Serum from Patients Undergoing Remote Ischemic Preconditioning Protects Cultured Human Intestinal Cells from Hypoxia-Induced Damage: Involvement of Matrixmetalloproteinase-2 and -9

Abstract

Remote ischemic preconditioning (RIPC) can be induced by transient occlusion of blood flow to a limb with a blood pressure cuff and exerts multiorgan protection from ischemia/reperfusion injury. Ischemia/reperfusion injury in the intestinal tract leads to intestinal barrier dysfunction and can result in multiple organ failure. Here we used an intestinal cell line (CaCo-2) to evaluate the effects of RIPC-conditioned patient sera on hypoxia-induced cell damage in vitro and to identify serum factors that mediate RIPC effects. Patient sera (n = 10) derived before RIPC (T0), directly after RIPC (T1) and 1 h after RIPC (T2) were added to the culture medium at the onset of hypoxia until 48 h after hypoxia. Reverse transcription-polymerase chain reaction, lactate dehydrogenase (LDH) assays, caspase-3/7 assays, silver staining, gelatin zymography and Western blotting were performed. Hypoxia led to morphological signs of cell damage and increased the release of LDH in cultures containing sera T0 (P < 0.01) and T1 (P < 0.05), but not sera T2, which reduced the hypoxia-mediated LDH release compared with sera T0 (P < 0.05). Gelatin zymography revealed a significant reduction of activities of the matrixmetalloproteinase (MMP)-2 and MMP-9 in the protective sera T2 compared with the nonprotective sera T0 (MMP-2: P < 0.01; MMP-9: P < 0.05). Addition of human recombinant MMP-2 and MMP-9 to MMP-deficient culture media increased the sensitivity of CaCo-2 cells to hypoxia-induced cell damage (P < 0.05), but did not result in a reduced phosphorylation of prosurvival kinases p42/44 and protein kinase B (Akt) or increased activity of caspase-3/7. Our results suggest MMP-2 and MMP-9 as currently unknown humoral factors that may be involved in RIPC-mediated cytoprotection in the intestine.

Kinetics and Signal Activation Properties of Circulating Factor(s) From Healthy Volunteers Undergoing Remote Ischemic Pre-Conditioning

“…The release of a circulating factor with a rapid onset of cardioprotection in the bioassay heart of the present study is consistent with prior experimental and clinical studies, which revealed evidence for protection with an interval of only 5 to 10 min between the RIPC stimulus and the injurious event 22, 23, 37, 38. The continuous presence of a circulating factor that provides cardioprotection in the bioassay mouse heart in the present study is again consistent with prior experimental and clinical studies, which revealed evidence of long-lasting protection 24, 26, 27, 39 for up to 1 week after the RIPC stimulus (28).…”

Postoperative Neurocognitive Dysfunction in Patients Undergoing Cardiac Surgery after Remote Ischemic Preconditioning: A Double-Blind Randomized Controlled Pilot Study

“…With respect to the underlying pathways of RIPC, we showed that serum taken from patients after RIPC had a different capability of protecting cells during hypoxia than the serum taken before RIPC, and the involvement of matrix-metalloproteinases 2 and 9 in the mechanism conferring protection was demonstrated in the serum taken after RIPC [31]. These data support the idea that humoral factors are involved in RIPC-mediated effects.…”

Serum from young, sedentary adults who underwent passive heat therapy improves endothelial cell angiogenesis via improved nitric oxide bioavailability

“…Our data also add to the growing evidence that serum from human subjects who have undergone healthy lifestyle interventions can confer cellular protection [37][38][39][40][41][42]. In general, beneficial changes in cellular phenotypes cannot be attributed to changes in anyone (or several) circulating factors.…”