Hydrogen sulfide alleviates hyperhomocysteinemia-mediated skeletal muscle atrophy via mitigation of oxidative and endoplasmic reticulum stress injury.

Although hyperhomocysteinemia (HHcy) occurs due to the deficiency in cystathionine-β-synthase (CBS) causing skeletal muscle dysfunction, it is still unclear whether this effect is mediated through oxidative/endoplasmic reticulum (ER)-stress or both. Nevertheless, there is no treatment option available to improve HHcy-mediated muscle injury. Hydrogen sulfide (H2S) is an anti-oxidant compound and patients with CBS mutation do not produce H2S. In this study, we hypothesized that H2S mitigates HHcy-induced redox imbalance/ER-stress during skeletal muscle atrophy via JNK-phosphorylation. We used CBS+/- mice to study HHcy-mediated muscle atrophy and treated them with sodium hydrogen sulfide (NaHS, an H2S donor). Proteins and mRNAs were examined by Western blots and qPCR. Pro-inflammatory cytokines were also measured. Muscle mass and strength were studied via fatigue-susceptibility test. Our data revealed that HHcy was detrimental to skeletal mass, particularly gastrocnemius and quadriceps muscles weights. We noticed that oxidative-stress were reversed by NaHS in Hcy-treated C2C12 cells. Interestingly, ER-stress markers (GRP78, ATF6, pIRE1α, and pJNK) were elevated in-vivo and in-vitro, and NaHS mitigated these effects. Additionally, we observed that JNK-phosphorylation was upregulated in C2C12 after Hcy treatment, but NaHS could not reduce this effect. Furthermore, inflammatory cytokines IL-6 and TNF-α were higher in plasma from CBS+/- as compared to wild-type mice. FOXO1-mediated Atrogin-1 and MuRF-1 upregulation were attenuated by NaHS. Functional studies revealed that NaHS administration improved muscle fatigability in CBS+/- mice. In conclusion, our work provides evidence that NaHS is beneficial in mitigating HHcy-mediated skeletal injury incited by oxidative/ER-stress responses.