Prior exposure to microcystin alters host gut resistome and is associated with dysregulated immune homeostasis in translatable mouse models

A strong association between exposure to the common harmful algal bloom toxin microcystin and the altered host gut microbiome has been shown. We tested the hypothesis that prior exposure to the cyanotoxin microcystin-LR may alter the host resistome. We show that the mice exposed to microcystin-LR had an altered microbiome signature that harbored antibiotic resistance genes. Host resistome genotypes such as mefA, msrD, mel, ant6, and tet40 increased in diversity and relative abundance following microcystin-LR exposure. Interestingly, the increased abundance of these genes was traced to resistance to common antibiotics such as tetracycline, macrolides, glycopeptide, and aminoglycosides, crucial for modern-day treatment of several diseases. Increased abundance of these genes was positively associated with increased expression of PD1, a T-cell homeostasis marker, and pleiotropic inflammatory cytokine IL-6 with a concomitant negative association with immunosurveillance markers IL-7 and TLR2. Microcystin-LR exposure also caused decreased TLR2, TLR4, and REG3G expressions, increased immunosenescence, and higher systemic levels of IL-6 in both wild-type and humanized mice. In conclusion, the results show a first-ever characterization of the host resistome following microcystin-LR exposure and its connection to host immune status and antimicrobial resistance that can be crucial to understand treatment options with antibiotics in microcystin-exposed subjects in clinical settings.

Environmental Microcystin exposure in underlying NAFLD-induced exacerbation of neuroinflammation, blood-brain barrier dysfunction, and neurodegeneration are NLRP3 and S100B dependent

Nonalcoholic fatty liver disease (NAFLD) has been shown to be associated with extrahepatic comorbidities including neuronal inflammation and Alzheimer's-like pathology. Environmental and genetic factors also act as a second hit to modulate severity and are expected to enhance the NAFLD-linked neuropathology. We hypothezied that environmental microcystin-LR (MC-LR), a toxin produced by harmful algal blooms of cyanobacteria, exacerbates the neuroinflammation and degeneration of neurons associated with NAFLD. Using a mouse model of NAFLD, exposed to MC-LR subsequent to the onset of fatty liver, we show that the cyanotoxin could significantly increase proinflammatory cytokine expression in the frontal cortex and cause increased expression of Lcn2 and HMGB1. The above effects were NLRP3 inflammasome activation-dependent since the use of NLRP3 knockout mice abrogated the increase in inflammation. NLRP3 was also responsible for decreased expression of the blood-brain barrier (BBB) tight junction proteins Occludin and Claudin 5 suggesting BBB dysfunction was parallel to neuroinflammation following microcystin exposure. An increased circulatory S100B release, a hallmark of astrocyte activation in MC-LR exposed NAFLD mice also confirmed BBB integrity loss, but the astrocyte activation observed in vivo was NLRP3 independent suggesting an important role of a secondary S100B mediated crosstalk. Mechanistically, conditioned medium from reactive astrocytes and parallel S100B incubation in neuronal cells caused increased inducible NOS, COX-2, and higher BAX/ Bcl2 protein expression suggesting oxidative stress-mediated neuronal cell apoptosis crucial for neurodegeneration. Taken together, MC-LR exacerbated neuronal NAFLD-linked comorbidities leading to cortical inflammation, BBB dysfunction, and neuronal apoptosis.

Andrographolide Attenuates Gut-Brain-Axis Associated Pathology in Gulf War Illness by Modulating Bacteriome-Virome Associated Inflammation and Microglia-Neuron Proinflammatory Crosstalk

Gulf War Illness (GWI) is a chronic multi-symptomatic illness that is associated with fatigue, pain, cognitive deficits, and gastrointestinal disturbances and presents a significant challenge to treat in clinics. Our previous studies show a role of an altered Gut–Brain axis pathology in disease development and symptom persistence in GWI. The present study utilizes a mouse model of GWI to study the role of a labdane diterpenoid andrographolide (AG) to attenuate the Gut–Brain axis-linked pathology. Results showed that AG treatment in mice (100 mg/kg) via oral gavage restored bacteriome alterations, significantly increased probiotic bacteria Akkermansia, Lachnospiraceae, and Bifidobacterium, the genera that are known to aid in preserving gut and immune health. AG also corrected an altered virome with significant decreases in virome families Siphoviridae and Myoviridae known to be associated with gastrointestinal pathology. AG treatment significantly restored tight junction proteins that correlated well with decreased intestinal proinflammatory mediators IL-1β and IL-6 release. AG treatment could restore Claudin-5 levels, crucial for maintaining the BBB integrity. Notably, AG could decrease microglial activation and increase neurotrophic factor BDNF, the key to neurogenesis. Mechanistically, microglial conditioned medium generated from IL-6 stimulation with or without AG in a concentration similar to circulating levels found in the GWI mouse model and co-incubated with neuronal cells in vitro, decreased Tau phosphorylation and neuronal apoptosis. In conclusion, we show that AG treatment mitigated the Gut–Brain-Axis associated pathology in GWI and may be considered as a potential therapeutic avenue for the much-needed bench to bedside strategies in GWI.

Higher intestinal and circulatory lactate associated NOX2 activation leads to an ectopic fibrotic pathology following microcystin co-exposure in murine fatty liver disease

Clinical studies implicated an increased risk of intestinal fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). Our previous studies have shown that microcystin-LR (MC-LR) exposure led to altered gut microbiome and increased abundance of lactate producing bacteria and intestinal inflammation in underlying NAFLD. This led us to further investigate the effects of the MC-LR, a PP2A inhibitor in activating the TGF-β fibrotic pathway in the intestines that might be mediated by increased lactate induced redox enzyme NOX2. Exposure to MC-LR led to higher lactate levels in circulation and in the intestinal content. The higher lactate levels were associated with NOX2 activation in vivo that led to increased Smad2/3-Smad4 co-localization and high alpha-smooth muscle actin (α-SMA) immunoreactivity in the intestines. Mechanistically, primary mouse intestinal epithelial cells treated with lactate and MC-LR separately led to higher NOX2 activation, phosphorylation of TGFβR1 receptor and subsequent Smad 2/3-Smad4 co-localization inhibitable by apocynin (NOX2 inhibitor), FBA (a peroxynitrite scavenger) and DMPO (a nitrone spin trap), catalase and superoxide dismutase. Inhibition of NOX2-induced redox signaling also showed a significant decrease in collagen protein thus suggesting a strong redox signaling induced activation of an ectopic fibrotic manifestation in the intestines. In conclusion, the present study provides mechanistic insight into the role of microcystin in dysbiosis-linked lactate production and subsequently advances our knowledge in lactate-induced NOX2 exacerbation of the cell differentiation and fibrosis in the NAFLD intestines.

Early microcystin-LR exposure-linked inflammasome activation in mice causes development of fatty liver disease and insulin resistance

Evidence from pediatric studies show that infants and children are at risk for early exposure to microcystin. The present report tests the hypothesis that early life exposure to microcystin (MC), a principal component of harmful algal blooms followed by a juvenile exposure to high-fat diet feeding potentiate the development of nonalcoholic fatty liver disease phenotype in adulthood. Results showed classical symptoms of early NAFLD linked inflammation. Cytokines and chemokines such as CD68, IL-1β, MCP-1, and TNF-α, as well as α-SMA were increased in the groups that were exposed to MC-LR with the high-fat diet compared to the vehicle group. Also, mechanistically, NLRP3 KO mice showed a significant decrease in the inflammation and NAFLD phenotype and resisted the metabolic changes such as insulin resistance and glucose metabolism in the liver. The data suggested that MC-LR exposure and subsequent NLRP3 inflammasome activation in childhood could impact liver health in juveniles.

TLR Antagonism by Sparstolonin B Alters Microbial Signature and Modulates Gastrointestinal and Neuronal Inflammation in Gulf War Illness Preclinical Model

The 1991 Persian Gulf War veterans presented a myriad of symptoms that ranged from chronic pain, fatigue, gastrointestinal disturbances, and cognitive deficits. Currently, no therapeutic regimen exists to treat the plethora of chronic symptoms though newer pharmacological targets such as microbiome have been identified recently. Toll-like receptor 4 (TLR4) antagonism in systemic inflammatory diseases have been tried before with limited success, but strategies with broad-spectrum TLR4 antagonists and their ability to modulate the host-microbiome have been elusive. Using a mouse model of Gulf War Illness, we show that a nutraceutical, derived from a Chinese herb Sparstolonin B (SsnB) presented a unique microbiome signature with an increased abundance of butyrogenic bacteria. SsnB administration restored a normal tight junction protein profile with an increase in Occludin and a parallel decrease in Claudin 2 and inflammatory mediators high mobility group box 1 (HMGB1), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in the distal intestine. SsnB also decreased neuronal inflammation by decreasing IL-1β and HMGB1, while increasing brain-derived neurotrophic factor (BDNF), with a parallel decrease in astrocyte activation in vitro. Mechanistically, SsnB inhibited the binding of HMGB1 and myeloid differentiation primary response protein (MyD88) to TLR4 in the intestine, thus attenuating TLR4 downstream signaling. Studies also showed that SsnB was effective in suppressing TLR4-induced nod-like receptor protein 3 (NLRP3) inflammasome activation, a prominent inflammatory disease pathway. SsnB significantly decreased astrocyte activation by decreasing colocalization of glial fibrillary acid protein (GFAP) and S100 calcium-binding protein B (S100B), a crucial event in neuronal inflammation. Inactivation of SsnB by treating the parent molecule by acetate reversed the deactivation of NLRP3 inflammasome and astrocytes in vitro, suggesting that SsnB molecular motifs may be responsible for its anti-inflammatory activity.

Host Akkermansia muciniphila Abundance Correlates With Gulf War Illness Symptom Persistence via NLRP3-Mediated Neuroinflammation and Decreased Brain-Derived Neurotrophic Factor

Neurological disorders are commonly reported among veterans who returned from the Gulf war. Veterans who suffer from Gulf War illness (GWI) complain of continued symptom persistence that includes neurological disorders, muscle weakness, headaches, and memory loss, that developed during or shortly after the war. Our recent research showed that chemical exposure associated microbial dysbiosis accompanied by a leaky gut connected the pathologies in the intestine, liver, and brain. However, the mechanisms that caused the symptoms to persist even 30 years after the war remained elusive to investigators. In this study, we used a rodent model of GWI to investigate the persistence of microbiome alterations, resultant chronic inflammation, and its effect on neurotrophic and synaptic plasticity marker BDNF. The results showed that exposure to GW chemicals (the pesticide permethrin and prophylactic drug pyridostigmine bromide) resulted in persistent pathology characterized by the low relative abundance of the probiotic bacteria Akkermansia muciniphila in the gut, which correlated with high circulatory HMGB1 levels, blood-brain barrier dysfunction, neuroinflammation and lowered neurotrophin BDNF levels. Mechanistically, we used mice lacking the NLRP3 gene to investigate this inflammasome's role in observed pathology. These mice had significantly decreased inflammation and a subsequent increase in BDNF in the frontal cortex. This suggests that a persistently low species abundance of Akkermansia muciniphila and associated chronic inflammation due to inflammasome activation might be playing a significant role in contributing to chronic neurological problems in GWI. A therapeutic approach with various small molecules that can target both the restoration of a healthy microbiome and decreasing inflammasome activation might have better outcomes in treating GWI symptom persistence.

Altered Gut DNA virome diversity associated HMGB1 release regulates reactive Astrocytes-induced IL6 release preferably via TLR4-NFkB pathway in experimental Gulf War Illness

In a recent study, we showed that the gut DNA bacteriophage dysbiosis in Gulf War Illness (GWI) was strongly associated with compromised intestinal epithelial cell integrity, increased circulatory IL6 and neuroinflammation. The current study further investigates the mechanism of DNA bacteriophage-IL6 axis in neuroinflammation. Advancing the previous findings, we show that viral dysbiosis positively correlated with high mobility group box protein 1 (HMGB1; a damage-associated molecular pattern) expression and release in circulation following GWI induction in mice. The circulatory HMGB1 activated brain Astrocytes via altering brain endothelial tight junction proteins and crossing the blood-brain barrier. Interestingly, both in GWI mice and mouse primary Astrocytes cell culture showed an increased brain IL6 mRNA and subsequent protein expression. However, GWI mice treated with Ribavirin (used for partial gut viral sterility) showed decreased intestinal HMGB1 and brain IL6 expression. Mechanistically, HMGB1 activated innate immune response via IRAKs-IKKα-NFkB instead of either RAGE-MAPK or PI3K-mTOR pathway. Surprisingly, inhibition of RAGE or PI3K pathway in HMGB1 primed mouse Astrocyte cells showed a significant increase in IL6 expression and release suggesting NFkB activation as a preferential pathway in GWI-Astrocyte-induced IL6 release. In summary, GWI-associated gut viral dysbiosis associated intestinal HMGB1 release activates brain Astrocytes and IL6 release via toll-like receptor 4-NFkB dependent pathway, thus causing neuroinflammation in GWI. The above mechanism can form a basis for studying inflammation-associated neurocognitive abnormalities in GWI.

Microcystin exposure worsens nonalcoholic fatty liver disease associated ectopic glomerular toxicity via NOX-2-MIR21 axis

NAFLD often results in cardiovascular, intestinal and renal complications. Previous reports from our laboratory highlighted NAFLD induced ectopic inflammatory manifestations in the kidney that gave rise to glomerular inflammation. Extending our studies, we hypothesized that existing inflammatory conditions in NAFLD could make the kidneys more susceptible to environmental toxicity. Our results showed that exposure of Microcystin-LR (MC) in NAFLD mice caused a marked increase in cellular scarring with a concomitant increase in mesangial cell activation as observed by increased α-SMA in the extracellular matrix surrounding the glomeruli. Renal tissue surrounding the glomeruli also showed increased NOX2 activation as shown by greater co-localization of p47 Phox and its membrane component gp91Phox both in the mesangial cell and surrounding tissue. Mechanistically, mesangial cells incubated with apocynin, nitrone spin trap DMPO and miR21 inhibitor showed significantly decreased α-SMA, miR21 levels and proinflammatory cytokine release in the supernatant. In parallel, mice lacking miR21, known to be activated by NOX2, when exposed to MC in NAFLD showed decreased mesangial cell activation. Strikingly, phenyl boronic acid incubated cells that were exposed to MC showed significantly decreased mesangial cell activation showing that peroxynitrite might be the major reactive species involved in mediation of the activation process, release of proinflammatory micro RNAs and cytokines that are crucial for renal toxicity. Thus, in conclusion, MC exposure causes NOX2 activation that leads to mesangial cell activation and toxicity via release of peroxynitrite that also represses PTEN by the upregulation of miR21 thus amplifying the toxicity.

The Gut-Microbiome in Gulf War Veterans: A Preliminary Report

Gulf War Illness (GWI) is a chronic multi-symptom disorder affecting the central nervous system (CNS), immune and gastrointestinal (GI) systems of Gulf War veterans (GWV). We assessed the relationships between GWI, GI symptoms, gut microbiome and inflammatory markers in GWV from the Boston Gulf War Illness Consortium (GWIC). Three groups of GWIC veterans were recruited in this pilot study; GWV without GWI and no gastrointestinal symptoms (controls), GWV with GWI and no gastrointestinal symptoms (GWI-GI), GWV with GWI who reported gastrointestinal symptoms (GW+GI). Here we report on a subset of the first thirteen stool samples analyzed. Results showed significantly different gut microbiome patterns among the three groups and within the GWI +/-GI groups. Specifically, GW controls had a greater abundance of firmicutes and the GWI+GI group had a greater abundance of the phyla bacteroidetes, actinobacteria, euryarchaeota, and proteobacteria as well as higher abundances of the families Bacteroidaceae, Erysipelotrichaceae, and Bifidobacteriaceae. The GWI+GI group also showed greater plasma levels of the inflammatory cytokine TNF-RI and they endorsed significantly more chemical weapons exposure during the war and reported significantly greater chronic pain, fatigue and sleep difficulties than the other groups. Studies with larger samples sizes are needed to confirm these initial findings.

Exogenous PP2A inhibitor exacerbates the progression of nonalcoholic fatty liver disease via NOX2-dependent activation of miR21

Nonalcoholic fatty liver disease (NAFLD) is an emerging global pandemic. Though significant progress has been made in unraveling the pathophysiology of the disease, the role of protein phosphatase 2A (PP2A) and its subsequent inhibition by environmental and genetic factors in NAFLD pathophysiology remains unclear. The present report tests the hypothesis that an exogenous PP2A inhibitor leads to hepatic inflammation and fibrogenesis via an NADPH oxidase 2 (NOX2)-dependent pathway in NAFLD. Results showed that microcystin (MC) administration, a potent PP2A inhibitor found in environmental exposure, led to an exacerbation of NAFLD pathology with increased CD68 immunoreactivity, the release of proinflammatory cytokines, and stellate cell activation, a process that was attenuated in mice that lacked the p47phox gene and miR21 knockout mice. Mechanistically, leptin-primed immortalized Kupffer cells (a mimicked model for an NAFLD condition) treated with apocynin or nitrone spin trap 5,5 dimethyl-1- pyrroline N-oxide (DMPO) had significantly decreased CD68 and decreased miR21 and α-smooth muscle actin levels, suggesting the role of NOX2-dependent reactive oxygen species in miR21-induced Kupffer cell activation and stellate cell pathology. Furthermore, NOX2-dependent peroxynitrite generation was primarily responsible for cellular events observed following MC exposure since incubation with phenylboronic acid attenuated miR21 levels, Kupffer cell activation, and inflammatory cytokine release. Furthermore, blocking of the AKT pathway attenuated PP2A inhibitor-induced NOX2 activation and miR21 upregulation. Taken together, we show that PP2A may have protective roles, and its inhibition exacerbates NAFLD pathology via activating NOX2-dependent peroxynitrite generation, thus increasing miR21-induced pathology.NEW & NOTEWORTHY Protein phosphatase 2A inhibition causes nonalcoholic steatohepatitis (NASH) progression via NADPH oxidase 2. In addition to a novel emchanism of action, we describe a new tool to describe NASH histopathology.

Environmental microcystin targets the microbiome and increases the risk of intestinal inflammatory pathology via NOX2 in underlying murine model of Nonalcoholic Fatty Liver Disease

With increased climate change pressures likely to influence harmful algal blooms, exposure to microcystin, a known hepatotoxin and a byproduct of cyanobacterial blooms can be a risk factor for NAFLD associated comorbidities. Using both in vivo and in vitro experiments we show that microcystin exposure in NAFLD mice cause rapid alteration of gut microbiome, rise in bacterial genus known for mediating gut inflammation and lactate production. Changes in the microbiome were strongly associated with inflammatory pathology in the intestine, gut leaching, tight junction protein alterations and increased oxidative tyrosyl radicals. Increased lactate producing bacteria from the altered microbiome was associated with increased NOX-2, an NADPH oxidase isoform. Activationof NOX2 caused inflammasome activation as shown by NLRP3/ASCII and NLRP3/Casp-1 colocalizations in these cells while use of mice lacking a crucial NOX2 component attenuated inflammatory pathology and redox changes. Mechanistically, NOX2 mediated peroxynitrite species were primary to inflammasome activation and release of inflammatory mediators. Thus, in conclusion, microcystin exposure in NAFLD could significantly alter intestinal pathology especially by the effects on microbiome and resultant redox status thus advancing our understanding of the co-existence of NAFLD-linked inflammatory bowel disease phenotypes in the clinic.

Irradiation influence on the phenoloxidase pathway and an anti-oxidant defense mechanism in Spodoptera litura (Lepidoptera: Noctuidae) and its implication in radio-genetic 'F 1 sterility' and biorational pest suppression tactics

The present study was conducted to appraise the ontogenic radio-sensitivity of a serious tropical pest, Spodoptera litura (Fabr.). The molecular responses pertaining to the phenoloxidase (PO) pathway and an anti-oxidant defense mechanism were evaluated in order to understand its implication in pest control at pre-harvest and post-harvest intervals. Irradiation exhibited an inverse relationship with age with respect to impact on developmental and transcriptional responses. Transcript abundance of PO cascade enzymes, prophenoloxidase (slppo-2), its activating enzyme (slppae-1) and free-radical scavenging enzymes, superoxide dismutase (slsod) and catalase (slcat) was evaluated upon gamma irradiation alone and the dual-stress of radiation plus microbial challenge. The slppo-2, slppae-1, slsod and slcat transcripts were significantly up-regulated in F 1 L6 larvae (6th-instar) resulting from 100 Gy sub-sterilized male adults and unirradiated female moths. The extent of upregulation was relatively higher in comparison with L6 survivors (6th-instar larvae) developed from irradiated neonates (L1) treated with 100 Gy. Upon Photorhabdus challenge, the transcripts were down-regulated in irradiated L1 suggesting increased larval susceptibility to bacterial infections. Radioresistance increased with the age of the insect, and molecular responses (transcript abundance) of insect defense mechanism were less influenced when older age (F 1 progeny) were irradiated. These findings will help to optimize the gamma dose to be employed in inherited sterility technique for (pre-harvest) pest suppression and (post-harvest) phytosanitation and quarantine, and suggest compatible integration of biorational tactics including nuclear technology.

HMGB1-RAGE pathway drives peroxynitrite signaling-induced IBD-like inflammation in murine nonalcoholic fatty liver disease

Recent clinical studies found a strong association of colonic inflammation and Inflammatory bowel disease (IBD)-like phenotype with NonAlcoholic Fatty liver Disease (NAFLD) yet the mechanisms remain unknown. The present study identifies high mobility group box 1 (HMGB1) as a key mediator of intestinal inflammation in NAFLD and outlines a detailed redox signaling mechanism for such a pathway. NAFLD mice showed liver damage and release of elevated HMGB1 in systemic circulation and increased intestinal tyrosine nitration that was dependent on NADPH oxidase. Intestines from NAFLD mice showed higher Toll like receptor 4 (TLR4) activation and proinflammatory cytokine release, an outcome strongly dependent on the existence of NAFLD pathology and NADPH oxidase. Mechanistically intestinal epithelial cells showed the HMGB1 activation of TLR-4 was both NADPH oxidase and peroxynitrite dependent with the latter being formed by the activation of NADPH oxidase. Proinflammatory cytokine production was significantly blocked by the specific peroxynitrite scavenger phenyl boronic acid (FBA), AKT inhibition and NADPH oxidase inhibitor Apocynin suggesting NADPH oxidase-dependent peroxynitrite is a key mediator in TLR-4 activation and cytokine release via an AKT dependent pathway. Studies to ascertain the mechanism of HMGB1-mediated NADPH oxidase activation showed a distinct role of Receptor for advanced glycation end products (RAGE) as the use of inhibitors targeted against RAGE or use of deformed HMGB1 protein prevented NADPH oxidase activation, peroxynitrite formation, TLR4 activation and finally cytokine release. Thus, in conclusion the present study identifies a novel role of HMGB1 mediated inflammatory pathway that is RAGE and redox signaling dependent and helps promote ectopic intestinal inflammation in NAFLD.

TRPV4 attenuates M1 polarization and subsequent NASH progression by stalling CYP2E1-mediated redox toxicity via eNOS

M1 macrophage polarization in nonalcoholic steatohepatitis (NASH) liver has been impacted by several exogenous or endogenous factors including inflammatory stimuli, oxidative stress, and cytokines. In absence of an active endogenous defense mechanism, the M1 polarization bias potentiates NASH progression by intensified inflammation and intermittent fibrosis in the rodent model of liver injury. We introduce an endogenous defense mechanism in the liver that is mediated by TRPV4, a transient receptor potential calcium-permeable ion channel that responds to the cytotoxic liver environment and negatively regulates CYP2E1. We hypothesized that CYP2E1-mediated oxidative stress causes M1 polarization in experimental NASH and active TRPV4 inhibits CYP2E1 mediated inflammation with concomitant attenuation of M1 polarization. Since CYP2E1 takes center stage in redox toxicity we use a toxin model of NASH which uses pyrazole, a ligand and a substrate of CYP2E1 for inducing liver injury with NASH-like phenotype. Using both cyp2e1−/− and trpv4−/− mice, we show that in the absence of active TRPV4, CYP2E1 induced oxidative stress causes M1 polarization bias, that includes a significant increase in IL-1β, IL-12, IL-6 and IL-23 while CYP2E1 null or diallyl sulfide treated mice prevent it. Recently, we discovered that the TRPV4 modulates eNOS activation and nitric oxide release from Kupffer cell during an early stage of liver injury. Based on the adaptive NO increase in trpv4+/+ mice, NO donor administration in trpv4−/− mice abrogated CYP2E1-induced oxidative stress, M1 polarization, and NASH progression. Thus, a novel endogenous defense molecule TRPV4 can be a promising immunotherapeutic approach against chronic liver injury.

TRPV4 activation of endothelial nitric oxide synthase resists nonalcoholic fatty liver disease by blocking CYP2E1-mediated redox toxicity

NAFLD is a clinically progressive disease with steatosis, inflammation, endothelial dysfunction and fibrosis being the stages where clinical intervention becomes necessary. Lack of early biomarkers and absence of a FDA approved drug obstructs efforts for effective treatment. NAFLD progression is strongly linked to a balance between liver injury, tissue regeneration and the functioning of endogenous defense mechanisms. The failure of the defense pathways to resist the tissue damage arising from redox stress, one of the "multiple hits" in disease progression, give rise to heightened inflammation and occasional fibrosis. We introduce an endogenous defense mechanism in the liver that is mediated by TRPV4, a transient receptor potential calcium-permeable ion channel that responds to the cytotoxic liver environment and negatively regulates CYP2E1, a cytochrome p450 enzyme. Using Trpv4-/- mice and cultured primary cells, we show that TRPV4 is activated both by damage associated molecular pattern HMGB1 and collagen in diseased Kupffer cells that in turn activate the endothelial NOS (NOS3) to release nitric oxide (NO). The diffusible NO acts in a paracrine fashion in neighboring hepatocytes to deactivate the redox toxicity induced by CYP2E1. We also find that CYP2E1-mediated TRPV4 repression in late stages causes an unrestricted progression of disease. Thus, TRPV4 functions as a sensor of cell stress in the diseased fatty liver and constitutes an endogenous defense molecule, a novel concept with potential for therapeutic approaches against NAFLD, perhaps also against hepatic drug toxicity in general.

Association between exposures to brominated trihalomethanes, hepatic injury and type II diabetes mellitus

Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disorder in the Western world, commonly diagnosed in the majority of obese patients with type 2 diabetes mellitus (T2DM). Metabolic disrupting chemicals with short half-lives, such as those of halogenated structure (trihalomethanes, THM) have been linked with hepatic insulin resistance phenomena in animal studies. However, human studies evaluating the role of THM exposure on liver pathogenesis and T2DM disease process are scarce. The objectives of this study were to: i) determine the association of urinary brominated THM (BrTHM) levels and T2DM disease status, and ii) investigate the association between urinary BrTHM levels and serum alanine aminotransferase (ALT) concentrations, often used as surrogate markers of NAFLD. A pilot case-control study was conducted in Nicosia, Cyprus (n=95). Cases were physician-diagnosed T2DM patients and controls were healthy individuals. Liver enzymes, leptin and TNF-α were measured in sera, while urinary THM levels were measured using tandem mass spectrometry. Diabetics had higher levels of serum leptin, body mass index and ALT than the controls. Among all study participants those with serum ALT levels above the median (17IU/L) had higher mean tribromomethane (TBM) concentrations compared to those with serum ALT below 17IU/L. A significant increase in the odds of having above the median serum ALT levels [OR 6.38, 95% CI: 1.11, 42.84 (p=0.044)] was observed for each unit increase in creatinine-unadjusted urinary TBM levels, along with BMI and past smoking, after adjusting for possible confounders, such as urinary creatinine, age, sex, and leptin; no other THM compound showed a significant association with serum ALT. Logistic regression models for T2DM using the urinary BrTHM as exposure variables did not reach the predetermined level of significance. The interplay between exposures to BrTHM and the initiation of key pathophysiological events relating to hepatic injury (ALT) and inflammation (leptin) was recognized via the use of selected biomarkers of effect. Our evidence that THM could act as hepatic toxins with a further initiation of diabetogenic effects call for additional studies to help us better understand the disease process of the two co-morbidities (NAFLD and T2DM).

Trihalomethane exposure and biomonitoring for the liver injury indicator, alanine aminotransferase, in the United States population (NHANES 1999-2006)

Exposure to trihalomethanes (or THMs: chloroform, bromoform, bromodichloromethane, and dibromochloromethane [DBCM]) formed via drinking water disinfection has been associated with adverse reproductive outcomes and cancers of the digestive or genitourinary organs. However, few studies have examined potential associations between THMs and liver injury in humans, even though experimental studies suggest that these agents exert hepatotoxic effects, particularly among obese individuals. This study examined participants in the National Health and Nutrition Examination Survey (1999-2006, N=2781) to test the hypothesis that THMs are associated with liver injury as assessed by alanine aminotransferase (ALT) activity in circulation. Effect modification by body mass index (BMI) or alcohol consumption also was examined. Associations between blood THM concentrations and ALT activity were assessed using unconditional multiple logistic regression to calculate prevalence odds ratios (ORs) with 95% confidence intervals (CIs) for exposure among cases with elevated ALT activity (men: >40IU/L, women: >30IU/L) relative to those with normal ALT, after adjustment for variables that may confound the relationship between ALT and THMs. Compared to controls, cases were 1.35 times more likely (95% CI: 1.02, 1.79) to have circulating DBCM concentrations exceeding median values in the study population. There was little evidence for effect modification by BMI, although the association varied by alcohol consumption. Among non-drinkers, cases were more likely than controls to be exposed to DBCM (OR: 3.30, 95% CI: 1.37, 7.90), bromoform (OR: 2.88, 95% CI: 1.21, 6.81), or brominated THMs (OR: 4.00, 95% CI: 1.31, 12.1), but no association was observed among participants with low, or moderate to heavy alcohol consumption. Total THM levels exceeding benchmark exposure limits continue to be reported both in the United States and globally. Results from this study suggest a need for further characterization of ALT activity and possibly other hepatic or metabolic diseases in populations with elevated drinking water THM concentrations.

Expression, purification and characterization of allelic variants of MSP-1(42) from Indian Plasmodium falciparum isolates

The C-terminal 19 and 42 kDa fragments of Plasmodium falciparum merozoite surface protein 1 (MSP-1) have shown to be protective in animals against lethal parasite challenge. The MSP-1(19) being highly conserved may lack sufficient number of T-cell epitopes in order to elicit a broader response in genetically diverse populations. The inclusion of additional epitopes from the N-terminal MSP-1(42) has shown to enhance the protective efficacy of MSP-1(19) vaccine. In an attempt to examine the strain specific immunogenicity to MSP-1, we have cloned and expressed three diverse allelic variants of MSP-1(42) from Indian P. falciparum isolates in bacteria. Among three alleles, one was extremely rare and not been found before. These purified and refolded recombinant products were recognized by conformation specific monoclonal antibodies and hyper-immune sera. Immunization of mice and rabbits with the purified proteins generated high titer biologically active polyclonal antibodies supporting further development of this vaccine candidate antigen.

Radiation responses of Sf9, a highly radioresistant lepidopteran insect cell line

PURPOSE

Lepidopteran insect cells are known to exhibit very high radioresistance. Although very effective DNA excision-repair has been proposed as a contributing factor, a detailed understanding of insect cell radiation responses has not yet been obtained. Therefore, the study was carried out to understand the in vitro radiation responses of Sf9 lepidopteran cells.

MATERIALS AND METHODS

Exponentially growing asynchronous Sf9 cells (derived from ovaries of Spodoptera frugiperda) were exposed to gamma-radiation doses of 2-200 Gy. Cell survival, growth inhibition, cell cycle progression delay, alterations in cell morphology as well as induction of DNA damage, micronuclei and apoptosis were studied at various post-irradiation time intervals.

RESULTS

Biphasic survival response curves were obtained with D0 rising from 20 Gy (at doses < or = 60 Gy) to 85 Gy (between 60 and 200 Gy), corroborating earlier reports on lepidopteran cells. An additional downward deviation at 2 Gy indicated a hypersensitive response. Dose-dependent growth inhibition with a transient G2 delay starting 12 h and extending up to 48-96 h was observed at doses of 10-200 Gy, while a brief G1/S transition delay was observed only at higher doses (> or = 100 Gy). Significant DNA damage was detected only at 20 Gy and higher doses, in contrast with human cells that showed similar damage at 2 Gy. Interestingly, micronuclei were not induced at any of the doses tested, although spontaneous micronucleation was evident in <1% of cells. Lack of micronucleus induction even at doses that induced significant DNA damage and a transient G2 block (20-50 Gy) strongly indicated a role of holocentric lepidopteran chromosomes. Apoptosis was detected only in a small proportion of cells (3%) exposed to 200 Gy, and cell/nucleus size and granularity increased by 72-96 h post-irradiation in a dose-dependent manner. Sf9 nucleoids extracted at 2 M NaCl showed higher compactness than the nucleoids prepared from human cells.

CONCLUSIONS

It is clearly shown that lepidopteran cells are highly resistant to the induction of DNA damage and micronuclei, and display very low induction of apoptosis at doses up to 200 Gy. While the lack of micronucleus induction seems to be primarily due to the holocentric nature of their chromosomes, certain unique signalling pathways might be responsible for the low induction of apoptosis. Factors causing protection of Sf9 cellular DNA from radiation-induced damage are presently being investigated.

Characterization of biochemical based insecticide resistance mechanism by thermal bioassay and the variation of esterase activity in Culex quinquefasciatus

Biochemical mechanisms of insecticide resistance of thermal exposed and unexposed Culex quinquefasciatus strains are evaluated, which were not studied earlier. The activity of alpha- and beta-carboxylesterases and acetylcholinesterase of malathion susceptible and resistant strains were compared after thermal treatment. Three-day-old adult females were used for the malathion susceptibility test and biochemical assays, and males were used only for the susceptibility test. Thermal exposure brought about increase in resistance levels from 85% to 90% in males and 91% to 96.6% in females of resistant strain. The resistance status of the susceptibility strain was unchanged after thermal exposure. The activities of alpha- and beta-carboxylesterase of susceptible mosquitoes were within 800 and 700 U/mg protein, respectively. The alpha-carboxylesterase activity of the thermal exposed malathion-resistant population was significantly (t test, P < 0.05) higher than the unexposed resistant population, and the reverse was recorded in beta-carboxylesterase. The alpha-carboxylesterase activity of susceptible population was lower than the resistant population. The activity of alpha-carboxylesterase was higher than the beta-carboxylesterase in both the strains. Among the malathion resistant C. quinquefasciatus population, 2.3% population exhibited 30-40% inhibition which increased to 5.8% after the thermal exposure. Thermal exposure of mosquitoes increased the activity of both alpha-carboxylesterases and acetylcholinesterase but decreased the activity of beta-carboxylesterase.

Effect of temperature on development, eclosion, longevity and survivorship of malathion-resistant and malathion-susceptible strain of Culex quinquefasciatus

Density of vectors and development of resistance against insecticides are two important aspects in the control of vector-borne diseases. Here, effect of temperature on different aspects of development of malathion-resistant and susceptible strains of Culex quinquefasciatus was evaluated in the laboratory. Fourth-instar larvae of C. quinquefasciatus were exposed to 37 degrees C, 39 degrees C, 40 degrees C, and 41 degrees C, and their LT(50) values calculated. The fourth-instar larvae were subjected to heat for 4 h at 39 degrees C and live larvae were reared until the completion of life cycle. The larvae of malathion-resistant strain were more tolerant to heat than the larvae of malathion-susceptible ones. The difference in mortality between 37 degrees C, 39 degrees C, 40 degrees C, and 41 degrees C of both the strains of C. quinquefasciatus were highly significant. Pupation percentage of heat-exposed larvae of both the strains was higher and delayed than the control ones. The percentage of adult emergence from the heat-exposed larvae was significantly lower than the control. The adult female of malathion-resistant strain showed increased longevity when exposed to heat at larval stage but reverse was true in case of malathion-susceptible. The highlights of the study would help in the management of resistance of mosquito vectors in the tropics where variable climatic condition is observed.

Naturally acquired immunity and reduced susceptibility to falciparum malaria in two subpopulations of endemic eastern India

This study was aimed to assess the prevalence of naturally acquired humoral immune responses and their association with reduced susceptibility to malaria in children and adults with differential clinical conditions from an Indian zone where malaria is endemic. The study was undertaken in an eastern province of India (Keonjhar, Orissa) in a group of 341 children (both younger and older) and 98 adults living in two different areas, Town area and Forest area. They were studied for their parasitological and immunological profiles. Sera from different age-matched groups were screened by ELISA to measure IgG reactivities for characterizing humoral immune responses to the B-cell epitopes of Plasmodium falciparum MSP1, AMA1, RAP1 and EBA175 peptides and P. falciparum-infected erythrocyte lysate. In Town area, overall P. falciparum cases were 5.5%, whereas those in Forest area were 26.7%. We observed an age-wise increasing trend of immunity in these two populations. It was also noticed that the frequency of responders to stage-specific antigens was higher in individuals from the Town area where the frequency of malaria was lower. The naturally acquired humoral immune responses to different stage-specific antigens of P. falciparum reflect the reduced risk of malaria in the study groups. The higher frequency of seroresponders showed correlation with lower risk of developing malaria.

Effects of larval exposure to sublethal concentrations of the ecdysteroid agonists RH-5849 and tebufenozide (RH-5992) on male reproductive physiology in Spodoptera litura

Sublethal concentrations of the bisacylhydrazine moulting hormone agonists, RH-5849, and tebufenozide (RH-5992) were fed to sixth (final) instar larvae of Spodoptera litura. Both RH-5849 and tebufenozide adversely affected the mating success of S. litura when the surviving treated males were crossed with normal females. The ecdysone agonists decreased the longevity of treated males and of untreated females when crossed with treated males. The number of eggs laid by untreated females mated to treated males was decreased, and the fertility (percentage of hatching success) of the resulting eggs was reduced. These effects on male reproductive success were at least in part explained by a reduction in the number of sperm transferred during mating. The adverse effects of tebufenozide on male reproductive function were qualitatively the same as those of RH-5849, but tebufenozide was active at lower concentrations. To understand the reason for these adverse effects on male reproduction, we investigated the effects of the insecticides on male reproductive physiology. Male reproductive tract development and testicular volume of resulting adult moths were adversely affected by sublethal larval exposure to the ecdysone agonists. Dose-dependent reductions occurred in the production of eupyrene and apyrene spermatozoa in the adult testes, and in the number of spermatozoa released from the testes into the male reproductive tract. The descent into the male tract of both eupyrene and apyrene sperm was found to start at the normal stage of development in both normal and treated insects, but the daily rhythm of sperm descent was subsequently disturbed in the insecticide-treated moths. This affected the numbers of sperm in the upper vas deferens (UVD), seminal vesicle (SV), and duplex (duplex). Injections of RH-5849 given to pharate adult or newly emerged adult S. litura also caused drastic reduction in the number of sperm in the upper regions of the male tract, when measured 24 h after injection. The possible importance of pest population reduction through the sublethal anti-reproductive effects of insecticides is discussed.

Regulation of c-fos induction in lens epithelial cells by 12(S)HETE-dependent activation of PKC

PURPOSE

12(S)-Hydroxyeicosatetraenoic acid (12(S)HETE), a 12-lipoxygenase metabolite of arachidonic acid, is required for epidermal growth factor (EGF)-dependent DNA synthesis and c-fos induction in lens epithelial cells. The present study was undertaken to identify signal transduction events upstream of c-fos induction that may be regulated by 12(S)HETE.

METHODS

The rabbit lens epithelial cell line, N/N1003A, was cultured in serum-free medium, with or without EGF. Activation of PKC and other selected enzymes was examined in the presence of the lipoxygenase inhibitor baicalein and/or exogenous 12(S)HETE. Relative abundance of PKC isoforms in subcellular fractions was determined by immunoblot analysis with isoform-specific antibodies. PKC activity in subcellular fractions was measured by peptide substrate phosphorylation, with and without pseudosubstrate peptide inhibitor. Phosphorylated enzymes were detected by immunoblot analysis. Relative levels of c-fos mRNA were determined by RT/PCR with internal standard.

RESULTS

Baicalein blocked EGF-dependent translocation and activation of PKC, without affecting phosphorylation of Erk1/2. Of several PKC isoforms investigated (alpha, betaI, betaII, and gamma), only PKCalpha and betaII were significantly activated by EGF and inhibited by baicalein. 12(S)HETE, in combination with EGF, countered the effect of lipoxygenase inhibitors on PKC activation, and 12(S)HETE in the absence of EGF stimulated PKC translocation. Also of note, 12(S)HETE alone activated PKCgamma, an isoform that was not significantly activated by EGF. Inhibiting PKC activation with GF109203X blocked induction of c-fos by EGF but did not affect EGF-stimulated phosphorylation of Erk1/2, indicating that the effect of PKC on c-fos induction is independent of the Erk1/2 pathway.

CONCLUSIONS

In lens epithelial cells, 12(S)HETE-dependent activation of PKCalpha and betaII acts in concert with other EGF-dependent signals to induce c-fos mRNA.

Protective function of alpha-tocopherol against the process of cataractogenesis in humans

In a random trial 50 patients with unilateral/ bilateral idiopathic immature senile cataract (cortical n = 25, nuclear n = 25) requiring surgery at least in one eye were included in the present study. Reduced glutathione (GSH), vitamin E, malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) were studied in these patients receiving either vitamin E (n = 12 in each subgroup) or placebo (n = 13 in each group) for 30 days. A comparable increase of vitamin E in both types of lens homogenates of cataractous patients was observed in the study group. The level of GSH in cortical cataractous lenses in the study group was significantly raised (p < 0.001) whereas it was not increased significantly in nuclear cataractous lenses (p > 0.05) as compared to the placebo group. The percentage decrease in MDA levels was greater in cortical cataracts (38.07%) than in the nuclear type (27.94%). The activity of GSH-Px in cortical lenses was higher than that in the nuclear cataractous lens. The change in the size of lens opacity in cortical cataractous patients receiving vitamin E therapy was significantly decreased as compared to the placebo group. There may be a direct modulating effect of vitamin E on some GSH-related enzymes and the cortex of the lens might be protected more than the nucleus.

Comparison of sodium nitroprusside added peritoneal dialysis and standard haemodialysis

Thirty patients of acute or acute on chronic renal failure (ACRF) were randomly divided into two group of 15 cases each. Group A patients received 36 cycles of intermittent peritoneal dialysis (PD) with an exchange volume of one litre and duration of one hour per cycle. The 36 cycles of PD were divided into 12 clearance periods of 3 cycles each. Sodium Nitroprusside (SNP) was added in a dose of 4 mg/litre of dialysate in alternate clearance periods. Group B patients were given 4 hours of haemodialysis (HD) to compare the efficacy of two modes of dialysis. Symptomatic relief was observed in various uraemic signs and symptoms like vomiting, level of consciousness, fluid overload, hiccough and asterexis in most of the patients in both the groups. The percentage fall in blood urea and serum creatinine was 57.02 Vs 58.04 mg% and 46.9 Vs 47.8 mg% in group A and B respectively (P 70.5 each). Total dialysate urea removal following PD and HD was 118.8 +/- 57.3 gm and 98.5 +/- 37.0 gm respectively and also there was no significant difference in total creatinine removal. No untoward effects were observed with PD. However, following HD, 5 patients developed hypotension, supraventricular tachycardia was observed in one and disequilibrium syndrome in 8 of them. Therefore, it can be concluded that SNP added PD is comparable to 4 hours of haemodialysis both clinically as well as biochemically and in situations where facilities for HD do not exist or it is contraindicated, PD may be preferred mode of therapy.

Serum lipid peroxide and other enzyme levels of patients suffering from thermal injury

The levels of the lipid peroxidation product malondialdehyde (MDA) and the activity of transaminases and alkaline phosphatases were estimated in the sera of 25 thermally injured patients at various time intervals after injury. The level of MDA was increased during the early postburn period, whereas the activities of transaminases and alkaline phosphatase became elevated later after injury. It is concluded that an increased concentration of lipid peroxidation product (MDA) in the early postburn period may affect the spleen, liver and kidney, resulting in the release of enzymes into blood stream. Such damage may be checked by the antioxidants superoxide dismutase or allopurinol.

Effect of atenolol and labetalol on serum lipids

Adverse alterations in lipid profile suggesting higher atherogenicity were observed following 12 weeks treatment with atenolol in patients of hypertension. No significant alterations in lipid profile were observed with labetalol therapy.

Effect of vasodilator and surface active drugs on the efficacy of peritoneal dialysis

The effect of sodium nitroprusside (SNP), a vasodilator drug, and chlorpromazine (CPZ), a surface active drug, on the efficacy of peritoneal dialysis was studied in 25 patients with acute or acute on chronic renal failure in a double blind fashion. Each drug was added to the dialysate during different sets of cycles. In each patient, six clearance periods of 3 cycles each were studied and peritoneal clearances of creatinine and urea and ultrafiltration rates were measured during each clearance period. SNP increased the peritoneal clearance of creatinine and urea by 28.8 percent each (p < 0.001) while CPZ increased the peritoneal creatinine and urea clearance by 17.7 and 26.0 percent respectively (p < 0.001 each). Both drugs significantly increased the ultrafiltration rates (p < 0.001). SNP was found to be superior to CPZ and had prolonged effect even after cessation of administration.

Adenosine deaminase levels in cerebrospinal fluid in tuberculosis and bacterial meningitis

Adenosine deaminase activity was measured in cerebrospinal fluid of patients with confirmed tuberculous and bacterial meningitis. The values were compared with those of control subjects without meningitis. A statistically significant increase in the level of this enzyme was noted in the two types of meningitis, but no definite demarcation in the levels was observed between the two types. Therefore increases in adenosine deaminase activity may not be of such diagnostic significance as reported elsewhere.

Lipid profile in enteric fever

Lipid profile is known to alter in patients with severe sepsis, but few studies regarding the status of lipid levels in enteric fever are available. Twenty patients with enteric fever, belonging to different age groups and both sexes, along with an equal number of matched patients with fever due to non-enteric causes, were studied with regard to alterations in lipid profile. We observed a severe and protracted hypertriglyceridaemia, decrease in HDL-cholesterol levels and increase in LDL-cholesterol levels in patients with enteric fever at the peak of fever. The values returned to normal on recovery and convalescence. This study serves to highlight the complexity of lipid variation during Salmonella typhi infection.

Plasmodium berghei: oxidant defense system

Glutathione oxidant defense system protects the erythrocyte from oxidative damage. This defense system was studied in mouse erythrocytes infected with Plasmodium berghei and in isolated parasites. The efficiency of this system was found to be increased in parasitized erythrocytes compared to the normal erythrocytes. The increase in the components of the oxidant defense system in the parasitized cells could result from parasitic addition to these components. This defense system present in the parasite may protect the parasite from oxidative damage and help the parasite in its growth and development.

Glutathione peroxidase activity and reduced glutathione content in erythrocytes of patients with chronic renal failure

Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were examined with respect to glutathione peroxidase (GSH-Px) activity and reduced glutathione (GSH) contents. The activity of GSH-Px and GSH content were found to be lower in RBC from CRF patients as compared with normal RBC. These reduced levels of GSH and GSH-Px in the red cells of uraemic patients may predispose the cells to oxidative damage.

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