Protective effects of N-acetylcysteine on a chemical-induced murine model of asthma

Anti-inflammatory peptide therapeutics and the role of sulphur containing amino acids (cysteine and methionine) in inflammation suppression: A review

BACKGROUND

Inflammation serves as our body's immune response to combat infections, pathogens, viruses, and external stimuli. Inflammation can be classified into two types: acute inflammation and chronic inflammation. Non-steroidal anti-inflammatory medications (NSAIDs) are used to treat both acute and chronic inflammatory disorders. However, these treatments have various side effects such as reduced healing efficiency, peptic ulcers, gastrointestinal toxicities, etc. METHOD: This review assesses the potential of anti-inflammatory peptides (AIPs) derived from various natural sources, such as algae, fungi, plants, animals, and marine organisms. Focusing on peptides rich in cysteines and methionine, sulphur-containing amino acids known for their role in suppression of inflammation.

RESULT

Due to their varied biological activity, ability to penetrate cells, and low cytotoxicity, bioactive peptides have garnered interest as possible therapeutic agents. The utilisation of AIPs has shown great potential in the treatment of disorders associated with inflammation. AIPs can be obtained from diverse natural sources such as algae, fungi, plants, and animals. Cysteine and methionine are sulphur-containing amino acids that aid in the elimination of free radicals, hence assisting in the treatment of inflammatory diseases.

CONCLUSION

This review specifically examines several sources of AIPs including peptides that contain numerous cysteines and methionine. In addition, the biological characteristics of these amino acids and advancements in peptide delivery are also discussed.

Advances in the Use of N-Acetylcysteine in Chronic Respiratory Diseases

N-acetylcysteine (NAC) is widely used because of its mucolytic effects, taking part in the therapeutic protocols of cystic fibrosis. NAC is also administered as an antidote in acetaminophen (paracetamol) overdosing. Thanks to its wide antioxidative and anti-inflammatory effects, NAC may also be of benefit in other chronic inflammatory and fibrotizing respiratory diseases, such as chronic obstructive pulmonary disease, bronchial asthma, idiopathic lung fibrosis, or lung silicosis. In addition, NAC exerts low toxicity and rare adverse effects even in combination with other treatments, and it is cheap and easily accessible. This article brings a review of information on the mechanisms of inflammation and oxidative stress in selected chronic respiratory diseases and discusses the use of NAC in these disorders.

Protective effects and mechanisms of N-acetylcysteine on indomethacin-induced intestinal injury in a porcine model

This study aimed to investigate the effect of N-acetylcysteine (NAC) on indomethacin (IDMT)-induced intestinal injury in a piglet model and explore the underlying molecular mechanisms. Piglets were randomly divided into 3 treatment groups: (1) control group; (2) IDMT group; (3) NAC+IDMT group. The results showed that NAC administration significantly increased the average daily gain of piglets, attenuated the intestine hyperemia, and restored normal jejunal morphology. Further studies indicated that NAC administration significantly increased plasma citrulline concentration and jejunal villin expression, but decreased the content of proinflammatory cytokines in plasma and jejunum of IDMT-stimulated piglets. NAC administration selectively decreased the proportion of eosinophils but not neutrophils in plasma. Furthermore, NAC administration significantly increased the activities of superoxide dismutase and catalase in plasma but decreased the concentrations of hydrogen peroxide (plasma) and malondialdehyde (plasma and jejunum), as well as the activity of myeloperoxidase (jejunum) when comparing NAC+IDMT group with IDMT group. Gene Ontology analysis showed that the significantly enriched molecular function term was "ubiquitin-like protein ligase binding" for NAC+IDMT versus IDMT differentially regulated genes. In the biological process category, differentially regulated genes of NAC+IDMT versus IDMT were mainly enriched in immune-related terms. The major enrichments for differentially regulated proteins (DRPs) of NAC+IDMT versus IDMT were terms involved in lipid metabolism and immune response. KEGG pathway enrichment analysis showed that "arginine biosynthesis" was a significant enrichment term for the DRPs of NAC+IDMT versus IDMT. Further studies demonstrated that NAC administration up-regulated argininosuccinate synthase 1 mRNA expression and down-regulated arginase mRNA expression in the jejunum of IDMT-stimulated piglets. Moreover, the content of nitric oxide was restored to a normal level with the reduction of nitric oxide synthase activity. NAC administration ameliorated intestinal injury in IDMT-challenged piglets by enhancing antioxidant and anti-inflammatory functions and modulating arginine metabolism in the small intestine.

LINC1810064F22Rik sequesters miR-206-5p away from HDAC4 to exacerbate allergic airway inflammation and airway remodeling in an ovalbumin mouse model of asthma

Allergic inflammation and airway remodeling frequently occur in asthma. This study clarifies a novel LINC1810064F22Rik-mediated ceRNA mechanism involved in asthma-induced allergic inflammation and airway remodeling based on bioinformatics analysis and in vivo and in vitro experiments. The differentially expressed lncRNAs and downstream effectors were predicted in silico. The targeting relationship among LINC1810064F22Rik, miR-206-5p, and HDAC4 was predicted by bioinformatics analysis, which was further validated by dual luciferase reporter gene assay. The asthma-like airway inflammation was induced in mice using ovalbumin (OVA) sensitization/challenge with immune adjuvant Al(OH)₃, while alveolar epithelial cells (AECs) were exposed to IL-33 to mimic in vitro inflammatory environment. LINC1810064F22Rik and HDAC4 were highly expressed, while miR-206-5p was poorly expressed in the tracheal tissues of OVA mice and the IL-33-treated AECs. The OVA mice and IL-33-treated AECs were subjected to gain- or loss-of-function experiments to detect the interaction of LINC1810064F22Rik/miR-206-5p/HDAC4 axis and their effects on allergic inflammation and airway remodeling. LINC1810064F22Rik competitively bound to miR-206-5p, and miR-206-5p targeted and inhibited HDAC4. The in vivo animal experiments indicated that LINC1810064F22Rik promoted asthma-induced allergic inflammation and airway remodeling by sequestering miR-206-5p away from HDAC4. The evidence provided by our study highlighted the involvement of the LINC1810064F22Rik/miR-206-5p/HDAC4 axis in facilitating allergic airway inflammation and airway remodeling in OVA mice.

N-acetylcysteine for prevention and treatment of COVID-19: Current state of evidence and future directions

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes coronavirus disease 2019 (COVID-19) and can be associated with serious complications, including acute respiratory distress syndrome. This condition is accompanied by a massive release of cytokines, also denominated cytokine storm, development of systemic oxidative stress and a prothrombotic state. In this context, it has been proposed a role for acetylcysteine (NAC) in the management of patients with COVID-19. NAC is a molecule classically known for its mucolytic effect, but it also has direct and indirect antioxidant activity as a precursor of reduced glutathione. Other effects of NAC have also been described, such as modulating the immune and inflammatory response, counteracting the thrombotic state, and having an antiviral effect. The pharmacological activities of NAC and its effects on the mechanisms of disease progression make it a potential therapeutic agent for COVID-19. NAC is safe, tolerable, affordable, and easily available. Moreover, the antioxidant effects of the molecule may even prevent infection and play an important role as a complement to vaccination. Although the clinical efficacy and dosing regimens of NAC have been evaluated in the clinical setting with small series of patients, the results are promising. In this article, we review the pathogenesis of SARS-CoV-2 infection and the current knowledge of the mechanisms of action of NAC across disease stages. We also propose NAC posology strategies to manage COVID-19 patients in different clinical scenarios.

Immunomodulatory effects of N-acetyl cysteine treated SCAP

INTRODUCTION

Stem cells of the apical papilla (SCAP) play an important role in regenerative endodontic procedures (REPs). Previous studies have shown that during REPs, bacteria can activate the innate immune system and cause indirect stem cell toxicity, leading to the lysis of SCAP. N-acetylcysteine (NAC) treated cells are resistant to apoptosis and have increased differentiation capabilities. The immunomodulatory properties of NAC treated SCAP are still unknown. Hence, the aim of this study is to evaluate the interactions of SCAP pre-treated with and without NAC with the immune system.

METHODS

Flow cytometric analysis was performed to assess the effects of NAC on SCAP viability. Human SCAP were then cultured and were either pre-treated with NAC or non-treated and co-cultured with human Peripheral blood mononuclear cells (PBMCs). A lactate dehydrogenase assay was performed to evaluate the levels of immune cell mediated apoptosis followed by an enzyme-linked immunosorbent assay (ELISA) to measure levels of pro-inflammatory cytokines for these co-cultures. Data were analyzed using an ANOVA with a post-hoc Tukey test.

RESULTS

Cells treated with NAC had similar levels of viability as the controls. SCAP pre-treated with NAC had a significantly lower immune cell-mediated cytotoxicity to non-activated and activated PBMCs. The ELISA results showed that SCAP pre-treated with NAC induced lower levels of proinflammatory cytokines.

CONCLUSIONS

SCAP pre-treated with NAC have a higher chance of surviving the activated immune system. This information may provide a better insight into the properties of these stem cells and may be the key to making REPs more predictable.

The role of HMGB1 on TDI-induced NLPR3 inflammasome activation via ROS/NF-κB pathway in HBE cells

To explore the potential role of HMGB1 on TDI-induced NLRP3 inflammasome activation, HBE cells were treated with TDI-HSA conjugate to observe the changes of HMGB1, TLR4, NF-κB, Nrf2 and NLRP3 inflammasome related proteins expressions, ROS release and MMP. NAC, TPCA-1 and Resatorvid pre-treatments were applied to explore the effects of ROS, NF-κB and TLR4 on TDI-induced NLRP3 inflammasome activation. The CRISPR/Cas9 system was used to construct HMGB1 gene knockout HBE cell line and then to explore the role of HMGB1 on TDI-HSA induced NLRP3 inflammasome activation. GL pre-treatment was applied to further confirm the role of HMGB1. Results showed that TDI increased HMGB1, TLR4, P-p65, Nrf2 proteins expressions and ROS release, decreased MMP level and activated NLRP3 inflammasome in HBE cells in a dose dependent manner. NAC, TPCA-1 and Resatorvid pre-treatments decreased the expression of P-p65 and inhibited NLRP3 inflammasome activation. Inhibition of HMGB1 decreased Nrf2 expression and ROS release, improved MMP level and reduced NLRP3 inflammasome activation. GL ameliorated NLRP3 inflammasome activation via inhibiting HMGB1 regulated ROS/NF-κB pathway. These results indicated that HMGB1 was involved in TDI-induced NLRP3 inflammasome activation as a positive regulatory mechanism. The study provided a potential target for early prevention and treatment of TDI-OA.

The Role of Glutathione in Protecting against the Severe Inflammatory Response Triggered by COVID-19

The novel COVID-19 pandemic is affecting the world’s population differently: mostly in the presence of conditions such as aging, diabetes and hypertension the virus triggers a lethal cytokine storm and patients die from acute respiratory distress syndrome, whereas in many cases the disease has a mild or even asymptomatic progression. A common denominator in all conditions associated with COVID-19 appears to be the impaired redox homeostasis responsible for reactive oxygen species (ROS) accumulation; therefore, levels of glutathione (GSH), the key anti-oxidant guardian in all tissues, could be critical in extinguishing the exacerbated inflammation that triggers organ failure in COVID-19. The present review provides a biochemical investigation of the mechanisms leading to deadly inflammation in severe COVID-19, counterbalanced by GSH. The pathways competing for GSH are described to illustrate the events concurring to cause a depletion of endogenous GSH stocks. Drawing on evidence from literature that demonstrates the reduced levels of GSH in the main conditions clinically associated with severe disease, we highlight the relevance of restoring GSH levels in the attempt to protect the most vulnerable subjects from severe symptoms of COVID-19. Finally, we discuss the current data about the feasibility of increasing GSH levels, which could be used to prevent and subdue the disease.