Probes for INS

Transient receptor potential (TRP) channels play prominent roles in ion homeostasis by their ability to control cation influx. Mouse placentation is governed by the processes of trophoblast proliferation, invasion, differentiation, and fusion, all of which require calcium signaling. Although certain TRP channels have been shown to contribute to maternal-fetal transport of magnesium and calcium, a role for TRP channels in specific trophoblast functions has been disregarded. Using qRT-PCR and in situ hybridisation, the spatio-temporal expression pattern of TRP channels in the mouse placenta across gestation (E10.5-E18.5) was assessed. Prominent expression was observed for Trpv2, Trpm6, and Trpm7. Calcium microfluorimetry in primary trophoblast cells isolated at E14.5 of gestation further revealed the functional activity of TRPV2 and TRPM7. Finally, comparing TRP channels expression in mouse trophoblast stem cells (mTSCs) and mouse embryonic stem cells (mESC) confirmed the specific expression of TRPV2 during placental development. Moreover, TRP channel expression was similar in mTSCs compared to primary trophoblasts and validate mTSC as a model to study TRP channels in placental development. Collectivity, our results identify a specific spatio-temporal TRP channel expression pattern in trophoblasts, suggesting a possible involvement in regulating the process of placentation.

The pathology of skin immune diseases such as atopic dermatitis is closely related to the overproduction of cytokines by macrophages. Although the pathological functions of macrophages in skin are known, mechanisms of how they detect the tissue environment remain unknown. TRPV4, a nonselective cation channel with high Ca2+ permeability, is activated at physiological temperatures from 27 to 35°C and involved in the functional control of macrophages. However, the relationship between TRPV4 function in macrophages and skin immune disease is unclear. In this study, we demonstrate that TRPV4 activation inhibits NF-κB signaling, resulting in the suppression of IL-1β production in both human primary monocytes and macrophages derived from human primary monocytes. A TRPV4 activator also inhibited the differentiation of human primary monocytes into GM-CSF M1 macrophages but not M-CSF M2 macrophages. We also observed a significant increase in the number of inducible NO synthase-positive/TRPV4-negative dermal macrophages in atopic dermatitis compared with healthy human skin specimens. Our findings provide insight into the physiological relevance of TRPV4 to the regulation of macrophages during homeostasis maintenance and raise the potential for TRPV4 to be an anti-inflammatory target.

Fibroblast-like synoviocytes (FLS) and articular chondrocytes (AC) derive from a common pool of embryonic precursor cells. They are currently believed to engage in largely distinct differentiation programs to build synovium and articular cartilage and maintain healthy tissues throughout life. We tested this hypothesis by deeply characterizing and comparing their transcriptomic attributes. We profiled the transcriptomes of freshly isolated AC, synovium, primary FLS, and dermal fibroblasts from healthy adult humans using bulk RNA sequencing assays and downloaded published single-cell RNA sequencing data from freshly isolated human FLS. We integrated all data to define cell-specific signatures and validated findings with quantitative reverse transcription PCR of human samples and RNA hybridization of mouse joint sections. We identified 212 AC and 168 FLS markers on the basis of exclusive or enriched expression in either cell and 294 AC/FLS markers on the basis of similar expression in both cells. AC markers included joint-specific and pan-cartilaginous genes. FLS and AC/FLS markers featured 37 and 55 joint-specific genes, respectively, and 131 and 239 pan-fibroblastic genes, respectively. These signatures included many previously unrecognized markers with potentially important joint-specific roles. AC/FLS markers overlapped in their expression patterns among all FLS and AC subpopulations, suggesting that they fulfill joint-specific properties in all, rather than in discrete, AC and FLS subpopulations. This study broadens knowledge and identifies a prominent overlap of the human adult AC and FLS transcriptomic signatures. It also provides data resources to help further decipher mechanisms underlying joint homeostasis and degeneration and to improve the quality control of tissues engineered for regenerative treatments.

Microglia, resident macrophages of the central nervous system (CNS), are essential to brain development, homeostasis, and disease. Microglial activation and proliferation are hallmarks of many CNS diseases including neuropathic pain. However, molecular mechanisms that govern the spinal neuro-immune axis in the setting of neuropathic pain remain incompletely understood. Here we show that genetic ablation or pharmacological blockade of transient receptor potential vanilloid type 4 (TRPV4) markedly attenuated neuropathic pain-like behaviors in a mouse model of spared nerve injury. Mechanistically, microglia-expressed TRPV4 mediated microglial activation and proliferation and promoted functional and structural plasticity of excitatory spinal neurons through releasing lipocalin-2. Our results suggest that microglial TRPV4 channels reside at the center of the neuro-immune axis in the spinal cord that transforms peripheral nerve injury into central sensitization and neuropathic pain, thereby identifying TRPV4 as a promising new target for the treatment of chronic pain.