Laurence Chauvelot-Moachon

Tenofovir-Related Fanconi Syndrome with Nephrogenic Diabetes Insipidus in a Patient with Acquired Immunodeficiency Syndrome: The Role of Lopinavir-Ritonavir-Didanosine

Tenofovir-related tubular damage, like all other recently reported cases, occurred in patients receiving the protease inhibitor (PI) ritonavir, often with lopinavir. Increased plasma concentrations of didanosine were also observed after the addition of tenofovir. It was suspected that tenofovir with PIs interacted with renal organic anion transporters, leading to nephrotoxic tubular concentrations of tenofovir and systemic accumulation of didanosine. Until there is a better understanding of these interactions, close monitoring is recommended for patients receiving tenofovir, PIs, and didanosine.

Effects of interleukin-6 on cytochrome P450-dependent mixed-function oxidases in the rat

Intravenous treatment of male rats with recombinant human interleukin-6 (rhIL6) at 50, 100 and 200 micrograms/kg (corresponding to 4, 8 and 16 x 10(4) U/animal, respectively) reduced the activities of hepatic microsomal cytochrome P450-dependent monoxygenases to varying degrees. Ethylmorphine-N-demethylase activity fell to 53% of control values, an effect similar to that induced by 2.5 mg/kg Escherichia coli lipopolysaccharide (LPS). Ethoxycoumarin-O-deethylase activity was also sensitive to inhibition, whereas IL6 had little effect on the activities of other P450-dependent enzymes, including ethoxyresorufin-O-deethylase. Pentoxyresorufin dealkylase activity, which is representative of the cytochrome P450 IIB 1/2 subfamily, was unaffected by IL6 whereas LPS reduced it to 33.7% of control values. Another hepatocyte-related parameter, serum concentration of alpha 1-acid glycoprotein (AGP), was increased by up to 3.5-fold over baseline by IL6 and 10-fold by LPS. Recombinant human interleukin-1 beta (rhIL1 beta) (10 micrograms/kg, corresponding to 5 x 10(4) U/rat) and recombinant human tumor necrosis factor alpha (rhTNF) (150 micrograms/kg corresponding to 24 x 10(4) U/rat) were both as potent as LPS (2.5 mg/kg) in increasing serum AGP levels and reducing hepatic microsomal monoxygenase activities. IL6 did not potentiate the effects of rhIL1 beta. Hepatic microsomal glucuronyltransferase activities were little affected by LPS and unaffected by rhIL6. Finally, rhIL6 was more potent after i.p. injection than after i.v. or s.c. injection. These results suggest that the effects of LPS, TNF and IL1 on the mixed-function oxidase system in vivo may be due partly to an induction of IL6 in vivo. The different sensitivities of the enzymes to IL6 but not to IL1 or TNF may be due to the involvement of two distinct mechanisms.

Acute-phase response, interleukin-6, and alteration of cyclosporine pharmacokinetics.

Administration of interleukin‐6 partially reproduces the inhibitory effects of the acute‐phase response on cytochrome P450‐dependent drug metabolism. The aim of the study was to determine whether endogenous cytokine has such an effect in patients treated by cyclosporine, which is metabolized by the cytochrome P4503A subfamily.

Increase in tumor necrosis factor‐α production linked to the toxicity of indomethacin for the rat small intestine

1 The toxic effects of nonsteroidal anti‐inflammatory drugs for the lower gastrointestinal tract share certain features with inflammatory processes, suggesting that the release of inflammation cytokines such as TNF‐α may damage the intestine. 2 Rats received a s.c. injection of indomethacin. Then, jejunum‐ileum was taken up for the quantification of ulcerations, production of TNF‐α, nitrites and PGE2 ex vivo and activity of calcium‐independent NO synthase and myeloperoxydase. Activation of NO metabolism and myeloperoxydase were measured as potential effectors of TNF‐α. 3 Jejunum‐ileum from rats having received indomethacin (10 mg kg−1) produced TNF‐α ex vivo. Cytokine production was associated with the onset of macroscopic ulcerations of the small intestine, and preceded nitrite production and tissue activity of myeloperoxidase. 4 Similar intestinal ulcerations and upregulation of TNF‐α were obtained with flurbiprofen (30 mg kg−1), chemically unrelated to indomethacin. 5 TNF‐α production was proportional to the indomethacin dose (from 3–20 mg kg−1) and correlated with the surface area of ulcerations and nitrite production, 24 h after indomethacin administration. 6 Pretreatment of rats with RO 20‐1724, a type‐IV phosphodiesterase inhibitor which inhibits TNF‐α synthesis, substantially reduced jejunum‐ileum ulcerations, TNF‐α and nitrite production and tissue enzyme activities. 7 These findings provide evidence that TNF‐α is increased in indomethacin‐induced intestinal ulcerations and support suggestions that TNF‐α is involved at an early stage of nonsteroidal anti‐inflammatory drug toxicity for the small intestine.

Network of inflammatory cytokines and correlation with disease activity in ulcerative colitis

Objective:The inflammatory component of most human inflammatory chronic diseases implicates the production of proinflammatory cytokines. Tumor necrosis factor α (TNFα) and interleukin 1β (IL1β) seem to play an important role in ulcerative colitis (UC) in relevant experimental models. Moreover, antiTNF therapy seems promising experimentally and clinically. However, these cytokines, and TNFα more particularly, are hardly seen in vivo in such patients. The mediators of choice, correlated with disease activities or drug efficacy, remain unclear. To characterize in vivo the network of colonic cytokines in patients with UC, and the contribution of the various cytokines to disease activity we performed this study, using the colonic perfusion method.Methods:A 20-cm colon length was perfused. Perfusate samples were collected for cytokine determination by enzyme-linked immnoassays. Nineteen perfusions were performed in mild to moderate UC, including two successive perfusions in four patients. Six healthy control patients and four having Crohns disease (CD) with rectal involvement were studied. Endoscopic score, leukocyte scintigraphy, and systemic markers of inflammation were simultaneously quantified.Results:Large amounts of IL1β, TNFα, IL6, and IL8 were produced in UC patients with a highly significant correlation between TNFα, IL1β and IL8 two by two. Multivariate factorial analysis indicated that IL1β showed the best correlation with disease activity. Locally produced IL6 was strongly associated with circulating platelet counts. Moreover, production of inflammatory cytokines was associated with similar variations of disease activity in the four patients with two successive perfusions performed. The level of inflammatory cytokines in CD was lower than in UC; TNFα, IL1β, and IL6 were not found in any control patients.Conclusions:UC appears to be a chronic inflammatory disease characterized by high production of all four proinflammatory cytokines (IL1β, TNFα, IL6, and IL8). These results suggest that colonic perfusion may be a suitable method to evaluate the local anticytokine properties of new drugs, in correlation with disease activity and systemic markers of inflammation.

Effects of lipopolysaccharide on TNF-α production, hepatic NOS2 activity, and hepatic toxicity in rats with cirrhosis

BACKGROUND/AIMS Septic shock results in high mortality in patients with cirrhosis. Nitric oxide synthase 2 (NOS2) is induced by bacterial lipopolysaccharides (LPS) and plays a major role in the inflammatory response to bacterial infections. Little is known about the regulation of NOS2 in cirrhosis under septic conditions. Thus, the aim of this study was to determine tissue NOS2 activity, serum nitrate and tumor necrosis factor (TNF-alpha) levels and hepatic toxicity in cirrhotic rats after LPS administration. METHODS Serum nitrates, TNF-alpha and transaminases were determined after LPS-administration in rats with secondary biliary cirrhosis and in sham-operated rats. Liver, lung, aortic and peritoneal macrophage NOS2 activities were determined by converting L[14C] arginine into L[14C] citrulline in a calcium free medium. Nitrate and TNF-alpha production were determined in a culture medium of peritoneal macrophages after in vivo LPS administration. RESULTS LPS (1.5 mg/kg) induced 50% mortality in cirrhotic rats and no mortality in sham-operated rats. After LPS, TNF-alpha, nitrate and transaminase levels were significantly higher in cirrhotic rats compared to sham-operated rats. After LPS administration, there were no differences in NOS2 activity in the aorta, lungs, or peritoneal macrophages of the two groups, whereas NOS2 activity was significantly higher in the cirrhotic liver compared to the normal liver. CONCLUSIONS In rats with cirrhosis, LPS administration induces higher mortality, hepatic toxicity, hepatic NOS2 activation and TNF-alpha release than in sham-operated rats. These results confirm the harmful role of septic shock in liver disease.

Anti-tumor necrosis factor properties of non-peptide drugs in acute-phase responses

Dexamethasone (sodium phosphate), pentoxifylline, fusidic acid (sodium salt), pentamidine (isethionate) and R-phenylisopropyladenosine (R-PIA) were tested for their anti-tumor necrosis factor (TNF) activities in an endotoxin-induced shock rat model. All the drugs reduced serum TNF concentrations in a dose-dependent manner, whereas their effects on serum interleukin-6 levels differed. Doses that reduced TNF levels by 50% were 0.012 mg/kg for dexamethasone, 0.06 mg/kg for R-PIA, 0.24 mg/kg for pentamidine, 6.5 mg/kg for fusidic acid and 15 mg/kg for pentoxifylline. Administration of the drugs to rats before intraplantar injection of carrageenan reduced paw edema by 50-70%. Injection of a monoclonal anti-TNF antibody reproduced the inhibitory effect. Moreover, the time course of tissue-associated TNF following carrageenan injection was compatible with mediation of edema by TNF. Results obtained for this acute, non-immunological inflammatory reaction strongly suggest that the model is TNF-dependent. Our results reinforce the idea that TNF is a crucial target in the therapeutics of inflammatory reactions. These drugs, which are able to cross cell barriers, might have clinical applications in localized and/or chronic diseases in which TNF is involved.

Role of tumour necrosis factor-α and inducible nitric oxide synthase in the prevention of nitro-flurbiprofen small intestine toxicity

The present study compares the intestinal toxicity of nitro-flurbiprofen and flurbiprofen in order to determine their differential properties on tumour necrosis factor-alpha production and inducible nitric oxide synthase induction. Rats received one s.c. injection of flurbiprofen, nitro-flurbiprofen at equimolar dose of solvent. Twenty-four hours later, the rats were sacrificed and small intestine tissue was taken up for macroscopical quantification of ulceration, ex vivo production of tumour necrosis factor-alpha and nitrites, and determination of tissue inducible nitric oxide synthase and myeloperoxidase activities. Anti-inflammatory activity was examined in the carrageenan-induced paw edema model. We demonstrated that flurbiprofen induced dose-dependently small intestine production of tumour necrosis factor-alpha, nitrites, myeloperoxidase and inducible nitric oxide synthase activities. On the other hand, nitro-flurbiprofen did neither induce tumour necrosis factor-alpha nor nitrite production. Concurrently, no small intestine ulceration was observed with nitro-flurbiprofen whereas flurbiprofen induced dose-dependent ulceration. Nitro-flurbiprofen is devoid of intestinal toxicity despite inhibiting cyclooxygenase activity. This is associated with the absence of tumour necrosis factor-alpha and inducible nitric oxide synthase induction in normal rats. Nitro-flurbiprofen is an anti-inflammatory drug with a much more favorable gastro-intestinal toxicity profile than flurbiprofen.

Technetium Tc 99m hexamethyl propylene amine oxine leukocyte scintigraphy in patients with ulcerative colitis: correlation with clinical, biologic, endoscopic, and pathologic intensity, and local release of interleukin 8

BACKGROUND Technetium Tc 99m hexamethyl propylene amine oxine (99mTc-HMPAO) has been used to radiolabel leukocytes with promising results for its clinical use in inflammatory bowel disease. During active ulcerative colitis, colonoscopy is indicated to determine the extent and the intensity of the disease for proper management. The aim of this prospective study was to determine whether 99mTc-HMPAO-labeled leukocyte scintigraphy can give information similar to that obtained with colonoscopy during acute attacks of ulcerative colitis. METHODS Thirty-three consecutive patients with 50 acute episodes of ulcerative colitis underwent 99mTc-HMPAO scintigraphy and colonoscopy with biopsies. Scintigraphic determination of disease extent and intensity were compared with those obtained by colonoscopy with biopsies and clinicobiologic markers. RESULTS The scintigraphic index of disease intensity was correlated with endoscopic index, Truelove index, biologic markers, and local release of interleukin-8. The extent measured by scintigraphy was well correlated to the endoscopic and histologic extent. CONCLUSIONS 99mTc-HMPAO scintigraphy accurately determines the extent and the intensity of acute ulcerative colitis lesions. This noninvasive method can specify the extent and the intensity of an acute attack in patients with previously known ulcerative colitis.

Recombinant human interleukin 1β and tumor necrosis factor affect glycosylation of serumα1-acid glycoprotein in rats

Serum concentration and glycosylation of ratα1,-acid glycoprotein (α1-AGP) were evaluated after the in vivo administration of recombinant human interleukin-1β (rhIL-1β) and tumor necrosis factorα (rhTNF-α), alone or associated. The effect of LPS and turpentine was also studied. In all models, serumα1-AGP concentrations were increased and glycosylation was altered. Theα1-AGP levels reached 1.8 g/liter with cytokines alone, 2.1 g/liter with cytokines associated or LPS, and 3.4 g/liter with turpentine. Analysis by concanavalin A (Con A) affinoimmunoelectrophoresis (CAIE) revealed that the relative proportion of Con A unreactive form always decreased whatever the inducing agent. On the other hand, the resulting effect on the concentrations cf Con A unreactiveα1-AGP concentrations was an increase with cytokines alone or LPS and a decrease with cytokines associated or turpentine. These results suggest a dissociation between the alteration in the level ofα1-AGP synthesis and in the pattern of its glycosylation in the various inflammatory models.