Hydrogen sulfide attenuates hyperhomocysteinemia-induced blood-brain barrier permeability by inhibiting MMP-9

Abstract

Backgroud: Hyperhomocysteinemia (HHcy) is implicated in various neurovascular disorders including vascular dementia, subarachnoid hemorrhage and stroke. Elevated homocysteine (Hcy) levels are associated with increased oxidative stress and compromised blood–brain barrier (BBB) integrity. Hydrogen sulfide (H₂S) has recently emerged as potent neuroprotective molecule in various neurological conditions including those associated with HHcy. The present study evaluates the protective effect of sodium hydrogen sulfide (NaHS; a source of H₂S) on HHcy-induced BBB dysfunction and underpin molecular mechanisms.

Materials and methods: Supplementation of NaHS restored the increased BBB permeability in the cortex and hippocampus of HHcy animals assessed in terms of diffused sodium fluorescein and Evans blue tracer dyes in the brain. Activity of matrix metalloproteinases (MMPs) assessed by gelatinase activity and in situ gelatinase assay was restored to the normal in the cortex and hippocampus of HHcy animals supplemented with NaHS.

Results: Application of gelatin zymography revealed that specifically MMP-9 activity was increased in the cortex and hippocampus of HHcy animals, which was inhibited by NaHS supplementation. Real-time RT-PCR analysis showed that NaHS administration also decreased mRNA expression of MMP-9 in the hippocampus of HHcy animals. NaHS supplementation was further observed to reduce water retention in the brain regions of Hcy treated animals.

Conclusion: Taken together, these findings suggest that NaHS supplementation ameliorates HHcy-induced BBB permeability and brain edema by inhibiting the mRNA expression and activity of MMP-9. Therefore, H₂S and H₂S releasing drugs may be used as a novel therapeutic approach to treat HHcy-associated neurovascular disorders.

Keywords:

• Blood brain barrier
• brain edema
• homocysteine
• hydrogen sulfide
• matrix metalloproteinase

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

M.K. designed the study, performed the experiments, analyzed the data and prepared first draft of the manuscript. R.S. supervised the study and revised the manuscript. All authors have read and approved the final version of the manuscript.

Additional information

Funding

The financial assistance provided by the Department of Biotechnology (DBT), Govt. of India, (grant number BT/361/NE/TBP/2012) is acknowledged. The fellowship to MK from the University Grants Commission (UGC), New Delhi [F.17-7(J)/2004(SA-1)] is also acknowledged. The authors also acknowledge financial assistance provided under the promotion of University Research and Scientific Excellence (PURSE) by Department of Science and Technology (DST) New Delhi and under Special Assistance Program (SAP) of UGC (DRS Phase-II).