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Injury of the skin from exposure to toxic chemicals leads to the release of inflammatory mediators and the recruitment of immune cells. Nitrogen mustard (NM) and other alkylating agents cause severe cutaneous damage for which there are limited treatment options. Here, we show that combined treatment of vitamin D3 (VD3) and spironolactone (SP), a mineralocorticoid receptor antagonist, significantly improves the resolution of inflammation and accelerates wound healing after NM exposure. SP enhanced the inhibitory effect of VD3 on nuclear factor‐kB activity. Combined treatment of NM‐exposed mice with VD3 and SP synergistically inhibited the expression of iNOS in the skin and decreased the expression of matrix metallopeptidase‐9, C‐C motif chemokine ligand 2, interleukin (IL)‐1α, and IL‐1β. The combined treatment decreased the number of local proinflammatory M1 macrophages resulting in an increase in the M2/M1 ratio in the wound microenvironment. Apoptosis was also decreased in the skin after combined treatment. Together, this creates a proresolution state, resulting in more rapid wound closure. Combined VD3 and SP treatment is effective in modulating the immune response and activating anti‐inflammatory pathways in macrophages to facilitate tissue repair. Altogether, these data demonstrate that VD3 and SP may constitute an effective treatment regimen to improve wound healing after NM or other skin chemical injury., Our results demonstrate that vitamin D3 in combination with spironolactone treatment improves wound healing after nitrogen mustard (NM) exposure by modulating the immune response and activating anti‐inflammatory pathways. In addition to supportive treatment, this may expand the currently limited treatment options to improve clinical outcomes for NM injury.

Activin, a member of the TGF-β superfamily, is an important modulator of FSH synthesis and secretion and is involved in reproductive dysfunctions and cancers. It also regulates ovarian follicle development. To understand the mechanisms and pathways by which activin regulates follicle function, we performed a microarray study and identified 240 activin regulated genes in mouse granulosa cells. The gene most strongly inhibited by activin was Cyp26b1, which encodes a P450 cytochrome enzyme that degrades retinoic acid (RA). Cyp26b1 has been shown to play an important role in male germ cell meiosis, but its expression is largely lost in the ovary around embryonic d 12.5. This study demonstrated that Cyp26b1 mRNA was expressed in granulosa cells of follicles at all postnatal developmental stages. A striking inverse spatial and temporal correlation between Cyp26b1 and activin-βA mRNA expression was observed. Cyp26b1 expression was also elevated in a transgenic mouse model that has decreased activin expression. The Cyp26 inhibitor R115866 stimulated the proliferation of primary cultured mouse granulosa cells, and a similar effect was observed with RA and activin. A pan-RA receptor inhibitor, AGN194310, abolished the stimulatory effect of either RA or activin on granulosa cell proliferation, indicating an involvement of RA receptor-mediated signaling. Overall, this study provides new insights into the mechanisms of activin action in the ovary. We conclude that Cyp26b1 is expressed in the postnatal mouse ovary, regulated by activin, and involved in the control of granulosa cell proliferation.

Normal development of ovarian follicles is critical for female reproduction and endocrine function. We have identified retinoic acid (RA) and the RA-degrading enzyme CYP26B1 as novel regulators of ovarian follicle development. The current study was designed to examine the role of intracellular Ca2+ signaling in mediating the effects of RA/CYP26B1 on primary mouse granulosa cell proliferation. In Ca2+ imaging experiments, treatment of cultured granulosa cells with RA was found to increase the steady-state Ca2+ content of the endoplasmic reticulum (ER) stores. This correlated with increased store-operated Ca2+ entry and enhanced IP3-dependent Ca2+ release in response to purinergic stimulation. In proliferation assays, RA treatment or Cyp26b1 knockdown stimulated proliferation while Cyp26b1 overexpression or incubation with 2-APB, a blocker of ER Ca2+ release and store-operated Ca2+ entry, inhibited proliferation. These data support a model in which the RA regulates ovarian follicle development by stimulatin...

Normal development of ovarian follicles is critical for female reproduction and endocrine function. We have identified retinoic acid (RA) and the RA-degrading enzyme CYP26B1 as regulators of ovarian follicle development and showed that RA and a CYP26 inhibitor stimulated ovarian granulosa cell proliferation. The mechanism underpinning RA-dependent proliferation, however, is not known. The current study was designed to examine the role of intracellular calcium (Ca2+) signaling in mediating the effects of RA on primary mouse granulosa cell proliferation. In single-cell Ca2+ imaging experiments, treatment of cultured granulosa cells with RA increased the steady-state Ca2+ content of the endoplasmic reticulum (ER) stores. This correlated with increased store-operated Ca2+ entry (SOCE) and enhanced inositol 1,4,5-trisphosphate receptor (IP3R)-dependent Ca2+ release. In proliferation assays, RA treatment or Cyp26b1 knockdown stimulated proliferation, whereas Cyp26b1 overexpression inhibited proliferation. When RA was given together with 2-aminoethoxydiphenylborane (2-APB), a blocker of IP3R-dependent ER Ca2+ release and SOCE, with xestospongin C, a selective IP3R- receptor antagonist, or with 3,5-bis (trifluoromethyl)pyrazole (BTP-2), a specific SOCE blocker, the stimulatory effect of RA on cell proliferation was abolished. Further investigation showed that treatment with 2-APB or BTP-2 inhibited RA induction of RA response element (RARE) activation in granulosa cells, confirming an important role for Ca2+ signaling in mediating RA actions. Overall, these data support a model in which RA regulates ovarian follicle development by stimulating granulosa cell proliferation and that this stimulatory effect is at least in part driven by the modulation of Ca2+ signaling.