The effect of Walterinnesia aegyptia venom proteins on TCA cycle activity and mitochondrial NAD(+)-redox state in cultured human fibroblasts

Comprehensive investigations of key mitochondrial metabolic changes in senescent human fibroblasts

There is a paucity of detailed data related to the effect of senescence on the mitochondrial antioxidant capacity and redox state of senescent human cells. Activities of TCA cycle enzymes, respiratory chain complexes, hydrogen peroxide (H₂O₂), superoxide anions (SA), lipid peroxides (LPO), protein carbonyl content (PCC), thioredoxin reductase 2 (TrxR2), superoxide dismutase 2 (SOD2), glutathione peroxidase 1 (GPx1), glutathione reductase (GR), reduced glutathione (GSH), and oxidized glutathione (GSSG), along with levels of nicotinamide cofactors and ATP content were measured in young and senescent human foreskin fibroblasts. Primary and senescent cultures were biochemically identified by monitoring the augmented cellular activities of key glycolytic enzymes including phosphofructokinase, lactate dehydrogenase, and glycogen phosphorylase, and accumulation of H₂O₂, SA, LPO, PCC, and GSSG. Citrate synthase, aconitase, α-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, isocitrate dehydrogenase, and complex I-III, IIIII, and IV activities were significantly diminished in P25 and P35 cells compared to P5 cells. This was accompanied by significant accumulation of mitochondrial H₂O₂, SA, LPO, and PCC, along with increased transcriptional and enzymatic activities of TrxR2, SOD2, GPx1, and GR. Notably, the GSH/GSSG ratio was significantly reduced whereas NAD⁺/NADH and NADP⁺/NADPH ratios were significantly elevated. Metabolic exhaustion was also evident in senescent cells underscored by the severely diminished ATP/ADP ratio. Profound oxidative stress may contribute, at least in part, to senescence pointing at a potential protective role of antioxidants in aging-associated disease.

Venom of the desert black snake Walterinnesia aegyptia enhances anti-tumor immunity via its beneficial modulatory effects on pro- and anti-tumorigenic inflammatory mediators in cultured colon cancer cells

The role of inflammation in colon cancer is understood as a well-accepted factor that has the tendency to release multiple pro- and anti-tumorigenic inflammatory mediators. Inflammation-induced increased expression of anti-tumorigenic inflammatory mediators and decreased expression of pro-tumorigenic inflammatory mediators encourage beneficial inflammatory effects in terms of powerful anti-tumor immunity. The present study aims to screen the beneficial inflammatory effects of Walterinnesia aegyptia venom via determining its modulatory tendency on the expression of 40 pro- and anti-tumorigenic inflammatory mediators (cytokines/growth factors/chemokines) in LoVo human colon cancer cell line. LoVo-cells were treated with varying doses of crude venom of W. aegyptia. Cell viability was checked utilizing flow cytometry, and IC50 of venom was determined. Venom-induced inflammatory effects were evaluated on the expression of 40 different inflammatory mediators (12 anti-tumorigenic cytokines, 11 pro-tumorigenic cytokines, 7 pro-tumorigenic growth factors, 9 pro-tumorigenic chemokines and 1 anti-tumorigenic chemokine) in treated LoVo-cells [utilizing enzyme-linked immunosorbent assay (ELISA)] and compared with controls. Treatment of venom induced significant cytotoxic effects on inflamed LoVo-cells. IC50 treatment of venom caused significant modulations on the expression of 22 inflammatory mediators in treated LoVo-cells. The beneficial modulatory effects of venom were screened via its capability to significantly increase the expression of five powerful anti-tumorigenic mediators (IL-9, IL-12p40, IL-15, IL-1RA and Fractalkine) and decrease the expression of four major pro-tumorigenic mediators (IL-1β, VEGF, MCP-1 and MCP-3). Walterinnesia aegyptia venom-induced beneficial modulations on the expression of nine crucial pro/anti-tumorigenic inflammatory mediators can be effectively used to enhance powerful anti-tumor immunity against colon cancer.

Proteomic Identification and Quantification of Snake Venom Biomarkers in Venom and Plasma Extracellular Vesicles

The global exploration of snakebites requires the use of quantitative omics approaches to characterize snake venom as it enters into the systemic circulation. These omics approaches give insights into the venom proteome, but a further exploration is warranted to analyze the venom-reactome for the identification of snake venom biomarkers. The recent discovery of extracellular vesicles (EVs), and their critical cellular functions, has presented them as intriguing sources for biomarker discovery and disease diagnosis. Herein, we purified EV’s from the snake venom (svEVs) of Crotalus atrox and C. oreganus helleri, and from plasma of BALB/c mice injected with venom from each snake using EVtrap in conjunction with quantitative mass spectrometry for the proteomic identification and quantification of svEVs and plasma biomarkers. Snake venom EVs from C. atrox and C. o. helleri were highly enriched in 5′ nucleosidase, L-amino acid oxidase, and metalloproteinases. In mouse plasma EVs, a bioinformatic analysis for revealed upregulated responses involved with cytochrome P450, lipid metabolism, acute phase inflammation immune, and heat shock responses, while downregulated proteins were associated with mitochondrial electron transport, NADH, TCA, cortical cytoskeleton, reticulum stress, and oxidative reduction. Altogether, this analysis will provide direct evidence for svEVs composition and observation of the physiological changes of an envenomated organism.

Ascorbate ameliorates Echis coloratus venom-induced oxidative stress in human fibroblasts

Reports related to the effects of Echis coloratus venom (EcV) on the antioxidant capacity of human tissues is very scarce. The present study was undertaken to investigate the activities and gene expression levels of glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT), as well as the levels of reduced glutathione (GSH), oxidized glutathione (GSSG) and the generation rates of superoxide anions (SOA), hydrogen peroxide (H₂O₂) and lipid peroxides (LPO) in cultured human fibroblasts incubated with EcV, ascorbate (Asc) and EcV plus Asc at concentrations and incubation periods that maintained cell viability. Results indicated that the activities of all antioxidant enzymes and their corresponding transcripts underwent highly significant decreases and downregulation in EcV-treated cultures (0.5 µg/ml medium for 4 h) compared to venom-free controls (P<0.001). Additionally, there were concurrent equally significant increases in SOA, H₂O₂ and LPO generation rates in the venom-incubated cultures compared to controls (P<0.001). Results also indicated very significant decreases and parallel equally significant increases in GSH and GSSG levels respectively in the envenomed cultures compared to controls (P<0.001) leading to a drastically lower GSH/GSSG ratio. However, further incubation of the EcV-treated cultures with Asc (400 µM for 12 h) restored the activities and levels of all investigated parameters including the expression levels of the antioxidant genes to control venom-free values. It is concluded that Asc acted to neutralize the increased reactive oxygen species generation, thus ameliorating the EcV-induced oxidative stress and alleviating the downregulation of antioxidant genes.

The effect of Echis coloratus venom on biochemical and molecular markers of the antioxidant capacity in human fibroblasts

This study was undertaken to examine the activities and levels of major antioxidants/oxidants in cultured human fibroblasts incubated with a sublethal dose of Echis coloratus venom (EcV).

Glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR) activities and gene expression levels as well as reduced glutathione (GSH) levels, and the concurrent hydrogen peroxide (H₂O₂), superoxide anions (SOA), lipid peroxides (LPO) and oxidized glutathione (GSSG) generation rates were assayed in fibroblast cultures and sonicates incubated with 0.5 µg ml^–1 medium EcV for 4 h at 37°C.

Data indicated that the activities of all antioxidant enzymes were significantly decreased and their corresponding transcripts downregulated in EcV-incubated cells compared to controls (p < 0.001). In contrast, there were parallel equally significant increases in H₂O_2, SOA and LPO generation rates in venom-incubated cells compared to controls (p < 0.001). Additionally, GSH levels were significantly decreased and those of GSSG were equally significantly increased in venom-incubated cultures compared to controls (p < 0.001) leading to a lowered GSH/GSSG ratio.

In conclusion, incubation of fibroblast cultures with EcV resulted in a shift towards oxidative metabolism causing severe OS. This correlated with significant downregulation in the expression levels of all investigated antioxidant genes.