A.H.M. Nurun Nabi

Prorenin Receptor Blockade Inhibits Development of Glomerulosclerosis in Diabetic Angiotensin II Type 1a Receptor–Deficient Mice

Blockade of the renin-angiotensin system slows the progression of diabetic nephropathy but fails to abolish the development of end-stage nephropathy of diabetes. The prorenin-to-active renin ratio significantly increases in diabetes, and prorenin binding to its receptor in diabetic animal kidney induces the nephropathy without its conventional proteolytic activation, suggesting that angiotensin II (AngII) may not be the decisive factor causing the nephropathy. For identification of an AngII-independent mechanism, diabetes was induced in wild-type mice and AngII type 1a receptor gene-deficient mice by streptozotocin treatment, and their development and progression of diabetic nephropathy were assessed. In addition, prolonged inhibition of angiotensin-converting enzyme and prolonged prorenin receptor blockade were compared for their efficacy in preventing the nephropathy that occurred in diabetic AngII type 1a receptor gene-deficient mice. Only the prorenin receptor blockade with a short peptide of prorenin practically abolished the increased mitogen-activated protein kinase (MAPK) activation and nephropathy despite unaltered increase in AngII in diabetic kidney. These results indicate that the MAPK activation signal leads to the diabetic nephropathy but not other renin-angiotensin system-activated mechanisms in the glomeruli. It is not only AngII but also intraglomerular activation of MAPK by the receptor-associated prorenin that plays a pivotal role in diabetic nephropathy.

Slowly Progressive, Angiotensin II–Independent Glomerulosclerosis in Human (Pro)renin Receptor–Transgenic Rats

For defining the pathogenic effects of the (pro)renin receptor-transgenic rat, strains that overexpressed the human receptor were generated. Although transgenic rats were normotensive and euglycemic and had a renal angiotensin II (AngII) level that was comparable to that of wild-type rats, transgenic rats developed proteinuria with aging and significant glomerulosclerosis at 28 wk of age. In kidneys of 28-wk-old transgenic rats, mitogen-activated protein kinases (MAPK) were activated without recognizable tyrosine phosphorylation of the EGF receptor, and expression of TGF-beta1 was enhanced. In vivo infusion of the (pro)renin receptor blocker peptide (formerly handle region decoy peptide) significantly inhibited the development of glomerulosclerosis, proteinuria, MAPK activation, and TGF-beta1 expression in the kidneys, but the angiotensin-converting enzyme inhibitor did not attenuate these changes despite a significant decrease in the renal AngII level. In addition, recombinant rat prorenin stimulated MAPK activation in the human receptor-expressed cultured cells, but human receptor was unable to evoke the enzyme activity of rat prorenin. Thus, human (pro)renin receptor elicits slowly progressive nephropathy by AngII-independent MAPK activation in rats. This study clearly provided in vivo evidence for the AngII-independent MAPK activation by human (pro)renin receptor and induction of glomerulosclerosis with increased TGF-beta1 expression.

(Pro)Renin Receptor–Mediated Activation of Mitogen-Activated Protein Kinases in Human Vascular Smooth Muscle Cells

Blockade of (pro)renin receptor has benefits in diabetic angiotensin II type-1a-receptor–deficient mice, suggesting the importance of (pro)renin receptor–mediated intracellular signals. To determine the mechanism whereby the human (pro)renin receptor activates mitogen-activated protein kinases in human vascular smooth muscle cells (hVSMC), we treated the cells with recombinant human prorenin. Prorenin enhanced hVSMC proliferation and activated extracellular-signal–related protein kinase (ERK) in a dose- and time-dependent manner but did not influence activation of p38 or c-Jun NH2-terminal kinase. The activated ERK level was reduced to the control level by the tyrosine kinase inhibitor genistein, and the MEK inhibitor U0126 markedly reduced the activated ERK level to the control level, whereas the level of activated ERK was unaffected by the angiotensin-converting enzyme inhibitor imidaprilat or the angiotensin II receptor blocker candesartan. A human (pro)renin receptor was present in hVSMCs, and its knockdown with small interfering RNA (siRNA) significantly inhibited the prorenin-induced ERK activation. These results suggest that prorenin stimulates ERK phosphorylation in hVSMCs through the receptor-mediated activation of tyrosine kinase and subsequently MEK, independently of the generation of angiotensin II or the activation of its receptor. The (pro)renin receptor–mediated ERK signal transduction is thus a possible new therapeutic target for preventing vascular complications.

Renal Sympathetic Denervation Suppresses De Novo Podocyte Injury and Albuminuria in Rats With Aortic Regurgitation

Background— The presence of chronic kidney disease is a significant independent risk factor for poor prognosis in patients with chronic heart failure. However, the mechanisms and mediators underlying this interaction are poorly understood. In this study, we tested our hypothesis that chronic cardiac volume overload leads to de novo renal dysfunction by coactivating the sympathetic nervous system and renin-angiotensin system in the kidney. We also examined the therapeutic potential of renal denervation and renin-angiotensin system inhibition to suppress renal injury in chronic heart failure. Methods and Results— Sprague-Dawley rats underwent aortic regurgitation and were treated for 6 months with vehicle, olmesartan (an angiotensin II receptor blocker), or hydralazine. At 6 months, albuminuria and glomerular podocyte injury were significantly increased in aortic regurgitation rats. These changes were associated with increased urinary angiotensinogen excretion, kidney angiotensin II and norepinephrine (NE) levels, and enhanced angiotensinogen and angiotensin type 1a receptor gene expression and oxidative stress in renal cortical tissues. Aortic regurgitation rats with renal denervation had decreased albuminuria and glomerular podocyte injury, which were associated with reduced kidney NE, angiotensinogen, angiotensin II, and oxidative stress. Renal denervation combined with olmesartan prevented podocyte injury and albuminuria induced by aortic regurgitation. Conclusions— In this chronic cardiac volume-overload animal model, activation of the sympathetic nervous system augments kidney renin-angiotensin system and oxidative stress, which act as crucial cardiorenal mediators. Renal denervation and olmesartan prevent the onset and progression of renal injury, providing new insight into the treatment of cardiorenal syndrome.

Association of respiratory complications and elevated serum immunoglobulins with drinking water arsenic toxicity in human.

We assessed the relationship between chronic arsenic exposure through drinking water with respiratory complications and humoral immune response by measuring serum immunoglobulin profiles in the affected subjects (arsenicosis patients) living in the arsenic endemic rural villages of Bangladesh. The duration of exposure was determined through detailed history of the patients (n = 125) and the levels of arsenic in the drinking water and urine samples were determined. The mean duration of exposure in the patients was 7.4 ± 5.3 y, and the levels of arsenic in the drinking water and urine samples were 216 ± 211 and 223 ± 302 μ g/L, respectively, compared to 11 ± 20 and 29 ± 19 μ g/L, respectively, in the unexposed subjects. There was high prevalence of respiratory complications like breathing problems including chest sound, asthma, bronchitis and cough associated with drinking water arsenic toxicity. Arsenicosis patients had significantly elevated levels of IgG (P < 0.001) and IgE (P < 0.001) while the levels of IgA were also significantly higher (P < 0.005) but IgM were similar to that of the control subjects. Analysis of the clinical symptoms based on skin manifestations showed the levels of both IgG and IgE were significantly elevated during the initial stages while IgE were further elevated with the duration of arsenic exposure. Arsenicosis patients with respiratory complications had mean serum IgE levels of 706 ± 211 IU/mL compared to 542 ± 241 IU/mL in patients without apparent involvement with the respiratory system (P < 0.01). The eosinophil counts in the patients did not differ significantly from the unexposed subjects indicating that elevated levels of serum IgE might not be due to allergic diseases, rather it could be due to direct effects of arsenic. We found significant linear relationships between the levels of serum IgE and inorganic phosphorus (P < 0.05), and serum IgA levels with urinary excretion of arsenic (P < 0.001). These observations suggested that arsenic toxicity caused respiratory complications, induced changes in the humoral as well as mucosal immune responses.

Prediction of epitope-based peptides for the utility of vaccine development from fusion and glycoprotein of nipah virus using in silico approach.

This study aims to design epitope-based peptides for the utility of vaccine development by targeting glycoprotein G and envelope protein F of Nipah virus (NiV) that, respectively, facilitate attachment and fusion of NiV with host cells. Using various databases and tools, immune parameters of conserved sequence(s) from G and F proteins of different isolates of NiV were tested to predict probable epitope(s). Binding analyses of the peptides with MHC class-I and class-II molecules, epitope conservancy, population coverage, and linear B cell epitope prediction were analyzed. Predicted peptides interacted with seven or more MHC alleles and illustrated population coverage of more than 99% and 95%, for G and F proteins, respectively. The predicted class-I nonamers, SLIDTSSTI and EWISIVPNF, superimposed on the putative decameric B cell epitopes, were also identified as core sequences of the most probable class-II 15-mer peptides GPKVSLIDTSSTITI and EWISIVPNFILVRNT. These peptides were further validated for their binding to specific HLA alleles using in silico docking technique. Our in silico analysis suggested that the predicted epitopes, either GPKVSLIDTSSTITI or EWISIVPNFILVRNT, could be a better choice as universal vaccine component against NiV irrespective of different isolates which may elicit both humoral and cell-mediated immunity.

Expression of functional human (pro)renin receptor in silkworm (Bombyx mori) larvae using BmMNPV bacmid

The circulating RA (renin–angiotensin) system is essential for the regulation of blood pressure and electrolyte balance. Recently, plasma prorenin has been reported to significantly increase its level in diabetes and to be possibly non‐proteolytically activated by binding to the PRR [(pro)renin receptor] on the cell membrane reported in several tissues during circulation. Although many pathological aspects have been researched, there is a lack of sufficient information on the biochemical structure and biological function of this hPRR (human PRR) because of the difficulty in increasing hPRR expression. In the present study, GFPuv–hPRR (hPRR fused with green fluorescence protein when excited with long‐wave UV light) was successfully expressed by using BmMNPV (Bombyx mori multiple nucleopolyhedrovirus) bacmid DNA in silkworm (Bombyx mori) larvae. Some of the hPRR was expressed in the haemolymph of silkworm larvae and some of the hPRR was located in the fat body of silkworm larvae. The binding ability of hPRR expressed in the haemolymph and fat body with renin or prorenin was analysed by ELISA and surface plasmon resonance using a biosensor respectively. These binding assays suggest that the expressed hPRR has a functional bioactivity. hPRR preparation in silkworm larvae would, therefore, be useful for biochemical and biomedical researches related to PRR.

Function of Serum Complement in Drinking Water Arsenic Toxicity

Serum complement function was evaluated in 125 affected subjects suffering from drinking water arsenic toxicity. Their mean duration of exposure was 7.4 ± 5.3 yrs, and the levels of arsenic in drinking water and urine samples were 216 ± 211 and 223 ± 302 μg/L, respectively. The mean bactericidal activity of complement from the arsenic patients was 92% and that in the unexposed controls was 99% (P < 0.01), but heat-inactivated serum showed slightly elevated activity than in controls. In patients, the mean complement C3 was 1.56 g/L, and C4 was 0.29 g/L compared to 1.68 g/L and 0.25 g/L, respectively, in the controls. The mean IgG in the arsenic patients was 24.3 g/L that was highly significantly elevated (P < 0.001). Arsenic patients showed a significant direct correlation between C3 and bactericidal activity (P = 0.014). Elevated levels of C4 indicated underutilization and possibly impaired activity of the classical complement pathway. We conclude reduced function of serum complement in drinking water arsenic toxicity.

Analyses of Genetic Variations of Glutathione S-Transferase Mu1 and Theta1 Genes in Bangladeshi Tannery Workers and Healthy Controls

Glutathione S-transferases (GSTs) belong to a group of multigene detoxification enzymes, which defend cells against oxidative stress. Tannery workers are at risk of oxidative damage that is usually detoxified by GSTs. This study investigated the genotypic frequencies of GST Mu1 (GSTM1) and GST Theta1 (GSTT1) in Bangladeshi tannery workers and healthy controls followed by their status of oxidative stress and total GST activity. Of the 188 individuals, 50.0% had both GSTM1 and GSTT1 (+/+), 12.2% had GSTM1 (+/−), 31.4% had GSTT1 (−/+) alleles, and 6.4% had null genotypes (−/−) with respect to both GSTM1 and GSTT1 alleles. Among 109 healthy controls, 54.1% were double positive, 9.2% had GSTM1 allele, 32.1% had GSTT1 allele, and 4.6% had null genotypes. Out of 79 tannery workers, 44.3% were +/+, 16.8% were +/−, 30.5% were −/+, and 8.4% were −/−. Though the polymorphic genotypes or allelic variants of GSTM1 and GSTT1 were distributed among the study subjects with different frequencies, the differences between the study groups were not statistically significant. GST activity did not vary significantly between the two groups and also among different genotypes while level of lipid peroxidation was significantly higher in tannery workers compared to controls irrespective of their GST genotypes.

Application of the Subtractive Genomics and Molecular Docking Analysis for the Identification of Novel Putative Drug Targets against Salmonella enterica subsp. enterica serovar Poona

The emergence of novel pathogenic strains with increased antibacterial resistance patterns poses a significant threat to the management of infectious diseases. In this study, we aimed at utilizing the subtractive genomic approach to identify novel drug targets against Salmonella enterica subsp. enterica serovar Poona strain ATCC BAA-1673. We employed in silico bioinformatics tools to subtract the strain-specific paralogous and host-specific homologous sequences from the bacterial proteome. The sorted proteome was further refined to identify the essential genes in the pathogenic bacterium using the database of essential genes (DEG). We carried out metabolic pathway and subcellular location analysis of the essential proteins of the pathogen to elucidate the involvement of these proteins in important cellular processes. We found 52 unique essential proteins in the target proteome that could be utilized as novel targets to design newer drugs. Further, we investigated these proteins in the DrugBank databases and 11 of the unique essential proteins showed druggability according to the FDA approved drug bank databases with diverse broad-spectrum property. Molecular docking analyses of the novel druggable targets with the drugs were carried out by AutoDock Vina option based on scoring functions. The results showed promising candidates for novel drugs against Salmonella infections.