Characterization of a mechano-immuno-inflammatory signaling pathway in rat heart papillary muscles.

RACIOPPI F; PEREYRA E; DIAZ RG; CARENA T; PEREZ NG; GONANO LA; VILA PETROFF M

Buenos Aires

Congreso; Congreso Anual SAFIS 2023; 2023

SAFIS

Introduction: In the heart, when mechanical stress is sustained, it leads to adverse remodeling. It has been shown that mechanical stress triggers an inflammatory response that can damage the heart. However, if axial mechanical stretch induces inflammation has not been fully explored, and the exact mechanosensors involved that lead to inflammation in this context have not been examined.Objectives: To determine if mechanical stretch triggers inflammation in papillary muscles and evaluate the mechanosensors involved in signal transduction, in an attempt to describe a mechano-immuno-transduction pathway.Methods: Papillary muscles were dissected from left ventricles of male Wistar rats and mounted in chambers with HEPES at 30ºC. Lipopolysaccharide was added to the medium to induce NLRP3 priming. After determining minimum length, one muscle was stretched during the next 2 hours to reach 98% of maximum force development length (STR), while the other remained unstretched (CTR). To evaluate microtubule involvement, the same protocol was performed but in presence of microtubule inhibitor Colchicine (10 μM) (CTR+COL or STR+COL). RNA was extracted from muscle samples and cDNA was generated by reverse transcriptase reaction. Q-PCR was used to determine expression level of proinflammatory genes TNF-α, IL-18 and NLRP3. Statistical analysis was performed by T Test. Data are expressed as means ± SEM. Differences were considered significant at p ≤ 0.05. Results: A significant increase in TNF-α, IL-18 or NLRP3 gene expression was detected in stretched muscles. This increase was prevented by Colchicine treatment. TNF-α (%ratio of TNF-α /GAPDH mRNA: CTR: 100 ± 11,5(6); STR: 333,5 ± 89,5(7); CTR+COL: 100 ± 21,7 (7); STR+COL: 223,9 ± 65,2 (8)). IL18 (%ratio of IL18 /GAPDH mRNA: CTR: 100 ± 18,7(7); STR: 330,6 ± 90,5(7); CTR+COL: 100 ± 16 (8); STR+COL: 197,1 ± 60,4 (8)). NLRP3 (%ratio of NLRP3 /GAPDH mRNA: CTR: 100 ± 20.4(6); STR: 235,5 ± 48,3(7); CTR+COL: 100 ± 15.8 (7); STR+COL: 103,5 ± 18,63 (7)).