Keratin 17 Promotes T Cell Response in Allergic Contact Dermatitis by Upregulating C-C Motif Chemokine Ligand 20.

Allergic contact dermatitis (ACD) is a delayed-type hypersensitivity response to skin contact allergens in which keratinocytes are critical in the initiation of early responses. Keratin 17 (K17) is a cytoskeletal protein inducible under stressful conditions and regulates multiple cellular processes, especially in skin inflammatory diseases; however, knowledge regarding its contribution to ACD pathogenesis remains ill defined. In the present study, we clarified the proinflammatory role of K17 in an oxazolone (OXA)-induced contact hypersensitivity (CHS) murine model and identified the underlying molecular mechanisms. Our results showed that K17 was highly expressed in the lesional skin of ACD patients and OXA-induced CHS mice. Mice lacking K17 exhibited alleviated OXA-induced skin inflammation, including milder ear swelling, a reduced frequency of T cell infiltration, and decreased inflammatory cytokine levels. In vitro, K17 stimulated and activated human keratinocytes to produce plenty of proinflammatory mediators, especially the chemokine CCL20, and promoted keratinocyte-mediated T cell trafficking. The neutralization of CCL20 with a CCL20-neutralizing monoclonal antibody significantly alleviated OXA-induced skin inflammation in vivo. Moreover, K17 could translocate into the nucleus of activated keratinocytes through a process dependent on the nuclear-localization signal (NLS) and nuclear-export signal (NES) sequences, thus facilitating the activation and nuclear translocation of signal transducer and activator of transcription 3 (STAT3), further promoting the production of CCL20 and T cell trafficking to the lesional skin. Taken together, these results highlight the novel roles of K17 in driving allergen-induced skin inflammation and suggest targeting K17 as a potential strategy for ACD.

Neutrophil extracellular traps contribute to immune dysregulation in bullous pemphigoid via inducing B-cell differentiation and antibody production.

Bullous pemphigoid (BP), an autoimmune skin disease, is characterized by autoantibodies against hemidesmosomal proteins in the skin and mucous membranes. Neutrophils infiltrate BP skin lesions, however, their role in immune dysregulation remains unclear. We investigated whether BP involves aberrant neutrophil extracellular traps (NETs) formation in skin lesions and circulation; and examined the triggers and deleterious immuno-inflammatory consequences. In the present study, we found that circulating NET-related biomarker levels increased in serum and blister fluid of BP patients and significantly correlated with disease severity. Additionally, circulating neutrophils from BP patients displayed enhanced spontaneous NETs formation than healthy controls. In vitro, BP180-NC16A immune complexes-induced NETosis in neutrophils from BP patients, which was abrogated by Fcγ receptor and/or NADPH pathway blockade. Furthermore, the elevated levels of NETs from BP patients boosted autoantibody production by inducing B-cell differentiation into plasma cells, mediated by MAPK P38 cascade activation. Together, our findings provide strong evidence that NETs are involved in a pathogenic loop, causing excessive differentiation of B cells and promotion of autoantibody production. Hence, targeting aberrant neutrophil responses will provide novel potential targets for the treatment of BP.

A novel role of IL-17A in contributing to the impaired suppressive function of Tregs in psoriasis.

BACKGROUND: Regulatory T cells (Tregs) are crucial in maintaining T cell homeostasis and preventing autoimmune responses. Deficiencies in the suppressive function of Tregs contribute to the pathogenesis of various autoimmune diseases, such as psoriasis. However, whether IL-17A upregulation in psoriatic patients contributes to Treg dysfunction is unknown. OBJECTIVE: To explore the effect and underlying mechanism of IL-17A on the suppressive function of Tregs and to evaluate the restoration of the suppressive function of Tregs in psoriasis during anti-IL-17A (secukinumab) treatment. METHODS: In vitro suppression assays were performed with or without the addition of IL-17A to the coculture system. The release of inhibitory cytokines, including IL-10 and TGF-ß, was assessed by qRT-PCR and flow cytometry. RNA-sequencing was conducted to characterize the cellular responses of Tregs. IL-17A signaling activation was analyzed by flow cytometry and immunofluorescence. Blood samples were collected from three psoriasis patients before and after secukinumab treatment. RESULTS: IL-17A blocked the suppressive function of Tregs, possibly by inhibiting the release of TGF-ß and promoting the production of IFN-γ. Moreover, IL-17A activated the NF-κB signaling pathway in Tregs. Inhibition of the NF-κB pathway blocked IL-17A-induced upregulation of IFN-γ without affecting the secretion of TGF-ß by Tregs. Clinical treatment in psoriasis with secukinumab restored the suppressive function and increased production of TGF-ß in Tregs of psoriasis. CONCLUSION: Our study implies a crucial role of IL-17A in mediating the dysfunction of the Treg suppressive function in psoriasis. Secukinumab, which neutralizes IL-17A signaling, restored the suppressive function of Tregs to exert its antipsoriatic effect.

hsa_circ_0003738 Inhibits the Suppressive Function of Tregs by Targeting miR-562/IL-17A and miR-490-5p/IFN-γ Signaling Pathway.

Dysfunction in the suppressive function of regulatory T cells (Tregs) has been related to the pathogenesis of psoriasis. Accumulating evidence has demonstrated the importance of circular RNAs (circRNAs) in regulating various biological process, such as cell proliferation, apoptosis, etc. However, the role of circRNAs in modulating the suppressive functions of psoriatic Tregs and the underlying mechanisms have not been investigated. Here, by using circRNA microarray analysis, we discovered four upregulated and four downregulated circRNAs in psoriatic Tregs. Quantitative real-time PCR further confirmed a significant increase of circ_0003738 in psoriatic Tregs. Importantly, knockdown of circ_0003738 by lentivirus in psoriatic Tregs could restore their suppressive functions via inhibiting the secretion of proinflammatory cytokines interleukin-17A (IL-17A) and interferon (IFN)-γ. Moreover, we found that circ_0003738 could bind to miR-562 to release the inhibition of target gene IL-17RA (IL-17 receptor A), thus promoting IL-17A signaling in psoriatic Tregs. In parallel, circ_0003738 acted also as a sponge for miR-490-5p and relieved inhibition for the target gene IFNGR2, which promoted IFN-γ signaling in psoriatic Tregs. Our study demonstrated that upregulated circ_0003738 decreased the suppressive function of psoriatic Tregs via the miR-562/IL17RA and miR-490-5p/IFNGR2 (IFN-γ receptor 2) axis, which indicated the involvement of circRNAs in the pathogenesis of dysfunctional Tregs. These findings will provide new therapeutic targets for the treatment of psoriasis.

Anti-psoriatic properties of paeoniflorin: suppression of the NF-kappaB pathway and Keratin 17.

BACKGROUND: Psoriasis is a common inflammatory skin disease characterized by hyperproliferation of epidermal keratinocytes, however, there is still no curative therapy for psoriasis. Paeoniflorin (PF), a Chinese herbal medicine, has shown anti-inflammatory effects. OBJECTIVES: We aimed to illustrate the effect and associated mechanism of PF on keratinocyte proliferation using the IMQ-induced psoriasis mouse model. MATERIALS AND METHODS: The anti-psoriatic effect of PF in vivo and in vitro was assessed by western blot, RT-PCR, immunofluorescence, cell counting kit-8 and haematoxylin/eosin staining. RESULTS: In vivo, epidermal thickness, dermal infiltrated lymphocytes and the level of several antimicrobial peptides, pro-inflammatory cytokines, and K17 were significantly reduced in mice with topical application of PF. In vitro, PF inhibited the proliferation of HaCaT cells in a dose-dependent manner, down-regulated K17 expression, and suppressed NF-kappaB activation. CONCLUSION: Our findings indicate that PF may inhibit the proliferation of keratinocytes by targeting K17, suggesting that PF might be a potential target in the treatment of psoriasis.

Proteomic analyses bring new insights into the effect of a dark stress on lipid biosynthesis in Phaeodactylum tricornutum.

Microalgae biosynthesize high amount of lipids and show high potential for renewable biodiesel production. However, the production cost of microalgae-derived biodiesel hampers large-scale biodiesel commercialization and new strategies for increasing lipid production efficiency from algae are urgently needed. Here we submitted the marine algae Phaeodactylum tricornutum to a 4-day dark stress, a condition increasing by 2.3-fold the total lipid cell quotas, and studied the cellular mechanisms leading to lipid accumulation using a combination of physiological, proteomic (iTRAQ) and genomic (qRT-PCR) approaches. Our results show that the expression of proteins in the biochemical pathways of glycolysis and the synthesis of fatty acids were induced in the dark, potentially using excess carbon and nitrogen produced from protein breakdown. Treatment of algae in the dark, which increased algal lipid cell quotas at low cost, combined with optimal growth treatment could help optimizing biodiesel production.

Analysis of the Proteome of the Marine Diatom Phaeodactylum tricornutum Exposed to Aluminum Providing Insights into Aluminum Toxicity Mechanisms.

Trace aluminum (Al) concentrations can be toxic to marine phytoplankton, the basis of the marine food web, but the fundamental Al toxicity and detoxification mechanisms at the molecular levels are poorly understood. Using an array of proteomic, transcriptomic, and biochemical techniques, we describe in detail the cellular response of the model marine diatom Phaeodactylum tricornutum to a short-term sublethal Al stress (4 h of exposure to 200 µM total initial Al). A total of 2204 proteins were identified and quantified by isobaric tags for relative and absolute quantification (iTRAQ) in response to the Al stress. Among them, 87 and 78 proteins performing various cell functions were up- and down-regulated after Al treatment, respectively. We found that photosynthesis was a key Al toxicity target. The Al-induced decrease in electron transport rates in thylakoid membranes lead to an increase in reactive oxygen species (ROS) production, which cause increased lipid peroxidation. Several ROS-detoxifying proteins were induced to help decrease Al-induced oxidative stress. In parallel, glycolysis and pentose phosphate pathway were up-regulated in order to produce cell energy (NADPH, ATP) and carbon skeleton for cell growth, partially circumventing the Al-induced toxicity effects on photosynthesis. These cellular responses to Al stress were coordinated by the activation of various signal transduction pathways. The identification of Al-responsive proteins in the model marine phytoplankton P. tricornutum provides new insights on Al stress responses as well as a good start for further exploring Al detoxification mechanisms.

Effects of atrazine on photosynthesis and defense response and the underlying mechanisms in Phaeodactylum tricornutum.

Atrazine (ATZ) is a commonly used herbicide that has recently come under scrutiny due to potential environmental toxicity and contamination. In this study, we found that the administration of ATZ indeed leads to reduction of photosynthesis and oxidative stress in Phaeodactylum tricornutum at the treated doses higher than 100 µg L(-1) after 48 h. We further explored the effect of ATZ on photosystem II (PSII) and gene expression of electron transport chain. Collectively, our results may suggest that ATZ entered the chloroplasts in alga depending on ATZ's liposolubility and directly attacked on the electron transport chain, especially PSII, contributing to reactive oxygen species (ROS) burst. The increasing ROS could act as signals to induce or disturb the expression of photosynthesis-related genes, resulting in the imbalance of antioxidation and pro-oxidation in the alga.

Ammonium reduces chromium toxicity in the freshwater alga Chlorella vulgaris.

The aim of the present study was to investigate the protective effect of ammonium (NH4 (+)) on Cr toxicity to the freshwater alga Chlorella vulgaris. We followed an array of cellular functions and biomolecules in C. vulgaris cells exposed to 50 or 100 µM Cr at three different initial NH4 (+) concentrations (0.5, 3, and 10 mM). The results showed that Cr strongly inhibited cell yield of C. vulgaris, but 10 mM NH4 (+) could decrease by more than two-fold Cr toxicity on cell yield compared to exposure to 0.5 mM NH4 (+). Cr toxicity on gene transcripts and cellular substructure was also much lower at high than at low NH4 (+). Our results suggest that this protecting effect of NH4 (+) on intracellular Cr toxicity could be due to several factors, such as enhance uptake of phosphorus, increase in C and N assimilation efficiency, and increase transcription of photosynthesis-related genes.

Trace concentrations of imazethapyr (IM) affect floral organs development and reproduction in Arabidopsis thaliana: IM-induced inhibition of key genes regulating anther and pollen biosynthesis.

Understanding how herbicides affect plant reproduction and growth is critical to develop herbicide toxicity model and refine herbicide risk assessment. Although our knowledge of herbicides toxicity mechanisms at the physiological and molecular level in plant vegetative phase has increased substantially in the last decades, few studies have addressed the herbicide toxicity problematic on plant reproduction. Here, we determined the long-term (4-8 weeks) effect of a chiral herbicide, imazethapyr (IM), which has been increasingly used in plant crops, on floral organ development and reproduction in the model plant Arabidopsis thaliana. More specifically, we followed the effect of two IM enantiomers (R- and S-IM) on floral organ structure, seed production, pollen viability and the transcription of key genes involved in anther and pollen development. The results showed that IM strongly inhibited the transcripts of genes regulating A. thaliana tapetum development (DYT1: DYSFUNCTIONAL TAPETUM 1), tapetal differentiation and function (TDF1: TAPETAL DEVELOPMENT AND FUNCTION1), and pollen wall formation and developments (AMS: ABORTED MICROSPORES, MYB103: MYB DOMAIN PROTEIN 103, MS1: MALE STERILITY 1, MS2: MALE STERILITY 2). Since DYT1 positively regulates 33 genes involved in cell-wall modification (such as, TDF1, AMS, MYB103, MS1, MS2) that can catalyze the breakdown of polysaccharides to facilitate anther dehiscence, the consistent decrease in the transcription of these genes after IM exposure should hamper anther opening as observed under scanning electron microscopy. The toxicity of IM on anther opening further lead to a decrease in pollen production and pollen viability. Furthermore, long-term IM exposure increased the number of apurinic/apyrimidinic sites (AP sites) in the DNA of A. thaliana and also altered the DNA of A. thaliana offspring grown in IM-free soils. Toxicity of IM on floral organs development and reproduction was generally higher in the presence of the R-IM enantiomer than of the S-IM enantiomer. This study unraveled several IM toxicity targets and mechanisms at the molecular and structural level linked to the toxicity of IM trace concentrations on A. thaliana reproduction.

The effect of glufosinate on nitrogen assimilation at the physiological, biochemical and molecular levels in Phaeodactylum tricornutum.

This study investigated the effects of glufosinate, a widely used herbicide, on the marine diatom Phaeodactylum tricornutum through short-term toxicity tests at the physiological and gene transcriptional levels. Glufosinate (4 mg L(-1)) decreased the amount of pigments but increased reactive oxygen species (ROS) and malondialdehyde levels. As a glutamine synthetase (GS) inhibitor, glufosinate affected the transcripts and activities of key enzymes related to nitrogen assimilation. Transcript levels of GS and nitrate reductase (NR) in P. tricornutum decreased to only 57 and 26 % of the control. However, transcript levels of nitrate transporter (NRT) and the small subunit of glutamate synthase (GltD) were 1.79 and 1.76 times higher than that of the control. The activities of NRT, GS and GOGAT were consistent with gene expression except for NR, which was regulated mainly by post-translational modification. Furthermore, the results of electron microscopy showed that chloroplast structure was disrupted in response to glufosinate exposure. These results demonstrated that glufosinate first disturbed nitrogen metabolism and caused a ROS burst, which disrupted chloroplast ultrastructure. Ultimately, the growth of P. tricornutum was greatly inhibited by glufosinate.