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Ischemic brain injuries caused release of damage-associated molecular patterns (DAMPs) that activate microglia/macrophages (MG/MPs) by binding to Toll-like receptors. Using middle cerebral artery transiently occluded rats, we confirmed that MG/MPs expressed inducible nitric oxide synthase (iNOS) on 3days after reperfusion (dpr) in ischemic rat brain. iNOS expression almost disappeared on 7dpr when transforming growth factor-β1 (TGF-β1) expression was robustly increased. After transient incubation with TGF-β1 for 24h, rat primary microglial cells were incubated with lipopolysaccharide (LPS) and released NO level was measured. The NO release was persistently suppressed even 72h after removal of TGF-β1. The sustained TGF-β1 effects were not attributable to microglia-derived endogenous TGF-β1, as revealed by TGF-β1 knockdown and in vitro quantification studies. Then, boiled supernatants prepared from ischemic brain tissues showed the similar sustained inhibitory effects on LPS-treated microglial cells that were prevented by the TGF-β1 receptor-selective blocker SB525334. After incubation with TGF-β1 for 24h and its subsequent removal, LPS-induced phosphorylation of IκB kinases (IKKs), IκB degradation, and NFκB nuclear translocation were inhibited in a sustained manner. SB525334 abolished all these effects of TGF-β1. In consistent with the in vitro results, phosphorylated IKK-immunoreactivity was abundant in MG/MPs in ischemic brain lesion on 3dpr, whereas it was almost disappeared on 7dpr. The findings suggest that abundantly produced TGF-β1 in ischemic brain displays sustained anti-inflammatory effects on microglial cells by persistently inhibiting endogenous Toll-like receptor ligand-induced IκB degradation.

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IL-22 induces STAT3 phosphorylation and mediates psoriasis-related gene expression.However, the signaling mechanism leading from pSTAT3 to the expression of these genes remains unclear. We focused on Bcl-3, which is induced by STAT3 activation and mediates gene expression. In cultured human epidermal keratinocytes, IL-22 increased Bcl-3, which was translocated to the nucleus with p50 via STAT3 activation. The increases in CXCL8, S100As and human β-defensin 2 mRNA expression caused by IL-22 were abolished by siRNA against Bcl-3. Although CCL20 expression was also augmented by IL-22, the knockdown of Bcl-3 increased its level. Moreover, the combination of IL-22 and IL-17A enhanced Bcl-3 production, IL-22-induced gene expression, and the expression of other psoriasis-related genes, including those encoding IL-17C, IL-19, and IL-36γ. The expression of these genes (except for CCL20) was also suppressed by the knockdown of Bcl-3. Bcl-3 overexpression induced CXCL8 and HBD2 expression but not S100As expression. We also compared Bcl-3 expression between psoriatic skin lesions and normal skin. Immunostaining revealed strong signals for Bcl-3 and p50 in the nucleus of epidermal keratinocytes from psoriatic skin. The IL-22-STAT3-Bcl-3 pathway may be important in the pathogenesis of psoriasis.Keywords: Bcl-3 r IL-22 r p50 r Psoriasis r STAT3 Additional supporting information may be found in the online version of this article at the publisher's web-site Introduction IL-22 mainly affects epithelial cells and is important for defense against environmental insults such as infection and injury [1][2][3]. When skin is injured or invaded by a pathogen, IL-22 is produced by skin homing cells or recruited cells and signals through the IL-22 receptor (IL-22R) expressed on epidermal keratinocytes, Correspondence: Dr. Mikiko Tohyama e-mail: tohm@m.ehime-u.ac.jp resulting in an increased epidermal thickness and enhanced mRNA expression of various compounds, including S100 calcium-binding protein (S100A) family proteins, β-defensins, cytokines, and chemokines [4][5][6]. This response enhances cutaneous defenses and causes inflammation. These defense responses are enhanced in psoriasis, a chronic inflammatory cutaneous disease in which the skin exhibits a robust structure composed of a thick horny epidermal layer with altered keratinocyte differentiation and overexpression of antimicrobial peptides, cytokines, and chemokines from keratinocytes. It is thought that IL-22 and IL-17A mediate gene expression in the inflammatory response of psoriasis [7,8].www.eji-journal.eu Eur. J. Immunol. 2018. 48: 168-179 Allergy and inflammation 169Several studies have revealed important roles for STAT3 activation in the pathogenesis of psoriasis [9,10], and STAT3 is the principal mediator of IL-22 signaling [11,12]. Therefore, studies of IL-22-STAT3 signaling may be significant for elucidating the pathomechanisms of psoriasis. IL-22-responsive genes include CCL2 and suppressor of cytokine signaling 3 (SOCS3), which are known to be involved downstream o...

The skin microbiome influences skin pathophysiology. Palmoplantar pustulosis (PPP) is a chronic skin disease characterized by infectious‐like pustules on the palms and soles. These pustules are thought to be sterile because bacterial cultures obtained from the pustules are negative. However, culture methods are limited in their ability to identify all bacteria on the skin. We hypothesized that the “sterile” pustules of PPP do not lack bacteria, but rather contain a microbiome. To test this hypothesis, we identified bacteria in “sterile” pustules using non‐culture methods. We conducted Sanger and 16S rRNA sequencing using primers specific to the V1‐V2 region in PPP‐pustulovesicles (PVs) (n = 43) and pompholyx vesicle fluids (n = 15). Sanger sequencing identified some Staphylococcus, Propionibacterium, Streptococcus and Pyrinomonas species in PPP‐PVs but failed to identify any bacteria in most of the pompholyx vesicles. 16S rRNA sequencing of PPP‐PVs indicated the presence of a microbiome that included various phyla, including Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. At the genus level, smokers had higher levels of Staphylococcus in PPP‐PVs compared with non‐smokers. These results indicate that a microbiome exists in “sterile” pustules of PPP and that PPP smokers had higher levels of Staphylococcus in pustules. It is therefore necessary to reconsider the pathogenesis of PPP from the perspective of the microbiome.