Effect of oral N-acetyl cysteine supplementation in type 2 diabetic patients on intracellular glutathione content and innate immune responses to Burkholderia pseudomallei

New roles for glutathione: Modulators of bacterial virulence and pathogenesis

Low molecular weight (LMW) thiols contain reducing sulfhydryl groups that are important for maintaining antioxidant defense in the cell. Aside from the traditional roles of LMW thiols as redox regulators in bacteria, glutathione (GSH) has been reported to affect virulence and bacterial pathogenesis. The role of GSH in virulence is diverse, including the activation of virulence gene expression and contributing to optimal biofilm formation. GSH can also be converted to hydrogen sulfide (H₂S) which is important for the pathogenesis of certain bacteria. Besides GSH, some bacteria produce other LMW thiols such as mycothiol and bacillithiol that affect bacterial virulence. We discuss these newer reported functions of LMW thiols modulating bacterial pathogenesis either directly or indirectly and via modulation of the host immune system.

Nephroprotective effect of Artemisia herba alba aqueous extract in alloxan-induced diabetic rats

BACKGROUND AND AIM

In the present study, we investigate the phytochemical composition and the nephroprotective effects as well as the antioxidant properties of Artemisia herba alba aqueous extract in alloxan-induced experimental diabetes in rats.

EXPERIMENTAL PROCEDURE

Wistar rats were divided into four groups of seven rats each: Group I: Normal control (NC) received saline solution at 9‰ given by intraperitoneal way; Group II: Diabetic control (DC) received alloxan (150 mg/kg b.w) intraperitoneally; Group III: Normal control (NC + AHA) received saline solution at 9‰ and treated orally by AHA aqueous extract (400 mg/kg/b.w); Group IV: Diabetic control (DC + AHA) received alloxan solution (150 mg/kg b.w) intraperitoneally and treated by aqueous extract of AHA (400 mg/kg/b.w/day) orally after one week of alloxan administration. After 30 days, blood and tissue samples were collected for biochemical and histopathological analysis, respectively. Glomerular damage markers, including creatinine, serum urea, urine creatinine and urine urea levels were estimated. Creatinine clearance was also assessed. Oxidative stress parameters were assessed in the kidney homogenate.

RESULTS AND CONCLUSION

Alloxan-exposure resulted in significant increase in blood glucose and serum level of glomerular damage markers. The antioxidant enzyme activities were significantly downregulated associated with an increase in malondialdehyde (MDA) level over the baseline values. Artemisia herba alba aqueous extract supplementation significantly improved the studied parameters. In concluding, the results obtained suggests that Artemisia herbs-alba aqueous extract supplementation reduces alloxan-induced free radical generation, potentiates the antioxidant defense system and alleviates renal sensitivity to oxidative stress.

N‑acetyl cysteine protects HUVECs against lipopolysaccharide‑mediated inflammatory reaction by blocking the NF‑κB signaling pathway

The purpose of the study was to explore the potential protective effects of N‑acetylcysteine (NAC) against lipopolysaccharide (LPS)‑induced inflammatory injury to human umbilical vein endothelial cells (HUVECs). It was also assessed whether the underlying mechanism of this protective effect is mediated via suppression of the nuclear factor‑kappa B (NF‑κB) signaling pathway. Cell viability of HUVECs treated with different concentrations of NAC was assessed using Cell Counting Kit‑8 (CCK‑8) assay. The mRNA expression of inflammatory factors [interleukin‑8 (IL‑8), tumor necrosis factor α (TNF‑α), inducible nitric oxide synthase (iNOS), and intercellular cell adhesive molecule 1 (ICAM‑1)] were assessed using real time semi‑quantitative polymerase chain reaction. Protein expression levels of TNF‑α and IL‑8 were assessed using enzyme‑linked immunosorbent assay. Protein expression levels of ICAM‑1 and the NF‑κB signaling pathway were assessed using western blotting. Nitric reductase method was used to quantify nitric oxide (NO) and iNOS. LPS stimulated the production of TNF‑α, IL‑8, NO, and ICAM‑1 by HUVECs. Moreover, LPS induced activation of the NF‑κB signaling pathway and increased the protein expression of phosphorylated p65. However, pretreatment of HUVECs with NAC significantly attenuated the increase in the expression of inflammatory factors and the level of phosphorylated p65; this indicated that NAC prevented the activation of the NF‑κB signaling pathway. The present findings indicated that NAC protects HUVECs against LPS‑mediated inflammatory reaction and alleviates inflammation. The underlying mechanism is related to the NF‑κB signaling pathway. NAC appears to be a promising agent for prevention and treatment of inflammatory diseases.

Mitigating effects of antioxidant properties of Artemisia herba alba aqueous extract on hyperlipidemia and oxidative damage in alloxan-induced diabetic rats

Chronic hyperglycemia and excess reactive oxygen species overproduced in diabetes were associated with oxidative stress, led to continuous injury and functions damage to different organs: eyes, kidneys, neural and cardiovascular system. The present study was undertaken to evaluate the protective effect of Artemisia herba alba (AHA) leaf powder against alloxane-induced oxidative damage in diabetic rats. Rats were randomly divided into four groups: Group I controls received saline solution 9%; Group II was treated with 150 mg alloxane/(kg body weight) administered by intraperitoneal. Rats of Group III have received saline solution and treated with 400 mg AHA/(kg body weight). Animals of Group IV were treated with alloxane and AHA. Alloxane exposure led to increased blood glucose, total cholesterol, triglycerides, malondialdehyde, and a decrease in the antioxidants enzymes activities (catalase, glutathione peroxidase and glutathione-S-transferase). Administration of AHA aqueous extract ameliorated these parameters. These results demonstrate that AHA ameliorates hyperglycemia, hyperlipidemia and oxidative damage in alloxan-induced diabetes in rats.

The Synergistic Effects of the Glutathione Precursor, NAC and First-Line Antibiotics in the Granulomatous Response Against Mycobacterium tuberculosis

Mycobacterium tuberculosis (M. tb), the causative bacterial agent responsible for tuberculosis (TB) continues to afflict millions of people worldwide. Although the human immune system plays a critical role in containing M. tb infection, elimination proves immensely more challenging. Consequently, there has been a worldwide effort to eradicate, and limit the spread of M. tb through the conventional use of first-line antibiotics. Unfortunately, with the emergence of drug resistant and multi-drug resistant strains of M. tb the archetypical antibiotics no longer provide the same ascendancy as they once did. Furthermore, when administered, these first-line antibiotics commonly present severe complications and side effects. The biological antioxidant glutathione (GSH) however, has been demonstrated to have a profound mycobactericidal effect with no reported adverse consequences. Therefore, we examined if N-Acetyl Cysteine (NAC), the molecular precursor to GSH, when supplemented in combination with suboptimal levels of standalone first-line antibiotics would be sufficient to completely clear M. tb infection within in vitro derived granulomas from healthy subjects and individuals with type 2 diabetes (T2DM). Our results revealed that by virtue of immune modulation, the addition of NAC to subprime levels of isoniazid (INH) and rifampicin (RIF) was indeed capable of inducing complete clearance of M. tb among healthy individuals.

Anti-Cancer Drug HMBA Acts as an Adjuvant during Intracellular Bacterial Infections by Inducing Type I IFN through STING

The anti-proliferative agent hexamethylene bisacetamide (HMBA) belongs to a class of hybrid bipolar compounds developed more than 30 y ago for their ability to induce terminal differentiation of transformed cells. Recently, HMBA has also been shown to trigger HIV transcription from latently infected cells, via a CDK9/HMBA inducible protein-1 dependent process. However, the effect of HMBA on the immune response has not been explored. We observed that pretreatment of human peripheral blood mononuclear cells with HMBA led to a markedly increased production of IL-12 and IFN-γ, but not of TNF-α, IL-6, and IL-8 upon subsequent infection with Burkholderia pseudomallei and Salmonella enterica HMBA treatment was also associated with better intracellular bacterial control. HMBA significantly improved IL-12p70 production from CD14⁺ monocytes during infection partly via the induction of type I IFN in these cells, which primed an increased transcription of the p35 subunit of IL-12p70 during infection. HMBA also increased early type I IFN transcription in human monocytic and epithelial cell lines, but this was surprisingly independent of its previously reported effects on positive transcription elongation factor b and HMBA inducible protein-1. Instead, the effect of HMBA was downstream of a calcium influx, and required the pattern recognition receptor and adaptor STING but not cGAS. Our work therefore links the STING-IRF3 axis to enhanced IL-12 production and intracellular bacterial control in primary monocytes. This raises the possibility that HMBA or related small molecules may be explored as therapeutic adjuvants to improve disease outcomes during intracellular bacterial infections.

Glibenclamide impairs responses of neutrophils against Burkholderia pseudomallei by reduction of intracellular glutathione

The major risk factor for melioidosis, an infectious disease caused by B. pseudomallei, is diabetes mellitus. More than half of diabetic melioidosis patients in Thailand were prescribed glibenclamide. Recent evidence demonstrates that glibenclamide reduces pro-inflammatory cytokine production by polymorphonuclear neutrophils (PMNs) of diabetic individuals in response to this bacterial infection. However, the mechanisms by which glibenclamide affects cytokine production are unknown. We found that PMNs from glibenclamide-treated diabetic individuals infected with live B. pseudomallei in vitro showed lower free glutathione (GSH) levels compared with those of healthy individuals. Glibenclamide decreased GSH levels and glutathione peroxidase (GPx) of PMNs after exposed to live B. pseudomallei. Moreover, glibenclamide reduced cytokine production and migration capacity of infected PMNs, whereas GSH could restore these functions. Taken together, our data show a link between the effect of glibenclamide on GSH and PMN functions in response to B. pseudomallei that may contribute to the susceptibility of diabetic individuals to B. pseudomallei infection.

Antioxidant treatment ameliorates experimental diabetes-induced depressive-like behaviour and reduces oxidative stress in brain and pancreas

Studies have shown a relationship between diabetes mellitus (DM) and the development of major depressive disorder. Alterations in oxidative stress are associated with the pathophysiology of both diabetes mellitus and major depressive disorder. This study aimed to evaluate the effects of antioxidants N-acetylcysteine and deferoxamine on behaviour and oxidative stress parameters in diabetic rats. To this aim, after induction of diabetes by a single dose of alloxan, Wistar rats were treated with N-acetylcysteine or deferoxamine for 14 days, and then depressive-like behaviour was evaluated. Oxidative stress parameters were assessed in the prefrontal cortex, hippocampus, amygdala, nucleus accumbens and pancreas. Diabetic rats displayed depressive-like behaviour, and treatment with N-acetylcysteine reversed this alteration. Carbonyl protein levels were increased in the prefrontal cortex, hippocampus and pancreas of diabetic rats, and both N-acetylcysteine and deferoxamine reversed these alterations. Lipid damage was increased in the prefrontal cortex, hippocampus, amygdala and pancreas; however, treatment with N-acetylcysteine or deferoxamine reversed lipid damage only in the hippocampus and pancreas. Superoxide dismutase activity was decreased in the amygdala, nucleus accumbens and pancreas of diabetic rats. In diabetic rats, there was a decrease in catalase enzyme activity in the prefrontal cortex, amygdala, nucleus accumbens and pancreas, but an increase in the hippocampus. Treatment with antioxidants did not have an effect on the activity of antioxidant enzymes. In conclusion, animal model of diabetes produced depressive-like behaviour and oxidative stress in the brain and periphery. Treatment with antioxidants could be a viable alternative to treat behavioural and biochemical alterations induced by diabetes.