Interrupting the nitrosative stress fuels tumor-specific cytotoxic T lymphocytes in pancreatic cancer.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest tumors owing to its robust desmoplasia, low immunogenicity, and recruitment of cancer-conditioned, immunoregulatory myeloid cells. These features strongly limit the success of immunotherapy as a single agent, thereby suggesting the need for the development of a multitargeted approach. The goal is to foster T lymphocyte infiltration within the tumor landscape and neutralize cancer-triggered immune suppression, to enhance the therapeutic effectiveness of immune-based treatments, such as anticancer adoptive cell therapy (ACT). METHODS: We examined the contribution of immunosuppressive myeloid cells expressing arginase 1 and nitric oxide synthase 2 in building up a reactive nitrogen species (RNS)-dependent chemical barrier and shaping the PDAC immune landscape. We examined the impact of pharmacological RNS interference on overcoming the recruitment and immunosuppressive activity of tumor-expanded myeloid cells, which render pancreatic cancers resistant to immunotherapy. RESULTS: PDAC progression is marked by a stepwise infiltration of myeloid cells, which enforces a highly immunosuppressive microenvironment through the uncontrolled metabolism of L-arginine by arginase 1 and inducible nitric oxide synthase activity, resulting in the production of large amounts of reactive oxygen and nitrogen species. The extensive accumulation of myeloid suppressing cells and nitrated tyrosines (nitrotyrosine, N-Ty) establishes an RNS-dependent chemical barrier that impairs tumor infiltration by T lymphocytes and restricts the efficacy of adoptive immunotherapy. A pharmacological treatment with AT38 ([3-(aminocarbonyl)furoxan-4-yl]methyl salicylate) reprograms the tumor microenvironment from protumoral to antitumoral, which supports T lymphocyte entrance within the tumor core and aids the efficacy of ACT with telomerase-specific cytotoxic T lymphocytes. CONCLUSIONS: Tumor microenvironment reprogramming by ablating aberrant RNS production bypasses the current limits of immunotherapy in PDAC by overcoming immune resistance.

Regulation of lymphatic function and injury by nitrosative stress in obese mice.

OBJECTIVE: Obesity results in lymphatic dysfunction, but the cellular mechanisms that mediate this effect remain largely unknown. Previous studies in obese mice have shown that inducible nitric oxide synthase-expressing (iNOS+) inflammatory cells accumulate around lymphatic vessels. In the current study, we therefore tested the hypothesis that increased expression of iNOS results in nitrosative stress and injury to the lymphatic endothelial cells (LECs). In addition, we tested the hypothesis that lymphatic injury, independent of obesity, can modulate glucose and lipid metabolism. METHODS: We compared the metabolic changes and lymphatic function of wild-type and iNOS knockout mice fed a normal chow or high-fat diet for 16 weeks. To corroborate our in vivo findings, we analyzed the effects of reactive nitrogen species on isolated LECs. Finally, using a genetically engineered mouse model that allows partial ablation of the lymphatic system, we studied the effects of acute lymphatic injury on glucose and lipid metabolism in lean mice. RESULTS: The mesenteric lymphatic vessels of obese wild-type animals were dilated, leaky, and surrounded by iNOS+ inflammatory cells with resulting increased accumulation of reactive nitrogen species when compared with lean wild-type or obese iNOS knockout animals. These changes in obese wild-type mice were associated with systemic glucose and lipid abnormalities, as well as decreased mesenteric LEC expression of lymphatic-specific genes, including vascular endothelial growth factor receptor 3 (VEGFR-3) and antioxidant genes as compared with lean wild-type or obese iNOS knockout animals. In vitro experiments demonstrated that isolated LECs were more sensitive to reactive nitrogen species than blood endothelial cells, and that this sensitivity was ameliorated by antioxidant therapies. Finally, using mice in which the lymphatics were specifically ablated using diphtheria toxin, we found that the interaction between metabolic abnormalities caused by obesity and lymphatic dysfunction is bidirectional. Targeted partial ablation of mesenteric lymphatic channels of lean mice resulted in increased accumulation of iNOS+ inflammatory cells and increased reactive nitrogen species. Lymphatic ablation also caused marked abnormalities in insulin sensitivity, serum glucose and insulin concentrations, expression of insulin-sensitive genes, lipid metabolism, and significantly increased systemic and mesenteric white adipose tissue (M-WAT) inflammatory responses. CONCLUSIONS: Our studies suggest that increased iNOS production in obese animals plays a key role in regulating lymphatic injury by increasing nitrosative stress. In addition, our studies suggest that obesity-induced lymphatic injury may amplify metabolic abnormalities by increasing systemic and local inflammatory responses and regulating insulin sensitivity. These findings suggest that manipulation of the lymphatic system may represent a novel means of treating metabolic abnormalities associated with obesity.

Emerging role of innate B1 cells in the pathophysiology of autoimmune and neuroimmune diseases: Association with inflammation, oxidative and nitrosative stress and autoimmune responses.

B1 lymphocytes may be subdivided by CD5 and CD11b/Mac1 expression into B1a, with the CD5 and CD11b/Mac1 phenotype, and B1b, which present as CD19hiCD5loCD11bhi. B1b cells share many surface and functional characteristics with marginal zone B cells but differ in distribution and B cell receptor (BCR) signalling pathways. They are normally concentrated in the peritoneum, pleural cavities, spleen and bone marrow and function as efficient phagocytes and antigen-presenting cells (APCs). While peritoneal B1b cells are relatively anergic, they may be activated by high cytokine levels, notably IL-10, IL-5 and IL-21, CD40 signalling and high doses of Toll-like receptor (TLR) ligands in the context of pathogen invasion; TLR ligation is also necessary. Their anti-inflammatory effects include: secretion of natural IgM by splenic and bone marrow B1b cell subsets as an early response to pathogen invasion; tissue homeostasis and enabling the immunologically silent clearance of neoplastic and apoptotic cells; inhibition of pro-inflammatory cytokines and increased production of TGF-ß1, PGE2 and GcMAF by activated macrophages and dendritic cells; and, in the case of peritoneal B1 lymphocytes, acting as ultimate Breg precurors. Pro-inflammatory B1b properties may result from: abnormal trafficking; acting as APCs; and acting as a source of innate-response activator cells. Functional impairment or deficits in Bregs occur in multiple sclerosis, systemic lupus erythematosus and rheumatoid arthritis. Details are given of potential pathogenic roles of IgM and B1b lymphocytes in these autoimmune disorders and in deficit-schizophrenia, and how these changes relate to inflammatory and oxidative and nitrosative stress.

Andrographolide ameliorates silica induced pulmonary fibrosis.

The purpose of this study was to investigate the protective effect of andrographolide in silica-induced pulmonary fibrosis (PF) in mice and its underlying mechanisms. Male Swiss albino mice were divided into five groups: Normal control group, disease control group (1.5 mg silica/60 µL/mice) via oropharyngeal route, low dose (LD) group received silica + andrographolide (3 mg/kg), high dose (HD) group received silica + andrographolide (10 mg/kg), andrographolide per se group received 10 mg/kg andrographolide. Various bronchoalveolar lavage fluid (BALF) and biochemical parameters, inflammatory cytokines, histology and protein expression studies were carried out. Andrographolide significantly reduced total protein concentration, albumin, accumulation of inflammatory cells and lactate dehydrogenase (LDH) level in BALF. We found that andrographolide intervention led to decreased levels of the inflammatory cells including neutrophils, macrophages and lymphocytes in the BALF of the treated animals. In addition, andrographolide significantly reduced nitrite (p < 0.01 at HD), malondialdehyde (p < 0.01 at HD) and upregulated glutathione (p < 0.01 at HD) in silica challenged animals. Andrographolide showed anti-fibrotic activity by reducing collagen deposition and inflammation in lung. Histopathology revealed that andrographolide decreased irregular cellular nodules, inflammatory infiltration and fibrosis. Andrographolide intervention significantly reduced the expression of N-cadherin, α-SMA and vimentin (mesenchymal markers) and upregulated the expression of E-cadherin (an epithelial marker). Hence, andrographolide elicits its anti-pulmonary fibrotic effect by halting the progression of epithelial-to-mesenchymal transition (EMT) via affecting fibroblasts. We, to the best of our knowledge prove for the first time that andrographolide possesses potent antifibrotic activity by targeting inflammatory cells and EMT associated fibroblasts.

Natural regulatory IgM-mediated autoimmune responses directed against malondialdehyde regulate oxidative and nitrosative pathways and coupled with IgM responses to nitroso adducts attenuate depressive and physiosomatic symptoms at the end of term pregnancy.

AIM: We aimed to delineate the effects of immunoglobulin (Ig)M-mediated autoimmune responses directed against malondialdehyde (MDA) and nitroso (SNO) adducts on nitro-oxidative stress and depressive and physiosomatic symptoms (DPSS) at the end of term. METHODS: IgM responses to MDA, NO (nitroso) adducts formed by nitrosylation, and NO2 tyrosine formed by nitration were measured as well as hydroperoxides (ferrous oxidation xylenol orange), advanced protein oxidation products (AOPP), and NO metabolite (NOx) levels in women at the end of term pregnancy and in normal controls. RESULTS: IgM responses to MDA were significantly and inversely associated with AOPP, ferrous oxidation xylenol orange, and NOx and DPSS. IgM responses to NO adducts were significantly and inversely associated with DPSS and positively with NOx levels. There were significant associations between IgM responses to MDA, NO adducts, and NO2 tyrosine. The DPSS score was predicted by AOPP and a lifetime history of premenstrual syndrome (both positively) and IgM responses to NO adducts (inversely). Furthermore, 71.8% of the variance in the index of nitro-oxidative stress was explained by lowered IgM responses to MDA, antioxidant levels (zinc, total radical trapping parameter), and inflammatory mediators. CONCLUSION: Lowered levels of IgM responses to MDA during pregnancy are accompanied by a reduced regulation of nitro-oxidative processes thereby explaining increased oxidative and nitrosative stress biomarkers in association with DPSS. IgM responses to NO adducts, which reflect nitrosylation as a consequence of increased NO production, regulate DPSS symptoms at the end of term and are a trait marker of major depression. IgM responses to MDA are a key part of the compensatory anti-inflammatory responses system.

Oxidative and nitrosative stress defences of Helicobacter and Campylobacter species that counteract mammalian immunity.

Helicobacter and Campylobacter species are Gram-negative microaerophilic host-associated heterotrophic bacteria that invade the digestive tract of humans and animals. Campylobacter jejuni is the major worldwide cause of foodborne gastroenteritis in humans, while Helicobacter pylori is ubiquitous in over half of the world's population causing gastric and duodenal ulcers. The colonisation of the gastrointestinal system by Helicobacter and Campylobacter relies on numerous cellular defences to sense the host environment and respond to adverse conditions, including those imposed by the host immunity. An important antimicrobial tool of the mammalian innate immune system is the generation of harmful oxidative and nitrosative stresses to which pathogens are exposed during phagocytosis. This review summarises the regulators, detoxifying enzymes and subversion mechanisms of Helicobacter and Campylobacter that ultimately promote the successful infection of humans.