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Frank A. DeLano, Geert W. Schmid-Schönbein
PLoS One Infectious Diseases, 18.10.2024
Tilføjet 18.10.2024
by Frank A. DeLano, Geert W. Schmid-Schönbein The mechanism that triggers the progressive dysregulation of cell functions, inflammation, and breakdown of tissues during aging is currently unknown. We propose here a previously unknown mechanism due to tissue autodigestion by the digestive enzymes. After synthesis in the pancreas, these powerful enzymes are activated and transported inside the lumen of the small intestine to which they are compartmentalized by the mucin/epithelial barrier. We hypothesize that this barrier leaks active digestive enzymes (e.g. during meals) and leads to their accumulation in tissues outside the gastrointestinal tract. Using immune-histochemistry we provide evidence in young (4 months) and old (24 months) rats for significant accumulation of pancreatic trypsin, elastase, lipase, and amylase in peripheral organs, including liver, lung, heart, kidney, brain, and skin. The mucin layer density on the small intestine barrier is attenuated in the old and trypsin leaks across the tip region of intestinal villi with depleted mucin. The accumulation of digestive enzymes is accompanied in the same tissues of the old by damage to collagen, as detected with collagen fragment hybridizing peptides. We provide evidence that the hyperglycemia in the old is accompanied by proteolytic cleavage of the extracellular domain of the insulin receptor. Blockade of pancreatic trypsin in the old by a two-week oral treatment with a serine protease inhibitor (tranexamic acid) serves to significantly reduce trypsin accumulation in organs outside the intestine, collagen damage, as well as hyperglycemia and insulin receptor cleavage. These results support the hypothesis that the breakdown of tissues in aging is due to autodigestion and a side-effect of the fundamental requirement for digestion.
Læs mere Tjek på PubMedGarcia, Bruno; Ter Schiphorst, Benoit; Su, Fuhong; Picod, Adrien; Ikenna-Uba, Theo; Favory, Raphaël; Annoni, Filippo; Mebazaa, Alexandre; Vincent, Jean-Louis; Creteur, Jacques; Taccone, Fabio S.; Herpain, Antoine
Critical Care Explorations, 17.10.2024
Tilføjet 17.10.2024
OBJECTIVES: To analyze dynamic changes in the renin-angiotensin system (RAS) during septic shock, focusing on angiotensin-converting enzyme (ACE) activity and the balance between angiotensin peptides, using a mass spectrometry method. DESIGN: Experimental septic shock model induced by peritonitis in swine. SETTING: Experimental Laboratory, Department of Intensive Care, Erasme Hospital, Université Libre de Bruxelles. SUBJECTS: Forty time points from eight mechanically ventilated pigs. INTERVENTIONS: Septic shock was induced using intraperitoneal instillation of autologous feces, followed by standardized fluid resuscitation, norepinephrine infusion, antibiotic administration, and peritoneal lavage. MEASUREMENTS AND MAIN RESULTS: The induction of sepsis resulted in a significant increase in plasma renin activity and levels of angiotensin I and II, with a significant decrease in ACE activity observed from 4 hours post-resuscitation and a notable rise in the angiotensin I/angiotensin II ratio at 12 hours. Additionally, a shift toward the angiotensin-(1–7) axis was observed, evidenced by an increased angiotensin-(1–7)/angiotensin II ratio. CONCLUSIONS: The study highlighted dynamic shifts in the RAS during septic shock, characterized by reduced circulating ACE activity, elevated angiotensin I/II ratio, and a shift toward the angiotensin-(1–7) axis. These findings suggest an adaptive response within the RAS, potentially offering new insights into sepsis management and therapeutic targets.
Læs mere Tjek på PubMedChunyan Guo, Cuixiang Xu, Qing Feng, Xin Xie, Yan Li, Xiangrong Zhao, Jun Hu, Senbiao Fang, Lijun Shang
Journal of Medical Virology, 15.10.2024
Tilføjet 15.10.2024