Abstract
Cystathionine-γ-lyase (CSE) isa hydrogen sulfide (H
S)-synthesizing enzyme that promotesinflammation by upregulating H
S in sepsis. Liver sinusoidal endothelial cells (LSECs) are fenestrated endothelial cells (liver sieve) that undergo alteration during sepsis and H
S plays a role in this process. Substance P (SP) is encoded by the preprotachykinin A (PPTA) gene, and promotes inflammation in sepsis; however, its regulation by H
S is poorly understood. Furthermore, the interaction between H
S and SP in modulating LSEC fenestrations following sepsis remains unclear. This study aimed to investigate whether CSE/H
S regulates SP and the neurokinin-1 receptor (NK-1R) andmodulates fenestrations in LSECs following caecalligation and puncture (CLP)-induced sepsis. Here we report thatthe absence of either CSE or H
S protects against liver sieve defenestration and gaps formation in LSECsin sepsis by decreased SP-NK-1R signaling. Following sepsis, there is an increased expression of liver CSE and H
S synthesis, and plasma H
S levels, which were aligned with higher SP levels in the liver, lungs and plasma and NK-1R in the liver and lungs. The genetic deletion of CSE led to decreased sepsis-induced SP and NK-1R in the liver, lungs and plasma SP suggesting H
S synthesized through CSE regulates the SP-NK-1R pathway in sepsis. Further, mice deficient in the SP-encoding gene (PPTA) preservedsepsis-induced LSEC defenestrationand gaps formation, as seen by maintenance of patent fenestrations and fewer gaps. In conclusion, CSE/H
S regulates SP-NK-1R and modulates LSEC fenestrations in sepsis.