[Paper introduction] Cystine attenuates oxidative stress-induced tight junction permeability and intestinal inflammation in Caco-2 cells

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Amino Acids. 2021 May 15. doi: 10.1007/s00726-021-03001-y.

Cystine reduces tight junction permeability and intestinal inflammation induced by oxidative stress in Caco‑2 cells

Oxidative stress in the intestine produces proinflammatory cytokines and increases tight junction (TJ) permeability, leading to intestinal and systemic inflammation. Cystine is a substrate for glutathione and inhibits inflammation, but it is unclear whether cystine locally improves intestinal barrier dysfunction.

Here, we investigated the local effects of cystine on TJ permeability and intestinal inflammatory responses induced by oxidative stress.CaCo-2 cells were cultured in medium containing cystine for 24 h and then treated with hydrogen peroxide for 2 h.

We assessed TJ permeability by measuring the transepithelial electrical resistance (TEER) and paracellular transport of 4 kDa fluorescent isocyanated dextran (FD4). Cystine and glutathione concentrations were measured after pretreatment with cystine.

We measured the mRNA expression of inflammatory cytokines. Furthermore, TJ protein levels were assessed by measuring TJ protein expression in total cells and the ratio of TJ protein in detergent-insoluble/soluble fractions (IS/S ratio). Cystine treatment attenuated hydrogen peroxide-induced TJ permeability.

Cystine did not affect TJ protein expression in whole cells, but suppressed the IS/S ratio of claudin-4. Cystine treatment significantly increased intracellular cystine and glutathione concentrations. Cystine treatment suppressed the mRNA expression of inflammatory cytokines, and the mRNA level was significantly correlated with TJ permeability.

In conclusion, cystine treatment suppresses oxidative stress-induced intestinal barrier dysfunction locally by reducing the localized disruption of claudin-4. Furthermore, the effect of cystine on improving intestinal barrier function is associated with the suppression of oxidative stress-induced local inflammatory cytokine responses.

* Passive transport of substances through gaps (or intercellular spaces) between intestinal cells

Findings from a high-leucine essential amino acid mix! Suppresses exercise-induced muscle damage and elucidates early recovery from muscle loss⁉ [Paper introduction] High-leucine essential amino acids improve recovery from muscle damage after exercise in young men, independent of muscle protein synthesis

Findings from a high-leucine essential amino acid mix! Suppresses exercise-induced muscle damage and elucidates early recovery from muscle loss⁉ [Paper introduction] High-leucine essential amino acids improve recovery from muscle damage after exercise in young men, independent of muscle protein synthesis

Findings from a high-leucine essential amino acid mix! Suppresses exercise-induced muscle damage and elucidates early recovery from muscle loss⁉ [Paper introduction] High-leucine essential amino acids improve recovery from muscle damage after exercise in young men, independent of muscle protein synthesis

Original author:https://link.springer.com/article/10.1007/s00726-021-03001-y

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