Inflammatory Reactive Oxygen Species Research Articles

Roles of reactive oxygen species in inflammation and cancer.

Reactive oxygen species (ROS) constitute a spectrum of oxygenic metabolites crucial in modulating pathological organism functions. Disruptions in ROS equilibrium span various diseases, and current insights suggest a dual role for ROS in tumorigenesis and the immune response within cancer. This review rigorously examines ROS production and its role in normal cells, elucidating the subsequent regulatory network in inflammation and cancer. Comprehensive synthesis details the documented impacts of ROS on diverse immune cells. Exploring the intricate relationship between ROS and cancer immunity, we highlight its influence on existing immunotherapies, including immune checkpoint blockade, chimeric antigen receptors, and cancer vaccines. Additionally, we underscore the promising prospects of utilizing ROS and targeting ROS modulators as novel immunotherapeutic interventions for cancer. This review discusses the complex interplay between ROS, inflammation, and tumorigenesis, emphasizing the multifaceted functions of ROS in both physiological and pathological conditions. It also underscores the potential implications of ROS in cancer immunotherapy and suggests future research directions, including the development of targeted therapies and precision oncology approaches. In summary, this review emphasizes the significance of understanding ROS-mediated mechanisms for advancing cancer therapy and developing personalized treatments.

Oxidative stress activates transcription of Salmonella pathogenicity island-2 genes in macrophages

The type III secretion system encoded in the Salmonella pathogenicity island-2 (SPI-2) gene cluster facilitates intracellular growth of nontyphoidal Salmonella by interfering with the maturation of Salmonella-containing vacuoles along the degradative pathway. SPI-2 gene products also protect Salmonella against the antimicrobial activity of reactive oxygen species (ROS) synthesized by the phagocyte NADPH oxidase 2 (NOX2). However, a potential relationship between inflammatory ROS and the activation of transcription of SPI-2 genes by intracellular Salmonella is unclear. Here, we show that ROS engendered in the innate host response stimulate SPI-2 gene transcription. We found that the expression of SPI-2 genes in Salmonella-sustaining oxidative stress conditions involves DksA, a protein otherwise known to regulate the stringent response of bacteria to nutritional stress. We also demonstrate that the J and zinc-2-oxidoreductase domains of DnaJ as well as the ATPase activity of the DnaK chaperone facilitate loading of DksA onto RNA polymerase complexed with SPI-2 promoters. Furthermore, the DksA-driven transcription of SPI-2 genes in Salmonella experiencing oxidative stress is contingent on upstream OmpR, PhoP, and SsrB signaling events that participate in the removal of nucleoid proteins while simultaneously recruiting RNA polymerase to SPI-2 promoter regions. Taken together, our results suggest the activation of SPI-2 gene transcription in Salmonella subjected to ROS produced by the respiratory burst of macrophages protects this intracellular pathogen against NOX2-mediated killing. We propose that Salmonella have co-opted inflammatory ROS to induce SPI-2-mediated protective responses against NOX2 host defenses.

NOX2-Deficient Neutrophils Facilitate Joint Inflammation Through Higher Pro-Inflammatory and Weakened Immune Checkpoint Activities.

Immune-mediated arthritis is an important chronic inflammatory disease of joints causing debilitating morbidity in affected patients. The mechanisms underlying immune-mediated arthritis have been intensively investigated, however the cellular and molecular factors contributing to the joint inflammation in different redox conditions have not been clearly elucidated. Previous research showed that phagocyte-produced reactive oxygen species (ROS) plays an anti-inflammatory role in K/BxN serum-transfer arthritis and NOX2-deficient mice tend to have more severe arthritis. Although many leukocytes play critical roles in the development of immune-mediated arthritis, the role of neutrophils, which are the main producers of ROS in inflammation, is still controversial. We hence assessed the immunomodulatory function of neutrophils from arthritic joints of NOX2-deficient and wild type mice in this study. We found more neutrophils accumulation in NOX2-deficient inflamed joints. RNA-sequencing and quantitative PCR revealed significantly increased expression of acute inflammation genes including IL1b, Cxcl2, Cxcl3, Cxcl10 and Mmp3 in activated neutrophils from the inflamed joints of NOX2-deficient mice. Moreover, gene set enrichment analysis (GSEA) showed enriched gene signatures in type I and II IFN responses, IL-6-JAK-STAT3 signaling pathway and TNF-α signaling pathway via NF-κB in NOX2-deficient neutrophils. In addition, we found that NOX2-deficient neutrophils expressed lower levels of PD-L1 and were less suppressive than WT neutrophils. Moreover, treatment of PD-L1-Fc decreased cytokine expression and ameliorated the severity of inflammatory arthritis. Our results suggest that NOX2-derived ROS is critical for regulating the function and gene expression in arthritic neutrophils. Both the strong pro-inflammatory and weakened anti-inflammatory functions of neutrophils due to abnormal redox regulation may be targets of treatment for immune-mediated arthritis.

Insulin-like growth factor-I activates NFκB and NLRP3 inflammatory signalling via ROS in cancer cells

Previous studies have demonstrated that insulin-like growth factor-I (IGF-1) and reactive oxygen species (ROS) are involved in the development and progression of various cancers. However, their regulatory mechanism remains unknown. In this study, we treated cancer cells (HeLa, HepG2 and SW1116 cells) and normal cells (NCM-460) with IGF-1 at different concentrations and for different times and found that cancer cells produced large amounts of cytoplasmic ROS in cancer cells but not in normal cells. Further mechanistic analysis demonstrated that IGF-1 activated NFκB and NLRP3 inflammatory signalling in HeLa cells; systematic analysis indicated that IGF-1 activates NFκB and NLRP3, and the activation was cytosolic ROS- and NADPH oxidase 2 (NOX2)-dependent. Additionally, through coimmunoprecipitation experiments, we found that the IRS-1/COX2/mPGES-1/MAPKs/RAC2/NOX2 pathway nexus was involved in IGF-1-induced NFκB and NLRP3 production. Finally, we validated the regulatory mechanisms through IRS-1, mPGES-1 or NOX2 inhibition using their respective selective inhibitors or shRNA knockdown. Taken together, this is the first report on the mechanism by which IGF-1 activates NFκB and NLRP3 inflammatory signalling via ROS. These findings pave the way for an in-depth study of the role of IGF-1 and ROS in inflammation associated with the development and progression of cancer.

A new long-wavelength fluorescent probe for tracking peroxynitrite in live cells and inflammatory sites of zebrafish.

Peroxynitrite (OONO-), as a reactive oxygen species (ROS), would be mostly profoundly implicated in diseases such as inflammation in organisms. However, bioimaging of ONOO- still faces difficulties owing to the shortage of bioimaging and real-time dynamic tracking distribution of ROS in inflammation. To address this challenge, we designed and synthesized a long-wavelength fluorescent probe based on tricyanofuran (ACDM-BE), which exhibits a fast response (response time is 40 s), high selectivity and great sensitivity (LOD is approximately 21 nM) towards ONOO-. ACDM-BE was shown to be capable of detecting ONOO- in living cells and monitor the changes in ONOO- levels under the stimulus of various concentrations of SIN-1 (from 100 to 700 μM), which was successfully tracked by the fluorescence changes in live cells. It is worth noting that ACDM-BE further demonstrated its ability to track the dynamic changes of the level of ONOO- in the inflammatory sites of larval zebrafish. Thus, ACDM-BE could be employed as an efficient tool for exploiting the role of ONOO- in inflammation in living biosystems.

Novel aspects of the activation of NADPH oxidase in neutrophils of rheumatic patients on biological therapy

The relationship between inflammation and formation of reactive oxygen species (ROS) is still not completely understood and excessive inflammatory reaction is attributed to increased yet also to reduced ROS formation. To compare ROS formation in severe and low inflammation, neutrophil oxidative burst was analyzed in rheumatic patients before and during therapy with TNFα- or interleukin-6 receptor-neutralizing antibodies.Intracellular and extracellular ROS productions were evaluated on the basis of luminol- and isoluminol-enhanced chemiluminescence in isolated peripheral neutrophils. Disease activity score DAS28 and platelet to lymphocyte ratio were used as markers of arthritis activity and the intensity of systemic inflammation.Biological therapy effectively reduced the intensity of inflammation. Of the twenty-six patients studied eighteen achieved remission or low disease activity. Highly active arthritis persisted only in one patient, though prior to the therapy it was evident in all subjects tested. In patients receiving biological therapy, intracellular chemiluminescence was significantly higher than in patients before this therapy; ROS produced by neutrophils extracellularly were not affected.The increased ROS formation associated with reduced inflammation supports the need to revise the view of the role of ROS in inflammation - from toxic agents promoting inflammation towards a more complex view of ROS as regulators of immune pathways with inflammation-limiting capacity. From this perspective, the interference with neutrophil-derived oxidants may represent a new mechanism involved in the anti-inflammatory activity of biological therapy.

Role of Reactive Oxygen Species in Inflammation: A Minireview

Inflammation is a protective response of a multicellular organism to injury in order to localize, eliminate, and remove harmful stimuli as well as to recover (or replace) damaged tissues. There recently has been increasing evidence that reactive oxygen species (ROS) are involved in the initiation, progression, and resolution of the inflammatory response. Furthermore, ROS act as microbicidal agents and second messengers in the intracellular signaling. The latter function is performed via posttranslational modification of protein- associated redox-sensitive cysteine residues that can undergo oxidation. At the same time, there is clear evidence that overproduction of ROS may result in cell and tissue injury and contribute to chronic inflammation underlying many neurodegenerative, cardiovascular, and metabolic diseases. This review has focused on the role of ROS in the key inflammatory events (increased vascular permeability and leukocyte extravasation, respiratory burst and phagocytosis, and angiogenesis) and some events leading to the resolution of inflammation. In addition, the pathological function of ROS in oxidative stress is discussed.

Macrophages as target cells for Mayaro virus infection: involvement of reactive oxygen species in the inflammatory response during virus replication

Alphaviruses among the viruses that cause arthritis, consisting in a public health problem worldwide by causing localized outbreaks, as well as large epidemics in humans. Interestingly, while the Old World alphaviruses are arthritogenic, the New World alphaviruses cause encephalitis. One exception is Mayaro virus (MAYV), which circulates exclusively in South America but causes arthralgia and is phylogenetically related to the Old World alphaviruses. Although MAYV-induced arthritis in humans is well documented, the molecular and cellular factors that contribute to its pathogenesis are completely unknown. In this study, we demonstrated for the first time that macrophages, key players in arthritis development, are target cells for MAYV infection, which leads to cell death through apoptosis. We showed that MAYV replication in macrophage induced the expression of TNF, a cytokine that would contribute to pathogenesis of MAYV fever, since TNF promotes an inflammatory profile characteristic of arthritis. We also found a significant increase in the production of reactive oxygen species (ROS) at early times of infection, which coincides with the peak of virus replication and precedes TNF secretion. Treatment of the cells with antioxidant agents just after infection completely abolished TNF secretion, indicating an involvement of ROS in inflammation induced during MAYV infection.

Reactive Oxygen Species in Inflammation and Tissue Injury

Abstract Reactive oxygen species (ROS) are key signaling molecules that play an important role in the progression of inflammatory disorders. An enhanced ROS generation by polymorphonuclear neutrophils (PMNs) at the site of inflammation causes endothelial dysfunction and tissue injury. The vascular endothelium plays an important role in passage of macromolecules and inflammatory cells from the blood to tissue. Under the inflammatory conditions, oxidative stress produced by PMNs leads to the opening of inter-endothelial junctions and promotes the migration of inflammatory cells across the endothelial barrier. The migrated inflammatory cells not only help in the clearance of pathogens and foreign particles but also lead to tissue injury. The current review compiles the past and current research in the area of inflammation with particular emphasis on oxidative stress-mediated signaling mechanisms that are involved in inflammation and tissue injury.

Cytotoxic molecular mechanisms and cytoprotection by enzymic metabolism or autoxidation for glyceraldehyde, hydroxypyruvate and glycolaldehyde

Previously, we showed that dietary fructose or its carbonyl metabolites, glyceraldehyde and glycolaldehyde, could be oxidized by inflammatory reactive oxygen species (ROS), products of immune cells, to form highly toxic and genotoxic products, such as glyoxal. Glycolaldehyde-caused hepatocyte protein carbonylation likely resulted from glyoxal, an autoxidation product formed by ROS. Although hepatocyte protein carbonylation by glyoxal or d-glycolaldehyde was rapid, the product was unstable. Glyceraldehyde-induced protein carbonylation was slower and was also less cytotoxic. Non-toxic concentrations of H 2O 2 were then used to mimic inflammation and oxidative stress associated with fructose-induced non-alcoholic steatohepatitis (NASH). A slow infusion of H 2O 2 markedly increased glyoxal, glyceraldehyde, and glycolaldehyde-induced cytotoxicity and protein carbonylation. However, it had a smaller effect on glyceraldehyde-induced protein carbonylation. The cytotoxicities of both aldehydes were increased if glutathione (GSH)-depleted hepatocytes were used, presumably because of the increased ROS formation and subsequent glyoxal-induced protein carbonylation. Catalytic amounts of Cu or Fe increased the glycolaldehyde and glyceraldehyde-induced cytotoxicity and protein carbonylation resulting from autoxidation to glyoxal. Glyceraldehyde and glycolaldehyde were also detoxified by mitochondrial aldehyde dehydrogenase (ALDH2) as ALDH2 inhibitors increased their cytotoxicity. Hydroxypyruvate has not been previously tested for toxicity and was found to be the most toxic fructose metabolite. Catalytic amounts of Cu or Fe caused hydroxypruvate autoxidation, which formed extensive ROS, glycolaldehyde and glyoxal. Iron chelators EGTA or deferoxamine inhibited cytotoxicity as well as the extensive ROS formation. The Girard assay confirmed that glyoxal was a common autoxidation product from glyceraldehyde, glycolaldehyde and hydroxypyruvate.

Reactive oxygen species–independent activation of the IL-1β inflammasome in cells from patients with chronic granulomatous disease

Humans with chronic granulomatous diseases (CGDs) due to mutations in p47-phox have defective NADPH activity and thus cannot generate NADPH-dependent reactive oxygen species (ROS). The role of ROS in inflammation is controversial; some in vitro studies suggest that ROS are crucial for secretion of IL-1beta via inflammasome activation, whereas mice defective for ROS and patients with CGD have a proinflammatory phenotype. In this study, we evaluated activation of the IL-1beta inflammasome in cells from CGD patients. In contrast to previous studies using the small molecule diphenylene iodonium (DPI) as a ROS inhibitor, we found no decrease in either caspase-1 activation or secretion of IL-1beta and IL-18 in primary CGD monocytes. Moreover, activation of CGD monocytes by uric acid crystals induced a 4-fold higher level of IL-1beta secretion compared with that seen in monocytes from unaffected subjects, and this increase was not due to increased synthesis of the IL-1beta precursor. In addition, Western blot analysis of CGD cells revealed that caspase-1 activation was not decreased, but rather was increased compared with control cells. Examination of the effects exerted by the inhibition of ROS activity by DPI revealed that the decrease in IL-1beta secretion by DPI was actually due to inhibition of IL-1beta gene expression. Thus, inconsistent with the proinflammatory role of ROS, the present findings support the concept that ROS likely dampen inflammasome activation. The absence of ROS in CGD monocytes may explain the presence of an inflammatory phenotype characterized by granulomas and inflammatory bowel disease occurring in CGD patients.

Inflammatory ROS promote and cooperate with the Fanconi anemia mutation for hematopoietic senescence

The proinflammatory cytokine tumor necrosis factor alpha (TNFalpha) inhibits hematopoietic stem cell (HSC) expansion, interferes with HSC self-renewal and compromises the ability of HSC to reconstitute hematopoiesis. We have investigated mechanisms by which TNFalpha suppresses hematopoiesis using the genomic instability syndrome Fanconi anemia mouse model deficient for the complementation-group-C gene (Fancc). Examination of senescence makers, such as senescence-associated beta-galactosidase, HP1-gamma, p53 and p16(INK4A) shows that TNFalpha induces premature senescence in bone marrow HSCs and progenitor cells as well as other tissues of Fancc-/- mice. TNFalpha-induced senescence correlates with the accumulation of reactive oxygen species (ROS) and oxidative DNA damage. Neutralization of TNFalpha or deletion of the TNF receptor in Fancc-/- mice (Fancc-/-;Tnfr1-/-) prevents excessive ROS production and hematopoietic senescence. Pretreatment of TNFalpha-injected Fancc-/- mice with a ROS scavenger significantly reduces oxidative base damage, DNA strand breaks and senescence. Furthermore, HSCs and progenitor cells from TNFalpha-treated Fancc-/- mice show increased chromosomal aberrations and have an impaired oxidative DNA-damage repair. These results indicate an intimate link between inflammatory reactive oxygen species and DNA-damage-induced premature senescence in HSCs and progenitor cells, which may play an important role in aging and anemia.

Superoxide, peroxynitrite and oxidative/nitrative stress in inflammation

A considerable body of evidence suggests that formation of potent reactive oxygen species and resulting oxidative/nitrative stress play a major role in acute and chronic inflammation and pain. Much of the knowledge in this field has been gathered by the use of pharmacological and genetic approaches. In this mini review, we will evaluate recent advances made towards understanding the roles of reactive oxygen species in inflammation, focusing in particular on superoxide and peroxynitrite. Given the limited space to cover this broad topic, here we will refer the reader to comprehensive review articles whenever possible.

Antioxidants and Inflammatory Disease: Synthetic and Natural Antioxidants with Anti-Inflammatory Activity

Oxidants play a significant role in the pathogenesis of a number of disorders such as inflammation, rheumatoid arthritis, asthma, psoriasis and contact dermatitis leading to oxidative stress. Oxidative stress may be defined as an imbalance between cellular production of reactive oxygen species (ROS) and antioxidant defense mechanisms. ROS (e.g., superoxide radical, peroxynitryl, hydroxyl radical and hydrogen peroxide) are constantly produced as a result of metabolic reactions in living systems. The aim of this review is to describe recent developments in the study of antioxidants and their role in preventing the formation of ROS. The processes associated with inflammatory responses are complex and often involve ROS. There are many mediators, which initiate and amplify the inflammatory response such as histamine, serotonin, pro-inflammatory cytokines (interleukin-1B (IL-1b) and tumor necrosis factor (TNF-alpha), inflammatory cells (leukotrienes, macrophages), metabolic products of arachidonic acid (thomboxane A(2), prostaglandins and leukotrienes). The first part of this review focuses on the role of ROS in inflammation. The second part concerns synthetic antioxidants with antiinflammatory activity, and the third part addresses naturally occurring antioxidants with antiinflammatory activity.

The role of the antioxidative defense system in papulopustular acne.

Acne vulgaris frequently occurs in the second decade of life. The pathogenesis of the disease is multifactorial. In this study, we aimed to investigate the role of reactive oxygen species in inflammation of acne by determining the activity of antioxidant defense enzymes in leukocytes. Fifty-two patients with papulopustular type acne vulgaris and 36 healthy controls were enrolled. The severity of the disease was examined by the Global Acne Grading System, and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) enzymes as well as the level of thiobarbituric acid reactive substance (TBARS) were detected in leukocytes. The activities of SOD and GSH-Px were significantly decreased in the acne group. CAT activity and TBARS level were higher in patients than controls. Only a poor correlation was detected between GSH-Px activity and severity of the disease. Antioxidative defense enzymes are impaired in papulopustular acne, and drugs with antioxidative effects might be valuable in treatment.

Reactive oxygen species, antiproteases, and cytokines in sepsis

Although the shock syndrome is recognized as a form of "mediator poisoning", a plethora of details is hardly converging into a coherent concept of chronological and molecular order. As a model for organ failure in septic shock, three alternative experimental approaches with a common pathology are presented: When galactosamine-sensitized mice receive either lipopolysaccharide or leukotriene D4 or tumor necrosis factor alpha they develop fulminant hepatitis within few hours with a lethal outcome within one day. Detailed pharmacological intervention studies allow to conclude that endotoxin-induced leukotriene D4 release induces a transient ischemia by the known vasoconstrictive action of this eicosanoid. A following reperfusion/reoxygenation phase gives rise to superoxide formation which inactivates alpha 1 proteinase inhibitor. Thus a serine protease becomes active which is responsible for the processing of a monocytic tumor necrosis factor alpha precursor to be released into the circulation after proteolytic cleavage. By this sequence the final central mediator of shock and sepsis becomes systematically abundant. The concept arising from these studies reconciles previously known findings and provides a link between the role of reactive oxygen species in inflammation, the balance of proteases and antiproteases in the extracellular space and the release of the cytokine tumor necrosis factor in sepsis and shock.