Compartmentalised inducible nitric-oxide synthase activity in septic shock.
BACKGROUND
Previous experimental studies support a role for inducible nitric-oxide synthase (iNOS) in the pathogenesis of severe sepsis. The aim of the study was to characterise iNOS activity in different tissues in patients with septic shock.


METHODS
13 consecutive patients with septic shock caused by cellulitis were enrolled. Skin, muscle, fat, and artery samples were obtained from normal, inflamed, and putrescent areas to measure iNOS activity, and concentrations of tumour necrosis factor alpha (TNFalpha) and interleukin 1beta (IL-1beta). In two patients, iNOS activity was also assessed in peripheral blood mononuclear cells (PBMC) incubated with microorganisms causing the sepsis, or in macrophages isolated from suppurating peritoneal fluid incubated with IL-1beta.


RESULTS
Compared with normal and inflamed areas, iNOS activity was increased in putrescent areas for muscle (71-fold [95% CI 20-259] vs normal areas, 69-fold [19-246] vs inflamed areas; p<0.01 for each) and for fat (68-fold [23-199] and 49-fold [18-137], respectively; p<0.01), but not for skin. Compared with normal areas, putrescent areas of arteries showed increased iNOS expression (1280-fold [598-3153]; p<0.01). Compared with normal areas, TNFalpha and IL-1beta were increased in putrescent areas of arteries (223-fold and 41-fold, respectively; p<0.01 for each). PBMCs and tissue macrophages expressed iNOS. Plasma nitrite/nitrate concentrations inversely correlated with mean arterial pressure and systemic vascular resistance.


CONCLUSIONS
In human septic shock we found that iNOS activity is compartmentalised at the very site of infection and parallels expression of TNFalpha and IL-1beta. PBMCs and tissue macrophages can be a cellular source for iNOS.
Annane
D
D
Service de Réanimation Médicale, Hôpital Raymond Poincaré, Assistance Publique-Hôpitaux de Paris, Faculté de Médecine, France. djillali.annane@rpc.ap-hop-paris.fr
Sanquer
S
S
Sébille
V
V
Faye
A
A
Djuranovic
D
D
Raphaël
J C
JC
Gajdos
P
P
Bellissant
E
E
D000273:Adipose Tissue / Q000201:enzymology; D000328:Adult; D000368:Aged; D001424:Bacterial Infections / Q000201:enzymology* / Q000382:microbiology; D002481:Cellulitis / Q000201:enzymology* / Q000382:microbiology; D005260:Female; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000201:enzymology; D008264:Macrophages / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000201:enzymology; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D012772:Shock, Septic / Q000201:enzymology* / Q000382:microbiology; D012867:Skin / Q000201:enzymology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II