The synergistic induction of cyclooxygenase-2 in lung fibroblasts by angiotensin II and pro-inflammatory cytokines

Angiotensin Receptor Blockers Are Not Just for Hypertension Anymore

Beyond blood pressure control, angiotensin receptor blockers reduce common injury mechanisms, decreasing excessive inflammation and protecting endothelial and mitochondrial function, insulin sensitivity, the coagulation cascade, immune responses, cerebrovascular flow, and cognition, properties useful to treat inflammatory, age-related, neurodegenerative, and metabolic disorders of many organs including brain and lung.

Candesartan could ameliorate the COVID-19 cytokine storm

BACKGROUND

Angiotensin receptor blockers (ARBs) reducing inflammation and protecting lung and brain function, could be of therapeutic efficacy in COVID-19 patients.

METHODS

Using GSEA, we compared our previous transcriptome analysis of neurons injured by glutamate and treated with the ARB Candesartan (GSE67036) with transcriptional signatures from SARS-CoV-2 infected primary human bronchial epithelial cells (NHBE) and lung postmortem (GSE147507), PBMC and BALF samples (CRA002390) from COVID-19 patients.

RESULTS

Hundreds of genes upregulated in SARS-CoV-2/COVID-19 transcriptomes were similarly upregulated by glutamate and normalized by Candesartan. Gene Ontology analysis revealed expression profiles with greatest significance and enrichment, including proinflammatory cytokine and chemokine activity, the NF-kappa B complex, alterations in innate and adaptive immunity, with many genes participating in the COVID-19 cytokine storm.

CONCLUSIONS

There are similar injury mechanisms in SARS-CoV-2 infection and neuronal injury, equally reduced by ARB treatment. This supports the hypothesis of a therapeutic role for ARBs, ameliorating the COVID-19 cytokine storm.

Targeting the renin-angiotensin system to improve cancer treatment: Implications for immunotherapy

Renin-angiotensin system (RAS) inhibitors (RASi)-widely prescribed for the treatment of cardiovascular diseases-have considerable potential in oncology. The RAS plays a crucial role in cancer biology and affects tumor growth and dissemination directly and indirectly by remodeling the tumor microenvironment. We review clinical data on the benefit of RASi in primary and metastatic tumors and propose that, by activating immunostimulatory pathways, these inhibitors can enhance immunotherapy of cancer.

Novel long chain fatty acid derivatives of quercetin-3-O-glucoside reduce cytotoxicity induced by cigarette smoke toxicants in human fetal lung fibroblasts

Smoking has become a global health concern due to its association with many disease conditions, such as chronic obstructive pulmonary disease (COPD), cardiovascular diseases (CVD) and cancer. Flavonoids are plant polyphenolic compounds, studied extensively for their antioxidant, anti-inflammatory, and anti-carcinogenic properties. Quercetin-3-O-glucoside (Q3G) is a flavonoid which is widely found in plants. Six novel long chain fatty acid [stearic acid, oleic acid, linoleic acid, α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] derivatives of Q3G were evaluated for their potential in protecting human lung fibroblasts against cytotoxicity induced by selected cigarette smoke toxicants: 4-(methylnitrosoamino)-1-(3-pyridinyl)-1-butanone (NNK), benzo-α-pyrene (BaP), nicotine and chromium (Cr[VI]). Nicotine and Cr[VI] induced toxicity in fibroblasts and reduced the percentage of viable cells, while BaP and NNK did not affect cell viability. The fatty acid derivatives of Q3G provided protection against nicotine- and Cr[VI]-induced cell death and membrane lipid peroxidation. Based on the evaluation of inflammatory markers of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2), the fatty acid derivatives of Q3G were found to be effective in lowering the inflammatory response. Overall, these novel fatty acid esters of Q3G warrant further investigation as potential cytoprotective agents.

Poly (I:C) transfection induces mitochondrial-mediated apoptosis in cervical cancer

Polyinosinic acid:polycytidylic acid, known as poly (I:C), is an analogue of double‑stranded RNA, which exhibits direct antitumor effects against several types of cancer. The present study aimed to evaluate the role of poly (I:C) in the apoptosis of cervical cancer cells. The HeLa human cervical cancer cell line was used in the present study, and cell apoptosis was determined following poly (I:C) transfection. Furthermore, the mRNA levels of interferon (IFN)‑β, the production of reactive oxygen species (ROS), DNA damage, mitochondrial membrane potential (∆Ψm) and the release of cytochrome c, as well as caspase activation, were determined. The effect of IFN‑β on poly (I:C) transfection‑mediated apoptosis was also examined by IFN‑β knockdown. The results showed that poly (I:C) transfection markedly induced HeLa apoptosis, increased the protein levels of pro‑apoptotic B cell lymphoma‑2 (Bcl‑2)‑associated X protein (Bax) and BH3 interacting‑domain death agonist (Bid), and suppressed the protein expression levels of anti‑apoptotic Bcl‑2 and Survivin. However, poly (I:C) transfection increased the mRNA levels of IFN‑β, induced ROS production and increased the levels of phosphorylated γH2A.X, an indicator of DNA damage. In addition, poly (I:C) transfection decreased ∆Ψm, triggered the release of cytochrome c from the mitochondria to the cytosol, and induced caspase‑9 and ‑3 activation. IFN‑β knockdown decreased the poly (I:C)‑induced production of ROS and DNA damage, restored ∆Ψm and cytochrome c release, and suppressed caspase‑9 and ‑3 activation, thereby suppressing poly (I:C)‑mediated apoptosis in the HeLa cells. Together, the results of the present study demonstrated that poly (I:C) transfection induced IFN‑β, contributing to ROS production, DNA damage, and caspase‑9 and ‑3 activation in the HeLa cervical cancer cell line, leading to mitochondrial‑mediated apoptosis.

Adipose tissue-derived mesenchymal stem cells cultured at high density express IFN-β and suppress the growth of MCF-7 human breast cancer cells

Although it has been reported that mesenchymal stem cells (MSCs) suppress tumor growth in vitro and in vivo, little is known about the underlying molecular mechanisms. We found that type I interferon is expressed in adipose tissue-derived stem cells (ASCs) cultured at high density, and ASCs and their conditioned medium (ASC-CM) suppress the growth of MCF-7 cells in vitro. Growth inhibition was amplified by glucose deprivation that resulted from high density culture of ASCs after 3days. The cytotoxic effect of the ASC-CM obtained from high density culture of ASCs was neutralized by anti-IFN-β antibody. STAT1 was phosphorylated in MCF-7 cells treated with ASC-CM, and JAK1/JAK2 inhibitor treatment decreased STAT1 phosphorylation. The cytotoxic effect of ASC-CM was reduced especially by JAK1 inhibitors in MCF-7 cells. Our findings suggest that ASCs cultured at high density express type I interferons, which suppresses tumor growth via STAT1 activation resulting from IFN-β secretion in MCF-7 breast cancer cells.

Increased expression of chymase in inflammatory polyps in elderly patients with functional bowel disorder

Chymase, a chymotrypsin-like protease, is a non-angiotensin-converting enzyme (ACE) angiotensin II (Ang II)-generating enzyme. The aim of the present study was to investigate whether chymase activity was increased in inflammatory polyps of elderly patients with functional bowel disorder (FBD). This study enrolled 45 elderly patients with FBD and 44 healthy control individuals. Expression of chymase in intestinal mucosa was assessed using fluorescence quantitative polymerase chain reaction and immunohistochemistry (IHC). IHC showed an increased number of chymase-positive mast cells in inflammatory polyps than in healthy intestinal mucosa (P<0.05). Compared with healthy mucosa, expression of chymase at the mRNA and protein level was significantly higher in inflammatory polyps. The frequencies of the chymase GG genotype and the G allele type were higher in the intestinal mucosa of patients with FBD compared with healthy controls (66.67 versus 40.91%, 81.11 versus 63.63%, both P<0.05). The frequency of the G allele type in the intestinal mucosa of the C4 subgroup of FBD was higher than that in the control group. However, in other FBD subgroups, there was no difference between patients and controls. Based on the fact that enhanced chymase expression was observed in inflammatory polyps of elderly patients with FBD relative to those in healthy controls, it was concluded that chymase has a significant role in the pathogenesis of inflammatory polyps in elderly patients with FBD.

Cyclooxygenase-2 (COX-2) mediates arsenite inhibition of UVB-induced cellular apoptosis in mouse epidermal Cl41 cells

Inorganic arsenic is an environmental human carcinogen, and has been shown to act as a co-carcinogen with solar ultraviolet (UV) radiation in mouse skin tumor induction even at low concentrations. However, the precise mechanism of its co-carcinogenic action is largely unknown. Apoptosis plays an essential role as a protective mechanism against neoplastic development in the organism by eliminating genetically damaged cells. Thus, suppression of apoptosis is thought to contribute to carcinogenesis. It is known that cyclooxygenase-2 (COX-2) can promote carcinogenesis by inhibiting cell apoptosis under stress conditions; and our current studies investigated the potential contribution of COX-2 to the inhibitory effect of arsenite in UV-induced cell apoptosis in mouse epidermal Cl41 cells. We found that treatment of cells with low concentration (5 μM) arsenite attenuated cellular apoptosis upon UVB radiation accompanied with a coinductive effect on COX-2 expression and nuclear factor-κB (NFκB) transactivation. Our results also showed that the COX-2 induction by arsenite and UVB depended on an NFκB pathway because COX-2 co-induction could be attenuated in either p65-deficient or p50-deficient cells. Moreover, UVB-induced cell apoptosis could be dramatically reduced by the introduction of exogenous COX-2 expression, whereas the inhibitory effect of arsenite on UVB-induced cell apoptosis could be impaired in COX-2 knockdown C141 cells. Our results indicated that COX-2 mediated the anti-apoptotic effect of arsenite in UVB radiation through an NFκB-dependent pathway. Given the importance of apoptosis evasion during carcinogenesis, we anticipated that COX-2 induction might be at least partially responsible for the co-carcinogenic effect of arsenite on UVB-induced skin carcinogenesis.

Angiotensin II differentially modulates cyclooxygenase-2, microsomal prostaglandin E2 synthase-1 and prostaglandin I2 synthase expression in adventitial fibroblasts exposed to inflammatory stimuli

AIMS

To assess whether angiotensin II (Ang II) modulates key enzymes of the cyclooxygenase (COX)-2/prostanoid pathway, including prostaglandin E synthase-1 (mPGES-1) and prostacyclin synthase (PGIS) in rat aortic adventitial fibroblasts in the presence or absence of an inflammatory stimulus [interleukin (IL)-1β].

METHODS AND RESULTS

Fibroblasts stimulated with IL-1β (10 ng/ml, 24 h) and/or Ang II (0.1 μmol/l, 24 h) were used. IL-1β up-regulated COX-2 and mPGES-1 (protein and mRNA) and increased PGI2 and PGE2 release, without altering PGIS protein expression. Ang II did modify neither COX-2 and mPGES-1 expression nor prostanoid levels, but it induced PGIS expression. Interestingly, Ang II further enhanced IL-1β-induced COX-2 expression and PGI2 release and concomitantly reduced IL-1β-induced mPGES-1 expression. The AT1 receptor antagonist losartan prevented the effects of Ang II on IL-1β-induced COX-2 or mPGES-1 expression. IL-1β activated p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK)1/2 pathways, and coincubation with Ang II resulted in a higher and more sustained phosphorylation of both MAPK. Inhibition of either p38 MAPK (SB203580) or ERK1/2 (PD98059) reduced COX-2 and mPGES-1 expression in cells treated with IL-1β or the combination of IL-1β and Ang II. Ang II did not modify COX-2 transcriptional activity but increased COX-2 mRNA stability in IL-1β-treated cells; by contrast, it increased PGIS mRNA levels through a transcriptional mechanism.

CONCLUSION

Ang II differentially modulates key enzymes involved in prostanoid biosynthesis thereby altering the balance between PGI2/PGE2 in vascular cells exposed to inflammatory stimuli.

Lymphocyte responses exacerbate angiotensin II-dependent hypertension

Activation of the immune system by ANG II contributes to the pathogenesis of hypertension, and pharmacological suppression of lymphocyte responses can ameliorate hypertensive end-organ damage. Therefore, to examine the mechanisms through which lymphocytes mediate blood pressure elevation, we studied ANG II-dependent hypertension in scid mice lacking lymphocyte responses and wild-type controls. Scid mice had a blunted hypertensive response to chronic ANG II infusion and accordingly developed less cardiac hypertrophy. Moreover, lymphocyte deficiency led to significant reductions in heart and kidney injury following 4 wk of angiotensin. The muted hypertensive response in the scid mice was associated with increased sodium excretion, urine volumes, and weight loss beginning on day 5 of angiotensin infusion. To explore the mechanisms underlying alterations in blood pressure and renal sodium handling, we measured gene expression for vasoactive mediators in the kidney after 4 wk of ANG II administration. Scid mice and controls had similar renal expression for interferon-gamma, interleukin-1beta, and interleukin-6. By contrast, lymphocyte deficiency (i.e., scid mice) during ANG II infusion led to upregulation of tumor necrosis factor-alpha, endothelial nitric oxide synthase (eNOS), and cyclooxygenase-2 (COX-2) in the kidney. In turn, this enhanced eNOS and COX-2 expression in the scid kidneys was associated with exaggerated renal generation of nitric oxide, prostaglandin E(2), and prostacyclin, all of which promote natriuresis. Thus, the absence of lymphocyte activity protects from hypertension by allowing blood pressure-induced sodium excretion, possibly via stimulation of eNOS- and COX-2-dependent pathways.