Leptin Enhances Human β-Defensin-2 Production in Human Keratinocytes

Abstract

Leptin, an adipocyte-derived cytokine/hormone, modulates innate and adaptive immunity. Human ␤-defensin-2 (hBD-2) produced by epidermal keratinocytes promotes cutaneous antimicrobial defense, inflammation, and wound repair. We examined the in vitro effects of leptin on hBD-2 production in human keratinocytes. hBD-2 secretion and mRNA expression were analyzed by ELISA and RT-PCR, respectively. Although leptin alone was ineffective, it enhanced IL-1␤-induced hBD-2 secretion and mRNA expression in keratinocytes. IL-1␤-and IL-1␤ plus leptin-induced hBD-2 production both were suppressed by antisense oligonucleotides against nuclear factor-B (NF-B) p50 and p65; the latter was also suppressed by antisense signal transducer and activator of transcription (STAT)1 and STAT3. IL-1␤ enhanced the transcriptional activity of NF-B, whereas leptin enhanced STAT1 and STAT3 activity. The p38 MAPK inhibitor SB202190 suppressed IL-1␤-and IL-1␤ plus leptin-induced hBD-2 production, IL-1␤-induced NF-B activity, and leptin-induced STAT1 and STAT3 activity; contrastingly, the Janus kinase (JAK) 2 inhibitor AG490 suppressed IL-1␤ plus leptin-induced hBD-2 production and leptin-induced STAT1 and STAT3 activity. IL-1␤ induced serine phosphorylation of inhibitory B␣, STAT1, and STAT3. Leptin induced tyrosine and serine phosphorylation of STAT1 and STAT3, both of which were suppressed by AG490, and serine phosphorylation was also suppressed by SB202190. IL-1␤ or leptin individually induced threonine/tyrosine phosphorylation of p38 MAPK, whereas only leptin induced tyrosine phosphorylation of JAK2, suggesting that leptin may enhance hBD-2 production in keratinocytes by activating STAT1 and STAT3 via JAK2 and p38 MAPK in cooperation with NF-B, which is activated by IL-1␤. Leptin may promote cutaneous antimicrobial defense, inflammation, and wound repair via hBD-2. (Endocrinology 149: 5189 -5198, 2008)

Role of Leptin-Mediated Colonic Inflammation in Defense against Clostridium difficile Colitis

“…One of the possible mechanisms of leptin-mediated bactericidal inflammation could be increased cellular recruitment mediated by the leptin-STAT3 axis; however, other known mechanisms of leptin actions, like increased oxidative species production in neutrophils (36), increased mucin glycoprotein and antimicrobial peptide secretion (41,58,59), and maintenance of epithelial integrity (40), could also contribute to leptin-mediated bactericidal inflammation during acute C. difficile infection and will need further investigation. While our study does not directly quantify the numbers of C. difficile CFU, toxin A/B levels are an accurate measure of the critical C. difficile virulence factors and, in combination with C. difficile-specific GDH levels, are a reliable surrogate to monitor bacterial clearance.…”

Histamine induces human β-defensin-3 production in human keratinocytes

“…Transient transfection was performed using Fugene 6 (Roche, Indianapolis, IN) as previously described [27]. Keratinocytes were seeded in 24-well plates and grown to approximately 60% confluence.…”

“…Western blotting was performed as described [27,28]. In brief, keratinocytes were incubated with the indicated concentrations of histamine for the indicated periods and lysed in a lysis buffer; the resultant lysates were separated on SDS-PAGE and transferred to polyvinylidene difluoride membranes.…”

“…Antisense oligonucleotides against STAT1, STAT3, c-Fos, c-Jun, and random control oligonucleotide were synthesized by phosphoramidite chemistry, as previously described [27,29]. Negative siRNA control (catalog number 1022076) was purchased from QIAGEN (Tokyo, Japan) and siRNA against C/EBPb (identification number 114496, catalog number 16708) was purchased from Ambion (Austin, TX).…”

The antimycotic drugs itraconazole and terbinafine hydrochloride induce the production of human β-defensin-3 in human keratinocytes

“…Western blotting was performed as described previously (Kanda et al 2009b;Kanda and Watanabe 2008). In brief, keratinocytes were incubated with the vehicle or indicated concentrations of the antimycotics in the presence or absence of 10 nM PMA for the indicated periods and lysed in a lysis buffer.…”