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1,25-Dihydroxyvitamin D₃ attenuates IL-1β secretion by suppressing NLRP1 inflammasome activation by upregulating the NRF2-HO-1 pathway in epidermal keratinocytes.

ABSTRACT: The nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing protein (NLRP) inflammasome is a key inflammatory signaling pathway activated via a two-step signaling process consisting of priming and activation steps. Several studies have shown that 1,25-dihydroxyvitamin D3 (1,25(OH)₂VD₃) inhibits the priming step required for NLRP3 inflammasome activation in immune cells. However, as activating the NLRP1 inflammasome in keratinocytes does not necessarily require a priming step, whether 1,25(OH)₂VD₃ inhibits NLRP1 activation in unprimed keratinocytes is currently unknown. In this study, we showed that 1,25(OH)₂VD₃ inhibits nigericin-induced NLRP1 inflammasome activation in unprimed keratinocytes. 1,25(OH)₂VD₃ suppressed nigericin-induced interleukin-1β (IL-1β) secretion and caspase-1 activation in human primary keratinocytes. In addition, 1,25(OH)₂VD₃ significantly inhibited the formation of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) oligomers and specks, but not caspase-1 enzymatic activity, suggesting that 1,25(OH)₂VD₃ prevents NLRP1-ASC complex assembly in keratinocytes. Vitamin D receptor (VDR)-knockdown abolished the inhibitory effects of 1,25(OH)₂VD₃ on nigericin-induced ASC oligomerization and IL-1β secretion, suggesting that 1,25(OH)₂VD₃ suppresses inflammasome activation via VDR signaling. Furthermore, nigericin induced K⁺ efflux and cellular reactive oxygen species (ROS) production, and 1,25(OH)₂VD₃ pretreatment suppressed nigericin-induced ROS production. 1,25(OH)₂VD₃ increased the expression of both nuclear factor erythroid 2-related factor 2 (NRF2) and heme oxygenase-1 (HO-1), whereas HO-1 inhibition or NRF2 and HO-1 knockdown abrogated the inhibitory effects of 1,25(OH)₂VD₃ on IL-1β secretion. Our results indicate that 1,25(OH)₂VD₃ inhibits nigericin-induced activation step of NLRP1 inflammasome activation in unprimed keratinocytes. Our findings reveal the mechanism underlying the inhibitory effect of 1,25(OH)₂VD₃, which involves NRF2-HO-1 pathway activation through the VDR, providing further insight into the potential function of 1,25(OH)₂VD₃ as a therapeutic agent for inflammasome-related skin diseases.

SUBMITTER: Nakajo T

PROVIDER: S-EPMC8646996 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Inflammasomes are mediators of inflammation, and constitutively activated NLRP3 inflammasomes have been linked to interleukin-1? (IL-1?)-mediated tumorigenesis in human melanoma. Whereas NLRP3 regulation of caspase-1 activation requires the adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD (caspase recruitment domain)), caspase-1 activation by another danger-signaling sensor NLRP1 does not require ASC because NLRP1 contains a C-terminal CARD domain that facilitates direct caspase-1 activation via CARD-CARD interaction. We hypothesized that NLRP1 has additional biological activities besides IL-1? maturation and investigated its role in melanoma tumorigenesis. NLRP1 expression in melanoma was confirmed by analysis of 216 melanoma tumors and 13 human melanoma cell lines. Unlike monocytic THP-1 cells with prominent nuclear localization of NLRP1, melanoma cells expressed NLRP1 mainly in the cytoplasm. Knocking down NLRP1 revealed a tumor-promoting property of NLRP1 both in vitro and in vivo. Mechanistic studies showed that caspase-1 activity, IL-1? production, IL-1? secretion and nuclear factor-kB activity were reduced by knocking down of NLRP1 in human metastatic melanoma cell lines 1205Lu and HS294T, indicating that NLRP1 inflammasomes are active in metastatic melanoma. However, unlike previous reports showing that NLRP1 enhances pyroptosis in macrophages, NLRP1 in melanoma behaved differently in the context of cell death. Knocking down NLRP1 increased caspase-2, -9 and -3/7 activities and promoted apoptosis in human melanoma cells. Immunoprecipitation revealed interaction of NLRP1 with CARD-containing caspase-2 and -9, whereas NLRP3 lacking a CARD motif did not interact with the caspases. Consistent with these findings, NLRP1 activation but not NLRP3 activation reduced caspase-2, -9 and -3/7 activities and provided protection against apoptosis in human melanoma cells, suggesting a suppressive role of NLRP1 in caspase-3/7 activation and apoptosis via interaction with caspase-2 and -9. In summary, we showed that NLRP1 promotes melanoma growth by enhancing inflammasome activation and suppressing apoptotic pathways. Our study demonstrates a tumor-promoting role of NLRP1 in cancer cells.

Project description:Fibroblast growth factor 23 (FGF23), a hormone, mainly produced by osteocytes, regulates phosphate and vitamin D metabolism. By contrast, 1,25-dihydroxyvitamin D3, the active form of vitamin D, has been shown to enhance FGF23 production. While it is likely that osteocytes are heterogenous in terms of gene expression profiles, specific subpopulations of Fgf23-expressing osteocytes have not been identified. Single-cell RNA sequencing (scRNA-seq) technology can characterize the transcriptome of an individual cell. Recently, scRNA-seq has been used for bone tissue analysis. However, owing to technical difficulties associated with isolation of osteocytes, studies using scRNA-seq analysis to characterize FGF23-producing osteocytes are lacking. In this study, we characterized osteocytes secreting FGF23 from murine femurs in response to calcitriol (1,25-dihydroxyvitamin D3) using scRNA-seq. We first detected Dmp1, Mepe, and Phex expression in murine osteocytes by in situ hybridization and used these as marker genes of osteocytes. After decalcification, enzyme digestion, and removal of CD45+ cells, femoral bone cells were subjected to scRNA-seq. We identified cell clusters containing osteocytes using marker gene expression. While Fgf23 expression was observed in some osteocytes isolated from femurs of calcitriol-injected mice, no Fgf23 expression was detected in untreated mice. In addition, the expression of several genes which are known to be changed after 1,25-dihydroxyvitamin D3 treatment such as Ccnd2, Fn1, Igfbp7, Pdgfa, and Timp1 was also affected by calcitriol treatment in Fgf23-expressing osteocytes, but not in those lacking Fgf23 expression, even after calcitriol administration. Furthermore, box-and-whisker plots indicated that Fgf23 expression was observed in osteocytes with higher expression levels of the Fam20c, Dmp1, and Phex genes, whose inactivating mutations have been shown to cause FGF23-related hypophosphatemic diseases. These results indicate that osteocytes are heterogeneous with respect to their responsiveness to 1,25-dihydroxyvitamin D3, and sensitivity to 1,25-dihydroxyvitamin D3 is one of the characteristics of osteocytes with Fgf23 expression. It is likely that there is a subpopulation of osteocytes expressing several genes, including Fgf23, involved in phosphate metabolism.

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1,25-Dihydroxyvitamin D₃ attenuates IL-1β secretion by suppressing NLRP1 inflammasome activation by upregulating the NRF2-HO-1 pathway in epidermal keratinocytes.

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1,25-Dihydroxyvitamin D3 attenuates IL-1β secretion by suppressing NLRP1 inflammasome activation by upregulating the NRF2-HO-1 pathway in epidermal keratinocytes.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

1,25-Dihydroxyvitamin D₃ attenuates IL-1β secretion by suppressing NLRP1 inflammasome activation by upregulating the NRF2-HO-1 pathway in epidermal keratinocytes.