Transcription Factor RORα Research Articles

Melatonin as an inducer of Th17 cell differentiation: new mechanisms

Cells of the immune system are sensitive to the action of melatonin, and the most obvious target of the hormone is the Th17 T helper subset: in addition to two high-affinity membrane receptors for melatonin, MT1 and MT2, these cells express a nuclear receptor, RORα. Among the secondary messengers involved in the transmission of signals from melatonin receptors, proteins of the sirtuin family are currently of particular interest. It is known that in non-tumor cells, sirtuin 1 (SIRT1) not only increases its expression in response to melatonin, but is also involved in the implementation of melatonin effects, as indicated by inhibitory assays using a specific SIRT1 blocker or corresponding siRNA/shRNA. This relates to the regulation of circadian oscillators, as well as the anti-inflammatory, antioxidant and anti-apoptotic effects of melatonin. Further mechanisms of SIRT1 activity in the cell include transcriptional and posttranscriptional regulation of gene expression through deacetylation of histones and non-histone proteins, and the apparent target of SIRT1 is the transcription factor RORα. It is this factor that mediates classical melatonin/SIRT1-dependent transcriptional control of key circadian regulators, the genes of which have ROR-binding sequences in their promoters. These data raise questions about the functions of SIRT1 in other cells expressing RORα, in particular in Th17 T helper cells, for which it is one of two key differentiation factors, along with RORγt. And if for RORα such a connection still remains hypothetical, for RORγt it has been convincingly demonstrated in studies both in vivo and in vitro: it has been shown that SIRT1 directly binds to RORγt and stimulates the development of Th17 cells, and blockade of sirtuin suppresses the differentiation of these cells in normal and prevents the development of Th17-associated pathology in mice. Summarizing these data, we can confidently predict the existence of a new mechanism for the regulation of the T helper Th17 population by melatonin, through the activation of sirtuin SIRT1, and this mechanism must be taken into account when interpreting data on the immunoregulatory activity of melatonin.

Mechanisms of RORα-dependent effects of melatonin

The transcription factor RORα has not traditionally been attributed a fundamental role in the development of Th17 cells, but recent studies have shown that it is necessary for the formation of a pathogenic variant of Th17 cells, the so-called Th1-polarized Th17 (Th17.1). Since the transcriptional activity of RORα depends on ligand binding, the search for such ligands is highly relevant, and in this regard, melatonin is of particular interest. The question of the ability of RORα to directly bind melatonin remains open today; data on this problem are extremely contradictory. In 1995, I. Wiesenberg and colleagues identified RORα as a nuclear receptor for melatonin, demonstrating the hormone’s ability to enhance the binding of this factor to DNA and determining the dissociation constant for the interaction of RORα with melatonin using classical Scatchard analysis. In 2011, P.J. Lardone and colleagues “rediscovered” RORα as a receptor for melatonin by demonstrating the coprecipitation of melatonin with RORα. And in 2016, A.J. Slominski and colleagues published a paper that cast doubt on the possibility of melatonin binding to RORα based on molecular modeling of ligand-receptor interactions supported by functional studies. However, a careful analysis of these data indicates the ambiguity of this conclusion, allowing us to speak, rather, of medium or low binding affinity of the hormone to RORα, but not of its absence. This conclusion is also supported by the fact that RORα mediates many of the effects of melatonin, both physiological and pharmacological, including the regulation of circadian rhythms and oxidative metabolism, neuro- and cardioprotection, and control of the immune response. In general, the data available today allow us to consider the transcription factor RORα as a receptor for melatonin with medium affinity, although indirect regulation of this factor by the hormone is not excluded, and RORα-dependent mechanisms should contribute to the cellular response to melatonin, both under physiological conditions and in the case of pharmacological use of the hormone.

Hyperosmotic Stress Induces Inflammation and Excessive Th17 Response to Blunt T-Cell Immunity in Tilapia.

Despite the advances in study on osmotic physiology in bony fish, the mechanism by which the immune system, especially T-cell immunity, adapts and responds to osmotic stress remains unknown. In the current study, we investigated the response of T cells to hyperosmotic stress in the bony fish Nile tilapia (Oreochromis niloticus). As a euryhaline fish, tilapia was able to adapt to a wide range of salinities; however, hypertonic stress caused inflammation and excessive T-cell activation. Furthermore, hypertonic stress increased the expression of IL-17A in T cells, upregulated the transcription factor RORα, and activated STAT3 signaling, along with IL-6- and TGF-β1-mediated pathways, revealing an enhanced Th17 response in this early vertebrate. These hypertonic stress-induced events collectively resulted in an impaired antibacterial immune response in tilapia. Hypertonic stress elevated the intracellular ROS level, which in turn activated the p38-MK2 signaling pathway to promote IL-17A production by T cells. Both ROS elimination and the p38-MK2 axis blockade diminished the increased IL-17A production in T cells under hypertonic conditions. Moreover, the produced proinflammatory cytokines further amplified the hypertonic stress signaling via the MKK6-p38-MK2 axis-mediated positive feedback loop. To our knowledge, these findings represent the first description of the mechanism by which T-cell immunity responds to hypertonic stress in early vertebrates, thus providing a novel perspective for understanding the adaptive evolution of T cells under environmental stress.

Xiao-qing-long-tang ameliorates OVA-induced allergic rhinitis by inhibiting ILC2s through the IL-33/ST2 and JAK/STAT pathways

BackgroundAllergic rhinitis (AR) is a chronic inflammatory disease of the nasal mucosa that is mediated by immunoglobulin E (IgE). Xiao-qing-long-tang (XQLT) is a traditional Chinese medicine compound that is widely used to treat respiratory diseases such as AR. However, the underlying mechanism of the effect of XQLT on AR remains unclear. PurposeTo elucidate the effect of XQLT on ovalbumin (OVA)-induced AR and the mechanisms of action. MethodsThe therapeutic efficacy of XQLT was evaluated in a well-established OVA-induced AR mouse model. Nasal symptoms were analyzed, type 2 cytokines and OVA-sIgE levels were measured, nasal mucosa tissues were collected for histological analysis, and the changes of Group 2 innate lymphoid cells (ILC2s) and the IL-33/ST2 and JAK/STAT signaling pathways in the nasal mucosa were observed. ResultsXQLT significantly alleviated the nasal symptoms and histological damage to the nasal mucosa in AR mice, and reduced the levels of type 2 cytokines and OVA-sIgE. In addition, after XQLT treatment, the numbers of ILC2s in the nasal mucosa of AR mice were reduced, and the mRNA levels of the transcription factors GATA3 and ROR-α were decreased. Moreover, IL-33/ST2 signaling pathway was inhibited. The costimulatory cytokine associated JAK/STAT signaling pathway was also inhibited in ILC2s. ConclusionOur study demonstrated that XQLT regulated ILC2s through the IL-33/ST2 and JAK/STAT pathways to ameliorate type 2 inflammation in OVA-induced AR. These findings suggest that XQLT might be used to treat AR.

Innate lymphoid cells in depression: Current status and perspectives

The recent discovery of innate lymphoid cells (ILCs) has provided new insights into our understanding of the pathogenesis of many disease conditions with immune dysregulation. Type 1 innate lymphoid cells (ILC1s) induce type I immunity and are characterized by the expression of signature cytokine IFN-γ and the master transcription factor T-bet; ILC2s stimulate type II immune responses and are defined by the expression of signature cytokines IL-5 and IL-13, and transcription factors ROR-α and GATA3; ILC3s requires the transcription factor RORγt and produce IL-22 and IL-17. ILCs are largely tissue-resident and are enriched at barrier surfaces of the mammalian body. Increasing evidence shows that inflammation is involved in the pathogenesis of depression. Although few studies have directly investigated the role of ILCs in depression, several studies have examined the levels of cytokines produced by ILCs in depressed subjects. This review summarizes the potential roles of ILCs in depression. A better understanding of the biology of ILCs may lead to the development of new therapeutic strategies for the management of depression.

Transcription factor RORα enforces stability of the Th17 cell effector program by binding to a Rorc cis-regulatory element.

T helper 17 (Th17) cells regulate mucosal barrier defenses but also promote multiple autoinflammatory diseases. Although many molecular determinants of Th17 cell differentiation have been elucidated, the transcriptional programs that sustain Th17 cells invivo remain obscure. The transcription factor RORγt is critical for Th17 cell differentiation; however, it is not clear whether the closely related RORα, which is co-expressed in Th17 cells, has a distinct role. Here, we demonstrated that although dispensable for Th17 cell differentiation, RORα was necessary for optimal Th17 responses in peripheral tissues. The absence of RORα in Tcells led to reductions in both RORγt expression and effector function among Th17 cells. Cooperative binding of RORα and RORγt to a previously unidentified Rorc cis-regulatory element was essential for Th17 lineage maintenance invivo. These data point to a non-redundant role of RORα in Th17 lineage maintenance via reinforcement of the RORγt transcriptional program.

Multiscale 3D genome organization underlies ILC2 ontogenesis and allergic airway inflammation.

Innate lymphoid cells (ILCs) are well-characterized immune cells that play key roles in host defense and tissue homeostasis. Yet, how the three-dimensional (3D) genome organization underlies the development and functions of ILCs is unknown. Herein, we carried out an integrative analysis of the 3D genome structure, chromatin accessibility and gene expression in mature ILCs. Our results revealed that the local 3D configuration of the genome is rewired specifically at loci associated with ILC biology to promote their development and functional differentiation. Importantly, we demonstrated that the ontogenesis of ILC2s and the progression of allergic airway inflammation are determined by a unique local 3D configuration of the region containing the ILC-lineage-defining factor Id2, which is characterized by multiple interactions between the Id2 promoter and distal regulatory elements bound by the transcription factors GATA-3 and RORα, unveiling the mechanism whereby the Id2 expression is specifically controlled in group 2 ILCs.

Immunization With a DNA Vaccine Encoding the Toxoplasma gondii' s GRA39 Prolongs Survival and Reduce Brain Cyst Formation in a Murine Model.

Toxoplasma gondii, an obligate intracellular protozoan parasite, can cause infect almost all warm-blooded animals and humans. To evaluate the immunogenicity and protective efficacy of T. gondii GRA39 (TgGRA39) in mice by using DNA immunization, we constructed a recombinant eukaryotic plasmid pVAX-TgGRA39. The specific immune responses in immunized mice were analyzed by serum antibody and cytokine measurements, lymphocyte proliferation assays and flow cytometry of T lymphocyte subclasses. Also, protective efficacy against acute and chronic T. gondii infection was assessed by observing the survival time after challenge with the highly virulent T. gondii RH strain (Genotype I) and counting the number of cyst-forming in brain at 4 weeks post-infection with the cyst-forming PRU strain of T. gondii (Genotype II), respectively. Our results showed that DNA immunization with pVAX-GRA39 via intramuscular injection three times, at 2-week intervals could elicit humoral and cellular immune response, indicated by enhanced levels of IgG and IgG2a antibodies (a slightly elevated IgG2a to IgG1 ratio), and increased levels of cytokines IFN-γ, IL-2, IL-12, IL-17A, IL-17F, IL-22 and IL-23 and percentages of CD3+ CD4+ CD8- and CD3+ CD8+ CD4– T cells, in contrast to non-immunized mice. The significant increase in the expression levels of IL-6, TGF-β1, IL-1β, and the transcription factor factors RORγt, RORα, and STAT3 involved in the activation and pathway of Th17 and Tc17 cells, were also observed. However, no significant difference was detected in level of IL-4 and IL-10 (p > 0.05). These effective immune responses had mounted protective immunity against T. gondii infection, with a prolonged survival time (16.80 ± 3.50 days) and reduced cyst numbers (44.5%) in comparison to the control mice. Our data indicated that pVAX-TgGRA39 could induce effective humoral, and Th1-type, Th17, and Tc17 cellular immune responses, and may represent a promising vaccine candidate against both acute and chronic T. gondii infection.

RORα is a critical checkpoint for T cell and ILC2 commitment in the embryonic thymus.

Type 2 innate lymphoid cells (ILC2) contribute to immune homeostasis, protective immunity and tissue repair. Here we demonstrate that functional ILC2 can arise in the embryonic thymus, from shared T cell precursors, preceding the emergence of CD4+CD8+ (double-positive) T cells. Thymic ILC2 migrated to mucosal tissues with colonization of the intestinal lamina propria. RORα expression repressed T cell development, while promoting ILC2 in the thymus. From RNA-seq, ATAC-seq and ChIP-seq data we propose a revised transcriptional circuit to explain the co-development of T cells and ILC2 from common progenitors in the thymus. When Notch signaling is present, Bcl11b dampens Nfil3/Id2 expression, permitting E protein-directed T cell commitment. However, concomitant expression of RORα overrides the Nfil3/Id2 repression, allowing Id2 to repress E proteins and promote ILC2 differentiation. Thus, we demonstrate that RORα expression represents a critical checkpoint at the bifurcation of the T cell and ILC2 lineages in the embryonic thymus.

Pharmacological modulation of RORα controls fat browning, adaptive thermogenesis, and body weight in mice.

Beiging is an attractive therapeutic strategy to fight against obesity and its side metabolic complications. The loss of function of the nuclear transcription factor RORα has been related to a lean phenotype with higher thermogenesis in sg/sg mice lacking this protein. Here we show that pharmacological modulation of RORα activity exerts reciprocal and cell-autonomous effect on UCP1 expression ex vivo, in cellulo, and in vivo. The RORα inverse-agonist SR3335 upregulated UCP1 expression in brown and subcutaneous white adipose tissue (scWAT) explants of wild-type (WT) mice, whereas the RORα agonist SR1078 had the opposite effect. We confirmed the reciprocal action of these synthetic RORα ligands on gene expression, mitochondrial mass, and uncoupled oxygen consumption rate in cultured murine and human adipocytes. Time course analysis revealed stepwise variation in gene expression, first of TLE3, an inhibitor of the thermogenic program, followed by a reciprocal effect on PRDM16 and UCP1. Finally, RORα ligands were shown to be useful tools to modulate in vivo UCP1 expression in scWAT with associated changes in this fat depot mass. SR3335 and SR1078 provoked the opposite effects on the WT mice body weight, but without any effect on sg/sg mice. This slimming effect of SR3335 was related to an increased adaptive thermogenesis of the mice, as assessed by the rectal temperature of cold-stressed mice and induction of UCP1 in scWAT, as well as by indirect calorimetry in presence or not of a β3-adrenoceptor agonist. These data confirmed that RORα ligands could be useful tools to modulate thermogenesis and energy homeostasis.NEW & NOTEWORTHY The regulation of adipose tissue browning was not fully deciphered and required further studies explaining how the regulation of this process may be of interest for tackling obesity and related metabolic disorders. Our data confirmed the involvement of the transcription factor RORα in the regulation of nonshivering thermogenesis, and importantly, revealed the possibility to in vivo modulate its activity by synthetic ligands with beneficial consequences on fat mass and body weight of the mice.

Mammalian Target of Rapamycin Signaling Enhances Ovalbumin-Induced Neutrophilic Airway Inflammation by Promoting Th17 Cell Polarization in Murine Noneosinophilic Asthma Model.

Background: T helper 17 (Th17) is regarded as key immune cell in the pathogenesis of noneosinophilic asthma (NEA) due to the recruitment of neutrophils into the airways. The mammalian target of rapamycin (mTOR) is an important signaling molecule that plays a critical role in immune regulation. This study focused on mTOR signaling pathway in the regulation of Th17-mediated neutrophilic airway inflammation. Methods: Ovalbumin (OVA) T cell receptor transgenic DO11.10 mice (DO11.10 mice) were used to establish NEA model, and few mice received specific mTORC1 inhibitor rapamycin (RAPA) before intranasal administration of OVA. The severity of airway inflammation was determined by differential cell counts in bronchoalveolar lavage (BAL) fluids and histopathologic lung analysis. The levels of various cytokines in BAL fluids and lung tissues were measured. To determine the role of mTORC1 signaling in Th17 differentiation, naive T cells from wild-type (WT) and TSC1 knockout (KO) mice were cultured in Th17 skewing condition with or without RAPA in vitro and the production of IL-17A was compared. Results: Treatment with RAPA markedly attenuated OVA-induced neutrophilic airway inflammation in DO11.10 mice. Also the production of IL-17A was inhibited without affecting the production of interferon-γ (IFN-γ) and IL-4 in lungs. Furthermore, RAPA suppressed differentiation of Th17 cells in vitro, whereas enhanced activity of mTORC1 promoted Th17 cell differentiation and increased the expression of Th17-related transcription factors RORγt and RORα. Conclusion: These results suggested that mTOR promoted Th17 cell polarization and enhanced OVA-induced neutrophilic airway inflammation in experimental NEA.

The Transcription Factor RORα Preserves ILC3 Lineage Identity and Function during Chronic Intestinal Infection.

Innate lymphoid cells (ILCs) are critical for host defense and tissue repair but can also contribute to chronic inflammatory diseases. The transcription factor RORα is required for ILC2 development but is also highly expressed by other ILC subsets where its function remains poorly defined. We previously reported that Rorasg/sg bone marrow chimeric mice (C57BL/6J) were protected from Salmonella-induced intestinal fibrosis due to defective ILC3 responses. In this study, single-cell RNA analysis of ILCs isolated from inflamed tissues indicates that RORα perturbation led to a reduction in ILC3 lineages. Furthermore, residual Rorasg/sg ILC3s have decreased expression of key signature genes, including Rorc and activating cytokine receptors. Collectively, our data suggest that RORα plays a key role in preserving functional ILC3s by modulating their ability to integrate environmental cues to efficiently produce cytokines.

Low frequency of IL-10-producing B cells and high density of ILC2s contribute to the pathological process in Graves’ disease, which may be related to elevated-TRAb levels

IL-10-producing B Cells (B10) is a functionally defined regulatory B-cell subset. It plays an important role in the control of inflammation and autoimmune diseases, although it is present at low numbers in peripheral blood. Graves’ disease is an autoimmune disease characterized by the production of autoantibodies such as TRAb. ILC2s maintains Th2 polarization state by producing type-II cytokines. It is not clear whether the level of autoantibody is related to ILC2s and B10 cells in Graves’ disease. In this study, we analyzed the frequencies of B10, Treg cells and ILC2s, as well as the expression of related cytokines in peripheral blood from patients with Graves' disease and evaluated the correlation between B10 cell numbers and autoantibodies level. Our data showed that the frequency of B10 or Treg cells was significantly decreased in peripheral blood mononuclear cells from Graves' disease patients, while the percentage of ILC2s cells was increased; the levels of cytokine IL-5, IL-13 and related transcription factor RORα were up-regulated. Autoantibodies analysis also showed that high level of TRAb was accompanied by low rates of B10 cells in patients, there was a negative correlation trend. In addition, the analytical data from mouse disease models also showed similar results. It indicates that B10 cells may affect the production of TRAb by negative regulation of Th2 cells, while ILC2s can promote the production of autoantibodies such as TRAb by maintaining the dominant response state of Th2 cells.

Polychromic Reporter Mice Reveal Unappreciated Innate Lymphoid Cell Progenitor Heterogeneity and Elusive ILC3 Progenitors in Bone Marrow

SummaryInnate lymphoid cells (ILCs) play strategic roles in tissue homeostasis and immunity. ILCs arise from lymphoid progenitors undergoing lineage restriction and the development of specialized ILC subsets. We generated “5x polychromILC” transcription factor reporter mice to delineate ILC precursor states by revealing the multifaceted expression of key ILC-associated transcription factors (Id2, Bcl11b, Gata3, RORγt, and RORα) during ILC development in the bone marrow. This approach allowed previously unattained enrichment of rare progenitor subsets and revealed hitherto unappreciated ILC precursor heterogeneity. In vivo and in vitro assays identified precursors with potential to generate all ILC subsets and natural killer (NK) cells, and also permitted discrimination of elusive ILC3 bone marrow antecedents. Single-cell gene expression analysis identified a discrete ILC2-committed population and delineated transition states between early progenitors and a highly heterogeneous ILC1, ILC3, and NK precursor cell cluster. This diversity might facilitate greater lineage potential upon progenitor recruitment to peripheral tissues.

IL-25-regulated type 2 innate lymphoid cells activation promote allergic fungal rhinosinusitis

Objective: To investigate the regulation of IL-25 on type Ⅱ innate lymphoid cells (ILC2s) activation in the pathogenesis of allergic fungal rhinosinusitis (AFRS). Methods: Nasal mucosa tissues were collected from 16 AFRS patients and 12 patients, who underwent nasal endoscopic surgery for cerebrospinal rhinorrhea or skull base benign tumor during the period from June 2016 to June 2017 in Department of Rhinology, the First Affiliated Hospital of Zhengzhou University. Firstly, flow cytometry was used to detect ILC2s in nasal mucosa of both groups. Secondly, the expression of IL-25, IL-5 and IL-13 in nasal mucosa was detected by immunofluorescence and/or Western Blot assay. Finally, fungal extracts, IL-25 and glucocorticoids were used to stimulate nasal mucosal epithelial cells and tissues in vitro respectively to detect the regulatory effect of IL-25 on ILC2s. SPSS 16.0 software was used to analyze the data. Results: The prevalence of ILC2s in nasal tissues was higher in patients with AFRS than those of the control group ((3.85±1.52)%(Mean±SD) vs (0.32±0.10)%, U=9.00, P<0.05). There was a positive correlation between the prevalence of ILC2s and the number of eosinophils in nasal mucosa of patients with ARFS (r=0.80, P<0.05). The expression of IL-25, IL-5 and IL-13 in nasal mucosa epithelium of AFRS group was significantly higher than that of the control group (0.49±0.13 vs 0.23±0.09, 0.23±0.05 vs 0.10±0.04, 0.31±0.08 vs 0.14±0.07, t value was 5.90, 7.21, 5.69, respectively, all P<0.05). Fungal stimulation enhanced the expression of IL-25 protein in nasal epithelial cells of both groups (0.67±0.19 vs 0.25±0.12 (AFRS group), 0.62±0.17 vs 0.27±0.16 (control group), q value was 8.65, 9.26, respectively, all P<0.05). In the IL-25 stimulated nasal mucosa at a concentration of 1, 10 and 100 ng/ml, the expression level of retinoid acid-related orphan receptor α (RORα) mRNA was 2.07±1.53, 5.06±0.93, 7.38±2.30, respectively; the expression level of GATA binding protein 3 (GATA3) mRNA was 3.58±1.29, 6.14±1.55, 7.64±2.28, respectively; the expression level of IL-5 protein was 0.21±0.06, 0.32±0.06, 0.38±0.10, respectively; the expression level of IL-13 was 0.52±0.13, 0.69±0.22, 0.82±0.21, respectively, which were significantly higher than that in the unstimulated nasal mucosa (1.00±0.00, 1.00±0.00, 0.11±0.05, 0.35±0.15, F value was 63.45, 59.27, 49.35, 20.20, respectively, all P<0.05). The up-regulation could be inhibited by dexamethasone (F value was 89.20, 92.47, 99.63, 49.82, respectively, all P<0.05). Conclusions: Epithelial-derived IL-25 up-regulates the expression of IRC2s-dependent transcription factors RORα and GATA3 mRNA, which are positively correlated with elevated IL-13 and IL-5 expression levels in tissues, may be involved in AFRS inflammatory response, and are inhibited by glucocorticoids.

The transcription factor ROR alpha preserves group 3 innate lymphoid cell lineage identity and function

Abstract Innate lymphoid cells (ILCs) are critical for host defense and tissue repair. The transcription factor RORα is essential for ILC2 development but it is also highly expressed by ILC3s where its function remains poorly defined. Previously, we found that Rorasg/sg bone marrow transplant (BMT) mice were protected from intestinal fibrosis in a Salmonella--induced model of Crohn’s disease and that this is due to defective cytokine production by ILC3s. In the current study, whole transcriptome sequencing analysis reveals a striking downregulation of ILC3 signature genes in RORα-deficient ILC3s isolated from Salmonella infected mice. In particular, the expression of genes involved in sensing an inflammatory milieu is attenuated. Moreover, we find that Rorasg/sg ILC3s fail to express IL-17A following ex vivo stimulation with IL-23 and IL-1β. Consistent with these observations, we also find that Rorasg/sg BMT mice are more susceptible to Citrobacter rodentium infection due to attenuated expression of IL-22 and impaired induction of antimicrobial peptides. Collectively, our data suggests that RORα plays a key role in preserving functional ILC3s by modulating their ability to sense environmental cues that stimulate the efficient production of cytokines. These observations also suggest that targeting ILC3 cells could be of therapeutic benefit in fibrosis associated with Crohn’s disease.

Regulation of ABCA1 and ABCG1 transporter gene expression in the intraabdominal adipose tissue

Tissue specific expression of genes encoding the cholesterol transporters ABCA1 and ABCG1 as well as genes encoding the most important transcriptional regulators of adipogenesis (LXRα, LXRβ, PPARγ and RORα) has been investigated in intraabdominal adipose tissue (IAT) samples from obese patients and patients without overweight. A direct correlation between the content of ABCA1 and ABCG1 proteins and the RORα protein level (r = 0.480, p < 0.05; r = 0.435, p < 0.05, respectively) suggests involvement of the transcription factor RORα in the regulation of ABCA1 and ABCG1 protein levels in IAT. ABCA1 and ABCG1 gene expression positively correlated with such obesity indicators as body mass index (BMI) (r = 0.522, p = 0.004; r = 0.594, p = 0.001, respectively) and waist circumference (r = 0.403, p = 0.033; r = 0.474, p = 0.013, respectively). The development of obesity is also associated with decreased IAT levels of RORα and LXRβ mRNA (p = 0.016 and p = 0.002, respectively). This suggest that the nuclear factor RORα can play a significant role in the regulation of cholesterol metabolism and control IAT expression of ABCA1 and ABCG1 genes, while the level of IAT LXRβ gene expression may be an important factor associated with the development of obesity.

Exon 2 of Foxp3 contributes to the peripheral tolerance of the immune system

Abstract Foxp3 is essential for the development and function of CD4 regulatory T cells (Tregs) that maintain peripheral immune tolerance. A major difference of Foxp3 expression between human and mouse is the alternative splicing of exon 2 in human Tregs. In vitro studies showed that the exon 2 region of Foxp3 associates and inhibits the transcription factors RORα and RORγt, which are critical for Th17 differentiation. However the in vivo role of exon 2 is still unknown. By deleting exon 2 of mouse Foxp3 gene (dE2), we show here that peripheral and mesenteric lymph nodes of dE2 mice contained about twice amount of lymphocytes when compared with wildtype mice due to the higher level of CD4 T cell activation and proliferation. Exon 2 deletion resulted in more severe air way inflammation in OVA-induced chronic asthma, characterized by higher number of lymphocytes and eosinophils in bronchoalveolar lavage, and high level of OVA-specific serum IgE. CD4 T cells in the mediastinal lymph nodes of dE2 mice expressed higher IL-4, IL-9 and IFN-γ, but surprisingly not IL-17, compared with those in wild type mice. These data indicate that Foxp3 exon 2 is important in maintaining proper functions of peripheral Tregs, and thus contributes to the peripheral tolerance to dampen allergic inflammation against harmless antigens.

Effector γδ T Cell Differentiation Relies on Master but Not Auxiliary Th Cell Transcription Factors.

γδ T lymphocytes are programmed into distinct IFN-γ-producing CD27(+) (γδ27(+)) and IL-17-producing CD27(-) (γδ27(-)) subsets that play key roles in protective or pathogenic immune responses. Although the signature cytokines are shared with their αβ Th1 (for γδ27(+)) and Th17 (for γδ27(-)) cell counterparts, we dissect in this study similarities and differences in the transcriptional requirements of murine effector γδ27(+), γδ27(-)CCR6(-), and γδ27(-)CCR6(+) γδ T cell subsets and αβ T cells. We found they share dependence on the master transcription factors T-bet and RORγt for IFN-γ and IL-17 production, respectively. However, Eomes is fully dispensable for IFN-γ production by γδ T cells. Furthermore, the Th17 cell auxiliary transcription factors RORα and BATF are not required for IL-17 production by γδ27(-) cell subsets. We also show that γδ27(-) (but not γδ27(+)) cells become polyfunctional upon IL-1β plus IL-23 stimulation, cosecreting IL-17A, IL-17F, IL-22, GM-CSF, and IFN-γ. Collectively, our in vitro and in vivo data firmly establish the molecular segregation between γδ27(+) and γδ27(-) T cell subsets and provide novel insight on the nonoverlapping transcriptional networks that control the differentiation of effector γδ versus αβ T cell subsets.

Circadian molecular clock in lung pathophysiology.

Disrupted daily or circadian rhythms of lung function and inflammatory responses are common features of chronic airway diseases. At the molecular level these circadian rhythms depend on the activity of an autoregulatory feedback loop oscillator of clock gene transcription factors, including the BMAL1:CLOCK activator complex and the repressors PERIOD and CRYPTOCHROME. The key nuclear receptors and transcription factors REV-ERBα and RORα regulate Bmal1 expression and provide stability to the oscillator. Circadian clock dysfunction is implicated in both immune and inflammatory responses to environmental, inflammatory, and infectious agents. Molecular clock function is altered by exposomes, tobacco smoke, lipopolysaccharide, hyperoxia, allergens, bleomycin, as well as bacterial and viral infections. The deacetylase Sirtuin 1 (SIRT1) regulates the timing of the clock through acetylation of BMAL1 and PER2 and controls the clock-dependent functions, which can also be affected by environmental stressors. Environmental agents and redox modulation may alter the levels of REV-ERBα and RORα in lung tissue in association with a heightened DNA damage response, cellular senescence, and inflammation. A reciprocal relationship exists between the molecular clock and immune/inflammatory responses in the lungs. Molecular clock function in lung cells may be used as a biomarker of disease severity and exacerbations or for assessing the efficacy of chronotherapy for disease management. Here, we provide a comprehensive overview of clock-controlled cellular and molecular functions in the lungs and highlight the repercussions of clock disruption on the pathophysiology of chronic airway diseases and their exacerbations. Furthermore, we highlight the potential for the molecular clock as a novel chronopharmacological target for the management of lung pathophysiology.