RNA m6A methylation modulates airway inflammation in allergic asthma via PTX3-dependent macrophage homeostasis.

N6-methyladenosine (m6A), the most prevalent mRNA modification, has an important function in diverse biological processes. However, the involvement of m6A in allergic asthma and macrophage homeostasis remains largely unknown. Here we show that m6A methyltransferases METTL3 is expressed at a low level in monocyte-derived macrophages from childhood allergic asthma patients. Conditional knockout of Mettl3 in myeloid cells enhances Th2 cell response and aggravates allergic airway inflammation by facilitating M2 macrophage activation. Loss and gain functional studies confirm that METTL3 suppresses M2 macrophage activation partly through PI3K/AKT and JAK/STAT6 signaling. Mechanistically, m6A-sequencing shows that loss of METTL3 impairs the m6A-YTHDF3-dependent degradation of PTX3 mRNA, while higher PTX3 expression positively correlates with asthma severity through promoting M2 macrophage activation. Furthermore, the METTL3/YTHDF3-m6A/PTX3 interactions contribute to autophagy maturation in macrophages by modulating STX17 expression. Collectively, this study highlights the function of m6A in regulating macrophage homeostasis and identifies potential targets in controlling allergic asthma.

circS100A11 enhances M2a macrophage activation and lung inflammation in children with asthma.

BACKGROUND: Dysregulation of circRNAs is associated with a variety of human diseases; however, its role in childhood asthma is undefined. METHODS: The differential expression profiles of circRNAs were analyzed by microarray. The effects and mechanisms by which circRNAs influence macrophage activation were detected by quantitative real-time PCR, RNA immunoprecipitation assay, and chromatin immunoprecipitation assay, among others. The roles of circRNA and its host gene in asthma were tested in a cockroach allergen extract (CRE)-induced murine asthma model. RESULTS: We identified 372 circRNAs that were differentially expressed in PBMCs of children with asthma as compared with healthy controls. A circRNA with unknown function, circS100A11, was dominantly expressed in monocytes and significantly upregulated in children with asthma. circS100A11 facilitated M2a macrophage activation by enhancing translation of its host gene, S100A11, and exacerbated lung inflammation in a CRE-induced murine asthma model with macrophage-specific overexpression of circS100A11. Mechanistically, circS100A11 promoted S100A11 translation by competitively binding to CAPRIN1 to decrease the suppression of CAPRIN1 upon S100A11 translation. Then, S100A11 liberated SP3 from nucleolin and promoted SP3 binding to the STAT6 promoter to enhance STAT6 expression and M2a macrophage activation. Macrophage-specific knockdown of S100A11 could alleviate lung inflammation in a CRE-induced murine asthma model in vivo. CONCLUSIONS: circS100A11 and S100A11 promote M2a macrophage activation and lung inflammation in asthma model and may serve as potential therapeutic and diagnostic targets in children with asthma.

Hsa_circ_0004287 inhibits macrophage-mediated inflammation in an N6-methyladenosine-dependent manner in atopic dermatitis and psoriasis.

BACKGROUND: Circular RNA (circRNA) has been implicated in various diseases; however, its role in atopic dermatitis (AD) or psoriasis remains unclear. OBJECTIVE: We sought to determine the differential expression profiles of circRNAs in peripheral blood mononuclear cells between healthy controls and AD patients, and explore the mechanisms underlying the effects of circRNAs on the pathogenesis of AD. METHODS: The differential expression profiles of circRNAs were analyzed by circRNA microarray. In vitro function and mechanisms by which circRNAs regulate macrophage-mediated inflammation were detected by reverse transcription quantitative PCR, Western blot analysis, RNA stability assay, immunoprecipitation, ELISA, and methylated RNA immunoprecipitation assay. In vivo roles of circRNAs were determined in 2,4-dinitrochlorobenzene (DNCB)-induced dermatitis and imiquimod (IMQ)-induced psoriasis mouse model. RESULTS: We identified a functional unknown circRNA hsa_circ_0004287 from 88750 circRNAs, which was upregulated in peripheral blood mononuclear cells of both AD and psoriasis patients, and was mainly expressed by macrophages under inflammatory conditions. Hsa_circ_0004287 inhibited M1 macrophage activation in vitro, and macrophage-specific overexpression of hsa_circ_0004287 alleviated skin inflammation in both AD- and psoriasis-like mice. Mechanistically, hsa_circ_0004287 reduced the stability of its host gene metastasis associated lung adenocarcinoma transcript 1 (MALAT1) by competitively binding to IGF2BP3 with MALAT1 in an N6-methyladenosine (m6A)-dependent manner. Lower levels of MALAT1 promoted the ubiquitination degradation of S100A8/S100A9, thereby impeding p38/mitogen-activated protein kinase phosphorylation and macrophage-mediated inflammation. CONCLUSION: hsa_circ_0004287 inhibits M1 macrophage activation in an m6A-dependent manner in AD and psoriasis, and may serve as a general therapeutic candidate for AD and psoriasis.

TLR2 inhibition ameliorates the amplification effect of LPS on lipid accumulation and lipotoxicity in hepatic cells.

BACKGROUND: Gut microbiome dysbiosis is related to the pathogenesis of nonalcoholic fatty liver disease (NAFLD), and the role of toll-like receptor 2 (TLR2) in its molecular mechanism is controversial. Here, we investigated the effects and mechanisms of Escherichia coli-derived lipopolysaccharide (LPS) on lipid accumulation and lipotoxicity in palmitic acid (PA)-treated L02 cell as an NAFLD cell model, and the role of TLR2 in this process. METHODS: Oil red O staining assay and free fatty acid (FFA) content test were performed to determine the effects of LPS on lipid accumulation in a PA-induced NAFLD cell model with or without TLR2 inhibition. The levels of IL-6 and TNF-α were measured to investigate inflammation conditions. Hoechst 33342 staining assay and Caspase-3 activity assay were used to test cell apoptosis, and the expression levels of proteins in the IRS1/PI3K/AKT signaling pathway, TLR2/MyD88/IKKα/NF-κB signaling pathway, and mitochondrion-dependent apoptotic signaling pathway were detected using Western blot. RESULTS: Lipid accumulation, pro-inflammatory cytokine release, and cell apoptosis with high levels were observed in the PA-induced NAFLD cell model, and LPS aggravated these processes. Whereas TLR2 inhibition could significantly ameliorate PA-induced and LPS-amplified lipid accumulation, inflammatory, and cell apoptosis, it had no significant effect on L02 cells treated with LPS alone. CONCLUSIONS: These results were confirmed by activation or inhibition of the IRS1/PI3K/AKT signaling pathway, TLR2/MyD88/IKKα/NF-κB signaling pathway, and mitochondrion-dependent apoptotic signaling pathway, and were reflected by changes on their proteins expression. TLR2 is involved in PA-induced lipid accumulation and lipotoxicity in L02 cells, which could be aggravated by LPS, although LPS-induced amplification might not be through direct interaction with TLR2.

Correlation between pri-miR-124 (rs531564) polymorphism and congenital heart disease susceptibility in Chinese population at two different altitudes: a case-control and in silico study.

The development of congenital heart disease (CHD) is a complicated process and affected by multiple environmental factors, as genetic factors, and the interactions among those factors. Previous studies have shown that intrauterine hypoxic environment exposure is a risk factor of CHD, but the genetic factors involved in the process are not clear. In this study, given that tetralogy of Fallot (TOF) is a CHD with hypoxemia as its primary pathophysiological manifestation, an in silico analysis was performed to reveal the relationship between potential target genes (miR-124) with the energy metabolism in non-syndromic TOF patients' cardiomyocyte. Furthermore, the study investigated the correlation between the primary miR-124 (rs531564) polymorphism and CHD susceptibility in 432 sporadic patients and 450 controls from two different altitude provinces (city) in China. Our study indicated that the minor C allele of rs531564 correlated with reduced risk of CHD in the low altitude city. Besides, the C allele has elevated frequency in the high-altitude group. Therefore, our findings suggest that the minor C allele of rs531564 SNP may be involved in the reduction of the risk of CHD in a way that interacts with the intrauterine hypoxic environmental factors.

Teratozoospermia with amorphous sperm head associate with abnormal chromatin condensation in a Chinese family.

Male infertility affects approximately 7% of the male population. In about 40% of affected patients, the etiology remains unknown. Here, we report the cases of two infertile brothers who have a uniquely prevalent sperm phenotype with completely amorphous sperm heads. To investigate the mechanisms of familial teratozoospermia with amorphous sperm heads, chromatin condensation was assessed by aniline blue staining, western blot, sperm chromatin structure assay and atomic force microscopy in both the two brothers and 40 control fertile donors. Our results showed an abnormal condensation of chromatin with amorphous headed sperm. We suggest that abnormal chromatin condensation which was induced by disturbances in the process of histone-protamine replacement may be a possible cause of familial teratozoospermia with amorphous head, and the elasticity of sperm nuclei could be a new index to assess sperm quality. Additionally, for the first time, the current study provided a new biomechanics strategy for evaluating pathological sperm contributes to our understanding of teratozoospermia.Abbreviations: SCSA: sperm chromatin structure assay; AFM: atomic force microscopy; ICSI: intracytoplasmic sperm injection; HDS: high DNA stainability; DFI: DNA fragmentation index; PBS: phosphate-buffered saline; DTT: dithiothreitol; FITC: fluorescein isothiocyanate; DAPI: 4',6-diamidino-2-pheneylindole; SSC: standard saline citrate.