Kaliyamurthi Venkatachalam
@tnfu.ac.in
EDUCATION
PhD., PDF
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Modi Kiran Piyushbhai, Ambika Binesh, S. A. Shanmugam, and Kaliyamurthi Venkatachalam
Springer Science and Business Media LLC
Modi K. P. Bhai, Ambika Binesh, S. A. Shanmugam, and Kaliyamurthi Venkatachalam
Wiley
AbstractIn this study, a zebrafish embryo toxicity model was employed, utilizing 24 h postfertilization (hpf) zebrafish embryos. These embryos were treated with varying concentrations of mercuric chloride for 96 h under static conditions. We assessed multiple parameters that reflected developmental abnormalities, behavioral alterations, morphological anomalies, antioxidant enzyme activities, including those of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione S‐transferase (GST), immune messenger RNA transcription levels of key factors such as tumor necrosis factor α (TNF‐α), interleukin‐1β (IL‐1β), interleukin‐6 (IL‐6), and cyclooxygenase 2 (COX‐2), as well as protein expression of TNF‐α. The results revealed that embryos exposed to higher concentrations of mercury exhibited reduced hatchability and increased rates of morphological abnormalities and mortality at 48, 72, and 96 hpf. In addition, a concentration‐dependent increase in developmental abnormalities, including cardiac edema, reduced body length, yolk sac edema, scoliosis, and bent tails, was observed. Larval behaviors, such as touch‐induced escape responses, startle reactions, and turning actions, were found to be diminished in a concentration‐dependent manner. Additionally, the activities of various antioxidative enzymes, such as SOD, CAT, and GST, exhibited an increase at higher mercury concentrations, with the exception of GPX activity, which decreased significantly in a dose‐dependent manner (p < 0.05). Pro‐inflammatory cytokine transcription levels, specifically TNF‐α, IL‐1β, IL‐6, and COX‐2, were significantly upregulated in a dose‐dependent manner in the mercuric (II) chloride (HgCl2) treatment group compared with the control group. TNF‐α protein expression was notably elevated in the larvae group treated with 300 and 400 nM HgCl2.
Balachandar Venkatesan, Sumanth D. Prabhu, Kaliyamurthi Venkatachalam, Srinivas Mummidi, Anthony J. Valente, Robert A. Clark, Patrice Delafontaine, and Bysani Chandrasekar
Elsevier BV
Kaliyamurthi Venkatachalam, Balachandar Venkatesan, Anthony J. Valente, Peter C. Melby, Sailesh Nandish, Jane E.B. Reusch, Robert A. Clark, and Bysani Chandrasekar
Elsevier BV
WNT1-inducible signaling pathway protein-1 (WISP1), a member of the CYR61/CTGF/Nov family of growth factors, can mediate cell growth, transformation, and survival. Previously we demonstrated that WISP1 is up-regulated in post-infarct heart, stimulates cardiac fibroblast proliferation, and is induced by the proinflammatory cytokine tumor necrosis factor-α (TNF-α). Here we investigated (i) the localization of TNF-α and WISP1 in post-infarct heart, (ii) the mechanism of TNF-α-mediated WISP1 induction in primary human cardiac fibroblasts (CF), (iii) the role of WISP1 in TNF-α-mediated CF proliferation and collagen production, and (iv) the effects of WISP1 on TNF-α-mediated cardiomyocyte death. TNF-α and WISP1 expressions were increased in the border zones and non-ischemic remote regions of the post-ischemic heart. In CF, TNF-α potently induced WISP1 expression in cyclic AMP response element-binding protein (CREB)-dependent manner. TNF-α induced CREB phosphorylation in vitro and DNA binding and reporter gene activities in vivo. TNF-α induced CREB activation via ERK1/2, and inhibition of ERK1/2 and CREB blunted TNF-α-mediated WISP1 induction. Most importantly, WISP1 knockdown attenuated TNF-α stimulated collagen production and CF proliferation. Furthermore, WISP1 attenuated TNF-α-mediated cardiomyocyte death, thus demonstrating pro-mitogenic and pro-survival effects for WISP1 in myocardial constituent cells. Our results suggest that a TNF-α/WISP1 signaling pathway may contribute to post-infarct cardiac remodeling, a condition characterized by fibrosis and progressive cardiomyocyte loss.
Kaliyamurthi Venkatachalam, Sumanth D. Prabhu, Venkatapuram Seenu Reddy, William H. Boylston, Anthony J. Valente, and Bysani Chandrasekar
Elsevier BV
Ischemia/reperfusion (I/R) injury is characterized by the induction of oxidative stress and proinflammatory cytokine expression. Recently demonstrating that oxidative stress and TNF-α each stimulate interleukin (IL)-18 expression in cardiomyocytes, we hypothesized that I/R also induces IL-18 expression and thus exacerbates inflammation and tissue damage. Neutralization of IL-18 signaling should therefore diminish tissue injury following I/R. I/R studies were performed using a chronically instrumented closed chest mouse model. Male C57BL/6 mice underwent 30 min of ischemia by LAD coronary artery ligation followed by various periods of reperfusion. Sham-operated or ischemia-only mice served as controls. A subset of animals was treated with IL-18-neutralizing antibodies 1 h prior to LAD ligation. Ischemic LV tissue was used for analysis. Our results demonstrate that, compared with sham operation and ischemia alone, I/R significantly increased (i) oxidative stress (increased MDA/4-HNE levels), (ii) neutrophil infiltration (increased MPO activity), (iii) NF-κB DNA binding activity (p50, p65), and (iv) increased expression of IL-18Rβ, but not IL-18Rα or IL-18BP transcripts. Administration of IL-18-neutralizing antibodies significantly reduced I/R injury measured by reduced infarct size (versus control IgG). In isolated adult mouse cardiomyocytes, simulated ischemia/reperfusion enhanced oxidative stress and biologically active IL-18 expression via IKK-dependent NF-κB activation. These results indicate that IL-18 plays a critical role in I/R injury and thus represents a promising therapeutic target.
Bysani Chandrasekar, William H. Boylston, Kaliyamurthi Venkatachalam, Nicholas J.G. Webster, Sumanth D. Prabhu, and Anthony J. Valente
Elsevier BV
The adipocyte-derived cytokine adiponectin is known to exert anti-inflammatory and anti-apoptotic effects. In patients with atherosclerotic cardiovascular disease, circulating levels of adiponectin correlate inversely with those of the proinflammatory, proapoptotic cytokine interleukin (IL)-18. The opposing actions of IL-18 and adiponectin on both cell survival and inflammation led us to investigate whether adiponectin signaling antagonizes IL-18-mediated endothelial cell death and to identify the underlying molecular mechanisms. Treatment with IL-18 suppressed Akt phosphorylation and its associated kinase activity, induced IκB kinase (IKK)-NF-κB-dependent PTEN activation, and promoted endothelial cell death. Pretreatment with adiponectin stimulated APPL1-dependent AMPK activation, reversed Akt inhibition in a phosphatidylinositol 3-kinase-dependent manner, blocked IKK-NF-κB-PTEN signaling, reduced caspase-3 activity, blocked Bax translocation, and inhibited endothelial cell death. The cytoprotective effect of adiponectin signaling was recapitulated by treatment with the pharmacological AMPK activator 5-aminoimidazole-4-carboxamide-1-β-riboside. Collectively, these results demonstrated that adiponectin reverses IL-18-mediated endothelial cell death through an AMPK-associated mechanism, which may thus have therapeutic potential for diminishing IL-18-dependent vascular injury and inflammation.
Kaliyamurthi Venkatachalam, Srinivas Mummidi, Dolores M. Cortez, Sumanth D. Prabhu, Anthony J. Valente, and Bysani Chandrasekar
American Physiological Society
We investigated the expression of the proinflammatory cytokine interleukin (IL)-17 in cardiac fibroblasts and its induction by high glucose (HG). Our results show that primary mouse cardiac fibroblasts (mCFs) secrete low basal levels of IL-17 and that HG (25 mM d-glucose) as opposed to low glucose (5 mM d-glucose + 20 mM mannitol) significantly enhances its secretion. HG induces IL-17 mRNA expression by both transcriptional and posttranscriptional mechanisms. HG induces phosphoinositide 3- kinase [PI3K; inhibited by adenoviral (Ad).dominant negative (dn)PI3Kp85], Akt (inhibited by Ad.dnAkt1), and ERK (inhibited by PD-98059) activation and induces IL-17 expression via PI3K→Akt→ERK-dependent signaling. Moreover, mCFs express both IL-17 receptors A and C, and although IL-17RA is upregulated, HG fails to modulate IL-17RC expression. Furthermore, IL-17 stimulates net collagen production by mCFs. Pretreatment with the phytoalexin resveratrol blocks HG-induced PI3K-, Akt-, and ERK-dependent IL-17 expression. These results demonstrate that 1) cardiac fibroblasts express IL-17 and its receptors; 2) HG upregulates IL-17 and IL-17RA, suggesting a positive amplification loop in IL-17 signaling in hyperglycemia; 3) IL-17 enhances net collagen production; and 4) resveratrol can inhibit these HG-induced changes. Thus, in hyperglycemic conditions, IL-17 may potentiate myocardial inflammation, injury, and remodeling through autocrine and paracrine mechanisms, and resveratrol has therapeutic potential in ameliorating this effect.
Devang N. Patel, Carter A. King, Steven R. Bailey, Jeffrey W. Holt, Kaliyamurthi Venkatachalam, Alok Agrawal, Anthony J. Valente, and Bysani Chandrasekar
Elsevier BV
Elevated systemic levels of the acute phase C-reactive protein (CRP) are predictors of future cardiovascular events. There is evidence that CRP may also play a direct role in atherogenesis. Here we determined whether the proinflammatory interleukin (IL)-17 stimulates CRP expression in hepatocytes (Hep3B cell line and primary hepatocytes) and coronary artery smooth muscle cells (CASMC). Our results demonstrate that IL-17 potently induces CRP expression in Hep3B cells independent of IL-1β and IL-6. IL-17 induced CRP promoter-driven reporter gene activity that could be attenuated by dominant negative IκBα or C/EBPβ knockdown and stimulated both NF-κB and C/EBP DNA binding and reporter gene activities. Targeting NF-κB and C/EBPβ activation by pharmacological inhibitors, small interfering RNA interference and adenoviral transduction of dominant negative expression vectors blocked IL-17-mediated CRP induction. Overexpression of wild type p50, p65, and C/EBPβ stimulated CRP transcription. IL-17 stimulated p38 MAPK and ERK1/2 activation, and SB203580 and PD98059 blunted IL-17-mediated NF-κB and C/EBP activation and CRP transcription. These results, confirmed in primary human hepatocytes and CASMC, demonstrate for the first time that IL-17 is a potent inducer of CRP expression via p38 MAPK and ERK1/2-dependent NF-κB and C/EBPβ activation and suggest that IL-17 may mediate chronic inflammation, atherosclerosis, and thrombosis.