Rationale: Inflammatory bowel disease (IBD) is a relapsing and idiopathic disorder. The low therapeutic efficacy of IBD urgently prompts us to seek new treatment methods. Methods and Results: In this study, we report an adipose-derived mesenchymal stem cell (AT-MSC)-based treatment strategy in which AT-MSCs specifically deliver BMP inhibitor Grem1 and anti-inflammatory factor IL-10 to inflammatory colon tissues in SETD2 deficient dextran sulfate sodium (DSS)-induced colitis mouse models. Targeted delivery of Grem1 reduced colitis by promoting intestinal stem cell regeneration and enhancing mucosal regenerative capacity. Furthermore, targeted delivery of IL-10 reduced colitis by reducing inflammatory cytokines. Conclusion: Our AT-MSCs based therapeutic strategy effectively mitigated IBD. This study has deepened our understanding of IBD therapy and provided a theoretical foundation for its clinical treatment.
© The author(s).

The presence of distinct stem cells that maintain the interfollicular epidermis is highly debated. Here, we report a population of keratinocytes, marked by Thy1, in the basal layer of the interfollicular epidermis. We find that epidermal cells expressing differential levels of Thy1 display distinct transcriptional signatures. Thy1+ keratinocytes do not express T cell markers, express a unique transcriptional profile, cycle significantly slower than basal epidermal progenitors and display significant expansion potential in vitro. Multicolor lineage tracing analyses and mathematical modeling reveal that Thy1+ basal keratinocytes do not compete neutrally alike interfollicular progenitors and contribute long-term to both epidermal replenishment and wound repair. Importantly, ablation of Thy1+ cells strongly impairs these processes, thus indicating the non-redundant function of Thy1+ stem cells in the epidermis. Collectively, these results reveal a distinct stem cell population that plays a critical role in epidermal homeostasis and repair.
© 2022. The Author(s).

[Figure: see text].

Myeloid plasticity is a hallmark of the innate immune response to Toll-like receptor (TLR) activation. Here, we provide a protocol for monocyte cell fate tracking by adoptive transfer in the context of systemic inflammation induced by TLR7 activation, the principal innate immune receptor sensing viral RNA in mice. Defined monocyte subsets are isolated from the bone marrow of donor mice by cell sorting and adoptively transferred into the systemic circulation of congenic hosts, with or without concurrent activation of TLR7 via the topical application of the small molecule agonist, imiquimod, in a cream formulation that induces a systemic inflammatory response. Advantages are the precise definition of donor cell populations and resulting cell fate without the need for host conditioning in a model that recapitulates key aspects of the systemic inflammatory response to TLR7 stimulation.
Copyright © The Authors; exclusive licensee Bio-protocol LLC.

Circulating androgens can modulate immune cell activity, but the impact of androgens on viral pathogenesis remains unclear. Previous data demonstrate that testosterone reduces the severity of influenza A virus (IAV) infection in male mice by mitigating pulmonary inflammation rather than by affecting viral replication. To examine the immune responses mediated by testosterone to mitigate IAV-induced inflammation, adult male mice remained gonadally intact or were gonadectomized and treated with either placebo or androgen-filled (i.e., testosterone or dihydrotestosterone) capsules prior to sublethal IAV infection. Like intact males, treatment of gonadectomized males with androgens improved the outcome of IAV infection, which was not mediated by changes in the control of virus replication or pulmonary cytokine activity. Instead, androgens accelerated pulmonary leukocyte contraction to limit inflammation. To identify which immune cells were contracting in response to androgens, the composition of pulmonary cellular infiltrates was analyzed and revealed that androgens specifically accelerated the contraction of total pulmonary inflammatory monocytes during peak disease, as well as CD8+ T cells, IAV-specific CD8+ T numbers, cytokine production and degranulation by IAV-specific CD8+ T cells, and the influx of eosinophils into the lungs following clearance of IAV. Neither depletion of eosinophils nor adoptive transfer of CD8+ T cells could reverse the ability of testosterone to protect males against IAV suggesting these were secondary immunologic effects. The effects of testosterone on the contraction of immune cell numbers and activity were blocked by co-administration of the androgen receptor antagonist flutamide and mimicked by treatment with dihydrotestosterone, which was also able to reduce the severity of IAV in female mice. These data suggest that androgen receptor signaling creates a local pulmonary environment that promotes downregulation of detrimental inflammatory immune responses to protect against prolonged influenza disease.