Treg/Th17 imbalance in SLE, which was mediated as least partly by the ubiquitination of RORγt.

The Search for the Pathogenic T Cells in the Joint of Rheumatoid Arthritis: Which T-Cell Subset Drives Autoimmune Inflammation?

Rheumatoid arthritis (RA) is a chronic inflammatory disorder affecting systemic synovial tissues, leading to the destruction of multiple joints. Its etiology is still unknown, but T-cell-mediated autoimmunity has been thought to play critical roles, which is supported by experimental as well as clinical observations. Therefore, efforts have been made to elucidate the functions and antigen specificity of pathogenic autoreactive T cells, which could be a therapeutic target for disease treatment. Historically, T-helper (Th)1 and Th17 cells are hypothesized to be pathogenic T cells in RA joints; however, lines of evidence do not fully support this hypothesis, showing polyfunctionality of the T cells. Recent progress in single-cell analysis technology has led to the discovery of a novel helper T-cell subset, peripheral helper T cells, and attracted attention to the previously unappreciated T-cell subsets, such as cytotoxic CD4 and CD8 T cells, in RA joints. It also enables a comprehensive view of T-cell clonality and function. Furthermore, the antigen specificity of the expanded T-cell clones can be determined. Despite such progress, which T-cell subset drives inflammation is yet known.

E. coli LPS/TLR4/NF-κB Signaling Pathway Regulates Th17/Treg Balance Mediating Inflammatory Responses in Oral Lichen Planus

Oral lichen planus (OLP) is a chronic inflammatory autoimmune disease mediated by T cells. The imbalance of microflora has potential impacts on the onset and development of OLP, but the mechanism is still unclear. Here, we investigated the effects of Escherichia coli (E. coli) lipopolysaccharide (LPS) simulating the microbial enrichment state of OLP on T cell immune functions in vitro. Effect of E. coli LPS on the viability of T cell using CCK8 assay. After E. coli LPS pretreatment, the expression of the toll-like receptor 4 (TLR4), nuclear factor-kappa B p65 (NF-κB p65), cytokines, retinoic acid-related orphan receptor γt (RORγt), and forkhead box p3 (Foxp3) in the peripheral blood of OLP patients and normal controls (NC) were assessed using quantitative RT-PCR (qRT-PCR), western blot, and enzyme-linked immunosorbent assay (ELISA). Finally, Th17 and Treg cells were detected by flow cytometry. We found that the TLR4/NF-κB pathway was activated and the expression of interleukin (IL)-6 and IL-17 was increased in both groups after E. coli LPS stimulation. CC chemokine ligand (CCL)20 and CC chemokine receptor (CCR)4 expression was increased in OLP after E. coli LPS treatment, while no difference was found in CCR6 and CCL17 expression of both groups. Moreover, E. coli LPS treatment enhanced the proportion of Th17 cells, Th17/Treg ratio, and RORγt/Foxp3 ratio in OLP. In conclusion, E. coli LPS regulated Th17/Treg balance to mediate the inflammatory responses of OLP through the TLR4/NF-κB pathway in vitro, indicating that oral microbiota dysbiosis affected the chronic inflammatory state of OLP.

Disease mechanisms as subtypes: Immune dysfunction in Parkinson's disease

In recent years, the contraposition between inflammatory and neurodegenerative processes has been increasingly challenged. Inflammation has been emphasized as a key player in the onset and progression of Parkinson disease (PD) and other neurodegenerative disorders. The strongest indicators of the involvement of the immune system derived from evidence of microglial activation, profound imbalance in phenotype and composition of peripheral immune cells, and impaired humoral immune responses. Moreover, peripheral inflammatory mechanisms (e.g., involving the gut-brain axis) and immunogenetic factors are likely to be implicated. Even though several lines of preclinical and clinical studies are supporting and defining the complex relationship between the immune system and PD, the exact mechanisms are currently unknown. Similarly, the temporal and causal connections between innate and adaptive immune responses and neurodegeneration are unsettled, challenging our ambition to define an integrated and holistic model of the disease. Despite these difficulties, current evidence is providing the unique opportunity to develop immune-targeted approaches for PD, thus enriching our therapeutic armamentarium. This chapter aims to provide an extensive overview of past and present studies that explored the implication of the immune system in neurodegeneration, thus paving the road for the concept of disease modification in PD.

Human IL-23 is essential for IFN-γ-dependent immunity to mycobacteria

Patients with autosomal recessive (AR) IL-12p40 or IL-12Rβ1 deficiency display Mendelian susceptibility to mycobacterial disease (MSMD) due to impaired IFN-γ production and, less commonly, chronic mucocutaneous candidiasis (CMC) due to impaired IL-17A/F production. We report six patients from four kindreds with AR IL-23R deficiency. These patients are homozygous for one of four different loss-of-function IL23R variants. All six patients have a history of MSMD, but only two suffered from CMC. We show that IL-23 induces IL-17A only in MAIT cells, possibly contributing to the incomplete penetrance of CMC in patients unresponsive to IL-23. By contrast, IL-23 is required for both baseline and Mycobacterium-inducible IFN-γ immunity in both Vδ2+ γδ T and MAIT cells, probably contributing to the higher penetrance of MSMD in these patients. Human IL-23 appears to contribute to IL-17A/F-dependent immunity to Candida in a single lymphocyte subset but is required for IFN-γ-dependent immunity to Mycobacterium in at least two lymphocyte subsets.

Intestinal epithelial HDAC3 and MHC class II coordinate microbiota-specific immunity

Aberrant immune responses to resident microbes promote inflammatory bowel disease and other chronic inflammatory conditions. However, how microbiota-specific immunity is controlled in mucosal tissues remains poorly understood. Here, we found that mice lacking epithelial expression of microbiota-sensitive histone deacetylase 3 (HDAC3) exhibited increased accumulation of commensal-specific CD4+ T cells in the intestine, provoking the hypothesis that epithelial HDAC3 may instruct local microbiota-specific immunity. Consistent with this, microbiota-specific CD4+ T cells and epithelial HDAC3 expression were concurrently induced following early-life microbiota colonization. Further, epithelium-intrinsic ablation of HDAC3 decreased commensal-specific Tregs, increased commensal-specific Th17 cells, and promoted T cell-driven colitis. Mechanistically, HDAC3 was essential for NF-κB-dependent regulation of epithelial MHC class II (MHCII). Epithelium-intrinsic MHCII dampened local accumulation of commensal-specific Th17 cells in adult mice and protected against microbiota-triggered inflammation. Remarkably, HDAC3 enabled the microbiota to induce MHCII expression on epithelial cells and limit the number of commensal-specific T cells in the intestine. Collectively, these data reveal a central role for an epithelial histone deacetylase in directing the dynamic balance of tissue-intrinsic CD4+ T cell subsets that recognize commensal microbes and control inflammation.

T cells in idiopathic pulmonary fibrosis: crucial but controversial

Idiopathic pulmonary fibrosis (IPF) has been extensively studied in recent decades due to its rising incidence and high mortality. Despite an abundance of research, the mechanisms, immune-associated mechanisms, of IPF are poorly understood. While defining immunopathogenic mechanisms as the primary pathogenesis is controversial, recent studies have verified the contribution of the immune system to the fibrotic progression of IPF. Extensive evidence has shown the potential role of T cells in fibrotic progression. In this review, we emphasize the features of T cells in IPF and highlight the controversial roles of different subtypes of T cells or even two distinct effects of one type of T-cell in diverse settings, and multiple chemokines and cell products are discussed. Furthermore, we discuss the potential development of treatments targeting the immune molecules of T cells and the feasibility of immune therapies for IPF in clinical practice.

Intestinal recruitment of CCR6-expressing Th17 cells by suppressing miR-681 alleviates endotoxemia-induced intestinal injury and reduces mortality

INTRODUCTION

Sepsis or endotoxemia can induce intestinal dysfunction in the epithelial and immune barrier. Th17 cells, a distinct subset of CD4⁺ T-helper cells, act as "border patrol" in the intestine under pathological condition and in the previous studies, Th17 cells exhibited an ambiguous function in intestinal inflammation. Our study will explore a specific role of Th17 cells and its relevant mechanism in endotoxemia-induced intestinal injury.

MATERIALS AND METHODS

Lipopolysaccharide was used to establish mouse model of endotoxemia. miR-681 was analyzed by RT-PCR and northern blot analysis and its regulation by HIF-1α was determined by chromatin immunoprecipitation and luciferase reporter assay. Intestinal Th17 cells isolated from endotoxemic mice were quantitatively evaluated by flow cytometry and its recruitment to the intestine controlled by miR-681/CCR6 pathway was assessed by using anti-miRNA treatment and CCR6 knockout mice. Intestinal histopathology, villus length, intestinal inflammation, intestinal permeability, bacterial translocation and survival were investigated, by histology and TUNEL analysis, ELISA, measurement of diamine oxidase, bacterial culture, with or without anti-miR-681 treatment in endotoxemic wild-type and (or) CCR6 knockout mice.

RESULTS

In this study, we found that miR-681 was significantly promoted in intestinal Th17 cells during endotoxemia, which was dependent on hypoxia-inducible factor-1α (HIF-1α). Interestingly, miR-681 could directly suppress CCR6, which was a critical modulator for Th17 cell recruitment to the intestines. In vivo, anti-miR-681 enhanced survival, increased number of intestinal Th17 cells, reduced crypt and villi apoptosis, decreased intestinal inflammation and bacterial translocation, resulting in protection against endotoxemia-induced intestinal injury in mice. However, CCR6 deficiency could neutralize the beneficial effect of anti-miR-681 on the intestine during endotoxemia, suggesting that the increment of intestinal Th17 cells caused by anti-miR-681 relies on CCR6 expression.

CONCLUSION

The results of the study indicate that control of intestinal Th17 cells by regulating novel miR-681/CCR6 signaling attenuates endotoxemia-induced intestinal injury.

IgG2 rules: N-acetyl-β-D-glucosamine-specific IgG2 and Th17/Th1 cooperation may promote the pathogenesis of acute rheumatic heart disease and be a biomarker of the autoimmune sequelae of Streptococcus pyogenes

Antecedent group A streptococcal pharyngitis is a well-established cause of acute rheumatic fever (ARF) where rheumatic valvular heart disease (RHD) and Sydenham chorea (SC) are major manifestations. In ARF, crossreactive antibodies and T cells respond to streptococcal antigens, group A carbohydrate, N-acetyl-β-D-glucosamine (GlcNAc), and M protein, respectively, and through molecular mimicry target heart and brain tissues. In this translational human study, we further address our hypothesis regarding specific pathogenic humoral and cellular immune mechanisms leading to streptococcal sequelae in a small pilot study. The aims of the study were to (1) better understand specific mechanisms of pathogenesis in ARF, (2) identify a potential early biomarker of ARF, (3) determine immunoglobulin G (IgG) subclasses directed against GlcNAc, the immunodominant epitope of the group A carbohydrate, by reaction of ARF serum IgG with GlcNAc, M protein, and human neuronal cells (SK-N-SH), and (4) determine IgG subclasses deposited on heart tissues from RHD. In 10 pediatric patients with RHD and 6 pediatric patients with SC, the serum IgG2 subclass reacted significantly with GlcNAc, and distinguished ARF from 7 pediatric patients with uncomplicated pharyngitis. Three pediatric patients who demonstrated only polymigrating arthritis, a major manifestation of ARF and part of the Jones criteria for diagnosis, lacked the elevated IgG2 subclass GlcNAc-specific reactivity. In SC, the GlcNAc-specific IgG2 subclass in cerebrospinal fluid (CSF) selectively targeted human neuronal cells as well as GlcNAc in the ELISA. In rheumatic carditis, the IgG2 subclass preferentially and strongly deposited in valve tissues (n = 4) despite elevated concentrations of IgG1 and IgG3 in RHD sera as detected by ELISA to group A streptococcal M protein. Although our human study of ARF includes a very small limited sample set, our novel research findings suggest a strong IgG2 autoantibody response against GlcNAc in RHD and SC, which targeted heart valves and neuronal cells. Cardiac IgG2 deposition was identified with an associated IL-17A/IFN-γ cooperative signature in RHD tissue which displayed both IgG2 deposition and cellular infiltrates demonstrating these cytokines simultaneously. GlcNAc-specific IgG2 may be an important autoantibody in initial stages of the pathogenesis of group A streptococcal sequelae, and future studies will determine if it can serve as a biomarker for risk of RHD and SC or early diagnosis of ARF.

The involvement of TH17 cells in the pathogenesis of IBD

The pathogenesis of inflammatory bowel disease (IBD) is still unclear. Immune dysfunction may play a key role in the pathogenesis of IBD, in which the role of CD4⁺ T helper (Th) cells is particularly important. Th17 cells are a major component of CD4⁺ T cells, and their differentiation is regulated by a variety of extracellular signals, transcription factors, RNA, and posttranslational modifications. Th17 cells specifically produce IL-17 and play an important role in the protection of mucous membranes and epithelial tissues against infection by extracellular microbes. However, when immune regulation is dysfunctional, Th17 cells abnormally proliferate and produce large amounts of proinflammatory cytokines that can recruit other inflammatory cells, which together induce abnormal immune responses and result in the development of many autoimmune diseases. In recent years, studies have confirmed that Th17 cells play an important role in the pathogenesis of IBD, which makes it a possible target for IBD therapy. This article reviews the recent progress of Th17 cells involved in the pathogenesis of IBD and its targeted therapy.