The transcription factor c-Maf controls the production of interleukin-4 but not other Th2 cytokines

Investigation of Transcription Factor and Cytokine Gene Expression Levels in Helper T Cell Subsets Among Turkish Patients Diagnosed with ICF2 (Novel ZBTB24 gene Variant) and ICF3 (CDCA7 Variant) Syndrome

Immunodeficiency, centromeric region instability, facial anomalies syndrome (ICF), is a rare disease with autosomal recessive inheritance. ICF syndrome. It has been reported that ICF syndrome is caused by mutations in the DNMT3B (ICF1), ZBTB24 (ICF2), CDCA7 (ICF3), and HELLS (ICF4) genes. As a result of literature research, there are no studies on transcription factor and cytokine expressions of helper T cell subsets in ICF syndrome. In the study; Th1 (TBET, STAT1, STAT4), Th2 (GATA3, STAT6), Th17 (RORgt, STAT3), Treg (FoxP3, STAT5) transcription factors and the major cytokines of these cells (Th1; IFNG, Th2; IL4, Th17; IL17A-21-22, Treg; IL10, TGFβ) expressions were aimed to be evaluated by qRT-PCR. Patients (ICF3: three patients; ICF2: two patients), six heterozygous individual and five healthy controls were included in the study. All patients had hypogammaglobulinemia. Except for the CD19 cells of P2 from patients diagnosed with ICF3, the CD3, CD4, CD8, and CD19 cells in the other ICF3 patients were normal. However, the rates of these cells were low in patients with ICF2 syndrome. Factors belonging to patients' Th1, Th17 and Treg cells were significantly lower than the control. Additionally, novel mutation was detected in ZBTB24 gene (c.1121-2 A > T). Our study is the first molecular study on Th cell subsets in patients with ICF syndrome and a new mutation that causes ICF2 syndrome has been identified.

Maf expression in B cells restricts reactive plasmablast and germinal center B cell expansion

Precise regulation of B cell differentiation is essential for an effective adaptive immune response. Here, we show that B cell development in mice with B cell-specific Maf deletion is unaffected, but marginal zone B cells, germinal centre B cells, and plasmablasts are significantly more frequent in the spleen of naive Maf-deficient mice compared to wild type controls. In the context of a T cell-dependent immunization, Maf deletion causes increased proliferation of germinal centre B cells and extrafollicular plasmablasts. This is accompanied by higher production of antigen-specific IgG1 antibodies with minimal modification of early memory B cells, but a reduction in plasma cell numbers. Single-cell RNA sequencing shows upregulation of genes associated with DNA replication and cell cycle progression, confirming the role of Maf in cell proliferation. Subsequent pathway analysis reveals that Maf influences cellular metabolism, transporter activity, and mitochondrial proteins, which have been implicated in controlling the germinal centre reaction. In summary, our findings demonstrate that Maf acts intrinsically in B cells as a negative regulator of late B cell differentiation, plasmablast proliferation and germinal centre B cell formation.

Effects of tamoxifen on the immune response phenotype in equine peripheral blood mononuclear cells

Tamoxifen (TAM) is widely utilized in the prevention and treatment of human breast cancer and has demonstrated the potential to modulate the immune response. It has been proposed as a therapeutic tool for immune-mediated diseases. TAM has been investigated as a possible treatment for asthma-like conditions in horses, revealing specific impacts on the innate immune system. While the effects of TAM on equine neutrophils are well-documented, its influence on lymphocytes and the modulation of the immune response polarization remains unclear. This in vitro study employed peripheral blood mononuclear cells (PBMC) from healthy horses, exposing them to varying concentrations of the TAM and assessing the expression of genes involved in the polarization of the immune response (TBX21, IFNG, GATA3, IL4, IL10, FOXP3, and CTLA4) in PBMC stimulated or not with PMA/ionomycin. Additionally, the effect of TAM over the proportion of regulatory T cells (Treg) was also assessed. TAM did not significantly affect the expression of these genes and Treg at low concentrations. However, at the highest concentration, there was an impact on the expression of GATA3, IL4, IL10, and CTLA4 genes. These alterations in genes associated with a Th2 and regulatory response coincided with a noteworthy increase in drug-associated cytotoxicity but only at concentrations far beyond those achieved in pharmacological therapy. These findings suggest that the effects of TAM, as described in preclinical studies on asthmatic horses, may not be attributed to the modification of the adaptive response.

Multi-omics reveal mechanisms of high enteral starch diet mediated colonic dysbiosis via microbiome-host interactions in young ruminant

BACKGROUND

Although rumen development is crucial, hindgut undertakes a significant role in young ruminants' physiological development. High-starch diet is usually used to accelerate rumen development for young ruminants, but always leading to the enteral starch overload and hindgut dysbiosis. However, the mechanism behind remains unclear. The combination of colonic transcriptome, colonic luminal metabolome, and metagenome together with histological analysis was conducted using a goat model, with the aim to identify the potential molecular mechanisms behind the disrupted hindgut homeostasis by overload starch in young ruminants.

RESULT

Compared with low enteral starch diet (LES), high enteral starch diet (HES)-fed goats had significantly higher colonic pathology scores, and serum diamine oxidase activity, and meanwhile significantly decreased colonic mucosal Mucin-2 (MUC2) protein expression and fecal scores, evidencing the HES-triggered colonic systemic inflammation. The bacterial taxa Prevotella sp. P4-67, Prevotella sp. PINT, and Bacteroides sp. CAG:927, together with fungal taxa Fusarium vanettenii, Neocallimastix californiae, Fusarium sp. AF-8, Hypoxylon sp. EC38, and Fusarium pseudograminearum, and the involved microbial immune pathways including the "T cell receptor signaling pathway" were higher in the colon of HES goats. The integrated metagenome and host transcriptome analysis revealed that these taxa were associated with enhanced pathogenic ability, antigen processing and presentation, and stimulated T helper 2 cell (TH2)-mediated cytokine secretion functions in the colon of HES goats. Further luminal metabolomics analysis showed increased relative content of chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA), and decreased the relative content of hypoxanthine in colonic digesta of HES goats. These altered metabolites contributed to enhancing the expression of TH2-mediated inflammatory-related cytokine secretion including GATA Binding Protein 3 (GATA3), IL-5, and IL-13. Using the linear mixed effect model, the variation of MUC2 biosynthesis explained by the colonic bacteria, bacterial functions, fungi, fungal functions, and metabolites were 21.92, 20.76, 19.43, 12.08, and 44.22%, respectively. The variation of pathology scores explained by the colonic bacterial functions, fungal functions, and metabolites were 15.35, 17.61, and 57.06%.

CONCLUSIONS

Our findings revealed that enteral starch overload can trigger interrupted hindgut host-microbiome homeostasis that led to impaired mucosal, destroyed colonic water absorption, and TH2-mediated inflammatory process. Except for the colonic metabolites mostly contribute to the impaired mucosa, the nonnegligible contribution from fungi deserves more future studies focused on the fungal functions in hindgut dysbiosis of young ruminants. Video Abstract.

Cytokines in Follicular Helper T Cell Biology in Physiologic and Pathologic Conditions

Follicular helper T cells (Tfh) play a crucial role in generating high-affinity antibodies (Abs) and establishing immunological memory. Cytokines, among other functional molecules produced by Tfh, are central to germinal center (GC) reactions. This review focuses on the role of cytokines, including IL-21 and IL-4, in regulating B cell responses within the GC, such as differentiation, affinity maturation, and plasma cell development. Additionally, this review explores the impact of other cytokines like CXCL13, IL-10, IL-9, and IL-2 on GC responses and their potential involvement in autoimmune diseases, allergies, and cancer. This review highlights contributions of Tfh-derived cytokines to both protective immunity and immunopathology across a spectrum of diseases. A deeper understanding of Tfh cytokine biology holds promise for insights into biomedical conditions.

JunD functions as a transcription factor of IL-10 to regulate bacterial infectious inflammation in grass carp (Ctenopharyngodon idella)

IL-10 is a key anti-inflammatory mediator ensuring the protection of a host from excessive inflammation in response to pathogen infections, whose transcription or expression levels are tightly linked to the onset and progression of infectious diseases. An AP-1 family member called CiJunD was shown to be a transcription factor of IL-10 in grass carp (Ctenopharyngodon idella) in the current study. CiJunD protein harbored the conserved Jun and bZIP domains. Mutant experiments demonstrated that CiJunD bound to three specific sites on IL-10 promoter, i.e., 5'-ATTATTCATA-3', 5'-AGATGAGACATCT-3', and 5'-ATTATTCATC-3', mainly relying on the bZIP domain, and initiated IL-10 transcription. Expression data from the grass carp spleen infected by Aeromonas hydrophila and lipopolysaccharide (LPS) challenged spleen leukocytes indicated that the expressions of CiJunD and IL-10 were positively correlated, while the expression of pro-inflammatory cytokines, such as IL-1β, IL-6, IL-8, IFN-γ, and TNF-α, showed an overall downward trend when CiJunD and IL-10 peaked. The ability of CiJunD to down-regulate the production of pro-inflammatory cytokines and up-regulate the expression of IL-10, both with and without LPS stimulation, was confirmed by overexpression experiments. Meanwhile, the subcellular fractionation assay revealed that the nuclear translocation of CiJunD was significantly enhanced after the LPS challenge. Moreover, in vivo administration of grass carp with Oxamflatin, a potent agonist of JunD activity, could promote IL-10 but suppress the expression of pro-inflammatory cytokines. Intriguingly, tissue inflammation lesions and the survival rates of grass carp infected with A. hydrophila were also significantly improved by Oxamflatin administration. This work sheds light on the regulation mechanism by JunD of IL-10 expression and bacterial infectious inflammation for the first time, and it may present a viable method for preventing infectious diseases in fish by regulating IL-10 expression and inflammatory response.

Identification of small compounds that inhibit multiple myeloma proliferation by targeting c-Maf transcriptional activity

Multiple myeloma displays the clonal B cell expansion and the overproduction of monoclonal immunoglobulins. Genetic translocations at 14q32, particularly with partners like 16q23, lead to the dysregulation of oncogene expression, including the significant enhancement of c-Maf. This aberrant expression of c-Maf has prompted research into strategies for targeting this transcription factor as a potential therapeutic avenue for multiple myeloma treatment. In this study, we introduce a screening pipeline to test small compounds for their ability to inhibit c-Maf. Using a luciferase indicator driven by the Ccl8 gene promoter, we identified two small compounds that inhibit transcriptional activity of c-Maf. These molecules impede the proliferation of c-Maf-expressing myeloma cells, and repress the expression of c-Maf target genes such as ITGB7 and CCR1. Importantly, these molecules target c-Maf-expressing multiple myeloma cells, but not c-Maf-negative myeloma cells, showing potential for tailoring therapeutic intervention. In conclusion, our screening pipeline is effective to explore leads for a novel c-Maf inhibitor for multiple myeloma therapy.

Engineering the IL-4/IL-13 axis for targeted immune modulation

The structurally and functionally related interleukin-4 (IL-4) and IL-13 cytokines play pivotal roles in shaping immune activity. The IL-4/IL-13 axis is best known for its critical role in T helper 2 (Th2) cell-mediated Type 2 inflammation, which protects the host from large multicellular pathogens, such as parasitic helminth worms, and regulates immune responses to allergens. In addition, IL-4 and IL-13 stimulate a wide range of innate and adaptive immune cells, as well as non-hematopoietic cells, to coordinate various functions, including immune regulation, antibody production, and fibrosis. Due to its importance for a broad spectrum of physiological activities, the IL-4/IL-13 network has been targeted through a variety of molecular engineering and synthetic biology approaches to modulate immune behavior and develop novel therapeutics. Here, we review ongoing efforts to manipulate the IL-4/IL-13 axis, including cytokine engineering strategies, formulation of fusion proteins, antagonist development, cell engineering approaches, and biosensor design. We discuss how these strategies have been employed to dissect IL-4 and IL-13 pathways, as well as to discover new immunotherapies targeting allergy, autoimmune diseases, and cancer. Looking ahead, emerging bioengineering tools promise to continue advancing fundamental understanding of IL-4/IL-13 biology and enabling researchers to exploit these insights to develop effective interventions.

A bifurcated role for c-Maf in Th2 and Tfh2 cells during helminth infection

Differences in transcriptomes, transcription factor usage, and function have identified T follicular helper 2 (Tfh2) cells and T helper 2 (Th2) cells as distinct clusters of differentiation 4+",(CD4) T-cell subsets in settings of type-2 inflammation. Although the transcriptional programs driving Th2 cell differentiation and cytokine production are well defined, dependence on these classical Th2 programs by Tfh2 cells is less clear. Using cytokine reporter mice in combination with transcription factor inference analysis, the b-Zip transcription factor c-Maf and its targets were identified as an important regulon in both Th2 and Tfh2 cells. Conditional deletion of c-Maf in T cells confirmed its importance in type-2 cytokine expression by Th2 and Tfh2 cells. However, while c-Maf was not required for Th2-driven helminth clearance or lung eosinophilia, it was required for Tfh2-driven Immunoglobulin E production and germinal center formation. This differential regulation of cell-mediated and humoral immunity by c-Maf was a result of redundant pathways in Th2 cells that were absent in Tfh2 cells, and c-Maf-specific mechanisms in Tfh2 cells that were absent in Th2 cells. Thus, despite shared expression by Tfh2 and Th2 cells, c-Maf serves as a unique regulator of Tfh2-driven humoral hallmarks during type-2 immunity.

CRL4B complex-mediated H2AK119 monoubiquitination restrains Th1 and Th2 cell differentiation

CD4+ T helper (Th) cell differentiation is regulated by lineage-specific expression of transcription factors, which is tightly associated with epigenetic modifications, including histone acetylation and methylation. However, the factors regulating histone modifications involved in Th cell differentiation remain largely unknown. We herein demonstrated a critical role of Cullin 4B (CUL4B) in restricting Th1 and Th2 cell differentiation. CUL4B, which is assembled into the CUL4B-RING E3 ligase (CRL4B) complex, participates in various physiological and developmental processes through epigenetic repression of transcription. Depletion of Cul4b in CD4+ T cells enhanced Th1 and Th2 cell differentiation. In vivo, an aggravated Th2 response caused by the absence of CUL4B was observed in a murine asthma model. Mechanistically, the CRL4B complex promoted monoubiquitination at H2AK119 (H2AK119ub1) and polycomb repressive complex 2 (PRC2)-mediated trimethylation at H3K27 (H3K27me3) at Tbx21 and Maf and consequently repressed their expression during Th cell differentiation. Our study suggests that CRL4B complex-mediated H2AK119ub1 deposition functions to prevent the aberrant expression of Th1 and Th2 lineage-specific genes.

Homeostatic activation of aryl hydrocarbon receptor by dietary ligands dampens cutaneous allergic responses by controlling Langerhans cells migration

Dietary compounds can affect the development of inflammatory responses at distant sites. However, the mechanisms involved remain incompletely understood. Here, we addressed the influence on allergic responses of dietary agonists of aryl hydrocarbon receptor (AhR). In cutaneous papain-induced allergy, we found that lack of dietary AhR ligands exacerbates allergic responses. This phenomenon was tissue-specific as airway allergy was unaffected by the diet. In addition, lack of dietary AhR ligands worsened asthma-like allergy in a model of 'atopic march.' Mice deprived of dietary AhR ligands displayed impaired Langerhans cell migration, leading to exaggerated T cell responses. Mechanistically, dietary AhR ligands regulated the inflammatory profile of epidermal cells, without affecting barrier function. In particular, we evidenced TGF-β hyperproduction in the skin of mice deprived of dietary AhR ligands, explaining Langerhans cell retention. Our work identifies an essential role for homeostatic activation of AhR by dietary ligands in the dampening of cutaneous allergic responses and uncovers the importance of the gut-skin axis in the development of allergic diseases.

Dual activation of estrogen receptor alpha and glucocorticoid receptor upregulate CRTh2-mediated type 2 inflammation; mechanism driving asthma severity in women?

BACKGROUND

Type 2-high asthma is characterized by elevated levels of circulating Th2 cells and eosinophils, cells that express chemoattractant-homologous receptor expressed on Th2 cells (CRTh2). Severe asthma is more common in women than men; however, the underlying mechanism(s) remain elusive. Here we examined whether the relationship between severe asthma and type 2 inflammation differs by sex and if estrogen influences Th2 cell response to glucocorticoid (GC).

METHODS

Type 2 inflammation and the proportion of blood Th2 cells (CD4⁺ CRTh2⁺ ) were assessed in whole blood from subjects with asthma (n = 66). The effects of GC and estrogen receptor alpha (ERα) agonist on in vitro differentiated Th2 cells were examined. Expression of CRTh2, type 2 cytokines and degree of apoptosis (Annexin V⁺ , 7-AAD) were determined by flow cytometry, qRT-PCR, western blot and ELISA.

RESULTS

In severe asthma, the proportion of circulating Th2 cells and hospitalizations were higher in women than men. Women with severe asthma also had more Th2 cells and serum IL-13 than women with mild/moderate asthma. Th2 cells, eosinophils and CRTh2 mRNA correlated with clinical characteristics associated with asthma control in women but not men. In vitro, GC and ERα agonist treated Th2 cells exhibited less apoptosis, more CRTh2 as well as IL-5 and IL-13 following CRTh2 activation than Th2 cells treated with GC alone.

CONCLUSION

Women with severe asthma had higher levels of circulating Th2 cells than men, which may be due to estrogen modifying the effects of GC, enhancing Th2 cell survival and type 2 cytokine production.

The small molecule inhibitor BX-795 uncouples IL-2 production from inhibition of Th2 inflammation and induces CD4+ T cells resembling iTreg

Background

Treg cells have been shown to be an important part of immune-homeostasis and IL-2 which is produced upon T cell receptor (TCR)-dependent activation of T lymphocytes has been demonstrated to critically participate in Treg development.

Objective

To evaluate small molecule inhibitors (SMI) for the identification of novel IL-2/Treg enhancing compounds.

Materials and methods

We used TCR-dependent and allergen-specific cytokine secretion of human and mouse T cells, next generation messenger ribonucleic acid sequencing (RNA-Seq) and two different models of allergic airway inflammation to examine lead SMI-compounds.

Results

We show here that the reported 3-phosphoinositide dependent kinase-1 (PDK1) SMI BX-795 increased IL-2 in culture supernatants of Jurkat E6-1 T cells, human peripheral blood mononuclear cells (hPBMC) and allergen-specific mouse T cells upon TCR-dependent and allergen-specific stimulation while concomitantly inhibiting Th2 cytokine secretion. RNA-Seq revealed that the presence of BX-795 during allergen-specific activation of T cells induces a bona fide Treg cell type highly similar to iTreg but lacking Foxp3 expression. When applied in mugwort pollen and house dust mite extract-based models of airway inflammation, BX-795 significantly inhibited Th2 inflammation including expression of Th2 signature transcription factors and cytokines and influx into the lungs of type 2-associated inflammatory cells such as eosinophils.

Conclusions

BX-795 potently uncouples IL-2 production from Th2 inflammation and induces Th-IL-2 cells, which highly resemble induced (i)Tregs. Thus, BX-795 may be a useful new compound for the treatment of allergic diseases.

Re-programming mouse liver-resident invariant natural killer T cells for suppressing hepatic and diabetogenic autoimmunity

Invariant NKT (iNKT) cells comprise a heterogeneous group of non-circulating, tissue-resident T lymphocytes that recognize glycolipids, including alpha-galactosylceramide (αGalCer), in the context of CD1d, but whether peripheral iNKT cell subsets are terminally differentiated remains unclear. Here we show that mouse and human liver-resident αGalCer/CD1d-binding iNKTs largely correspond to a novel Zbtb16+Tbx21+Gata3+MaflowRorc– subset that exhibits profound transcriptional, phenotypic and functional plasticity. Repetitive in vivo encounters of these liver iNKT (LiNKT) cells with intravenously delivered αGalCer/CD1d-coated nanoparticles (NP) trigger their differentiation into immunoregulatory, IL-10+IL-21-producing Zbtb16highMafhighTbx21+Gata3+Rorc– cells, termed LiNKTR1, expressing a T regulatory type 1 (TR1)-like transcriptional signature. This response is LiNKT-specific, since neither lung nor splenic tissue-resident iNKT cells from αGalCer/CD1d-NP-treated mice produce IL-10 or IL-21. Additionally, these LiNKTR1 cells suppress autoantigen presentation, and recognize CD1d expressed on conventional B cells to induce IL-10+IL-35-producing regulatory B (Breg) cells, leading to the suppression of liver and pancreas autoimmunity. Our results thus suggest that LiNKT cells are plastic for further functional diversification, with such plasticity potentially targetable for suppressing tissue-specific inflammatory phenomena.

c-Maf enforces cytokine production and promotes memory-like responses in mouse and human type 2 innate lymphoid cells

Group‐2 innate lymphoid cells (ILC2s), which are involved in type 2 inflammatory diseases such as allergy, can exhibit immunological memory, but the basis of this ILC2 "trained immunity" has remained unclear. Here, we found that stimulation with IL‐33/IL‐25 or exposure to the allergen papain induces the expression of the transcription factor c‐Maf in mouse ILC2s. Chronic papain exposure results in high production of IL‐5 and IL‐13 cytokines and lung eosinophil recruitment, effects that are blocked by c‐Maf deletion in ILCs. Transcriptomic analysis revealed that knockdown of c‐Maf in ILC2s suppresses expression of type 2 cytokine genes, as well as of genes linked to a memory‐like phenotype. Consistently, c‐Maf was found highly expressed in human adult ILC2s but absent in cord blood and required for cytokine production in isolated human ILC2s. Furthermore, c‐Maf‐deficient mouse or human ILC2s failed to exhibit strengthened (“trained”) responses upon repeated challenge. Thus, the expression of c‐Maf is indispensable for optimal type 2 cytokine production and proper memory‐like responses in group‐2 innate lymphoid cells.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

Ding Chuan Tang Attenuates Airway Inflammation and Eosinophil Infiltration in Ovalbumin-Sensitized Asthmatic Mice

Asthma is a T helper 2 (Th2) cell-associated chronic inflammatory diseases characterized with airway obstruction, increased mucus production, and eosinophil infiltration. Conventional medications for asthma treatment cannot fully control the symptoms, and potential side effects are also the concerns. Thus, complement or alternative medicine (CAM) became a new option for asthma management. Ding Chuan Tang (DCT) is a traditional Chinese herbal decoction applied mainly for patients with coughing, wheezing, chest tightness, and asthma. Previously, DCT has been proved to improve children airway hyperresponsiveness (AHR) in a randomized and double-blind clinical trial. However, the mechanisms of how DCT alleviates AHR remain unclear. Since asthmatic features such as eosinophil infiltration, IgE production, and mucus accumulation are relative with Th2 responses, we hypothesized that DCT may attenuate asthma symptoms through regulating Th2 cells. Ovalbumin (OVA) was used as a stimulant to sensitize BALB/c mice to establish an asthmatic model. AHR was detected one day before sacrifice. BALF and serum were collected for immune cell counting and antibody analysis. Splenocytes were cultured with OVA in order to determine Th2 cytokine production. Lung tissues were collected for histological and gene expression analyses. Our data reveal that DCT can attenuate AHR and eosinophil accumulation in the 30-day sensitization asthmatic model. Histological results demonstrated that DCT can reduce cell infiltration and mucus production in peribronchial and perivascular site. In OVA-stimulated splenocyte cultures, a significant reduction of IL-5 and IL-13 in DCT-treated mice suggests that DCT may alleviate Th2 responses. In conclusion, the current study demonstrates that DCT has the potential to suppress allergic responses through the reduction of mucus production, eosinophil infiltration, and Th2 activity in asthma.

Re-Programming Autoreactive T Cells Into T-Regulatory Type 1 Cells for the Treatment of Autoimmunity

Systemic delivery of peptide-major histocompatibility complex (pMHC) class II-based nanomedicines can re-program cognate autoantigen-experienced CD4+ T cells into disease-suppressing T-regulatory type 1 (TR1)-like cells. In turn, these TR1-like cells trigger the formation of complex regulatory cell networks that can effectively suppress organ-specific autoimmunity without impairing normal immunity. In this review, we summarize our current understanding of the transcriptional, phenotypic and functional make up of TR1-like cells as described in the literature. The true identity and direct precursors of these cells remain unclear, in particular whether TR1-like cells comprise a single terminally-differentiated lymphocyte population with distinct transcriptional and epigenetic features, or a collection of phenotypically different subsets sharing key regulatory properties. We propose that detailed transcriptional and epigenetic characterization of homogeneous pools of TR1-like cells will unravel this conundrum.

Effective inactivated influenza vaccine for the elderly using a single-stranded RNA-based adjuvant

There is an unmet need for new influenza vaccine strategies that compensate for impaired vaccine responses in elderly individuals. Here, we evaluated the effectiveness of a single-stranded RNA (ssRNA) as an adjuvant to enhance the efficacy of inactivated influenza vaccine (IIV) in mouse models. Immunization with the ssRNA along with IIV reduced viral titers as well as pathological and inflammatory scores in the lungs after influenza challenge in aged mice. ssRNA induced balanced Th1/Th2 responses with an increase in IgA titers. Moreover, the ssRNA adjuvant markedly increased the frequency of influenza HA-specific T cells and IFN-γ production along with the expression of genes related to innate and adaptive immune systems that could overcome immunosenescence in aged mice. Our findings indicate that ssRNA is an efficient vaccine adjuvant that boosts cellular and humoral immunity in aged mice, demonstrating its potential as a novel adjuvant for currently available influenza virus vaccines for elderly individuals.

The Concept of Pathogenic TH2 Cells: Collegium Internationale Allergologicum Update 2021

T helper (TH) cells have evolved into distinct subsets that mediate specific immune responses to protect the host against a myriad of infectious and noninfectious challenges. However, if dysregulated, TH-cell subsets can cause inflammatory disease. Emerging evidence now suggests that human allergic disease is caused by a distinct subpopulation of pathogenic TH2 cells. Pathogenic TH2 cells from different type-2-driven diseases share a core phenotype and show overlapping functional attributes. The unique differentiation requirements, activating signals, and metabolic characteristics of pathogenic TH2 cells are just being discovered. A better knowledge of this particular TH2 cell population will enable the specific targeting of disease-driving pathways in allergy. In this review, we introduce a rational for classifying TH cells into distinct subsets, discuss the current knowledge on pathogenic TH2 cells, and summarize their involvement in allergic diseases.

miR-155 influences cell-mediated immunity in Balb/c mice treated with aflatoxin M1

Aflatoxin M1 (AFM1) is a 4-hydroxylated metabolite of aflatoxin B1 (AFB1). It induces various toxicological effects including immunotoxicity. In the present study, we investigated the effects of AFM1 on immune system and its modulation by MicroRNA (miR)-155. AFM1 was administered intraperitoneally at doses of 25 and 50 µg/kg for 28 days to Balb/c mice and different immune system parameters were analyzed. The levels of miR-155 and targeted proteins were evaluated in isolated T cells from spleens of mice. Spleen weight was reduced in mice exposed to AFM1 compared to negative control. Proliferation of splenocytes in response to phytohemagglutinin-A was reduced in mice exposed to AFM1. IFN-γ was decreased in mice exposed to AFM1, whereas IL-10 was increased. Concentration of IL-4 did not change different in mice exposed to AFM1 compared to negative control. Exposure to AFM1 reduced the expression of miR-155. Significant upregulation of phosphatidylinositol-3, 4, 5-trisphosphate 5-phosphatase 1 (Ship1) and suppressor of cytokine signaling 1 (Socs1) was observed in isolated T cells from spleens of mice treated with AFM1, but the transcription factor Maf (c-MAF) was not affected. These results suggest that miR-155 and targeted proteins might be involved in the immunotoxicity observed in mice exposed to AFM1.

Identification and characterization of a novel adiponectin receptor agonist adipo anti-inflammation agonist and its anti-inflammatory effects in vitro and in vivo

BACKGROUND AND PURPOSE

Adiponectin (APN) is an adipokine secreted from adipocytes that binds to APN receptors AdipoR1 and AdipoR2 and exerts an anti-inflammatory response through mechanisms not fully understood. There is a need to develop small molecules that activate AdipoR1 and AdipoR2 and to be used to inhibit the inflammatory response in lipopolysaccharide (LPS)-induced endotoxemia and other inflammatory disorders.

EXPERIMENTAL APPROACH

We designed 10 new structural analogues of an AdipoR agonist, AdipoRon (APR), and assessed their anti-inflammatory properties. Bone marrow-derived macrophages (BMMs) and peritoneal macrophages (PEMs) were isolated from mice. Levels of pro-inflammatory cytokines were measured by reverse transcription and real-time quantitative polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA) and microarray in LPS-induced endotoxemia mice and diet-induced obesity (DIO) mice in which systemic inflammation prevails. Western blotting, immunohistochemistry (IHC), siRNA interference and immunoprecipitation were used to detect signalling pathways.

KEY RESULTS

A novel APN receptor agonist named adipo anti-inflammation agonist (AdipoAI) strongly suppresses inflammation in DIO and endotoxemia mice, as well as in cultured macrophages. We also found that AdipoAI attenuated the association of AdipoR1 and APPL1 via myeloid differentiation marker 88 (MyD88) signalling, thus inhibiting activation of nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK) and c-Maf pathways and limiting the production of pro-inflammatory cytokines in LPS-induced macrophages.

CONCLUSION AND IMPLICATIONS

AdipoAI is a promising alternative therapeutic approach to APN and APR to suppress inflammation in LPS-induced endotoxemia and other inflammatory disorders via distinct signalling pathways.

Transcriptional regulation of adaptive and innate lymphoid lineage specification

Once alerted to the presence of a pathogen, activated CD4⁺ T cells initiate distinct gene expression programs that produce multiple functionally specialized T helper (Th) subsets. The cytokine milieu present at the time of antigen encounter instructs CD4⁺ T cells to differentiate into interferon-(IFN)-γ-producing Th1 cells, interleukin-(IL)-4-producing Th2 cells, IL-17-producing Th17 cells, follicular T helper (Tfh) cells, or regulatory T (Treg) cells. In each of these Th cell subsets, a single transcription factor has been identified as a critical regulator of its specialized differentiation program. In this context, the expression of the "master regulator" is necessary and sufficient to activate lineage-specific genes while restricting the gene expression program of alternative Th fates. Thus, the transcription factor T-bet controls Th1 differentiation program, while the development of Th2, Th17, Tfh, and Treg cells is dependent on transcription factors GATA3, RORγt, Bcl6, and Foxp3, respectively. Nevertheless, master regulators or, more precisely, lineage-defining transcription factors do not function in isolation. In fact, they interact with a complex network of transcription factors, orchestrating cell lineage specification programs. In this review, we discuss the concept of the combinatorial interactions of key transcription factors in determining helper T cell identity. Additionally, lineage-defining transcription factors have well-established functions beyond their role in CD4⁺ Th subsets. They play critically important functions at distinct stages during T cell development in the thymus and they control the development of innate lymphoid cells (ILCs) in the bone marrow. In tracking the journey of T cells traversing from the thymus to the periphery and during the immune response, we discuss in broad terms developmental stage and context-dependent functions of lineage-defining transcription factors in regulating specification programs of innate and adaptive lymphocytes.

CD4 T Helper Cell Subsets and Related Human Immunological Disorders

The immune system plays a critical role in protecting hosts from the invasion of organisms. CD4 T cells, as a key component of the immune system, are central in orchestrating adaptive immune responses. After decades of investigation, five major CD4 T helper cell (Th) subsets have been identified: Th1, Th2, Th17, Treg (T regulatory), and Tfh (follicular T helper) cells. Th1 cells, defined by the expression of lineage cytokine interferon (IFN)-γ and the master transcription factor T-bet, participate in type 1 immune responses to intracellular pathogens such as mycobacterial species and viruses; Th2 cells, defined by the expression of lineage cytokines interleukin (IL)-4/IL-5/IL-13 and the master transcription factor GAΤA3, participate in type 2 immune responses to larger extracellular pathogens such as helminths; Th17 cells, defined by the expression of lineage cytokines IL-17/IL-22 and the master transcription factor RORγt, participate in type 3 immune responses to extracellular pathogens including some bacteria and fungi; Tfh cells, by producing IL-21 and expressing Bcl6, help B cells produce corresponding antibodies; whereas Foxp3-expressing Treg cells, unlike Th1/Th2/Th17/Tfh exerting their effector functions, regulate immune responses to maintain immune cell homeostasis and prevent immunopathology. Interestingly, innate lymphoid cells (ILCs) have been found to mimic the functions of three major effector CD4 T helper subsets (Th1, Th2, and Th17) and thus can also be divided into three major subsets: ILC1s, ILC2s, and ILC3s. In this review, we will discuss the differentiation and functions of each CD4 T helper cell subset in the context of ILCs and human diseases associated with the dysregulation of these lymphocyte subsets particularly caused by monogenic mutations.

High plasma soluble levels of the immune checkpoint HLA-G molecule among bodybuilders

Introduction

Studies report that intense physical activity influences the down-regulation of immune function in athletes as well as the interaction between adipose tissue and the immune system.

Aim

This study aimed to compare the plasma soluble levels of the immune checkpoint HLA-G (sHLA-G) molecule with the fat mass and muscle mass index among 77 bodybuilders and 64 controls.

Results

The comparisons of the percentage of body fat (%BF) revealed that the groups of male and female bodybuilders showed a statistically significant reduction in the percentage of body fat when compared to their control group, (P <0.0001, for both comparisons). Regarding sHLA-G levels, the comparisons showed that the group of male bodybuilders had significantly higher sHLA-G levels compared to the group of female bodybuilders (P = 0.0011).

Conclusion

Our results showed that in bodybuilders with less body fat, the systemic levels of soluble HLA-G, an immunological molecule with recognized immunosuppressive function, are significantly higher and suggest that this immune mechanism may corroborate the immunosuppressive state in athletes undergoing intense and prolonged physical training.

Investigation of Linc-MAF-4 expression as an effective marker in brucellosis

Brucellosis is a zoonotic disease that is one of the most common infectious diseases. Cellular immunity is the main immune response against brucella. Long non coding RNAs are a new subset of genes that could regulate cell function and may gene regulation. We aim to investigate whether the level of Linc-MAF-4 and cMAF have considerable differences in brucella infection. In this experiment 99 patients with brucellosis were divided into three groups of acute, undertreatment and relapse and 30 volunteers with negative serologic tests as control group. The expression levels were detected using quantitative polymerase chain reaction (qPCR). Statistical analysis was performed using SPSS software version 25.0. Results showed that the expression of Linc-MAF-4 was significantly increased in the acute group in comparison to control and relapse groups. Also, cMAF expression was significantly increased in the relapse group versus the control group. Our study showed these genes play important roles in the immune response include regulating naïve T cell differentiation to T helper cells in Brucella infection. We propose that Linc-MAF-4 could be a potential biomarker for the screening, diagnosis and treatment of brucellosis.

The evolving role of T-bet in resistance to infection

The identification of T-bet as a key transcription factor associated with the development of IFNγ-producing CD4⁺ T cells predicted a crucial role for T-bet in cell-mediated immunity and in resistance to many intracellular infections. This idea was reinforced by initial reports showing that T-bet-deficient mice were more susceptible to pathogens that survived within the lysosomal system of macrophages. However, subsequent studies revealed IFNγ-dependent, T-bet-independent pathways of resistance to diverse classes of microorganisms that occupy other intracellular niches. Consequently, a more complex picture has emerged of how T-bet and the related transcription factor eomesodermin (EOMES) coordinate many facets of the immune response to bona fide pathogens as well as commensals. This article provides an overview of the discovery and evolutionary relationship between T-bet and EOMES and highlights the studies that have uncovered broader functions of T-bet in innate and adaptive immunity and in the development of the effector and memory T cell populations that mediate long-term resistance to infection.

c-MAF, a Swiss Army Knife for Tolerance in Lymphocytes

Beyond its well-admitted role in development and organogenesis, it is now clear that the transcription factor c-Maf has owned its place in the realm of immune-related transcription factors. Formerly introduced solely as a Th2 transcription factor, the role attributed to c-Maf has gradually broadened over the years and has extended to most, if not all, known immune cell types. The influence of c-Maf is particularly prominent among T cell subsets, where c-Maf regulates the differentiation as well as the function of multiple subsets of CD4 and CD8 T cells, lending it a crucial position in adaptive immunity and anti-tumoral responsiveness. Recent research has also revealed the role of c-Maf in controlling Th17 responses in the intestine, positioning it as an essential factor in intestinal homeostasis. This review aims to present and discuss the recent advances highlighting the particular role played by c-Maf in T lymphocyte differentiation, function, and homeostasis.

Functions and regulation of T cell-derived interleukin-10

Interleukin (IL)-10 is an essential anti-inflammatory cytokine and functions as a negative regulator of immune responses to microbial antigens. IL-10 is particularly important in maintaining the intestinal microbe-immune homeostasis. Loss of IL-10 promotes the development of inflammatory bowel disease (IBD) as a consequence of an excessive immune response to the gut microbiota. IL-10 also functions more generally to prevent excessive inflammation during the course of infection. Although IL-10 can be produced by virtually all cells of the innate and adaptive immune system, T cells constitute a non-redundant source for IL-10 in many cases. The various roles of T cell-derived IL-10 will be discussed in this review. Given that IL-10 is at the center of maintaining the delicate balance between effective immunity and tissue protection, it is not surprising that IL-10 expression is highly dynamic and tightly regulated. We summarize the environmental signals and molecular pathways that regulate IL-10 expression. While numerous studies have provided us with a deep understanding of IL-10 biology, the majority of findings have been made in murine models, prompting us to highlight gaps in our knowledge about T cell-derived IL-10 in the human system.

Epigenetic and transcriptional mechanisms for the regulation of IL-10

IL-10 is a critical immunoregulatory cytokine expressed in virtually all immune cell types. Maintaining a delicate balance between effective immune response and tolerance requires meticulous and dynamic control of IL-10 expression both epigenetically and transcriptionally. In this Review, we describe the epigenetic mechanisms controlling IL-10 expression, including chromatin remodeling, 3D chromatin loops, histone modification and DNA methylation. We discuss the role of transcription factors in directing chromatin modifications, with a special highlight on the emerging concept of pioneer transcription factors in setting up the chromatin landscape in T helper cells for IL-10 induction. Besides summarizing the recent progress on transcriptional regulation in specialized IL-10 producers such as type 1 regulatory T cells, regulatory B cells and regulatory innate lymphoid cells, we also discuss common transcriptional mechanisms for IL-10 regulation that are shared with other IL-10 producing cells.

Role of MafB in macrophages

The transcription factor MafB regulates macrophage differentiation. However, studies on the phenotype of Mafb-deficient macrophages are still limited. Recently, it was shown that the specific expression of MafB permits macrophages to be distinguished from dendritic cells. In addition, MafB has been reported to be involved in various diseases related to macrophages. Studies using macrophage-specific Mafb-deficient mice show that MafB is linked to atherosclerosis, autoimmunity, obesity, and ischemic stroke, all of which exhibit macrophage abnormality. Therefore, MafB is hypothesized to be indispensable for the regulation of macrophages to maintain systemic homeostasis and may serve as an innovative target for treating macrophage-related diseases.

The Metabolic Requirements of Th2 Cell Differentiation

Upon activation, naïve CD4⁺ T cells differentiate into a number of specialized T helper (Th) cell subsets. Th2 cells are central players in immunity to helminths and are implicated in mediating the inflammatory pathology associated with allergies. The differentiation of Th2 cells is dependent on transcription factors such as GATA3 and STAT6, which prime Th2 cells for the secretion of interleukin- (IL-) 4, IL-5, and IL-13. Several lines of work now suggest that differentiating Th2 cells in the lymph node are potent IL-4 cytokine producers, but do not become competent IL-5- and IL-13-producing cells until after receiving cues from non-lymphoid tissue. It is evident that Th2 cells that enter tissues undergo considerable changes in chromatin architecture and gene expression, and that over this time, the metabolic requirements of these cells change considerably. Herein, we discuss the metabolic requirements of Th2 cells during their early and late differentiation, focusing on the impact of glucose and lipid metabolism, mTOR activation, the nuclear receptor PPAR-γ and several metabolites.

Decoding inflammation, its causes, genomic responses, and emerging countermeasures

Inflammation is the mechanism of diseases caused by microbial, autoimmune, allergic, metabolic and physical insults that produce distinct types of inflammatory responses. This aetiologic view of inflammation informs its classification based on a cause‐dependent mechanism as well as a cause‐directed therapy and prevention. The genomic era ushered in a new understanding of inflammation by highlighting the cell's nucleus as the centre of the inflammatory response. Exogenous or endogenous inflammatory insults evoke genomic responses in immune and non‐immune cells. These genomic responses depend on transcription factors, which switch on and off a myriad of inflammatory genes through their regulatory networks. We discuss the transcriptional paradigm of inflammation based on denying transcription factors’ access to the nucleus. We present two approaches that control proinflammatory signalling to the nucleus. The first approach constitutes a novel intracellular protein therapy with bioengineered physiologic suppressors of cytokine signalling. The second approach entails control of proinflammatory transcriptional cascades by targeting nuclear transport with a cell‐penetrating peptide that inhibits the expression of 23 out of the 26 mediators of inflammation along with the nine genes required for metabolic responses. We compare these emerging anti‐inflammatory countermeasures to current therapies. The transcriptional paradigm of inflammation offers nucleocentric strategies for microbial, autoimmune, metabolic, physical and other types of inflammation afflicting millions of people worldwide.

From Discrete to Continuous Modeling of Lymphocyte Development and Plasticity in Chronic Diseases

The molecular events leading to differentiation, development, and plasticity of lymphoid cells have been subject of intense research due to their key roles in multiple pathologies, such as lymphoproliferative disorders, tumor growth maintenance and chronic diseases. The emergent roles of lymphoid cells and the use of high-throughput technologies have led to an extensive accumulation of experimental data allowing the reconstruction of gene regulatory networks (GRN) by integrating biochemical signals provided by the microenvironment with transcriptional modules of lineage-specific genes. Computational modeling of GRN has been useful for the identification of molecular switches involved in lymphoid specification, prediction of microenvironment-dependent cell plasticity, and analyses of signaling events occurring downstream the activation of antigen recognition receptors. Among most common modeling strategies to analyze the dynamical behavior of GRN, discrete dynamic models are widely used for their capacity to capture molecular interactions when a limited knowledge of kinetic parameters is present. However, they are less powerful when modeling complex systems sensitive to biochemical gradients. To compensate it, discrete models may be transformed into regulatory networks that includes state variables and parameters varying within a continuous range. This approach is based on a system of differential equations dynamics with regulatory interactions described by fuzzy logic propositions. Here, we discuss the applicability of this method on modeling of development and plasticity processes of adaptive lymphocytes, and its potential implications in the study of pathological landscapes associated to chronic diseases.

Helper T cell differentiation

CD4+ T helper cells are key regulators of host health and disease. In the original model, specialized subsets of T helper cells are generated following activation through lineage-specifying cytokines and transcriptional programs, but recent studies have revealed increasing complexities for CD4+ T-cell differentiation. Here, we first discuss CD4+ T-cell differentiation from a historical perspective by highlighting the major studies that defined the distinct subsets of T helper cells. We next describe the mechanisms underlying CD4+ T-cell differentiation, including cytokine-induced signaling and transcriptional networks. We then review current and emerging topics of differentiation, including the plasticity and heterogeneity of T cells, the tissue-specific effects, and the influence of cellular metabolism on cell fate decisions. Importantly, recent advances in cutting-edge approaches, especially systems biology tools, have contributed to new concepts and mechanisms underlying T-cell differentiation and will likely continue to advance this important research area of adaptive immunity.

Maf deficiency in T cells dysregulates Treg - TH17 balance leading to spontaneous colitis

The maintenance of homeostasis in the gut is a major challenge for the immune system. Here we demonstrate that the transcription factor MAF plays a central role in T cells for the prevention of gastro-intestinal inflammation. Conditional knock out mice lacking Maf in all T cells developed spontaneous late-onset colitis, correlating with a decrease of FOXP3⁺RORγt⁺ T cells proportion, dampened IL-10 production in the colon and an increase of inflammatory T_H17 cells. Strikingly, FOXP3⁺ specific conditional knock out mice for MAF did not develop colitis and demonstrated normal levels of IL-10 in their colon, despite the incapacity of regulatory T cells lacking MAF to suppress colon inflammation in Rag1^−/− mice transferred with naïve CD4⁺ T cells. We showed that one of the cellular sources of IL-10 in the colon of these mice are T_H17 cells. Thus, MAF is critically involved in the maintenance of the gut homeostasis by regulating the balance between T_reg and T_H17 cells either at the level of their differentiation or through the modulation of their functions.

Regulation of Interleukin-10 Expression

Interleukin (IL)-10 is an essential anti-inflammatory cytokine that plays important roles as a negative regulator of immune responses to microbial antigens. Loss of IL-10 results in the spontaneous development of inflammatory bowel disease as a consequence of an excessive immune response to the gut microbiota. IL-10 also functions to prevent excessive inflammation during the course of infection. IL-10 can be produced in response to pro-inflammatory signals by virtually all immune cells, including T cells, B cells, macrophages, and dendritic cells. Given its function in maintaining the delicate balance between effective immunity and tissue protection, it is evident that IL-10 expression is highly dynamic and needs to be tightly regulated. The transcriptional regulation of IL-10 production in myeloid cells and T cells is the topic of this review. Drivers of IL-10 expression as well as their downstream signaling pathways and transcription factors will be discussed. We will examine in more detail how various signals in CD4⁺ T cells converge on common transcriptional circuits, which fine-tune IL-10 expression in a context-dependent manner.

Transcriptomic and proteomic host response to Aspergillus fumigatus conidia in an air-liquid interface model of human bronchial epithelium

Aspergillus fumigatus (A. fumigatus) is a wide-spread fungus that is a potent allergen in hypersensitive individuals but also an opportunistic pathogen in immunocompromised patients. It reproduces asexually by releasing airborne conidiospores (conidia). Upon inhalation, fungal conidia are capable of reaching the airway epithelial cells (AECs) in bronchial and alveolar tissues. Previous studies have predominantly used submerged monolayer cultures for studying this host-pathogen interaction; however, these cultures do not recapitulate the mucocililary differentiation phenotype of the in vivo epithelium in the respiratory tract. Thus, the aim of this study was to use well-differentiated primary human bronchial epithelial cells (HBECs) grown at the air-liquid interface (ALI) to determine their transcriptomic and proteomic responses following interaction with A. fumigatus conidia. We visualized conidial interaction with HBECs using confocal laser scanning microscopy (CLSM), and applied NanoString nCounter and shotgun proteomics to assess gene expression changes in the human cells upon interaction with A. fumigatus conidia. Western blot analysis was used to assess the expression of top three differentially expressed proteins, CALR, SET and NUCB2. CLSM showed that, unlike submerged monolayer cultures, well-differentiated ALI cultures of primary HBECs were estimated to internalize less than 1% of bound conidia. Nevertheless, transcriptomic and proteomic analyses revealed numerous differentially expressed host genes; these were enriched for pathways including apoptosis/autophagy, translation, unfolded protein response and cell cycle (up-regulated); complement and coagulation pathways, iron homeostasis, nonsense mediated decay and rRNA binding (down-regulated). CALR and SET were confirmed to be up-regulated in ALI cultures of primary HBECs upon exposure to A. fumigatus via western blot analysis. Therefore, using transcriptomics and proteomics approaches, ALI models recapitulating the bronchial epithelial barrier in the conductive zone of the respiratory tract can provide novel insights to the molecular response of bronchial epithelial cells upon exposure to A. fumigatus conidia.

Thy-1 (CD90) Signaling Preferentially Promotes RORγt Expression and a Th17 Response

Thy-1 (CD90) is a glycosylphosphatidylinositol-anchored protein (GPI-AP) with signaling properties that is abundant on mouse T cells. Upon antibody-mediated crosslinking, Thy-1 provides a T cell receptor (TcR)-like signal that is sufficient to drive CD4⁺ T cell proliferation and differentiation into effector cells when costimulatory signals are provided by syngeneic lipopolysaccharide-matured bone marrow-derived dendritic cells. In this study, we investigated the impact of Thy-1 signaling on the production of the T helper (Th) cell subset-associated cytokines, interferon (IFN) γ, interleukin (IL)-4 and IL-17A, as well as the in vitro polarization of highly purified resting CD4⁺ T cells into Th1, Th2, and Th17 cells. Although CD8⁺ T cells expressed more Thy-1 than CD4⁺ T cells, both T cell populations were equally responsive to Thy-1 stimulation. In contrast to TcR stimulation of CD3⁺ T cells, which favored IFNγ and IL-4 production, Thy-1 signaling favored IL-17 synthesis, indicating a previously unidentified difference between the consequences of Thy-1 and TcR signal transduction. Moreover, Thy-1 signaling preferentially induced the Th17-associated transcription factor RORγt in CD4⁺ T cells. As with TcR signaling, Thy-1 stimulation of CD4⁺ T cells under the appropriate polarizing conditions resulted in Th1, Th2 or Th17 cell induction; however, Thy-1 stimulation induced nearly 7- and 2-fold more IL-4 and IL-17A, respectively, but only slightly more IFNγ. The ability to provide a TcR-like signal capable of promoting T helper cell differentiation and cytokine synthesis was not common to all GPI-APs since cross-linking of Ly6A/E with mitogenic mAb did not promote substantial production of IFNγ, IL-4 or IL-17, although there was a substantial proliferative response. The preferential induction of RORγt and Th17 cytokine synthesis as a consequence of Thy-1 signaling suggests a default T helper cell response that may enhance host defense against extracellular pathogens.

CD4+ T Cell Subsets and Pathways to HIV Latency

Latent infection of CD4⁺ T cells is the main barrier to eradicating HIV-1 infection from infected patients. The cellular and molecular mechanisms involved in the establishment and maintenance of latent infection are directly linked to the transcriptional program of the different CD4⁺ T cell subsets targeted by the virus. In this review, we provide an overview of how T cell activation, T cell differentiation into functional subsets, and the mode of initial viral infection influence HIV proviral transcription and entry into latency.

Transcriptional regulation of CD4+ TH cells that mediate tissue inflammation

Acquired and genetic immunodeficiencies have revealed an indispensable role for CD4⁺ T cells in the induction of protective host immune responses against a myriad of microbial pathogens. Influenced by the cytokines present in the microenvironment, activated CD4⁺ T cells may differentiate into several highly-specialized helper subsets defined by the production of distinct signature cytokines tailored to combat diverse classes of pathogens. The process of specification and differentiation is controlled by networks of core, master, and accessory transcription factors, which ensure that CD4⁺ T helper (T_H ) cell responses mounted against an invading microbe are of the correct specificity and type. However, aberrant activation or inactivation of transcription factors can result in sustained and elevated expression of immune-related genes, leading to chronic activation of CD4⁺ T_H  cells and organ-specific autoimmunity. In this review, we provide an overview of the molecular basis of CD4⁺ T_H  cell differentiation and examine how combinatorial expression of transcription factors, which promotes genetic plasticity of CD4⁺ T_H  cells, can contribute to immunological dysfunction of CD4⁺ T_H responses. We also discuss recent studies which highlight the potential of exploiting the genetic plasticity of CD4⁺ T_H  cells in the treatment of autoimmune and other immune-mediated disorders.

Transcriptional Programs Underlying Cd4 T Cell Differentiation and Functions

Understanding the basis of cellular differentiation is a fundamental issue in developmental biology but also for the comprehension of pathological processes. In fact, the palette of developmental decisions for naive CD4 T cells is a critical aspect of the development of appropriate immune responses which could control infectious processes or cancer growth. However, the current accumulation of data on CD4 T cells biology reveals a complex world with different helper populations. Naive CD4 T cells can differentiate into different subtypes in response to cytokine stimulation. This stimulation involves a complex transcriptional network implicating the activation of Signal Transducer and Activator of Transcription but also master regulator transcription factors allowing the functions of each helper T lymphocyte subtype. In this review, we will present an overview of the transcriptional regulation which controls process of helper T cells differentiation. We will focus on the role of initiator transcriptional factors and on master regulators but also on other nonspecific transcriptional factors which refine the T helper polarization to stabilize or modulate the differentiation program.

Effector T Helper Cell Subsets in Inflammatory Bowel Diseases

The gastrointestinal tract is a site of high immune challenge, as it must maintain a delicate balance between tolerating luminal contents and generating an immune response toward pathogens. CD4⁺ T cells are key in mediating the host protective and homeostatic responses. Yet, CD4⁺ T cells are also known to be the main drivers of inflammatory bowel disease (IBD) when this balance is perturbed. Many subsets of CD4⁺ T cells have been identified as players in perpetuating chronic intestinal inflammation. Over the last few decades, understanding of how each subset of Th cells plays a role has dramatically increased. Simultaneously, this has allowed development of therapeutic innovation targeting specific molecules rather than broad immunosuppressive agents. Here, we review the emerging evidence of how each subset functions in promoting and sustaining the chronic inflammation that characterizes IBD.

Immune modulation of Th1, Th2, and T-reg transcriptional factors differing from cytokine levels in Schistosoma japonicum infection

In spite of long-term integrated control programs for Schistosoma japonicum infection in China, the infection is still persistent due to its zoonotic transmission and disease severity which further complicate its control. Th1, Th2, and T-reg cells are involved in S. japonicum immunity; however, their exact roles in immunopathology of this infection are still questionable. Therefore, the monitoring of these T cell subsets' immune responses during a primary infection of S. japonicum at both transcriptional (mRNA) and protein (cytokines) levels would be essential to point out. In experimentally infected white New Zealand rabbits, mRNA expression levels of TBX2, IRF8, GATA3, STAT6, FoxP3, and MAFF were evaluated using qPCR, whereas Th1 (IFN-γ and TNF-α), Th2 (IL4 and IL13), and T-reg (IL10 and TGF-β1) cytokines were measured by ELISA test. Those parameters were estimated at two phases: the first being 4 and 8 weeks post-infection and the second phase at 12 weeks post-infection. The infected rabbits were categorized into group1 which was treated with praziquantel after the 8th week of infection and group 2 which was left untreated. In the first stage of infection, Th1 was superior to the other types at both mRNA (TBX2 and IRF8) and protein (IFN-γ and TNF-α) levels, but at the late stage, Th2 cytokines (IL4 and IL13) were surprisingly dominated without comparable change in Th2 transcriptional level in group 1. Concisely, the evaluation of T cell transcriptional factors provided clearer evidence about T cellular roles which would be a valuable supplement to control this disease in terms of protective and therapeutic vaccinations.

Cutting Edge: c-Maf Is Required for Regulatory T Cells To Adopt RORγt+ and Follicular Phenotypes

Regulatory T cells (Tregs) adopt specialized phenotypes defined by coexpression of lineage-defining transcription factors, such as RORγt, Bcl-6, or PPARγ, alongside Foxp3. These Treg subsets have unique tissue distributions and diverse roles in maintaining organismal homeostasis. However, despite extensive functional characterization, the factors driving Treg specialization are largely unknown. In this article, we show that c-Maf is a critical transcription factor regulating this process in mice, essential for generation of both RORγt⁺ Tregs and T follicular regulatory cells, but not for adipose-resident Tregs. c-Maf appears to function primarily in Treg specialization, because IL-10 production, expression of other effector molecules, and general immune homeostasis are not c-Maf dependent. As in other T cells, c-Maf is induced in Tregs by IL-6 and TGF-β, suggesting that a combination of inflammatory and tolerogenic signals promote c-Maf expression. Therefore, c-Maf is a novel regulator of Treg specialization, which may integrate disparate signals to facilitate environmental adaptation.

Differentiation of IL-17-Producing Invariant Natural Killer T Cells Requires Expression of the Transcription Factor c-Maf

c-Maf belongs to the large Maf family of transcription factors and plays a key role in the regulation of cytokine production and differentiation of T_H2, T_H17, T_FH, and Tr1 cells. Invariant natural killer T (iNKT) cells can rapidly produce large quantity of T_H-related cytokines such as IFN-γ, IL-4, and IL-17A upon stimulation by glycolipid antigens, such as α-galactosylceramide (α-GalCer). However, the role of c-Maf in iNKT cells and iNKT cells-mediated diseases remains poorly understood. In this study, we demonstrate that α-GalCer-stimulated iNKT cells express c-Maf transcript and protein. By using c-Maf-deficient fetal liver cell-reconstituted mice, we further show that c-Maf-deficient iNKT cells produce less IL-17A than their wild-type counterparts after α-GalCer stimulation. While c-Maf deficiency does not affect the development and activation of iNKT cells, c-Maf is essential for the induction of IL-17-producing iNKT (iNKT17) cells by IL-6, TGF-β, and IL-1β, and the optimal expression of RORγt. Accordingly, c-Maf-deficient iNKT17 cells lose the ability to recruit neutrophils into the lungs. Taken together, c-Maf is a positive regulator for the expression of IL-17A and RORγt in iNKT17 cells. It is a potential therapeutic target in iNKT17 cell-mediated inflammatory disease.

Genomic Programming of Human Neonatal Dendritic Cells in Congenital Systemic and In Vitro Cytomegalovirus Infection Reveal Plastic and Robust Immune Pathway Biology Responses

Neonates and especially premature infants are highly susceptible to infection but still can have a remarkable resilience that is poorly understood. The view that neonates have an incomplete or deficient immune system is changing. Human neonatal studies are challenging, and elucidating host protective responses and underlying cognate pathway biology, in the context of viral infection in early life, remains to be fully explored. In both resource rich and poor settings, human cytomegalovirus (HCMV) is the most common cause of congenital infection. By using unbiased systems analyses of transcriptomic resources for HCMV neonatal infection, we find the systemic response of a preterm congenital HCMV infection, involves a focused IFN regulatory response associated with dendritic cells. Further analysis of transcriptional-programming of neonatal dendritic cells in response to HCMV infection in culture revealed an early dominant IFN-chemokine regulatory subnetworks, and at later times the plasticity of pathways implicated in cell-cycle control and lipid metabolism. Further, we identify previously unknown suppressed networks associated with infection, including a select group of GPCRs. Functional siRNA viral growth screen targeting 516-GPCRs and subsequent validation identified novel GPCR-dependent antiviral (ADORA1) and proviral (GPR146, RGS16, PTAFR, SCTR, GPR84, GPR85, NMUR2, FZ10, RDS, CCL17, and SORT1) roles. By contrast a gene family cluster of protocadherins is significantly differentially induced in neonatal cells, suggestive of possible immunomodulatory roles. Unexpectedly, programming responses of adult and neonatal dendritic cells, upon HCMV infection, demonstrated comparable quantitative and qualitative responses showing that functionally, neonatal dendritic cell are not overly compromised. However, a delay in responses of neonatal cells for IFN subnetworks in comparison with adult-derived cells are notable, suggestive of subtle plasticity differences. These findings support a set-point control mechanism rather than immaturity for explaining not only neonatal susceptibility but also resilience to infection. In summary, our findings show that neonatal HCMV infection leads to a highly plastic and functional robust programming of dendritic cells in vivo and in vitro. In comparison with adults, a minimal number of subtle quantitative and temporal differences may contribute to variability in host susceptibility and resilience, in a context dependent manner.

IL-4 enhances IL-10 production in Th1 cells: implications for Th1 and Th2 regulation

IL-10 is an immunomodulatory cytokine with a critical role in limiting inflammation in immune-mediated pathologies. The mechanisms leading to IL-10 expression by CD4⁺ T cells are being elucidated, with several cytokines implicated. We explored the effect of IL-4 on the natural phenomenon of IL-10 production by a chronically stimulated antigen-specific population of differentiated Th1 cells. In vitro, IL-4 blockade inhibited while addition of exogenous IL-4 to Th1 cultures enhanced IL-10 production. In the in vivo setting of peptide immunotherapy leading to a chronically stimulated Th1 phenotype, lack of IL-4Rα inhibited the induction of IL-10. Exploring the interplay of Th1 and Th2 cells through co-culture, Th2-derived IL-4 promoted IL-10 expression by Th1 cultures, reducing their pathogenicity in vivo. Co-culture led to upregulated c-Maf expression with no decrease in the proportion of T-bet⁺ cells in these cultures. Addition of IL-4 also reduced the encephalitogenic capacity of Th1 cultures. These data demonstrate that IL-4 contributes to IL-10 production and that Th2 cells modulate Th1 cultures towards a self-regulatory phenotype, contributing to the cross-regulation of Th1 and Th2 cells. These findings are important in the context of Th1 driven diseases since they reveal how the Th1 phenotype and function can be modulated by IL-4.