Suppression of TCF4 promotes a ZC3H12A-mediated self-sustaining inflammatory feedback cycle involving IL-17RA/IL-17RE epidermal signaling

IL-17C is an epithelial cell-derived proinflammatory cytokine whose transcriptional regulation remains unclear. Analysis of the IL17C promoter region identified TCF4 as putative regulator, and siRNA knockdown of TCF4 in human keratinocytes (KCs) increased IL17C. IL-17C stimulation of KCs (along with IL-17A and TNF-α stimulation) decreased TCF4 and increased NFKBIZ and ZC3H12A expression in an IL-17RA/RE-dependent manner, thus creating a feedback loop. ZC3H12A (MCPIP1/Regnase-1), a transcriptional immune-response regulator, also increased following TCF4 siRNA knockdown, and siRNA knockdown of ZC3H12A decreased NFKBIZ, IL1B, IL36G, CCL20, and CXCL1, revealing a proinflammatory role for ZC3H12A. Examination of lesional skin from the KC-Tie2 inflammatory dermatitis mouse model identified decreases in TCF4 protein concomitant with increases in IL-17C and Zc3h12a that reversed following the genetic elimination of Il17c, Il17ra, and Il17re and improvement in the skin phenotype. Conversely, interference with Tcf4 in KC-Tie2 mouse skin increased Il17c and exacerbated the inflammatory skin phenotype. Together, these findings identify a role for TCF4 in the negative regulation of IL-17C, which, alone and with TNF-α and IL-17A, feed back to decrease TCF4 in an IL-17RA/RE-dependent manner. This loop is further amplified by IL-17C-TCF4 autocrine regulation of ZC3H12A and IL-17C regulation of NFKBIZ to promote self-sustaining skin inflammation.

Metabolic effects of air pollution exposure and reversibility

Air pollution involving particulate matter smaller than 2.5 μm in size (PM2.5) is the world's leading environmental risk factor contributing to mortality through cardiometabolic pathways. In this study, we modeled early life exposure using chow-fed C57BL/6J male mice that were exposed to real-world inhaled, concentrated PM2.5 (~10 times ambient levels/~60-120 μg/m3) or filtered air over a 14-week period. We investigated the effects of PM2.5 on phenotype, the transcriptome, and chromatin accessibility and compared these with the effects of a prototypical high-fat diet (HFD) as well as cessation of exposure on phenotype reversibility. Exposure to PM2.5 impaired glucose and insulin tolerance and reduced energy expenditure and 18FDG-PET uptake in brown adipose tissue. Multiple differentially expressed gene clusters in pathways involving metabolism and circadian rhythm were noted in insulin-responsive tissues. Although the magnitude of transcriptional change detected with PM2.5 exposure was lower than that observed with a HFD, the degree of alteration in chromatin accessibility after PM2.5 exposure was significant. The novel chromatin remodeler SMARCA5 (SWI/SNF complex) was regulated in response to PM2.5 exposure, the cessation of which was associated with a reversal of insulin resistance and restoration of chromatin accessibility and nucleosome positioning near transcription start sites, as well as a reversal of exposure-induced changes in the transcriptome, including SMARCA5. These changes indicate pliable epigenetic control mechanisms following cessation of exposure.

Exposure to Air Pollution Disrupts Circadian Rhythm through Alterations in Chromatin Dynamics

Particulate matter ≤2.5μm (PM_2.5) air pollution is a leading environmental risk factor contributing disproportionately to the global burden of non-communicable disease. We compared impact of chronic exposure to PM_2.5 alone, or with light at night exposure (LL) on metabolism. PM_2.5 induced peripheral insulin resistance, circadian rhythm (CR) dysfunction, and metabolic and brown adipose tissue (BAT) dysfunction, akin to LL (with no additive interaction between PM_2.5 and LL). Transcriptomic analysis of liver and BAT revealed widespread but unique alterations in CR genes, with evidence for differentially accessible promoters and enhancers of CR genes in response to PM_2.5 by ATAC-seq. The histone deacetylases 2, 3, and 4 were downregulated with PM_2.5 exposure, with increased promoter occupancy by the histone acetyltransferase p300 as evidenced by ChIP-seq. These findings suggest a previously unrecognized role of PM_2.5 in promoting CR disruption and metabolic dysfunction through epigenetic regulation of circadian targets.

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Air pollution disrupts the circadian rhythm (CR) similar to light at night

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Dysregulated circadian genes result in insulin resistance and metabolic diseases

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PM_2.5 alters chromatin structure of circadian genes at regulatory regions

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PM_2.5 alters chromatin structure by recruiting histone acetyl transferase (HAT), p300

Oxidative stress pathways of air pollution mediated toxicity: Recent insights

Ambient air pollution is a leading environmental cause of morbidity and mortality globally with most of the outcomes of cardiovascular origin. While numerous mechanisms are proposed to explain the link between air pollutants and cardiovascular events, the evidence supports a role for oxidative stress as a critical intermediary pathway in the transduction of systemic responses in the cardiovascular system. Indeed, alterations in vascular function are a critical step in the development of cardiometabolic disorders such as hypertension, diabetes, and atherosclerosis. This review will provide an overview of the impact of particulate and gaseous pollutants on oxidative stress from human and animal studies published in the last five years. We discuss current gaps in knowledge and evidence to date implicating the role of oxidative stress with an emphasis on inhalational exposures. We conclude with the identification of gaps, and an exhortation for further studies to elucidate the impact of oxidative stress in air pollution mediated effects.

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Particulate matter air pollution is the leading risk factor for cardiovascular morbidity and mortality globally.

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Mechanisms of oxidative stress mediated pathways.

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How does lung inflammation crucial to inhalational exposure mediate systemic toxicity?

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Review of recent animal and human exposure studies providing insights into oxidative stress pathways.

Alpha2B-Adrenergic Receptor Overexpression in the Brain Potentiate Air Pollution-induced Behavior and Blood Pressure Changes

Fine ambient particulate matter (PM2.5) is able to induce sympathetic activation and inflammation in the brain. However, direct evidence demonstrating an essential role of sympathetic activation in PM2.5-associated disease progression is lacking. We assess the contribution of α2B-adrenergic receptor (Adra2b) in air pollution-associated hypertension and behavioral changes in this study. Wild-type mice and Adra2b-transgenic mice overexpressing Adra2b in the brain (Adra2bTg) were exposed to concentrated PM2.5 or filtered air for 3 months via a versatile aerosol concentrator exposure system. Mice were fed with a high salt diet (4.0% NaCl) for 1 week at week 11 of exposure to induce blood pressure elevation. Intra-arterial blood pressure was monitored by radio-telemetry and behavior changes were assessed by open field, light-dark, and prepulse inhibition tests. PM2.5 exposure increased Adra2b in the brain of wild-type mice. Adra2b overexpression enhanced the anxiety-like behavior and high salt diet-induced blood pressure elevation in response to air pollution but not filtered air exposure. Adra2b overexpression induced upregulation of inflammatory genes such as TLR2, TLR4, and IL-6 in the brain exposed to PM2.5. In addition, there were increased frequencies of activated effector T cells and increased expression of oxidative stress-related genes, such as SOD1, NQO1, Nrf2, and Gclm in Adra2bTg mice compared with wild-type mice. Our results provide new evidence of distinct behavioral changes consistent with anxiety and blood pressure elevation in response to high salt intake and air pollution exposure, highlighting the importance of centrally expressed Adra2b in the vulnerability to air pollution exposure.

Microbe-host interplay in atopic dermatitis and psoriasis

Despite recent advances in understanding microbial diversity in skin homeostasis, the relevance of microbial dysbiosis in inflammatory disease is poorly understood. Here we perform a comparative analysis of skin microbial communities coupled to global patterns of cutaneous gene expression in patients with atopic dermatitis or psoriasis. The skin microbiota is analysed by 16S amplicon or whole genome sequencing and the skin transcriptome by microarrays, followed by integration of the data layers. We find that atopic dermatitis and psoriasis can be classified by distinct microbes, which differ from healthy volunteers microbiome composition. Atopic dermatitis is dominated by a single microbe (Staphylococcus aureus), and associated with a disease relevant host transcriptomic signature enriched for skin barrier function, tryptophan metabolism and immune activation. In contrast, psoriasis is characterized by co-occurring communities of microbes with weak associations with disease related gene expression. Our work provides a basis for biomarker discovery and targeted therapies in skin dysbiosis.

Atopic dermatitis (AD) and psoriasis (PSO) are associated with dysbiosis. Here, by analyses of skin microbiome and host transcriptome of AD and PSO patients, the authors find distinct microbial and disease-related gene transcriptomic signatures that differentiate both diseases.

5967A randomized trial of yoga therapy for reflex syncope

Background

Reflex syncope (RS), the most common cause of syncope is usually recurrent, associated with decreased quality of life, and frustrates both the clinicians and the patients with a paucity of effective treatment options.

Purpose

To assess the effectiveness of yoga therapy on the recurrence of reflex syncope.

Methods

Subjects with recurrent RS (>3 episodes) and positive head-up tilt test were enrolled prospectively, and randomized to conventional therapy with physical maneuvres (Group 1) and yoga therapy (Group 2). Group 1 patients were taught physical counter-pressure maneuvers as per guidelines. Group 2 patients were taught yoga for 7 sessions by a certified Yoga instructor/therapist, and then advised to perform yoga for 60 minutes at least five days/week for six months. The Yoga module consisted of Pranayama (breathing techniques), Asanas (Postures) and Dhyana (Meditation) for 60 minutes/session. Both groups were followed up monthly for 6 months in the syncope clinic noting down the recurrences and the quality of life using the syncope functional status questionnaire score.

Result

The study group consisted of 97 patients (group 1: 46 patients and group 2: 51 patients) enrolled prospectively between June 2015 to February 2017. The mean age was 33.1±16.6 years, with male: female ratio 1.1:1, and a mean of 6.4±6.06 syncope episodes (group 1: 6.8±8.0 vs. group 2: 6.0±4.0; p=0.551). The mean duration of symptoms was 17.1±20.71 months (group 1: 16.1±22.8 months vs. group 2: 17.8±19.1 months; p=0.694). There was a significant decrease in the recurrences of syncope in the yoga group compared to the conventional group at three months (group 1: 1.8±1.4 vs group 2: 0.8±0.9, P<0.001) as well as six months follow-up (group 1: 3.38±3.0 vs group 2: 0.98±1.23, P<0.001). The quality of life score at 6 months improved in 20 patients in group 1 and in 45 patients in group 2 (<0.001).

Conclusion

Guided yoga therapy is superior to conventional measures in reducing the number of syncopal episodes and improves the quality of life in patients with reflex syncope. Yoga therapy should be considered as treatment strategy for patients with reflex syncope.

Leukocyte CD300a Contributes to the Resolution of Murine Allergic Inflammation

CD300a is an inhibitory receptor for mast cells and eosinophils in allergic inflammation (AI); however, the spatiotemporal expression of CD300a and its potential roles in the resolution of AI are still to be determined. In this study, employing a mouse model of allergic peritonitis, we demonstrate that CD300a expression on peritoneal cells is regulated from inflammation to resolution. Allergic peritonitis-induced CD300a^-/- mice had a rapid increase in their inflammatory cell infiltrates and tryptase content in the peritoneal cavity compared with wild type, and their resolution process was significantly delayed. CD300a^-/- mice expressed lower levels of ALX/FPR2 receptor on peritoneal cells and had higher levels of LXA₄ in the peritoneal lavage. CD300a activation on mouse bone marrow-derived mast cells regulated ALX/FPR2 expression levels following IgE-mediated activation. Together, these findings indicate a role for CD300a in AI and its resolution, in part via the specialized proresolving mediator LXA₄ and ALX/FPR2 receptor pathway activation.

The CD48 receptor mediates Staphylococcus aureus human and murine eosinophil activation

BACKGROUND

Allergy is characterized by eosinophilia and an increased susceptibility to microbial infection. Atopic dermatitis (AD) is typically associated with Staphylococcus aureus (SA) colonization. Some of the mechanisms by which SA and its exotoxins interact with eosinophils remain elusive. CD48, a glycosylphosphatidylinositol-anchored receptor belonging to the CD2 family, participates in mast cells-SA stimulating cross-talk, facilitates the formation of the mast cell/eosinophils effector unit and as expressed by eosinophils, mediates experimental asthma.

OBJECTIVE

To investigate the role of CD48 expressed on human peripheral blood and mouse bone marrow-derived eosinophils (BMEos) in their interaction with heat-killed SA and its three exotoxins, Staphylococcal enterotoxin B (SEB), protein A (PtA) and peptidoglycan (PGN).

METHODS

Eosinophils were obtained from human peripheral blood and BM of WT and CD48-/- mice. SA was heat killed and eosinophils-SA/exotoxins interactions were analyzed by confocal microscopy, adhesion and degranulation, cell viability, cytokine release and cell signalling. In addition, peritonitis was induced by SEB injection into CD48-/- and WT mice. CD48 expression was studied in AD patients' skin and as expressed on their leucocytes in the peripheral blood.

RESULTS

We provide evidence for the recognition and direct physical interaction between eosinophils and SA/exotoxins. Skin of AD patients showed a striking increase of eosinophil-associated CD48 expression while on peripheral blood leucocytes it was down-regulated. SA/exotoxins enhanced CD48 eosinophil expression, bound to CD48 and caused eosinophil activation and signal transduction. These effects were significantly decreased by blocking CD48 on human eosinophils or in BMEos from CD48-/- mice. We have also explored the role of CD48 in a SEB-induced peritonitis model in CD48-/- mice by evaluating inflammatory peritoneal cells, eosinophil numbers and activation.

CONCLUSIONS

These data demonstrate the important role of CD48 in SA/exotoxins-eosinophil activating interactions that can take place during allergic responses and indicate CD48 as a novel therapeutic target for allergy and especially of AD.

Mast cells' integrated actions with eosinophils and fibroblasts in allergic inflammation: implications for therapy

Mast cells (MCs) and eosinophils (Eos) are the key players in the development of allergic inflammation (AI). Their cross-talk, named the Allergic Effector Unit (AEU), takes place through an array of soluble mediators and ligands/receptors interactions that enhance the functions of both the cells. One of the salient features of the AEU is the CD48/2B4 receptor/ligand binding complex. Furthermore, MCs and Eos have been demonstrated to play a role not only in AI but also in the modulation of its consequence, i.e., fibrosis/tissue remodeling, by directly influencing fibroblasts (FBs), the main target cells of these processes. In turn, FBs can regulate the survival, activity, and phenotype of both MCs and Eos. Therefore, a complex three players, MCs/Eos/FBs interaction, can take place in various stages of AI. The characterization of the soluble and physical mediated cross talk among these three cells might lead to the identification of both better and novel targets for the treatment of allergy and its tissue remodeling consequences.

Eosinophils interaction with mast cells: the allergic effector unit

Mast cells (MC) and eosinophils are the key effector cells of allergy (Minai-Fleminger and Levi-Schaffer, Inflamm Res 58:631-638, 2009). In general, allergic reactions have two phases, namely, an early phase and a late phase. MC and eosinophils abundantly coexist in the inflamed tissue in the late and chronic phases and cross talk in a bidirectional manner. This bidirectional interaction between MC and eosinophils is mediated by both physical cell-cell contacts through cell surface receptors such as CD48 receptors CD48, 2B4 , 2B4 and soluble mediators through various specific granular mediators, arachidonic acid metabolites, cytokines cytokines , and chemokines, collectively termed the "Allergic Effector Unit" (AEU) (Elishmereni et al., Allergy 66:376-385, 2011; Minai-Fleminger et al., Cell Tissue Res 341:405-415, 2010). These bidirectional interactions can be studied in vitro in a customized coculture system of MC and eosinophils derived from either mouse or human source.

Delineation of an epitope on domain I of Japanese encephalitis virus Envelope glycoprotein using monoclonal antibodies

The Envelope glycoprotein (E-protein) of Japanese encephalitis virus (JEV) is the major structural component on the virion surface and is a primary target for the host immune system. Two monoclonal antibodies (MAbs) NHA-I (IgG2b) and NHA-II (IgM) against JEV (Indian strain 733913) were earlier developed in the authors' laboratory and found to be cross-reactive to nuclear histones. However, the epitope specificity of these MAbs has remained unknown. The present study was carried out to delineate the epitopes recognised by these MAbs on the E-protein of JEV strain 733913. The variable regions of the NHA-I and NHA-II were sequenced and the tertiary structures predicted. Molecular docking of the MAbs with the structural model of the JEV E-protein demonstrated that NHA-I binds to a predicted antigenic determinant (residue position 18-33) in domain-I. To understand the epitope specificity and check for possible cross-reactivity of these MAbs, comparative analysis of interactions with the known crystallographic structure of the West Nile virus (WNV) E-protein was also carried out. The studies predicted a differential binding of NHA-I but not of NHA-II between JEV and WNV. Mutagenesis studies could help analyse the specificity of NHA-I. The NHA-II appears to be cross-reactive as it docked in the groove region between domains I and III of both the JEV and WNV E-proteins. In laboratory assays, namely, ELISA and immunofluorescence assay both the MAbs reacted equally with JEV while the NHA-I did not show any reactivity with WNV. In silico results were thus validated by laboratory experiments. The present study would help in better understanding of virus-host interactions at the molecular level, and also be useful for the future design of vaccines as well as peptide based diagnostics.