Comprehensive Analysis of Zinc Derivatives Pro-proliferative, Anti-Apoptotic and Antimicrobial Effect on Human Fibroblasts and Keratinocytes in a Simulated, Nutrient-deficient Environment In Vitro.

Zinc as therapeutic agent in skin and wound care has been known for centuries, but its role is controversial and comprehensive investigations in nutrient-deficient environments are lacking. We aimed to provide a broad analysis of different zinc derivatives on proliferation, apoptosis and antimicrobial properties in a simulated nutrient-deficient environment in vitro. Human fibroblasts (CRL2522) and keratinocytes (HaCaT) were treated with a broad concentration range (10 - 0.0001 µg/mL) of zinc-sulfate (ZnSO4), -gluconate (ZnGluc) and -histidine (ZnHis) for 1-6 days under nutrient-deficient media conditions. Cell proliferation was investigated by XTT assay. Targeted analyzes in proliferation (E2F1, PCNA) and apoptosis (TP53) associated genes were performed via qRT-PCR and apoptosis was determined via FACS (annexin V/7-AAD staining). Antimicrobial efficacy was investigated using a quantitative suspension method against S. aureus, P. aeruginosa, E. coli, and C. albicans. The results indicated that 0.1 to 0.001 µg/mL Zn increased cell proliferation in both cell lines. Fibroblasts were more susceptible with significant proliferation peaks on days 2 & 6, and days 1 & 4 for keratinocytes. No relevant changes in gene expression were detected for E2F1 and PCNA nor for TP53. Annexin-V/7-AAD-staining of fibroblasts revealed a small, yet insignificant reduction of apoptosis induction for ZnGluc and ZnSO4. ZnGluc and ZnSO4 (0.1%) achieved high microbial reductions (4-5 log10 reductions) against tested pathogens. ZnGluc and ZnSO4 showed relevant pro-proliferative and antimicrobial, as well as tendential anti-apoptotic features in a simulated nutrient-deficient microenvironment in vitro. This further validates a potential benefit of local zinc treatment in deficient wound microenvironments.

Smooth muscle cells relay acute pulmonary inflammation via distinct ADAM17/ErbB axes.

In acute pulmonary inflammation, danger is first recognized by epithelial cells lining the alveolar lumen and relayed to vascular responses, including leukocyte recruitment and increased endothelial permeability. We supposed that this inflammatory relay critically depends on the immunological function of lung interstitial cells such as smooth muscle cells (SMC). Mice with smooth muscle protein-22α promotor-driven deficiency of the disintegrin and metalloproteinase (ADAM) 17 (SM22-Adam17(-/-)) were investigated in models of acute pulmonary inflammation (LPS, cytokine, and acid instillation). Underlying signaling mechanisms were identified in cultured tracheal SMC and verified by in vivo reconstitution experiments. SM22-Adam17(-/-) mice showed considerably decreased cytokine production and vascular responses in LPS- or acid-induced pulmonary inflammation. In vitro, ADAM17 deficiency abrogated cytokine release of primary SMC stimulated with LPS or supernatant of acid-exposed epithelial cells. This was explained by a loss of ADAM17-mediated growth factor shedding. LPS responses required ErbB1/epidermal growth factor receptor transactivation by TGFα, whereas acid responses required ErbB4 transactivation by neuregulins. Finally, LPS-induced pulmonary inflammation in SM22-Adam17(-/-) mice was restored by exogenous TGFα application, confirming the involvement of transactivation pathways in vivo. This highlights a new decisive immunological role of lung interstitial cells such as SMC in promoting acute pulmonary inflammation by ADAM17-dependent transactivation.