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1.
Sci Rep ; 14(1): 10555, 2024 05 08.
Article in English | MEDLINE | ID: mdl-38719902

ABSTRACT

Heat stress exposure in intermittent heat waves and subsequent exposure during war theaters pose a clinical challenge that can lead to multi-organ dysfunction and long-term complications in the elderly. Using an aged mouse model and high-throughput sequencing, this study investigated the molecular dynamics of the liver-brain connection during heat stress exposure. Distinctive gene expression patterns induced by periodic heat stress emerged in both brain and liver tissues. An altered transcriptome profile showed heat stress-induced altered acute phase response pathways, causing neural, hepatic, and systemic inflammation and impaired synaptic plasticity. Results also demonstrated that proinflammatory molecules such as S100B, IL-17, IL-33, and neurological disease signaling pathways were upregulated, while protective pathways like aryl hydrocarbon receptor signaling were downregulated. In parallel, Rantes, IRF7, NOD1/2, TREM1, and hepatic injury signaling pathways were upregulated. Furthermore, current research identified Orosomucoid 2 (ORM2) in the liver as one of the mediators of the liver-brain axis due to heat exposure. In conclusion, the transcriptome profiling in elderly heat-stressed mice revealed a coordinated network of liver-brain axis pathways with increased hepatic ORM2 secretion, possibly due to gut inflammation and dysbiosis. The above secretion of ORM2 may impact the brain through a leaky blood-brain barrier, thus emphasizing intricate multi-organ crosstalk.


Subject(s)
Brain , Gene Expression Profiling , Liver , Animals , Mice , Liver/metabolism , Brain/metabolism , Male , Transcriptome , Brain-Gut Axis , Heat-Shock Response/genetics , Mice, Inbred C57BL , Signal Transduction , Aging/genetics , Aging/metabolism
2.
BMC Pharmacol Toxicol ; 24(1): 78, 2023 12 13.
Article in English | MEDLINE | ID: mdl-38093299

ABSTRACT

BACKGROUND: Microcystins (MCs), potent hepatotoxins pose a significant health risk to humans, particularly children, who are more vulnerable due to higher water intake and increased exposure during recreational activities. METHODS: Here, we investigated the role of host microbiome-linked acetate in modulating inflammation caused by early-life exposure to the cyanotoxin Microcystin-LR (MC-LR) in a juvenile mice model. RESULTS: Our study revealed that early-life MC-LR exposure disrupted the gut microbiome, leading to a depletion of key acetate-producing bacteria and decreased luminal acetate concentration. Consequently, the dysbiosis hindered the establishment of a gut homeostatic microenvironment and disrupted gut barrier function. The NOD-like receptor family pyrin domain - containing 3 (NLRP3) inflammasome, a key player in MC-induced hepatoxicity emerged as a central player in this process, with acetate supplementation effectively preventing NLRP3 inflammasome activation, attenuating hepatic inflammation, and decreasing pro-inflammatory cytokine production. To elucidate the mechanism underlying the association between early-life MC-LR exposure and the progression of metabolic dysfunction associated steatotic liver disease (MASLD), we investigated the role of acetate binding to its receptor -G-protein coupled receptor 43 (GPR43) on NLRP3 inflammasome activation. Our results demonstrated that acetate-GPR43 signaling was crucial for decreasing NLRP3 protein levels and inhibiting NLRP3 inflammasome assembly. Further, acetate-induced decrease in NLRP3 protein levels was likely mediated through proteasomal degradation rather than autophagy. Overall, our findings underscore the significance of a healthy gut microbiome and its metabolites, particularly acetate, in the progression of hepatotoxicity induced by early life toxin exposure, crucial for MASLD progression. CONCLUSIONS: This study highlights potential therapeutic targets in gut dysbiosis and NLRP3 inflammasome activation for mitigating toxin-associated inflammatory liver diseases.


Subject(s)
Gastrointestinal Microbiome , NLR Family, Pyrin Domain-Containing 3 Protein , Animals , Mice , Acetates , Dysbiosis/chemically induced , Inflammasomes , Inflammation/drug therapy , Microcystins/toxicity , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism
3.
Int J Mol Sci ; 24(22)2023 Nov 15.
Article in English | MEDLINE | ID: mdl-38003543

ABSTRACT

Harmful algal bloom toxin microcystin has been associated with metabolic dysfunction-associated steatotic liver disease (MASLD) progression and hepatocellular carcinoma, though the mechanisms remain unclear. Using an established mouse model of MASLD, we show that the NLRP3-Hsp70-TLR4 axis drives in part the inflammation of the liver lobule that results in the progression of MASLD to metabolic dysfunction-associated steatohepatitis (MASH). Results showed that mice deficient in NLRP3 exhibited decreased MASH pathology, blocked Hsp70 expression, and co-binding with NLRP3, a crucial protein component of the liver inflammasome. Hsp70, both in the liver lobule and extracellularly released in the liver vasculature, acted as a ligand to TLR4 in the liver, primarily in hepatocytes to activate the NF-κB pathway, ultimately leading to hepatic cell death and necroptosis, a crucial pathology of MASH progression. The above studies show a novel insight into an inflammasome-triggered Hsp70-mediated inflammation that may have broader implications in MASLD pathology. MASLD to MASH progression often requires multiple hits. One of the mediators of progressive MASLD is environmental toxins. In this research report, we show for the first time a novel mechanism where microcystin-LR, an environmental toxin, advances MASLD to MASH by triggering the release of Hsp70 as a DAMP to activate TLR4-induced inflammation in the liver.


Subject(s)
Inflammasomes , Non-alcoholic Fatty Liver Disease , Mice , Animals , Inflammasomes/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/genetics , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Toll-Like Receptor 4/genetics , Toll-Like Receptor 4/metabolism , Harmful Algal Bloom , Microcystins/toxicity , Non-alcoholic Fatty Liver Disease/metabolism , Inflammation/metabolism
4.
Int J Mol Sci ; 24(4)2023 Feb 20.
Article in English | MEDLINE | ID: mdl-36835663

ABSTRACT

The pathophysiology of Gulf War Illness (GWI) remains elusive even after three decades. The persistence of multiple complex symptoms along with metabolic disorders such as obesity worsens the health of present Gulf War (GW) Veterans often by the interactions of the host gut microbiome and inflammatory mediators. In this study, we hypothesized that the administration of a Western diet might alter the host metabolomic profile, which is likely associated with the altered bacterial species. Using a five-month symptom persistence GWI model in mice and whole-genome sequencing, we characterized the species-level dysbiosis and global metabolomics, along with heterogenous co-occurrence network analysis, to study the bacteriome-metabolomic association. Microbial analysis at the species level showed a significant alteration of beneficial bacterial species. The beta diversity of the global metabolomic profile showed distinct clustering due to the Western diet, along with the alteration of metabolites associated with lipid, amino acid, nucleotide, vitamin, and xenobiotic metabolism pathways. Network analysis showed novel associations of gut bacterial species with metabolites and biochemical pathways that could be used as biomarkers or therapeutic targets to ameliorate symptom persistence in GW Veterans.


Subject(s)
Dysbiosis , Gastrointestinal Microbiome , Mice , Animals , Gulf War , Diet, Western , Gastrointestinal Microbiome/physiology , Bacteria , Obesity
5.
Cells ; 13(1)2023 12 27.
Article in English | MEDLINE | ID: mdl-38201260

ABSTRACT

Gulf War (GW) veterans show gastrointestinal disturbances and gut dysbiosis. Prolonged antibiotic treatments commonly employed in veterans, especially the use of fluoroquinolones and aminoglycosides, have also been associated with dysbiosis. This study investigates the effect of prolonged antibiotic exposure on risks of adverse renal pathology and its association with gut bacterial species abundance in underlying GWI and aims to uncover the molecular mechanisms leading to possible renal dysfunction with aging. Using a GWI mouse model, administration of a prolonged antibiotic regimen involving neomycin and enrofloxacin treatment for 5 months showed an exacerbated renal inflammation with increased NF-κB activation and pro-inflammatory cytokines levels. Involvement of the high mobility group 1 (HMGB1)-mediated receptor for advanced glycation end products (RAGE) activation triggered an inflammatory phenotype and increased transforming growth factor-ß (TGF-ß) production. Mechanistically, TGF-ß- induced microRNA-21 upregulation in the renal tissue leads to decreased phosphatase and tensin homolog (PTEN) expression. The above event led to the activation of protein kinase-B (AKT) signaling, resulting in increased fibronectin production and fibrosis-like pathology. Importantly, the increased miR-21 was associated with low levels of Lachnospiraceae in the host gut which is also a key to heightened HMGB1-mediated inflammation. Overall, though correlative, the study highlights the complex interplay between GWI, host gut dysbiosis, prolonged antibiotics usage, and renal pathology via miR-21/PTEN/AKT signaling.


Subject(s)
HMGB1 Protein , Kidney Diseases , MicroRNAs , Animals , Mice , Anti-Bacterial Agents/adverse effects , Proto-Oncogene Proteins c-akt , Dysbiosis , Gulf War , Chronic Disease , Clostridiales , Fibrosis , Inflammation , Transforming Growth Factor beta
6.
Toxins (Basel) ; 14(12)2022 12 01.
Article in English | MEDLINE | ID: mdl-36548732

ABSTRACT

Epidemiological studies have reported a strong association between liver injury and incidences of hepatocellular carcinoma in sections of humans globally. Several preclinical studies have shown a strong link between cyanotoxin exposure and the development of nonalcoholic steatohepatitis, a precursor of hepatocellular carcinoma. Among the emerging threats from cyanotoxins, new evidence shows cylindrospermopsin release in freshwater lakes. A known hepatotoxin in higher concentrations, we examined the possible role of cylindrospermopsin in causing host gut dysbiosis and its association with liver pathology in a mouse model of toxico-pharmacokinetics and hepatic pathology. The results showed that oral exposure to cylindrospermopsin caused decreased diversity of gut bacteria phyla accompanied by an increased abundance of Clostridioides difficile and decreased abundance of probiotic flora such as Roseburia, Akkermanssia, and Bacteroides thetaiotamicron, a signature most often associated with intestinal and hepatic pathology and underlying gastrointestinal disease. The altered gut dysbiosis was also associated with increased Claudin2 protein in the intestinal lumen, a marker of gut leaching and endotoxemia. The study of liver pathology showed marked liver inflammation, the release of damage-associated molecular patterns, and activation of toll-like receptors, a hallmark of consistent and progressive liver damage. Hepatic pathology was also linked to increased Kupffer cell activation and stellate cell activation, markers of progressive liver damage often linked to the development of liver fibrosis and carcinoma. In conclusion, the present study provides additional evidence of cylindrospermopsin-linked progressive liver pathology that may be very well-linked to gut dysbiosis, though definitive evidence involving this link needs to be studied further.


Subject(s)
Carcinoma, Hepatocellular , Gastrointestinal Microbiome , Liver Neoplasms , Animals , Mice , Humans , Carcinoma, Hepatocellular/metabolism , Kupffer Cells/metabolism , Kupffer Cells/pathology , Gastrointestinal Microbiome/physiology , Dysbiosis , Liver/metabolism , Liver Cirrhosis/pathology , Liver Neoplasms/metabolism , Inflammation/metabolism
7.
Sci Rep ; 12(1): 11516, 2022 07 07.
Article in English | MEDLINE | ID: mdl-35799048

ABSTRACT

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.


Subject(s)
Gastrointestinal Microbiome , Immunosenescence , Microcystins , Animals , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Homeostasis , Interleukin-6 , Mice , Microcystins/toxicity , Toll-Like Receptor 2
8.
Commun Biol ; 5(1): 552, 2022 06 07.
Article in English | MEDLINE | ID: mdl-35672382

ABSTRACT

Chronic multisymptom illness (CMI) affects a subsection of elderly and war Veterans and is associated with systemic inflammation. Here, using a mouse model of CMI and a group of Gulf War (GW) Veterans' with CMI we show the presence of an altered host resistome. Results show that antibiotic resistance genes (ARGs) are significantly altered in the CMI group in both mice and GW Veterans when compared to control. Fecal samples from GW Veterans with persistent CMI show a significant increase of resistance to a wide class of antibiotics and exhibited an array of mobile genetic elements (MGEs) distinct from normal healthy controls. The altered resistome and gene signature is correlated with mouse serum IL-6 levels. Altered resistome in mice also is correlated strongly with intestinal inflammation, decreased synaptic plasticity, reversible with fecal microbiota transplant (FMT). The results reported might help in understanding the risks to treating hospital acquired infections in this population.


Subject(s)
Gulf War , Veterans , Aged , Chronic Disease , Humans , Inflammation/genetics
9.
Brain Sci ; 11(7)2021 Jul 09.
Article in English | MEDLINE | ID: mdl-34356139

ABSTRACT

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-1ß 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.

10.
Toxicology ; 461: 152901, 2021 09.
Article in English | MEDLINE | ID: mdl-34416350

ABSTRACT

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.


Subject(s)
Blood-Brain Barrier/drug effects , Marine Toxins/toxicity , Microcystins/toxicity , NLR Family, Pyrin Domain-Containing 3 Protein/genetics , Non-alcoholic Fatty Liver Disease/physiopathology , Animals , Apoptosis/drug effects , Blood-Brain Barrier/pathology , Disease Models, Animal , Environmental Exposure/adverse effects , Inflammasomes/metabolism , Inflammation/pathology , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Neuroinflammatory Diseases/physiopathology , Oxidative Stress/drug effects , S100 Calcium Binding Protein beta Subunit/metabolism
11.
Nutrients ; 12(9)2020 Sep 10.
Article in English | MEDLINE | ID: mdl-32927823

ABSTRACT

Persistence of Gulf War illness (GWI) pathology among deployed veterans is a clinical challenge even after almost three decades. Recent studies show a higher prevalence of obesity and metabolic disturbances among Gulf War veterans primarily due to the existence of post-traumatic stress disorder (PTSD), chronic fatigue, sedentary lifestyle, and consumption of a high-carbohydrate/high-fat diet. We test the hypothesis that obesity from a Western-style diet alters host gut microbial species and worsens gastrointestinal and neuroinflammatory symptom persistence. We used a 5 month Western diet feeding in mice that received prior Gulf War (GW) chemical exposure to mimic the home phase obese phenotype of the deployed GW veterans. The host microbial profile in the Western diet-fed GWI mice showed a significant decrease in butyrogenic and immune health-restoring bacteria. The altered microbiome was associated with increased levels of IL6 in the serum, Claudin-2, IL6, and IL1ß in the distal intestine with concurrent inflammatory lesions in the liver and hyperinsulinemia. Microbial dysbiosis was also associated with frontal cortex levels of increased IL6 and IL1ß, activated microglia, decreased levels of brain derived neurotrophic factor (BDNF), and higher accumulation of phosphorylated Tau, an indicator of neuroinflammation-led increased risk of cognitive deficiencies. Mechanistically, serum from Western diet-fed mice with GWI significantly increased microglial activation in transformed microglial cells, increased tyrosyl radicals, and secreted IL6. Collectively, the results suggest that an existing obese phenotype in GWI worsens persistent gastrointestinal and neuronal inflammation, which may contribute to poor outcomes in restoring cognitive function and resolving fatigue, leading to the deterioration of quality of life.


Subject(s)
Gastrointestinal Microbiome/physiology , Obesity/microbiology , Obesity/pathology , Persian Gulf Syndrome/microbiology , Persian Gulf Syndrome/pathology , Animals , Diet, High-Fat/adverse effects , Disease Models, Animal , Dysbiosis/complications , Dysbiosis/microbiology , Dysbiosis/pathology , Gastroenteritis/complications , Gastroenteritis/microbiology , Gastroenteritis/pathology , Gastrointestinal Tract/microbiology , Gastrointestinal Tract/pathology , Hepatitis/complications , Hepatitis/microbiology , Hepatitis/pathology , Inflammation , Liver/microbiology , Liver/pathology , Mice , Neuritis/complications , Neuritis/microbiology , Neuritis/pathology , Neurons/microbiology , Neurons/pathology , Obesity/complications , Persian Gulf Syndrome/complications
12.
Brain Sci ; 10(8)2020 Aug 08.
Article in English | MEDLINE | ID: mdl-32784362

ABSTRACT

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-1ß (IL-1ß), and interleukin-6 (IL-6) in the distal intestine. SsnB also decreased neuronal inflammation by decreasing IL-1ß 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.

13.
Article in English | MEDLINE | ID: mdl-32781293

ABSTRACT

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-ß 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 TGFßR1 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.


Subject(s)
Fibrosis/pathology , Intestinal Mucosa/metabolism , Intestines/drug effects , Lactic Acid/metabolism , Microcystins/toxicity , NADPH Oxidase 2/metabolism , Non-alcoholic Fatty Liver Disease/metabolism , Animals , Cell Line , Enzyme Inhibitors/toxicity , Fibrosis/enzymology , Fibrosis/etiology , Intestinal Mucosa/drug effects , Intestines/enzymology , Intestines/pathology , Lactic Acid/blood , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , NADPH Oxidase 2/antagonists & inhibitors , Non-alcoholic Fatty Liver Disease/blood , Non-alcoholic Fatty Liver Disease/enzymology , Non-alcoholic Fatty Liver Disease/pathology , Phosphorylation
14.
Neurosci Insights ; 15: 2633105520942480, 2020.
Article in English | MEDLINE | ID: mdl-32832901

ABSTRACT

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.

15.
J Neuroinflammation ; 17(1): 201, 2020 Jul 04.
Article in English | MEDLINE | ID: mdl-32622362

ABSTRACT

BACKGROUND: Recent clinical and basic research implicated a strong correlation between NAFLD/NASH phenotypes with ectopic manifestations including neuroinflammation and neurodegeneration, but the mediators and critical pathways involved are not well understood. Lipocalin 2 (Lcn2) is one of the important mediators exclusively produced in the liver and circulation during NASH pathology. METHODS: Using murine model of NASH, we studied the role of Lcn2 as a potent mediator of neuroinflammation and neurodegeneration in NASH pathology via the liver-brain axis. RESULTS: Results showed that high circulatory Lcn2 activated 24p3R (Lipocalin2 receptor) in the brain and induced the release of high mobility group box 1 (HMGB1) preferably from brain cells. Released HMGB1 acted as a preferential ligand to toll-like receptor 4 (TLR4) and induced oxidative stress by activation of NOX-2 signaling involving activated p65 protein of the NF-κB complex. Further, the HMGB1-derived downstream signaling cascade activated NLRP3 inflammasome and release of proinflammatory cytokines IL-6 and IL-1ß from brain cells. In addition, to advance our present understanding, in vitro studies were performed in primary brain endothelial cells where results showed high circulatory Lcn2 influenced HMGB1 secretion. Mechanistically, we also showed that elevated Lcn2 level in underlying NASH might be a likely cause for induction of blood-brain barrier dysfunction since the adipokine decreased the expression of tight junction protein Claudin 5 and caused subsequent elevation of pro-inflammatory cytokines IL-6 and IL-1ß. CONCLUSION: In conclusion, the NASH-induced brain pathology might be because of increased Lcn2-induced release of HMGB1 and accompanying neuroinflammation.


Subject(s)
Blood-Brain Barrier/metabolism , Brain/metabolism , Inflammation/metabolism , Lipocalin-2/blood , Liver/metabolism , Non-alcoholic Fatty Liver Disease/metabolism , Animals , Blood-Brain Barrier/pathology , Brain/pathology , Cytokines/metabolism , Disease Models, Animal , HMGB1 Protein/metabolism , Inflammasomes/metabolism , Inflammation/pathology , Liver/pathology , Mice , NF-kappa B/metabolism , Non-alcoholic Fatty Liver Disease/pathology , Oxidative Stress/physiology , Signal Transduction/physiology , Toll-Like Receptor 4/metabolism
16.
Environ Toxicol Pharmacol ; 80: 103457, 2020 Nov.
Article in English | MEDLINE | ID: mdl-32687983

ABSTRACT

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-1ß, 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.


Subject(s)
Inflammasomes/metabolism , Insulin Resistance , Marine Toxins/toxicity , Microcystins/toxicity , Non-alcoholic Fatty Liver Disease/chemically induced , Water Pollutants, Chemical/toxicity , Animals , Diet, High-Fat/adverse effects , Liver/drug effects , Liver/immunology , Male , Mice , Mice, Inbred C57BL , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Non-alcoholic Fatty Liver Disease/immunology , Non-alcoholic Fatty Liver Disease/metabolism
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