Apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) is an adaptor molecule that has recently been implicated in the activation of caspase-1. We have studied the role of ASC in the host defense against the intracellular pathogen Listeria monocytogenes. ASC was found to be essential for the secretion of IL-1β/IL-18, but dispensable for IL-6, TNF-α, and IFN-β production, in macrophages infected with Listeria. Activation of caspase-1 was abolished in ASC-deficient macrophages, whereas activation of NF-κB and p38 was unaffected. In contrast, secretion of IL-1β, IL-6, and TNF-α was reduced in TLR2-deficient macrophages infected with Listeria; this was associated with impaired activation of NF-κB and p38, but normal caspase-1 processing. Analysis of Listeria mutants revealed that cytosolic invasion was required for ASC-dependent IL-1β secretion, consistent with a critical role for cytosolic signaling in the activation of caspase-1. Secretion of IL-1β in response to lipopeptide, a TLR2 agonist, was greatly reduced in ASC-null macrophages and was abolished in TLR2-deficient macrophages. These results demonstrate that TLR2 and ASC regulate the secretion of IL-1β via distinct mechanisms in response to Listeria. ASC, but not TLR2, is required for caspase-1 activation independent of NF-κB in Listeria-infected macrophages.

Several previous lines of research have suggested, indirectly, that mouse lifespan is particularly susceptible to endocrine or nutritional signals in the first few weeks of life, as tested by manipulations of litter size, growth hormone levels, or mutations with effects specifically on early-life growth rate. The pace of early development in mice can also be influenced by exposure of nursing and weanling mice to olfactory cues. In particular, odors of same-sex adult mice can in some circumstances delay maturation. We hypothesized that olfactory information might also have a sex-specific effect on lifespan, and we show here that lifespan of female mice can be increased significantly by odors from adult females administered transiently, i.e. from 3 days until 60 days of age. Female lifespan was not modified by male odors, nor was male lifespan susceptible to odors from adults of either sex. Conditional deletion of the G protein Gαo in the olfactory system, which leads to impaired accessory olfactory system function and blunted reproductive priming responses to male odors in females, did not modify the effect of female odors on female lifespan. Our data provide support for the idea that very young mice are susceptible to influences that can have long-lasting effects on health maintenance in later life, and provide a potential example of lifespan extension by olfactory cues in mice.

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Keratinocytes are key structural cells in cell migration during wound repair. Keratinocyte migration is dysfunctional in diabetes and results in non-healing, however, the reason for this is unclear. Using bulk and single cell sequencing, we identified that Th17 CD4+ T-cells predominate as does an IL-17A signature in human diabetic wound tissue compared to non-diabetic controls. The effects of increased IL-17A in diabetic skin on keratinocyte function is unknown. To examine this, we subjected isolated keratinocytes to scratch injury and a 24hr rIL-17A (20ng) stimulation. We observed a significant decrease in migration rate in IL-17A stimulated keratinocytes compared to their controls. Next, we examined migration related genes in keratinocytes from mice fed with a normal (ND) or a high fat (HFD) diet. Integrin alpha 3 subunit, Itga3, (a protein known to delay keratinocyte migration during wound re-epithelialization) was higher in diabetic (HFD) keratinocytes compared to ND controls at baseline and with rIL-17A. We analyzed epigenetic enzymes known to increase gene expression and identified that JMJD3, a histone demethylase that relaxes chromatin, was increased both in diabetic keratinocytes from our human scRNA-seq and in murine diabetic keratinocytes with rIL17A. Further, treatment with a JMJD3-specific inhibitor (GSK-J4) decreased Itga3 in diabetic keratinocytes, suggesting that JMJD3 may be relevant to IL-17A-mediated regulation of integrin alpha 3 and other keratinocyte migration genes. Continued investigation into upstream IL-17A signaling in normal and diabetic keratinocytes that alters downstream migration is crucial for our understanding of impaired keratinocyte functions associated with diabetic wound repair. NIH T32 AI 007413, Research Training in Experimental Immunology Rackham Pre-Candidate Graduate Student Research Grant, University of Michigan