Inflammatory kidney injury in trichloroethylene hypersensitivity syndrome mice: Possible role of C3a receptor in the accumulation of Th17 phenotype

Endothelin-1 down-regulated vascular endothelial growth factor A is involved in trichloroethene-induced kidney injury

The mechanism of kidney injury in occupational medicamentosa-like dermatitis due to trichloroethylene exposure is not well understood. This study aimed to investigate the role of endothelin-1 (ET-1)/vascular endothelial-derived growth factor-A (VEGF-A) in trichloroethylene (TCE)-induced renal injury. Forty BALB/c female mice were used in this study to build the TCE-sensitization mouse model. Transmission electron microscopic observation, histological examination, periodic acid-Schiff staining, serum urea nitrogen, creatinine, and urinary total protein levels were used to reflect renal injury. Glypican1, syndecan1, ET-1 and VEGF-A protein levels were measured by western blot. Serum ET-1 level was also measured. Tumor necrosis factor alpha (TNF-α) and vascular cell adhesion molecule-1 (VCAM-1) were detected by immunohistochemistry. The results showed that TCE-sensitized mouse kidneys were damaged and accompanied by increased serum ET-1. After treatment with CGS 35066, the inhibitor of endothelin converting enzyme-1 (ECE-1), kidney ET-1, TNF-α and VCAM-1 levels decreased, and renal function improved in TCE+CGS 35066–sensitized positive mice. In addition, kidney VEGF-A, glomerular endothelial cell glypican1 and syndecan1 levels increased, and endothelial cell damage was alleviated after treatment with CGS 35066. The results suggest that inhibiting ECE-1 could alleviate glomerular endothelial cell injury by inhibiting ET-1 expression, thus promoting endothelial cell repair by upregulating VEGF-A.

Renal tubular cell necroptosis: A novel mechanism of kidney damage in trichloroethylene hypersensitivity syndrome mice

Trichloroethylene (TCE) hypersensitivity syndrome (THS), called occupational medicamentosa-like dermatitis due to TCE (OMDT) in China, is a fatal occupational disorder caused by TCE exposure. Visceral damage, including kidney injury, is one of the major complications. Necroptosis is a regulated cell death form linked to local inflammatory response. This study aimed to investigate whether renal cell necroptosis was involved in TCE-induced kidney injury. A Balb/c mouse model of TCE sensitization was utilized to study mechanisms of modulation of TCE-induced renal necroptosis. Renal histology (using light and transmission electron microscopy) and renal tubular impairment indexes, including α1-microglobulin (α1-MG), and β2-microglobulin (β2-MG), were evaluated. In addition, tissue expression of necroptosis-related proteins, including tumor necrosis factor (TNF)-α, TNF receptor 1 (TNFR1), receptor-interacting protein kinase 3 (RIPK3), p-RIK3, mixed lineage kinase domain-like protein (MLKL), and p-MLKL, were also evaluated. The study here confirmed TCE sensitization caused damage to renal tubules and renal tubular epithelial cell (RTEC) necroptosis. In mice treated with R7050 (a specific TNFα antagonist), it was also seen that inhibition of TNFα expression could effectively inhibit RTEC necroptosis and improve renal function in the TCE-sensitized mice. Taken together, these results help to define a novel mechanism by which RTEC necroptosis plays a key role in TCE-induced kidney damage.

Proteome Profile of Trigeminal Ganglion in Murine Model of Allergic Contact Dermatitis: Complement 3 Pathway Contributes to Itch and Pain Sensation

Allergic contact dermatitis (ACD) is a common inflammatory dermatosis characterized by persistent itch and pain after topical contact with reactive chemicals. Although it has been long recognized as a type-IV hypersensitivity, its complexity of pathophysiology mechanism makes it still a clinical aporia in treatment. In this study, we aimed to identify crucial proteins involved in the nociceptive sensation of ACD. Based on a chemical-induced ACD murine model, we collected trigeminal ganglions of ACD and control mice for quantitative tandem mass tag (TMT)-labeling proteomic analysis. Immunohistochemistry was further practiced to validate the bioinformatic analysis. A total of 7685 proteins were identified and analyzed. Sixty-four proteins were significantly upregulated, and 75 proteins were downregulated in ACD mice. GO analysis demonstrated that the changed proteins were significantly enriched in terms of immune and peptidase activity in ACD mice. Proteins involved in the complement and coagulation cascades were notably changed in the KEGG enrichment analysis. The upregulation of complement component 3 (C3) in trigeminal satellite cells of ACD mice was further confirmed by immunohistochemistry. ACD upregulated C3 in trigeminal satellite cells. The complement system in sensory ganglion might play an essential role in forming pruritic and nociceptive sensations in ACD.

Glomerular Damage in Trichloroethylene-Sensitized Mice: Targeting Cathepsin L-Induced Hyperactive mTOR Signaling

Trichloroethylene (TCE) is a serious health hazard for workers with daily exposure, causing occupational medicamentosa-like dermatitis due to TCE (OMDT) and glomerular damage. Recent studies suggest that mTORC1 signaling is activated in various glomerular disorders; however, the role of mTORC1 signaling in TCE-induced glomerular damage remains to be explored. In the present study, 6 OMDT patients were enrolled and a TCE-sensitized mouse model was established to investigate molecular mechanisms underlying the glomerular damage associated with OMDT. Glomerular damage was assessed by levels of urine nephrin, H&E staining, and renal function test. Ultrastructural change of podocyte was investigated by transmission electron microscopy. The podocyte-related molecules including nephrin, α-actinin-4, and integrin β1 were visualized by immunofluorescence. The activation of mTORC1 signaling was confirmed by Western blot. Glomerular apoptosis was examined by the TUNEL test and Western blotting. Expression and location of cathepsin L (CTSL) were assessed by RT-PCR and immunofluorescence. Our results showed that TCE sensitization caused damage to glomerular structural integrity and also increased the activation of mTORC1 signaling, which was accompanied by podocyte loss, hypertrophy, and glomerular apoptosis. Importantly, we also found that over-expressed CTSL was mainly located in podocyte and CTSL inhibition could partially block the activation of mTORC1 signaling. Thus, our findings suggested a novel mechanism whereby hyperactive mTOR signaling contributes to TCE sensitization–induced and immune-mediated glomerular damage via CTSL activation.