Effects of alpha-melanocyte stimulating hormone on the expression of intercellular adhesion molecule-1 and renal function in acute ischemic renal failure in rats / 대한내과학회지

BACKGROUND: Acute renal failure is a reversible process in majority of cases but mechanisms of renal injury or recovery are poorly understood. Recently neutrophil infiltration is reported to potentiate inflammatory and cytotoxic cascade in ischemic renal injury and alpha-melanocyte stimulating hormone has been reported to have a potent anti-inflammatory properties in a variety of animal models. We examined the beneficial effects of alpha-MSH in acute ischemic renal injury in rats and tried to clarify its action mechanism. METHODS: After unilateral nephrectomy, renal artery of contralateral kidney was clamped for 40 minutes and reperfused in female Sprague-Dawley rats. alpha-MSH (50(mu)g) and vehicle was injected intraperitoneally immediately after and 6, 24 hours after reperfusion. Biochemical, histological data, ICAM-1 mRNA, protein expressions and polymorphonuclear cell infiltration were examined. RESULTS: alpha-MSH significantly attenuated the renal injury, measured by plasma BUN and creatinine level and also the degree of severity of histological injury (BUN 125.2+/-14.6 mg/dL : 46+/-19.6 mg/dL (p=0.004), creatinine 3.65+/-0.81 mg/dL : 1.47+/-0.5 mg/dL (p=0.005) at 24 hours after reperfusion, BUN 88+/-12.5 mg/dL : 25.5+/-15.8mg/dl (p=0.002), creatinine 2.76+/-0.5 mg/dL : 0.93+/-0.2 mg/dL (p=0.002) at 72 hours after reperfusion and 5.4+/-1.94/ 2.6+/-0.77 (p=0.006) at 24 hours after reperfusion in histilogical grading system). In the alpha-MSH treated groups, ICAM-1 mRNA expression decreased significantly compared to the vehicle treated ischemic group in 72 hours after reperfusion (0.49+/-0.01/0.31+/-0.2, p<0.008). ICAM-1 protein expression also decreased in alpha-MSH treated group, but it was not statistically significant. Polymorphonuclear cell infiltration showed a significant decrease in the alpha-MSH treated group at 24 hours after reperfusion (5.05+/-1.8/1.59+/-0.4, p=0.009). CONCLUSION: alpha-MSH attenuates ischemic renal injury by inhibiting the expression of ICAM-1 and subsequent polymorphonuclear cell infiltration. These results provide a rationale of alpha-MSH as a potential therapeutic drug in acute renal failure.

Peripheral Blood Mononuclear Cell Culture Supernatant Increase Fas Expression in human Proximal Tubular Cell After the Initiation of Hemodialysis in Chronic Renal Failure Patients / 대한신장학회잡지

Residual renal function rapidly declines after the initiation of hemodialysis and its mechanisms are supposed to be associated with frequent hypotensive episodes during hemodialysis and subsequent ischemic injury to remnant nephron, but blood-membrane interaction might play an important role because of its ability to activate complement system and other various humoral and cellular mechanisms. Blood monocytes are activated by complements, bacterial contaminants and activated monocytes are known to secrete multiple proinflammatory cytokines such as TNF-alpha, IL-1 beta. The expression of TNF-alpha and IL-1 beta in mRNA and protein level were examined by RT-PCR and ELISA respectively in patients with ESRD after the initiation of hemodialysis. Author also investigated the mRNA expression of Fas in human proximal tubular cell culture in the presence of TNF-alpha and PBMC culture supernatant before and after the initiation of hemodialysis. Compared to PBMC separated before the initiation of HD, the amount of cytokine mRNA from PBMC separated after the initiation of HD showed increased tendency from 0.97+/-0.2 to 1.12+/-0.28 for TNF-alpha(p=0.29), from 1.03+/-0.18 to 1.10+/-027 for IL-1 beta (p=0.54). TNF-alpha and IL-l beta protein level in PBMC culture supernatant also showed increased tendency from 2.25+/-0.5 to 4.254+/-3.77 for TNF-alpha (p=0.10), from 3.5+/-2.08 to 4.0+/-4.3 for IL-1 beta(p=0,25). TNF-alpha increased Fas mRNA expression dose-dependently compared to control but it was not statistically significant(p=0,37, 0.22). Compared to the the level of Fas expression in HPTC cultured in the presence of pre HD PBMC supernatant, the level of Fas expression increased significantly in the presence of post HD PBMC supernatant (0.64+/- 057 vs 1.05+/- 0.12, p=0.01). As a conclusion, cytokine gene expression and secretion can increase as a result of blood-membrane interaction and these might have some influence on the loss of residual renal function in CRF patients maintained on hemodialysis.

Effects of alpha-Melanocyte Stimulating Hormone on Apoptosis and Fas Expression in Ischemic Renal Injury in Rats / 대한신장학회잡지

Apoptosis frequently occurs in acute renal injury but molecular mechanisms responsible for this distinct form of cell death are largely unknown. Fas belongs to the TNF/nerve growth factor superfamily and engagement by Fas ligand induces apoptosis in various epithelial cells. To investigate the role of apoptosis and associated molecular mechanisms, we examined the occurrence of apoptosis and Fas expression as well as the therapeutic effect of alpha-MSH, a potent anti-inflammatory cytokine in ischemic ARF rat model as well as its effect on Fas expression. The expression of Fas was studied by western blot analysis and semiquantitative RT-PCR. Apoptosis was assessed by the TUNEL method and the degree of apoptosis and Fas expression, as well as biochemical, histological data were compared between the alpha-MSH and the vehicle treated groups in 40 minute renal artery clamping ischemic ARF rat models. Intraperitoneally administered alpha-MSH significantly reduced renal injury, measured by plasma blood urea nitrogen, creatinine level and the degree of tubular necrosis(106.5+/-13.3/54.7+/-5.45mg/dL for BUN, 1.77+/-0.29/1.03+/-0.06mg/dL for creatinine 24 hours after ischemia)(p=0.003, p=0.01), (5.4+/-1.94/2.6+/-0.7 for injury score 24 hours after ischemia)(p=0.01). Ischemia caused significant upregulation of Fas mRNA and protein and was accompanied by morphological evidence of apoptosis. alpha-MSH significantly reduced the degree of apoptosis, as well as Fas[(mean apoptotic cell : 23.7+/-12.5/11.0+/-5.7 per 200 field at 4 hours after ischemia(p=0.04), 31.6+/-24.7/18.1+/-11.5 per 200 field at 24 hours after ischemia(p=0.25)]. (Fas protein expression : sham : 1409+/-355DI(densitometric index)) 2818.3+/-1100/1306+/-643.4DI at 24 hours and 5541.5+/-1597.5/ 2866.7+/-788.9DI at 72 hours after ischemia)(p=0.07, 0.047). These results suggest that Fas upregulation induced tubular cell apoptosis may contribute to the pathogenesis of ischemic ARF and the beneficial effect of alpha-MSH is partially mediated by these inhibitory effects on Fas system.