Renin-angiotensin system inhibitors reduce the progression of mesangioproliferative glomerulonephritis: 10 year follow-up

Primary membranoproliferative glomerulonephritis in Sfax, Tunisia: epidemiologic profile and prognostic factors

Introduction

membranoproliferative glomerulo nephritis (MPGN) is a rare kidney disease with a poor prognosis as 50% of patients attend the end stage renal failure after 10 years of follow up. Several factors have been described associated with poor renal prognosis. The aim of our study is to determine the epidemiologic profile and to identify prognostic factors of MPGN.

Methods

our study is retrospective over a period of 16 years (January 1996 - December 2011) including all cases of primary MPGN aged more than 15 years, collected at the nephrology department of Hedi Chaker University Hospital, Sfax, Tunisia.

Results

we collected 118 cases of primary MPGN, with mean age of 45 (SD 19) years. The incidence of MPGN has decreased from 10 cases/year between 1996 and 1999 to 5 cases/year between 2008 and 2011. Seventy-nine percent of patients (n=93) had renal failure at the moment of diagnosis (e-GFR less than 60 ml/min/1.73m²;). After a mean follow-up of 51.9 (SD 44) months, progression to end stage renal failure was observed in 43.5% of followed cases (n=20). On univariate analysis, factors associated with death or progression to end stage renal failure were initial renal failure and sclerotic glomeruli (respectively p at 0.040 and 0.032). Multivariate analysis indicated that initial renal failure was significantly correlated with death or progression to end stage renal failure (HR: 0.14, 95% CI (0.033-0.593), p=0.008).

Conclusion

there has been a decline in the number of cases of MPGN diagnosed in our hospital. The presence of renal failure at diagnosis was associated with death or progression to end stage renal failure.

Influence of angiotensin-converting enzyme inhibitor ramipril on indicators of tubular kidney lesion in patients with chronic glomerulonephritis

To research and deepen the understanding of the links between morphological tubular kidney lesion parameters and serum markers – neutrophil gelatinase-associated lipocalin (NGAL) and interleukin-18 (IL-18), in patients with chronic glomerulonephritis (CGN) with saved renal function, as well as to estimate therapeutic correction of identified changes using ACE inhibitor ramipril. The diagnosis of “chronic glomerulonephritis” was verified based on clinical, laboratory and morphological data. Patients were divided into 2 clinical groups: patients with CGN and arterial hypertension (AH) and without AH. We used the data of renal biopsies to analyze the indicators of tubular kidney lesion in patients with CGN. Levels of serum NGAL and IL-18 were measured by means of ELISA kits. Treatment of patients was carried out over 24 weeks using the ACE inhibitor ramipril. The average daily dose of ramipril for the entire treatment period for patients with AH was 12.8±5.6 mg, patients of the second group – without AH, were treated with ramipril at a dose of 2.5 mg. On the basis of rank correlation analysis, we demonstrated that the level of serum NGAL is directly correlated with interstitial fibrosis (r=0.65; p<0.05), serum IL-18 – with dystrophic changes in the epithelium of renal tubules (r=0.81; p<0.05).

Conclusion. Serum levels of NGAL and IL-18 are one of the most sensitive markers of tubular kidney lesion and have diagnostic efficiency up to 97%. A 24-week treatment with ACE inhibitor ramipril in patients with CGN with and without AH leads to a decrease in the levels of tubular kidney lesion markers.

Inhibition of Glycoprotein VI Clustering by Collagen as a Mechanism of Inhibiting Collagen-Induced Platelet Responses: The Example of Losartan

Exposure of platelets to collagen triggers the formation of a platelet clot. Pharmacological agents capable of inhibiting platelet activation by collagen are thus of potential therapeutic interest. Thrombus formation is initiated by the interaction of the GPIb-V-IX complex with collagen-bound vWF, while GPVI interaction with collagen triggers platelet activation that is reinforced by ADP and thromboxane A2. Losartan is an angiotensin II (Ang II) type I receptor (AT1R) antagonist proposed to have an antiplatelet activity via the inhibition of both the thromboxane A2 (TXA2) receptor (TP) and the glycoprotein VI (GPVI). Here, we characterized in vitro the effects of losartan at different doses on platelet responses: losartan inhibited platelet aggregation and secretion induced by 1 μg.mL^-1 and 10 μg.mL^-1 of collagen with an IC50 of ~ 6 μM. Losartan inhibited platelet responses induced by the GPVI specific collagen related peptide but not by the α2β1 specific peptide. However, losartan did not inhibit the binding of recombinant GPVI to collagen, which is not in favor of a simple competition. Indeed, the clustering of GPVI observed in flow cytometry and using the Duolink methodology, was inhibited by losartan. The impact of a therapeutic dose of losartan (100 mg/day) on platelet responses was analyzed ex vivo in a double blind study. No statistically significant differences were observed between losartan-treated (n=25) and non-treated (n=30) patients in terms of collagen and U46619-induced platelet activation. These data indicate that in treated patients, losartan does not achieve a measurable antiplatelet effect but provide the proof of concept that inhibiting collagen-induced GPVI clustering is of pharmacological interest to obtain an antithrombotic efficacy.