Hydrogen Sulfide and Neurogenic Inflammation in a Murine Model of Polymicrobial Sepsis

Ph.DDOCTOR OF PHILOSOPH

Hydrogen Sulfide and Neurogenic Inflammation in Polymicrobial Sepsis: Involvement of Substance P and ERK-NF-κB Signaling

Hydrogen sulfide (H2S) has been shown to induce transient receptor potential vanilloid 1 (TRPV1)-mediated neurogenic inflammation in polymicrobial sepsis. However, endogenous neural factors that modulate this event and the molecular mechanism by which this occurs remain unclear. Therefore, this study tested the hypothesis that whether substance P (SP) is one important neural element that implicates in H2S-induced neurogenic inflammation in sepsis in a TRPV1-dependent manner, and if so, whether H2S regulates this response through activation of the extracellular signal-regulated kinase-nuclear factor-κB (ERK-NF-κB) pathway. Male Swiss mice were subjected to cecal ligation and puncture (CLP)-induced sepsis and treated with TRPV1 antagonist capsazepine 30 minutes before CLP. DL-propargylglycine (PAG), an inhibitor of H2S formation, was administrated 1 hour before or 1 hour after sepsis, whereas sodium hydrosulfide (NaHS), an H2S donor, was given at the same time as CLP. Capsazepine significantly attenuated H2S-induced SP production, inflammatory cytokines, chemokines, and adhesion molecules levels, and protected against lung and liver dysfunction in sepsis. In the absence of H2S, capsazepine caused no significant changes to the PAG-mediated attenuation of lung and plasma SP levels, sepsis-associated systemic inflammatory response and multiple organ dysfunction. In addition, capsazepine greatly inhibited phosphorylation of ERK1/2 and inhibitory κBα, concurrent with suppression of NF-κB activation even in the presence of NaHS. Furthermore, capsazepine had no effect on PAG-mediated abrogation of these levels in sepsis. Taken together, the present findings show that H2S regulates TRPV1-mediated neurogenic inflammation in polymicrobial sepsis through enhancement of SP production and activation of the ERK-NF-κB pathway

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Effect of NaHS or PAG and capsazepine and effect of NaHS and PD98059 on NF-κB activation in nuclear extracts of lung and liver tissues in septic mice.

<p>Mice were randomly given NaHS (10 mg/kg, i.p.) at the same time of CLP or PAG (50 mg/kg, i.p.) 1 hour before (“prophylactic”) or 1 hour after (“therapeutic”) CLP; and capsazepine (<i>Capz</i>) (15 mg/kg, s.c.) or vehicle (DMSO) 30 minutes before CLP. Some mice were injected PD98059 (10 mg/kg, i.p.) or vehicle (DMSO) 1 hour before CLP. Sham mice were used as controls. Eight hours after CLP or sham operation, effect of (A) NaHS or (B) PAG and capsazepine and (C) effect of NaHS and PD98059 on the DNA-binding activity of NF-κB were measured. Results shown are the mean values ± SEM (n = 8–12 mice per group). *P<0.01 versus sham; **P<0.01 versus CLP+vehicle; †P<0.01 versus CLP+NaHS+vehicle. ‡P<0.01 versus CLP+NaHS+vehicle.</p

Effect of PAG and capsazepine on protein levels of cytokines and chemokines in the lungs and liver of septic mice.

<p>Mice were randomly given PAG (50 mg/kg, i.p.) 1 hour before (“prophylactic”; PAG+CLP+Vehicle or PAG+CLP+Capz) or 1 hour after (“therapeutic”; CLP+PAG+Vehicle or CLP+PAG+Capz) CLP; and capsazepine (<i>Capz</i>) (15 mg/kg, s.c.) or vehicle (DMSO) 30 minutes before CLP. Sham mice were used as controls. Eight hours after CLP or sham operation, protein levels of (A) TNF-α, (B) IL-1β, (C) IL-6, (D) MIP-1α and (E) MIP-2 were measured. Results shown are the mean values ± SEM (n = 8–12 mice per group). *P<0.01 versus sham; **P<0.01 versus CLP+vehicle; †P<0.05 versus CLP+vehicle.</p

Effect of NaHS or PAG and capsazepine on ERK_1/2 activation in the lungs and liver of septic mice.

<p>Mice were randomly given NaHS (10 mg/kg, i.p.) at the same time of CLP or PAG (50 mg/kg, i.p.) 1 hour before (“prophylactic”) or 1 hour after (“therapeutic”) CLP; and capsazepine (<i>Capz</i>) (15 mg/kg, s.c.) or vehicle (DMSO) 30 minutes before CLP. Sham mice were used as controls. Eight hours after CLP or sham operation, effect of (A) NaHS or (B) PAG and capsazepine on phospho-ERK_1/2 and total ERK_1/2 expression levels were measured. A representative western blot image is shown, with densitometry data expressed as average ratios of phospho-ERK_1/2 to total ERK_1/2. Results shown are the mean values ± SEM (n = 6 mice per group). *P<0.01 versus sham; **P<0.01 versus CLP+vehicle; †P<0.01 versus CLP+NaHS+vehicle.</p

Effect of PAG and capsazepine on protein and mRNA levels of SP in septic mice.

<p>Mice were randomly given PAG (50 mg/kg, i.p.) 1 hour before (“prophylactic”) or 1 hour after (“therapeutic”) CLP; and capsazepine (<i>Capz</i>) (15 mg/kg, s.c.) or vehicle (DMSO) 30 minutes before CLP. Sham mice were used as controls. Eight hours after CLP or sham operation, (A) lung and (B) plasma SP levels, and (C) lung PPT-A mRNA levels were measured. Results shown are the mean values ± SEM (n = 8–12 mice per group). *P<0.01 versus sham; **P<0.01 versus CLP+vehicle.</p

Effect of PAG and capsazepine on liver dysfunction and lung edema in septic mice.

<p>Mice were randomly given PAG (50 mg/kg, i.p.) 1 hour before (“prophylactic”) or 1 hour after (“therapeutic”) CLP; and capsazepine (<i>Capz</i>) (15 mg/kg, s.c.) or vehicle (DMSO) 30 minutes before CLP. Sham mice were used as controls. Eight hours after CLP or sham operation, plasma levels of (A) ALT and (B) AST, and (C) lung wet-to-dry weight ratio were measured. Results shown are the mean values ± SEM (n = 10–15 mice per group). *P<0.01 versus sham; **P<0.01 versus CLP+vehicle; ‡P<0.05 versus CLP+vehicle.</p

Effect of NaHS and capsazepine on liver dysfunction and lung edema in septic mice.

<p>Mice were randomly given NaHS (10 mg/kg, i.p.) or vehicle (DMSO) at the same time of CLP; and capsazepine (<i>Capz</i>) (15 mg/kg, s.c.) or vehicle (DMSO) 30 minutes before CLP. Sham mice were used as controls. Eight hours after CLP or sham operation, plasma levels of (A) ALT and (B) AST, and (C) lung wet-to-dry weight ratio were measured. Results shown are the mean values ± SEM (n = 10–15 mice per group). *P<0.01 versus sham; **P<0.01 versus CLP+vehicle; ‡P<0.05 versus CLP+vehicle; †P<0.01 versus CLP+NaHS+vehicle.</p