Sepsis exacerbates Alzheimer's disease pathophysiology, modulates the gut microbiome, increases neuroinflammation and amyloid burden.

While our understanding of the molecular biology of Alzheimer's disease (AD) has grown, the etiology of the disease, especially the involvement of peripheral infection, remains a challenge. In this study, we hypothesize that peripheral infection represents a risk factor for AD pathology. To test our hypothesis, APP/PS1 mice underwent cecal ligation and puncture (CLP) surgery to develop a polymicrobial infection or non-CLP surgery. Mice were euthanized at 3, 30, and 120 days after surgery to evaluate the inflammatory mediators, glial cell markers, amyloid burden, gut microbiome, gut morphology, and short-chain fatty acids (SCFAs) levels. The novel object recognition (NOR) task was performed 30 and 120 days after the surgery, and sepsis accelerated the cognitive decline in APP/PS1 mice at both time points. At 120 days, the insoluble Aß increased in the sepsis group, and sepsis modulated the cytokines/chemokines, decreasing the cytokines associated with brain homeostasis IL-10 and IL-13 and increasing the eotaxin known to influence cognitive function. At 120 days, we found an increased density of IBA-1-positive microglia in the vicinity of Aß dense-core plaques, compared with the control group confirming the predictable clustering of reactive glia around dense-core plaques within 15 µm near Aß deposits in the brain. In the gut, sepsis negatively modulated the α- and ß-diversity indices evaluated by 16S rRNA sequencing, decreased the levels of SCFAs, and significantly affected ileum and colon morphology in CLP mice. Our data suggest that sepsis-induced peripheral infection accelerates cognitive decline and AD pathology in the AD mouse model.

A crosstalk between gut and brain in sepsis-induced cognitive decline.

BACKGROUND: Sepsis is a potentially fatal disease characterized by acute organ failure that affects more than 30 million people worldwide. Inflammation is strongly associated with sepsis, and patients can experience impairments in memory, concentration, verbal fluency, and executive functioning after being discharged from the hospital. We hypothesize that sepsis disrupts the microbiota-gut-brain axis homeostasis triggering cognitive impairment. This immune activation persists during treatment, causing neurological dysfunction in sepsis survivors. METHODS: To test our hypothesis, adult Wistar rats were subjected to cecal-ligation and perforation (CLP) or sham (non-CLP) surgeries. The animals were subjected to the [11C]PBR28 positron emission tomography (PET)/computed tomography (CT) imaging at 24 h and 10 days after CLP and non-CLP surgeries. At 24 h and 10 days after surgery, we evaluated the gut microbiome, bacterial metabolites, cytokines, microglia, and astrocyte markers. Ten days after sepsis induction, the animals were subjected to the novel object recognition (NOR) and the Morris water maze (MWM) test to assess their learning and memory. RESULTS: Compared to the control group, the 24-h and 10-day CLP groups showed increased [11C]PBR28 uptake, glial cells count, and cytokine levels in the brain. Results show that sepsis modulates the gut villus length and crypt depth, alpha and beta microbial diversities, and fecal short-chain fatty acids (SCFAs). In addition, sepsis surviving animals showed a significant cognitive decline compared with the control group. CONCLUSIONS: Since several pharmacological studies have failed to prevent cognitive impairment in sepsis survivors, a better understanding of the function of glial cells and gut microbiota can provide new avenues for treating sepsis patients.

Receptor for Advanced Glycation End Products (RAGE) Mediates Cognitive Impairment Triggered by Pneumococcal Meningitis.

Pneumococcal meningitis is a life-threatening infection of the central nervous system (CNS), and half of the survivors of meningitis suffer from neurological sequelae. We hypothesized that pneumococcal meningitis causes CNS inflammation via the disruption of the blood-brain barrier (BBB) and by increasing the receptor for advanced glycation end product (RAGE) expression in the brain, which causes glial cell activation, leading to cognitive impairment. To test our hypothesis, 60-day-old Wistar rats were subjected to meningitis by receiving an intracisternal injection of Streptococcus pneumoniae or artificial cerebrospinal fluid as a control group and were treated with a RAGE-specific inhibitor (FPS-ZM1) in saline. The rats also received ceftriaxone 100 mg/kg intraperitoneally, bid, and fluid replacements. Experimental pneumococcal meningitis triggered BBB disruption after meningitis induction, and FPS-ZM1 treatment significantly suppressed BBB disruption. Ten days after meningitis induction, surviving animals were free from infection, but they presented increased levels of TNF-α and IL-1ß in the prefrontal cortex (PFC); high expression levels of RAGE, amyloid-ß (Aß1-42), and microglial cell activation in the PFC and hippocampus; and memory impairment, as evaluated by the open-field, novel object recognition task and Morris water maze behavioral tasks. Targeted RAGE inhibition was able to reduce cytokine levels, decrease the expression of RAGE and Aß1-42, inhibit microglial cell activation, and improve cognitive deficits in meningitis survivor rats. The sequence of events generated by pneumococcal meningitis can persist long after recovery, triggering neurocognitive decline; however, RAGE blocker attenuated the development of brain inflammation and cognitive impairment in experimental meningitis.

Lipoic Acid and Fish Oil Combination Potentiates Neuroinflammation and Oxidative Stress Regulation and Prevents Cognitive Decline of Rats After Sepsis.

Sepsis causes organ dysfunction due to an infection, and it may impact the central nervous system. Neuroinflammation and oxidative stress are related to brain dysfunction after sepsis. Both processes affect microglia activation, neurotrophin production, and long-term cognition. Fish oil (FO) is an anti-inflammatory compound, and lipoic acid (LA) is a universal antioxidant substance. They exert neuroprotective roles when administered alone. We aimed at determining the effect of FO+LA combination on microglia activation and brain dysfunction after sepsis. Microglia cells from neonatal pups were co-treated with lipopolysaccharide (LPS) and FO or LA, alone or combined, for 24 h. Cytokine levels were measured. Wistar rats were subjected to sepsis by cecal ligation and perforation (CLP) and treated orally with FO, LA, or FO+LA. At 24 h after surgery, the hippocampus, prefrontal cortex, and total cortex were obtained and assayed for levels of cytokines, myeloperoxidase (MPO) activity, protein carbonyls, superoxide dismutase (SOD), and catalase (CAT) activity. At 10 days after surgery, brain-derived neurotrophic factor (BDNF) levels were determined and behavioral tests were performed. The combination diminished in vitro levels of pro-inflammatory cytokines. The combination reduced TNF-α in the cortex, IL-1ß in the prefrontal cortex, as well as MPO activity, and decreased protein carbonyls formation in all structures. The combination enhanced catalase activity in the prefrontal cortex and hippocampus, elevated BDNF levels in all structures, and prevented behavioral impairment. In summary, the combination was effective in preventing cognitive damage by reducing neuroinflammation and oxidative stress and increasing BDNF levels.

Maternal deprivation increases microglial activation and neuroinflammatory markers in the prefrontal cortex and hippocampus of infant rats.

A relationship between neuroinflammation and the development of psychiatric disorder have been revealed by many studies in the past decade. Although studies have shown that stressors can induce long-term changes that may be related to behavioral responses, these alterations have been poorly studied soon after a stressor, such as maternal deprivation (MD). Thus, this study was designed to investigate the acute effect of experimental induction of MD on inflammatory and microglial activation markers in the brain of infant rats. Early MD was induced from postnatal day (PND) 1-10. On PND 10 the prefrontal cortex (PFC) and hippocampus from MD and control groups were removed to investigate microglial activation and neuroinflammatory markers. In the PFC the expressions of cluster of differentiation molecule 11B (CD11B), toll-like receptor (TLR)-2, and TLR-4 were increased in rats subjected to MD. The arginase expression was elevated in the PFC and hippocampus of maternally deprived rats. The cytokines interleukin-5 (IL-5), -6, -7, -10, tumor necrosis factor (TNF-α), and interferon gamma (INF-γ) were increased in the PFC of MD rats group. In the PFC the macrophage inflammatory proteins (MIP)-1α levels were reduced in MD rats group. In the hippocampus only the levels of TNF-α and INF-γ were elevated in infant rats subjected to MD. In conclusion, our results support the hypothesis that neuroinflammation and microglial activation, mainly in the PFC, could be involved with changes in the brain resident cells following MD, and these alterations could be associated to the development of psychiatric conditions late in life.

Long-Term Cognitive Outcomes After Sepsis: a Translational Systematic Review.

Sepsis is systemic inflammatory response syndrome with a life-threatening organ dysfunction that is caused by an unbalanced host immune response in an attempt to eliminate invasive microorganisms. We posed questions, "Does sepsis survivor patients have increased risk of neuropsychiatric manifestations?" and "What is the mechanism by which sepsis induces long-term neurological sequelae, particularly substantial cognitive function decline in survivor patients and in pre-clinical sepsis models?" The studies were identified by searching PubMed/MEDLINE (National Library of Medicine), PsycINFO, EMBASE (Ovid), LILACS (Latin American and Caribbean Health Sciences Literature), IBECS (Bibliographical Index in Spanish in Health Sciences), and Web of Science databases for peer-reviewed journals that were published until January 2018. A total of 3555 papers were included in the primary screening. After that, 130 articles were selected for the study. A number of pre-clinical studies have shown an auto amplification of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-1ß, and IL-6 in the first few hours after sepsis induction, also increased blood-brain barrier permeability, elevated levels of matrix metalloproteinases, increased levels of damage-associated molecular patterns were demonstrated. In addition, the rodents presented long-term cognitive impairment in different behavioral tasks that were prevented by blocking the mechanism of action of these inflammatory mediators. Clinical studies have showed that sepsis survivors presented increased bodily symptoms such as fatigue, pain, visual disturbances, gastrointestinal problems, and neuropsychiatric problems compared to before sepsis. Sepsis leaves the survivors with an aftermath of physiological, neuropsychiatric, and functional impairment. Systematic review registration: CRD42017071755.

Small molecule disruption of G protein ßγ subunit signaling reprograms human macrophage phenotype and prevents autoimmune myocarditis in rats.

The purpose of this study was to determine whether blocking of G protein ßγ (Gßγ) signaling halts heart failure (HF) progression by macrophage phenotype manipulation. Cardiac Gßγ signaling plays a crucial role in HF pathogenesis. Previous data suggested that inhibiting Gßγ signaling reprograms T helper cell 1 (Th1) and Th2 cytokines, suggesting that Gßγ might be a useful drug target for treating HF. We investigated the efficacy of a small molecule Gßγ inhibitor, gallein, in a clinically relevant, experimental autoimmune myocarditis (EAM) model of HF as well as in human macrophage phenotypes in vitro. In the myocardium of HF patients, we observed that G protein coupled receptor kinase (GRK)2 levels were down-regulated compared with healthy controls. In rat EAM, treatment with gallein effectively improved survival and cardiac function, suppressed cardiac remodeling, and further attenuated myocardial protein expression of GRK2 as well as high mobility group box (HMGB)1 and its cascade signaling proteins. Furthermore, gallein effectively inhibited M1 polarization and promoted M2 polarization in vivo in the EAM heart and in vitro in human monocyte-derived macrophages. Taken together, these data suggest that the small molecule Gßγ inhibitor, gallein, could be an important pharmacologic therapy for HF as it can switch the phenotypic reprogramming from M1 to M2 phenotype in a rat model of EAM heart and in human macrophages.

Tiny molecule, big power: Multi-target approach for curcumin in diabetic cardiomyopathy.

Diabetic cardiomyopathy (DCM) is described as impaired cardiac diastolic and systolic functions. Diabetes mellitus (DM), a related cardiovascular disease, has become one of the major causes of death in DM patients. Mortality in these diseases is 2 to 3 times higher than in non-DM patients with cardiovascular disease. The progression of DCM and the cellular and molecular perturbations associated with the pathogenesis are complex and multifactorial. Although considerable progress has been achieved, the molecular etiologies of DCM remain poorly understood. There is an expanding need for natural antidiabetic medicines that do not cause the side effects of modern drugs. Curcumin, a pleiotropic molecule, from Curcuma longa, is known to possess numerous impacts such as scavenging free radical, antioxidant, antitumor, and antiinflammatory activities. The reports from preclinical and clinical findings revealed that curcumin can reverse insulin resistance, hyperglycemia, obesity, and obesity-related metabolic diseases. The current review provides an updated overview of the possible molecular mechanism of DCM and multitarget approach of curcumin in alleviating DCM and diabetic complication. Additionally, we mentioned the approaches that are currently being implemented to improve the bioavailability of this promising natural product in diabetes therapeutics.

Curcumin alleviates renal dysfunction and suppresses inflammation by shifting from M1 to M2 macrophage polarization in daunorubicin induced nephrotoxicity in rats.

The molecular mechanism of curcumin in macrophage polarization remains unknown in renal failure. We examined, whether curcumin treatment is associated with the modulation of renal function and macrophage phenotype switch in daunorubicin (DNR) induced nephrotoxicity model. Sprague-Dawley rats were treated with a cumulative dose of 9mg/kg DNR (i.v). Followed by curcumin (100mg/kg) administration orally every day for 6weeks. DNR treated rats showed nephrotoxicity as evidenced by worsening renal function, which was assessed by measuring creatinine and blood urea nitrogen in serum. These changes were reversed by treatment with curcumin, which resulted in significant improvement in renal function. Furthermore, curcumin increased cluster of differentiation (CD)163 expression, and down-regulated renal expression of antigen II type I receptor (AT1R), endothelin (ET)1, ET receptor type A and B (ETAR and ETBR), CD68 and CD80. Renal protein expression of extracellular signal-regulated kinase (ERK)1/2 and nuclear factor (NF)κB p65 were increased in DNR treated rats, and treatment with curcumin attenuated these increased expression. Curcumin mediated a further increase in the levels of interleukin (IL)-10. In addition, the expression of M1 phenotype was increased in DNR treated rats, which were attenuated by curcumin. Taken together, our results demonstrated that polyphenol curcumin has an ability to improve renal function and might induce the phenotypic switching from M1 to M2 macrophage polarization in DNR induced nephrotoxicity in rats.

Modulation of Macrophage Polarization and HMGB1-TLR2/TLR4 Cascade Plays a Crucial Role for Cardiac Remodeling in Senescence-Accelerated Prone Mice.

The aim of this study was to investigate the role of macrophage polarization in aging heart. Macrophage differentiation is pathogenically linked to many inflammatory and immune disorders. It is often preceded by myocardial inflammation, which is characterized by increased cardiac damage and pro-inflammatory cytokine levels. Therefore, we investigated the hypothesis that senescence accelerated-prone (SAMP8) mice cardiac tissue would develop macrophage polarization compared with senescence-resistant control (SAMR1) mice. Both SAMP8 and SAMR1 mice were sacrificed when they became six month old. We evaluated, histo-pathological changes and modifications in protein expression by Western blotting and immuno-histochemical staining for M1 and M2 macrophage markers, high mobility group protein (HMG)B1 and its cascade proteins, pro-inflammatory factors and inflammatory cytokines in cardiac tissue. We observed significant upregulation of HMGB1, toll-like receptor (TLR)2, TLR4, nuclear factor (NF)κB p65, tumor necrosis factor (TNF)α, cyclooxygenase (COX)2, interferon (IFN)γ, interleukin (IL)-1ß, IL-6 and M1 like macrophage specific marker cluster of differentiation (CD)68 expressions in SAMP8 heart. In contrast, M2 macrophage specific marker CD36, and IL-10 expressions were down-regulated in SAMP8 mice. The results from the study demonstrated that, HMGB1-TLR2/TLR4 signaling cascade and induction of phenotypic switching to M1 macrophage polarization in SAMP8 mice heart would be one of the possible reasons behind the cardiac dysfunction and thus it could become an important therapeutic target to improve the age related cardiac dysfunction.

Molecular targets of quercetin with anti-inflammatory properties in atopic dermatitis.

Atopic dermatitis (AD) is an inflammatory skin disease. Over the past few decades, AD has become more prevalent worldwide. Quercetin, a naturally occurring polyphenol, shows antioxidant, anti-inflammatory, and antiallergic activities. Several recent clinical and preclinical findings suggest quercetin as a promising natural treatment for inflammatory skin diseases. Significant progress in elucidating the molecular mechanisms underlying the anti-AD properties of quercetin has been achieved in the recent years. Here, we discuss the use of quercetin as treatment for AD, with a particular focus on the molecular basis of its effect. We also briefly discuss the approaches to improve the bioavailability of quercetin.

Schisandrin B Ameliorates ICV-Infused Amyloid ß Induced Oxidative Stress and Neuronal Dysfunction through Inhibiting RAGE/NF-κB/MAPK and Up-Regulating HSP/Beclin Expression.

Amyloid ß (Aß)-induced neurotoxicity is a major pathological mechanism of Alzheimer's disease (AD). Our previous studies have demonstrated that schisandrin B (Sch B), an antioxidant lignan from Schisandra chinensis, could protect mouse brain against scopolamine- and cisplatin-induced neuronal dysfunction. In the present study, we examined the protective effect of Sch B against intracerebroventricular (ICV)-infused Aß-induced neuronal dysfunction in rat cortex and explored the potential mechanism of its action. Our results showed that 26 days co-administration of Sch B significantly improved the behavioral performance of Aß (1-40)-infused rats in step-through test. At the same time, Sch B attenuated Aß-induced increases in oxidative and nitrosative stresses, inflammatory markers such as inducible nitric oxide syntheses, cyclooxygenase-2, interleukin-1ß (IL-1ß), IL-6, and tumor necrosis factor-α, and DNA damage. Several proteins such as receptor for advanced glycation end products (RAGE), nuclear factor-κB, mitogen-activated protein kinases, and apoptosis markers were over expressed in Aß-infused rats but were significantly inhibited by Sch B treatment. Furthermore, Sch B negatively modulated the Aß level with simultaneous up-regulation of HSP70 and beclin, autophagy markers in Aß-infused rats. The aforementioned effects of Sch B suggest its protective role against Aß-induced neurotoxicity through intervention in the negative cycle of RAGE-mediated Aß accumulation during AD patho-physiology.

Telmisartan treatment targets inflammatory cytokines to suppress the pathogenesis of acute colitis induced by dextran sulphate sodium.

The renin angiotensin system (RAS) is essential for the regulation of cardiovascular and renal functions to maintain the fluid and electrolyte homeostasis. Recent studies have demonstrated a locally expressed RAS in various tissues of mammals, which is having pathophysiological roles in those organ system. Interestingly, local RAS has important role during the inflammatory bowel disease pathogenesis. Further to delineate its role and also to identify the potential effects of telmisartan, an angiotensin receptor blocker, we have used a mouse model of acute colitis induced by dextran sulphate sodium. We have used 0.01 and 5mg/kg body weight doses of telmisartan and administered as enema to facilitate the on-site action and to reduce the systemic adverse effects. Telmisartan high dose treatment significantly reduced the disease activity index score when compared with the colitis control mice. In addition, oxidative stress and endoplasmic reticulum stress markers expression were also significantly reduced when compared with the colitis control mice. Subsequent experiments were carried out to investigate some of the mechanisms underlying its anti-inflammatory effects and identified that the mRNA levels of pro-inflammatory cytokines such as tumour necrosis factor α, interleukin 1ß, interleukin 6 and monocyte chemoattractant protein 1 as well as cellular DNA damage were significantly suppressed when compared with the colitis control mice. Similarly the apoptosis marker proteins such as cleaved caspase 3 and 7 levels were down-regulated and anti-apoptotic protein Bcl2 level was significantly upregulated by telmisartan treatment. These results indicate that blockade of RAS by telmisartan can be an effective therapeutic option against acute colitis.

Schisandrin B prevents doxorubicin induced cardiac dysfunction by modulation of DNA damage, oxidative stress and inflammation through inhibition of MAPK/p53 signaling.

Doxorubicin (Dox) is a highly effective antineoplastic drug. However, Dox-induced apoptosis in cardiomyocytes leads to irreversible degenerative cardiomyopathy, which limits Dox clinical application. Schisandrin B (Sch B), a dibenzocyclooctadiene derivative isolated from the fruit of Schisandra chinensis, has been shown to protect against oxidative damage in liver, heart and brain tissues in rodents. In current study, we investigated possible protective effects of Sch B against Dox-induced cardiomyopathy in mice. Mice received a single injection of Dox (20 mg/kg IP). Five days after Dox administration, left ventricular (LV) performance was significantly depressed and was improved by Sch B treatment. Sch B prevented the Dox-induced increase in lipid peroxidation, nitrotyrosine formation, and metalloproteinase activation in the heart. In addition, the increased expression of phospho-p38 MAPK and phospho-MAPK activated mitogen kinase 2 levels by Dox were significantly suppressed by Sch B treatment. Sch B also attenuated Dox-induced higher expression of LV proinflammatory cytokines, cardiomyocyte DNA damage, myocardial apoptosis, caspase-3 positive cells and phopho-p53 levels in mice. Moreover, LV expression of NADPH oxidase subunits and reactive oxygen species were significantly less in Sch B treatment mice after Dox injection. These findings suggest that Sch B attenuates Dox-induced cardiotoxicity via antioxidative and anti-inflammatory effects.

Mulberry leaf diet protects against progression of experimental autoimmune myocarditis to dilated cardiomyopathy via modulation of oxidative stress and MAPK-mediated apoptosis.

AIM OF THE STUDY: To examine the protective effects of dietary administration of Mulberry leaves (ML) on postmyocarditis dilated cardiomyopathy (DCM) focusing on oxidative and endoplasmic reticulum stresses and adverse myocardial remodeling. MATERIALS AND METHODS: In this study, we used a rat model of cardiac myosin-induced experimental autoimmune myocarditis to test the effects of ML diet (MLD) (5%) on various markers of cardiac remodeling and function. After 4 weeks of immunization, the rats were fed with 5% MLD for 4 weeks. By the end of the study, echocardiography was performed to assess the myocardial dimensions. The heart tissue was used for histopathology and Western blotting analyses. RESULTS: Our study showed that the postmyocarditis rats exhibited increased oxidative stress when compared with the control rats. MLD supplementation suppressed this change, compared with vehicle treatment. In addition, postmyocarditis rats showed significant elevation of the endoplasmic reticulum stress markers, which were prevented by the MLD supplementation. Similarly the vehicle-treated rats suffered with the adverse myocardial remodeling in the form of fibrosis as evidenced by the Azan-Mallory staining and immunohistochemistry for collagen-III levels, compared with the control rats. However, MLD treatment not only markedly attenuated cardiac fibrosis, but also improved the left ventricular ejection fraction and fractional shortening. Interestingly, the myocardial levels of endothelin-1, activated members of mitogen-activated protein kinase (MAPK) pathway, and vascular endothelial growth factor (VEGF) were significantly attenuated by MLD, indicating that the antihypertrophic effects of MLD are partially mediated via endothelin-1, MAPK, and VEGF pathway. CONCLUSION: Collectively, these results suggest that supplementation of rats with 5% MLD has the ability to regulate cardiac remodeling and improves cardiac function and hence contributes to prevent the development of postmyocarditis dilated cardiomyopathy.

Involvement of AMPK and MAPK signaling during the progression of experimental autoimmune myocarditis in rats and its blockade using a novel antioxidant.

There are various reports suggesting the role of angiotensin (Ang) receptor blockers, Ang converting enzyme inhibitors, calcium channel blockers, diuretics and antioxidants against the progression of experimental autoimmune myocarditis (EAM) to dilated cardiomyopathy (DCM). Most of them were reported to be effective during this adverse cardiac remodeling. Recently much attention has been paid to studying the involvement of AMP-activated protein kinase (AMPK) and mitogen activated protein kinase (MAPK) in various cardiovascular ailments. AMPK acts as a master sensor of cellular energy balance via maintenance of lipid and glucose metabolism. Evidences also suggest the relation between AMPK and oxidative stress during physiological and pathological myocardial cellular function. Since, it is of interest to identify the roles of AMPK and MAPK during the progression of EAM to DCM and also the effect of edaravone, a novel free radical scavenger, against its progression. For this, we have carried out western blotting, histopathological staining and immunohistochemical analyses to measure the myocardial expressions of AMPK signaling and oxidative stress related parameters in normal and vehicle or edaravone-treated EAM rats, respectively. We identified the myocardial levels of phospho Akt and phosphoinositide 3-kinase, which are the upstream proteins of AMPK and MAPK activation and both were up-regulated in the vehicle-treated rats, whereas candesartan treatment significantly reversed these changes. We have also measured the myocardial levels of p-AMPKα, different isoforms of protein kinase C and MAPK signaling proteins. All of these protein levels were significantly elevated in the hearts of DCM rats whereas edaravone treatment significantly reversed these changes. In viewing these results, we can suggest that along with MAPK, AMPK signaling also plays a crucial role in the progression of EAM and it can be effectively blocked by the treatment with a novel antioxidant, edaravone.

Modulation of AT-1R/MAPK cascade by an olmesartan treatment attenuates diabetic nephropathy in streptozotocin-induced diabetic mice.

There is increasing evidence that angiotensin (Ang)-II plays an unprecedented role in diabetic complications. It could also be an important therapeutic target for ameliorating various diseases, especially diabetic nephropathy (DN). We therefore studied the beneficial effects of olmesartan, an Ang-II type 1 receptor (AT-1R) blocker in streptozotocin (150 mg/kg, BW)-induced diabetic kidney disease in mice. The diabetic kidney mice displayed upregulated protein expression levels of AT-1R, AT-2R, ERK-1/2, p-p38 MAPK, p-MAPKAPK-2, ET-1, p-JNK, p-c-Jun, TGF-ß1, and gp91-phox, and all of these effects were expectedly downregulated by an olmesartan treatment. Also, immunohistochemical analysis, and Azan-Mallory and HE staining were performed to examine the expression of collagen-III and fibronectin, renal fibrosis, and hypertrophy, respectively. Furthermore, olmesartan treatment significantly abrogated the downregulation of ACE-2 and Ang-(1-7) mas R protein expression in diabetic kidney mice. Considering all these findings together, the AT-1R/MAPK pathway might be a potential therapeutic target in diabetes kidney disease, and olmesartan treatment could have beneficial effects on DN by modulating the AT-1R/MAPK pathway.