Pathological Remodeling of the Gut Barrier as a Prodromal Event of High-Fat Diet-Induced Obesity.

Intestinal barrier alterations represent a primum movens in obesity and related intestinal dysfunctions. However, whether gut barrier remodeling represents prodromal events in obesity before weight gain, metabolic alterations, and systemic inflammation remains unclear. Herein, we examined morphologic changes in the gut barrier in a mouse model of high-fat diet (HFD) since the earliest phases of diet assumption. C57BL/6J mice were fed with standard diet (SD) or HFD for 1, 2, 4, or 8 weeks. Remodeling of intestinal epithelial barrier, inflammatory infiltrate, and collagen deposition in the colonic wall was assessed by histochemistry and immunofluorescence analysis. Obese mice displayed increased body and epididymal fat weight along with increased plasma resistin, IL-1ß, and IL-6 levels after 8 weeks of HFD. Starting from 1 week of HFD, mice displayed (1) a decreased claudin-1 expression in lining epithelial cells, (2) an altered mucus in goblet cells, (3) an increase in proliferating epithelial cells in colonic crypts, (4) eosinophil infiltration along with an increase in vascular P-selectin, and (5) deposition of collagen fibers. HFD intake is associated with morphologic changes in the large bowel at mucosal and submucosal levels. In particular, the main changes include alterations in the mucous layer and intestinal epithelial barrier integrity and activation of mucosal defense-enhanced fibrotic deposition. These changes represent early events occurring before the development of obesity condition that could contribute to compromising the intestinal mucosal barrier and functions, opening the way for systemic dissemination.

Enteric Glia and Brain Astroglia: Complex Communication in Health and Disease along the Gut-Brain Axis.

Several studies have provided interesting evidence about the role of the bidirectional communication between the gut and brain in the onset and development of several pathologic conditions, including inflammatory bowel diseases (IBDs), neurodegenerative diseases, and related comorbidities. Indeed, patients with IBD can experience neurologic disorders, including depression and cognitive impairment, besides typical intestinal symptoms. In parallel, patients with neurodegenerative disease, such as Parkinson disease and Alzheimer disease, are often characterized by the occurrence of functional gastrointestinal disorders. In this context, enteric glial cells and brain astrocytes are emerging as pivotal players in the initiation/maintenance of neuroinflammatory responses, which appear to contribute to the alterations of intestinal and neurologic functions observed in patients with IBD and neurodegenerative disorders. The present review was conceived to provide a comprehensive and critical overview of the available knowledge on the morphologic, molecular, and functional changes occurring in the enteric glia and brain astroglia in IBDs and neurologic disorders. In addition, our intent is to identify whether such alterations could represent a common denominator involved in the onset of comorbidities associated with the aforementioned disorders. This might help to identify putative targets useful to develop novel pharmacologic approaches for the therapeutic management of such disturbances.

Dietary Supplementation with the Probiotic SF68 Reinforces Intestinal Epithelial Barrier in Obese Mice by Improving Butyrate Bioavailability.

SCOPE: Modifications in intestinal microbiota and its metabolites, the short-chain fatty acids (SCFA) are main factors altering intestinal epithelial barrier integrity and eliciting the onset of a meta-inflammation observed in obesity. The present study is aimed at evaluating the efficacy of Enterococcus faecium (SF68) administration in counteracting the impairment of gut barrier and enteric inflammation in a model of diet-induced obesity, characterizing the molecular mechanisms underlying such beneficial effects. METHODS AND RESULTS: Male C57BL/6J mice, fed with standard diet (SD) or high-fat diet (HFD), are treated with SF68 (108  CFU day-1 ). After 8 weeks, plasma interleukin (IL)-1ß and lipopolysaccharide binding protein (LBP) are measured, analysis of fecal microbiota composition and butyrate content as well as intestinal malondialdehyde, myeloperoxidase, mucins, tight junction protein, and butyrate transporter expression are investigated. After 8 weeks, SF68 administration counteracts the body weight gain in HFD mice, reducing plasma IL-1ß and LBP. In parallel, SF68 treatment acts against the intestinal inflammation in HFD-fed animals and improves the intestinal barrier integrity and functionality in obese mice via the increase in tight junction protein and intestinal butyrate transporter (sodium-coupled monocarboxylate transporter 1 ) expression. CONCLUSIONS: Supplementation with SF68 reduces intestinal inflammation and reinforces the enteric epithelial barrier in obese mice, improving the transport and utilization of butyrate.

Role of cyclooxygenase pathways in bowel fibrotic remodelling in a murine model of experimental colitis.

OBJECTIVE: Gut fibrosis occurs under chronic inflammation. This study examined the effects of different cyclooxygenase (COX) inhibitors on fibrosis in the inflamed colon. METHODS: Colitis was induced by 2,4-dinitrobenzenesulfonic acid (DNBS) in albino male Sprague-Dawley rats. After 6, 12 and 18 days, macroscopic and microscopic damage, collagen and elastic fibre content were examined. At day 6, pro-fibrotic factors (collagen I and III, hydroxyproline, fibronectin, matrix metalloproteinase-2 and -9), transforming growth factor-beta (TGF-ß) signalling [TGF-ß, Ras homolog gene family member A (RhoA), phosphorylated small mother against decapentaplegic (pSMAD)-2 and -6] and peristalsis were assessed, and the effects of indomethacin, SC-560 or celecoxib were tested. KEY FINDINGS: Six days after DNBS administration, significant histopathological signs of fibrotic remodelling were observed in rats. At day 6, pro-fibrotic factors were up-regulated and colonic peristalsis was altered. COX inhibitors reversed the histochemical, molecular and functional changes in the fibrotic colon. COX inhibition reduced TGF-ß expression, SMAD2 phosphorylation and RhoA, and increased SMAD6 expression. CONCLUSIONS: Colonic fibrosis is associated with altered bowel motility and induction of profibrotic factors driven by TGF-ß signalling. COX-1 and COX-2 inhibition counteracts this fibrotic remodelling by the modulation of TGF-ß/SMAD signalling, mainly via SMAD6 induction and reduction in SMAD2 phosphorylation.

Intestinal histomorphological and molecular alterations in patients with Parkinson's disease.

BACKGROUND AND PURPOSE: Changes in gut microbiota composition, enteric inflammation, impairments of the intestinal epithelial barrier and neuroplastic changes in the enteric nervous system have been reported in Parkinson's disease (PD) patients and could contribute to the onset of both neurological and gastrointestinal symptoms. However, their mutual interplay has rarely been investigated. This study evaluated, in an integrated manner, changes in faecal microbiota composition, morphofunctional alterations of colonic mucosal barrier and changes of inflammatory markers in blood and stools of PD patients. METHODS: Nineteen PD patients and nineteen asymptomatic subjects were enrolled. Blood lipopolysaccharide binding protein (LBP, marker of altered intestinal permeability) and interleukin-1ß (IL-1ß) levels, as well as stool IL-1ß and tumour necrosis factor (TNF) levels, were evaluated. Gut microbiota analysis was performed. Epithelial mucins, collagen fibres, claudin-1 and S100-positive glial cells as markers of an impairment of the intestinal barrier, mucosal remodelling and enteric glial activation were evaluated on colonic mucosal specimens collected during colonoscopy. RESULTS: Faecal microbiota analysis revealed a significant difference in the α-diversity in PD patients compared to controls, while no differences were found in the ß-diversity. Compared to controls, PD patients showed significant chenags in plasma LBP levels, as well as faecal TNF and IL-1ß levels. The histological analysis showed a decrease in epithelial neutral mucins and claudin-1 expression and an increased expression of acidic mucins, collagen fibres and S100-positive glial cells. CONCLUSIONS: Parkinson's disease patients are characterized by enteric inflammation and increased intestinal epithelial barrier permeability, as well as colonic mucosal barrier remodelling, associated with changes in gut microbiota composition.

The intestinal barrier in disorders of the central nervous system.

The intestinal barrier, which primarily consists of a mucus layer, an epithelial barrier, and a gut vascular barrier, has a crucial role in health and disease by facilitating nutrient absorption and preventing the entry of pathogens. The intestinal barrier is in close contact with gut microbiota on its luminal side and with enteric neurons and glial cells on its tissue side. Mounting evidence now suggests that the intestinal barrier is compromised not only in digestive disorders, but also in disorders of the central nervous system (CNS), such as Parkinson's disease, autism spectrum disorder, depression, multiple sclerosis, and Alzheimer's disease. After providing an overview of the structure and functions of the intestinal barrier, we review existing preclinical and clinical studies supporting the notion that intestinal barrier dysfunction is present in neurological, neurodevelopmental, and psychiatric disorders. On the basis of this evidence, we discuss the mechanisms that possibly link gut barrier dysfunction and CNS disorders and the potential impact that evaluating enteric barriers in brain disorders could have on clinical practice, in terms of novel diagnostic and therapeutic strategies, in the near future.

Targeting SIRT1 Rescues Age- and Obesity-Induced Microvascular Dysfunction in Ex Vivo Human Vessels.

BACKGROUND: Experimental evidence suggests a key role of SIRT1 (silent information regulator 1) in age- and metabolic-related vascular dysfunction. Whether these effects hold true in the human microvasculature is unknown. We aimed to investigate the SIRT1 role in very early stages of age- and obesity-related microvascular dysfunction in humans. METHODS: Ninety-five subjects undergoing elective laparoscopic surgery were recruited and stratified based on their body mass index status (above or below 30 kg/m2) and age (above or below 40 years) in 4 groups: Young Nonobese, Young Obese, Old Nonobese, and Old Obese. We measured small resistance arteries' endothelial function by pressurized micromyography before and after incubation with a SIRT1 agonist (SRT1720) and a mitochondria reactive oxygen species (mtROS) scavenger (MitoTEMPO). We assessed vascular levels of mtROS and nitric oxide availability by confocal microscopy and vascular gene expression of SIRT1 and mitochondrial proteins by qPCR. Chromatin immunoprecipitation assay was employed to investigate SIRT1-dependent epigenetic regulation of mitochondrial proteins. RESULTS: Compared with Young Nonobese, obese and older patients showed lower vascular expression of SIRT1 and antioxidant proteins (FOXO3 [forkhead box protein O3] and SOD2) and higher expression of pro-oxidant and aging mitochondria proteins p66Shc and Arginase II. Old Obese, Young Obese and Old Nonobese groups endothelial dysfunction was rescued by SRT1720. The restoration was comparable to the one obtained with mitoTEMPO. These effects were explained by SIRT1-dependent chromatin changes leading to reduced p66Shc expression and upregulation of proteins involved in mitochondria respiratory chain. CONCLUSIONS: SIRT1 is a novel central modulator of the earliest microvascular damage induced by age and obesity. Through a complex epigenetic control mainly involving p66Shc and Arginase II, it influences mtROS levels, NO availability, and the expression of proteins of the mitochondria respiratory chain. Therapeutic modulation of SIRT1 restores obesity- and age-related endothelial dysfunction. Early targeting of SIRT1 might represent a crucial strategy to prevent age- and obesity-related microvascular dysfunction.

From the intestinal mucosal barrier to the enteric neuromuscular compartment: an integrated overview on the morphological changes in Parkinson's disease.

Gastrointestinal dysfunctions represent the most common non-motor symptoms in Parkinson's disease (PD). Of note, changes in gut microbiota, impairments of intestinal epithelial barrier (IEB), bowel inflammation and neuroplastic rearrangements of the enteric nervous system (ENS) could be involved in the pathophysiology of the intestinal disturbances in PD. In this context, although several review articles have pooled together evidence on the alterations of enteric bacteria-neuro-immune network in PD, a revision of the literature on the specific morphological changes occurring in the intestinal mucosal barrier, the ENS and enteric muscular layers in PD, is lacking. The present review provides a complete appraisal of the available knowledge on the morphological alterations of intestinal mucosal barrier, with particular focus on IEB, ENS and enteric muscular layers in PD. In particular, our intent was to critically discuss whether, based on evidence from translational studies and pre-clinical models, morphological changes in the intestinal barrier and enteric neuromuscular compartment contribute to the pathophysiology of intestinal dysfunctions occurring in PD.

Donepezil improves vascular function in a mouse model of Alzheimer's disease.

Cardiovascular complications in Alzheimer's disease (AD) patients can occur years to decades prior to the onset of clinical symptoms of the disease. Donepezil represents the most effective drug in the treatment of AD. However, the potential effect of donepezil on vascular function and structure remains largely unexplored. Here, we assessed the impact of donepezil on the vascular phenotype of an established model of accelerated senescence that develops spontaneously AD, the SAMP8 mouse. Three groups of animals were included: SAMR1 (control strain), SAMP8, and SAMP8 treated with donepezil. Treatment with donepezil was administered from the 4th to the 6th month of life. At 6 months, after cognitive tests by Morris Water Maze, animals were euthanized, and their mesenteric arteries were processed for functional experiments. Untreated SAMP8 developed cognitive impairment compared to SAMR1, while donepezil treatment significantly attenuated cognitive dysfunction. SAMP8 exhibited a higher media-to-lumen ratio than SAMR1 and donepezil-treated animals. Endothelial function was impaired in SAMP8 animals compared to SAMR1. The addition of vitamin C improved the vasodilatory response to acetylcholine in SAMP8. Treatment with donepezil improved endothelial function in SAMP8 animals and reduced the additional vasodilation induced by vitamin C. In conclusion, in the SAMP8 AD model, cognitive impairment is associated with endothelial dysfunction and vascular remodeling which could contribute to cardiovascular events in AD since the prodromal phases of the disease. Treatment with donepezil alleviates vascular dysfunction associated with AD through an increase in NO availability likely by counteracting inflammation and oxidative stress.

NLRP3 at the crossroads between immune/inflammatory responses and enteric neuroplastic remodelling in a mouse model of diet-induced obesity.

BACKGROUND AND PURPOSE: Enteric neurogenic/inflammation contributes to bowel dysmotility in obesity. We examined the role of NLRP3 in colonic neuromuscular dysfunctions in mice with high-fat diet (HFD)-induced obesity. EXPERIMENTAL APPROACH: Wild-type C57BL/6J and NLRP3-KO (Nlrp3-/- ) mice were fed with HFD or standard diet for 8 weeks. The activation of inflammasome pathways in colonic tissues from obese mice was assessed. The role of NLRP3 in in vivo colonic transit and in vitro tachykininergic contractions and substance P distribution was evaluated. The effect of substance P on NLRP3 signalling was tested in cultured cells. KEY RESULTS: HFD mice displayed increased body and epididymal fat weight, cholesterol levels, plasma resistin levels and plasma and colonic IL-1ß levels, colonic inflammasome adaptor protein apoptosis-associated speck-like protein containing caspase-recruitment domain (ASC) and caspase-1 mRNA expression and ASC immunopositivity in macrophages. Colonic tachykininergic contractions were enhanced in HFD mice. HFD NLRP3-/- mice developed lower increase in body and epididymal fat weight, cholesterol levels, systemic and bowel inflammation. In HFD Nlrp3-/- mice, the functional alterations of tachykinergic pathways and faecal output were normalized. In THP-1 cells, substance P promoted IL-1ß release. This effect was inhibited upon incubation with caspase-1 inhibitor or NK1 antagonist and not observed in ASC-/- cells. CONCLUSION AND IMPLICATIONS: In obesity, NLRP3 regulates an interplay between the shaping of enteric immune/inflammatory responses and the activation of substance P/NK1 pathways underlying the onset of colonic dysmotility. Identifying NLRP3 as a therapeutic target for the treatment of bowel symptoms related to obesity.

Enteric Glia at the Crossroads between Intestinal Immune System and Epithelial Barrier: Implications for Parkinson Disease.

Over recent years, several investigations have suggested that Parkinson's disease (PD) can be regarded as the consequence of a bowel disorder. Indeed, gastrointestinal symptoms can occur at all stages of this neurodegenerative disease and in up to a third of cases, their onset can precede the involvement of the central nervous system. Recent data suggest that enteric glial cells (EGCs) may play a major role in PD-related gastrointestinal disturbances, as well as in the development and progression of the central disease. In addition to their trophic and structural functions, EGCs are crucial for the homeostatic control of a wide range of gastrointestinal activities. The main purpose of this review was to provide a detailed overview of the role of EGCs in intestinal PD-associated alterations, with particular regard for their participation in digestive and central inflammation as well as the dynamic interactions between glial cells and intestinal epithelial barrier. Accumulating evidence suggests that several pathological intestinal conditions, associated with an impairment of barrier permeability, may trigger dysfunctions of EGCs and their shift towards a proinflammatory phenotype. The reactive gliosis is likely responsible for PD-related neuroinflammation and the associated pathological changes in the ENS. Thus, ameliorating the efficiency of mucosal barrier, as well as avoiding IEB disruption and the related reactive gliosis, might theoretically prevent the onset of PD or, at least, counteract its progression.

Deepening the Mechanisms of Visceral Pain Persistence: An Evaluation of the Gut-Spinal Cord Relationship.

The management of visceral pain is a major clinical problem in patients affected by gastrointestinal disorders. The poor knowledge about pain chronicization mechanisms prompted us to study the functional and morphological alterations of the gut and nervous system in the animal model of persistent visceral pain caused by 2,4-dinitrobenzenesulfonic acid (DNBS). This agent, injected intrarectally, induced a colonic inflammation peaking on day 3 and remitting progressively from day 7. In concomitance with bowel inflammation, the animals developed visceral hypersensitivity, which persisted after colitis remission for up to three months. On day 14, the administration of pain-relieving drugs (injected intraperitoneally and intrathecally) revealed a mixed nociceptive, inflammatory and neuropathic pain originating from both the peripheral and central nervous system. At this time point, the colonic histological analysis highlighted a partial restitution of the tunica mucosa, transmural collagen deposition, infiltration of mast cells and eosinophils, and upregulation of substance P (SP)-positive nerve fibers, which were surrounded by eosinophils and MHC-II-positive macrophages. A significant activation of microglia and astrocytes was observed in the dorsal and ventral horns of spinal cord. These results suggest that the persistence of visceral pain induced by colitis results from maladaptive plasticity of the enteric, peripheral and central nervous systems.

Prodromal Intestinal Events in Alzheimer's Disease (AD): Colonic Dysmotility and Inflammation Are Associated with Enteric AD-Related Protein Deposition.

Increasing evidence suggests that intestinal dysfunctions may represent early events in Alzheimer's disease and contribute to brain pathology. This study examined the relationship between onset of cognitive impairment and colonic dysfunctions in a spontaneous AD model before the full development of brain pathology. SAMP8 mice underwent Morris water maze and assessment of faecal output at four, six and eight months of age. In vitro colonic motility was examined. Faecal and colonic Aß, tau proteins, α-synuclein and IL-1ß were assessed by ELISA. Colonic citrate synthase activity was assessed by spectrophotometry. Colonic NLRP3, caspase-1 and ASC expression were evaluated by Western blotting. Colonic eosinophil density and claudin-1 expression were evaluated by immunohistochemistry. The effect of Aß on NLRP3 signalling and mitochondrial function was tested in cultured cells. Cognitive impairment and decreased faecal output occurred in SAMP8 mice from six months. When compared with SAMR1, SAMP8 animals displayed: (1) impaired in vitro colonic contractions; (2) increased enteric AD-related proteins, IL-1ß, active-caspase-1 expression and eosinophil density; and (3) decreased citrate synthase activity and claudin-1 expression. In THP-1 cells, Aß promoted IL-1ß release, which was abrogated upon incubation with caspase-1 inhibitor or in ASC-/- cells. Aß decreased mitochondrial function in THP-1 cells. In SAMP8, enteric AD-related proteins deposition, inflammation and impaired colonic excitatory neurotransmission, occurring before the full brain pathology development, could contribute to bowel dysmotility and represent prodromal events in AD.

Intestinal epithelial barrier and neuromuscular compartment in health and disease.

A number of digestive and extra-digestive disorders, including inflammatory bowel diseases, irritable bowel syndrome, intestinal infections, metabolic syndrome and neuropsychiatric disorders, share a set of clinical features at gastrointestinal level, such as infrequent bowel movements, abdominal distension, constipation and secretory dysfunctions. Several lines of evidence indicate that morphological and molecular changes in intestinal epithelial barrier and enteric neuromuscular compartment contribute to alterations of both bowel motor and secretory functions in digestive and extra-digestive diseases. The present review has been conceived to provide a comprehensive and critical overview of the available knowledge on the morphological and molecular changes occurring in intestinal epithelial barrier and enteric neuromuscular compartment in both digestive and extra-digestive diseases. In addition, our intent was to highlight whether these morphological and molecular alterations could represent a common path (or share some common features) driving the pathophysiology of bowel motor dysfunctions and related symptoms associated with digestive and extra-digestive disorders. This assessment might help to identify novel targets of potential usefulness to develop original pharmacological approaches for the therapeutic management of such disturbances.

Pathological remodelling of colonic wall following dopaminergic nigrostriatal neurodegeneration.

BACKGROUND AND AIM: Patients with Parkinson's disease (PD) are often characterized by functional gastrointestinal disorders. Such disturbances can occur at all stages of PD and precede the typical motor symptoms of the disease by many years. However, the morphological alterations associated with intestinal disturbances in PD are undetermined. This study examined the remodelling of colonic wall in 6-hydroxydopamine (6-OHDA)-induced PD rats. METHODS: 8 weeks after 6-OHDA injection animals were sacrificed. Inflammatory infiltrates, collagen deposition and remodelling of intestinal epithelial barrier and tunica muscularis in the colonic wall were assessed by histochemistry, immunohistochemistry, immunofluorescence and western blot analysis. RESULTS: 6-OHDA rats displayed significant alterations of colonic tissues as compared with controls. Signs of mild inflammation (eosinophil infiltration) and a transmural deposition of collagen fibres were observed. Superficial colonic layers were characterized by severe morphological alterations. In particular, lining epithelial cells displayed a reduced claudin-1 and transmembrane 16A/Anoctamin 1 (TMEM16A/ANO1) expression; goblet cells increased their mucin expression; colonic crypts were characterized by an increase in proliferating epithelial cells; the density of S100-positive glial cells and vimentin-positive fibroblast-like cells was increased as well. Several changes were found in the tunica muscularis: downregulation of α-smooth muscle actin/desmin expression and increased proliferation of smooth muscle cells; increased vimentin expression and proliferative phenotype in myenteric ganglia; reduction of interstitial cells of Cajal (ICCs) density. CONCLUSIONS: A pathological remodelling occurs in the colon of 6-OHDA rats. The main changes include: enhanced fibrotic deposition; alterations of the epithelial barrier; activation of mucosal defense; reduction of ICCs. These results indicate that central nigrostriatal denervation is associated with histological changes in the large bowel at mucosal, submucosal and muscular level. These alterations might represent morphological correlates of digestive symptoms in PD.

Microvascular Endothelial Dysfunction in Patients with Obesity.

PURPOSE OF REVIEW: To examine the state of the art on the pathogenesis of endothelial dysfunction in the microcirculation of patients with obesity, focusing on the complex relationship between the consolidated and the novel mechanisms involved in this alteration. RECENT FINDINGS: Human obesity is associated with vascular endothelial dysfunction, caused by a reduced nitric oxide availability secondary to an enhanced oxidative stress production. Pro-inflammatory cytokine generation, secreted by perivascular adipose tissue, is a major mechanism whereby obesity is associated with a reduced vascular NO availability. Vasculature also represents a source of low-grade inflammation and oxidative stress which contribute to endothelial dysfunction in obese patients. Recently, a direct influence of arginase on endothelial function by reducing nitric oxide availability was demonstrated in small vessels from patients with severe obesity. This effect is modulated by ageing and related to the high levels of vascular oxidative stress. Oxidative stress, inflammation, and enzymatic pathways are important players in the pathophysiology of obesity-related vascular disease. The identification of new therapeutic approaches able to interfere with these mechanisms will result in more effective prevention of the cardiovascular complications associated with obesity.

Microvascular Endothelial Dysfunction in Human Obesity: Role of TNF-α.

Context: Endothelium guarantees vascular homeostasis by the opposite action of substances by vasodilating/antithrombogenic and vasoconstricting/prothrombotic activities. Obesity is characterized by endothelial dysfunction associated with a condition of vascular low-grade inflammation. Evidence Acquisition: Analysis of available basic or clinical papers published in peer-reviewed international journals on microcirculation and obesity. Evidence Synthesis: Vascular low-grade inflammation, which characterizes obesity, is secondary to abnormal production of proinflammatory cytokines, including TNF-α. TNF-α, generated either in small vessels or within the perivascular adipose tissue (PVAT) of patients with obesity, stimulates reactive oxygen species generation, mainly through NAD(P)H oxidase activation, which in turn reduces nitric oxide (NO) availability. These aspects are highlighted by the insulin resistance status and macronutrient intake that characterize the obesity condition. Oxidant excess has also been proposed as a mechanism whereby TNF-α interferes with the endothelin-1/NO system at the level of small vessels from patients with obesity. Conclusions: In obesity, microvasculature from visceral fat is an important source of low-grade inflammation and oxidative stress that, together with the PVAT, directly contribute to vascular changes, favoring the development and acceleration of the vascular atherothrombotic process in this clinical condition.

Interplay between colonic inflammation and tachykininergic pathways in the onset of colonic dysmotility in a mouse model of diet-induced obesity.

BACKGROUND: The murine model of high fat diet (HFD)-induced obesity is characterized by an increment of intestinal permeability, secondary to an impairment of mucosal epithelial barrier and enteric inflammation, followed by morphofunctional rearrangement of the enteric nervous system. The present study investigated the involvement of abdominal macrophages in the mechanisms underlying the development of enteric dysmotility associated with obesity. METHODS: Wild type C57BL/6J mice were fed with HFD (60% kcal from fat) or normocaloric diet (NCD, 18% kcal from fat) for 8 weeks. Groups of mice fed with NCD or HFD were treated with clodronate encapsulated into liposomes to deplete abdominal macrophages. Tachykininergic contractions, elicited by electrical stimulation or exogenous substance P (SP), were recorded in vitro from longitudinal muscle colonic preparations. Substance P distribution was examined by confocal immunohistochemistry. The density of macrophages in the colonic wall was examined by immunohistochemical analysis. Malondialdehyde (MDA, colorimetric assay) and IL-1ß (ELISA assay) levels were also evaluated. RESULTS: MDA and IL-1ß levels were increased in colonic tissues from HFD-treated animals. In colonic preparations, electrically evoked tachykininergic contractions were enhanced in HFD mice. Immunohistochemistry displayed an increase in substance P immunoreactivity in myenteric ganglia, as well as in the muscular layers of colonic cryosections from obese mice. Macrophage depletion in HFD mice was associated with a significant reduction of colonic inflammation. In addition, the decrease in macrophage density attenuated the morphofunctional alterations of tachykininergic pathways observed in obese mice. CONCLUSION: Obesity elicited by HFD determines a condition of colonic inflammation, followed by a marked rearrangement of motor excitatory tachykininergic enteric nerves. Macrophage depletion counteracted the morphofunctional changes of colonic neuromuscular compartment, suggesting a critical role for these immune cells in the onset of enteric dysmotility associated with obesity.

Aging Modulates the Influence of Arginase on Endothelial Dysfunction in Obesity.

Objective- Arginase can reduce NO availability. In this study, we explored arginase as a determinant of endothelial dysfunction in small arteries from obese patients and its relationship with aging and microvascular remodeling. Approach and Results- Small arteries were dissected after subcutaneous fat biopsies and evaluated on a pressurized micromyograph. Endothelium-dependent vasodilation was assessed by acetylcholine, repeated under L-NAME ( N G-nitro-L-arginine-methyl ester), N(ω)-hydroxy-nor-l-arginine (arginase inhibitor) and gp91ds-tat (NADPH [nicotinamide adenine dinucleotide phosphate oxidase] oxidase inhibitor) in vessels from young (age <30 years) control and obese and old (>30 years) control and obese subjects. Media-lumen ratio and amount of vascular wall fibrosis were used as markers of vascular remodeling. Amount of vascular superoxide anions and NO production were determined with immunofluorescence, whereas arginase expression was quantified using Western blot and quantitative polymerase chain reaction. Obese and older age groups had lower vascular NO, as well as higher media-lumen ratio, wall fibrosis, intravascular superoxide, and blunted inhibitory effect of L-NAME on acetylcholine versus controls and younger age groups. N(ω)-hydroxy-nor-l-arginine restored the acetylcholine-induced vasodilation in young and, to a lesser extent, in old obese subjects. This effect was abolished by addition of L-NAME. Gp91ds-tat increased the vasodilatory response to N(ω)-hydroxy-nor-l-arginine in old obese. Superoxide anions and arginase I/II levels were higher in the vascular wall of obese versus controls. Conclusions- Arginase contributes to microvascular endothelial dysfunction in obesity. Its impact is reduced by aging because of higher levels of vascular oxidative stress. Obesity is accompanied by accelerated microvascular remodeling, the extent of which is related to the amount of arginase in the vascular wall.

Cell-specific pattern of berberine pleiotropic effects on different human cell lines.

The natural alkaloid berberine has several pharmacological properties and recently received attention as a potential anticancer agent. In this work, we investigated the molecular mechanisms underlying the anti-tumor effect of berberine on glioblastoma U343 and pancreatic carcinoma MIA PaCa-2 cells. Human dermal fibroblasts (HDF) were used as non-cancer cells. We show that berberine differentially affects cell viability, displaying a higher cytotoxicity on the two cancer cell lines than on HDF. Berberine also affects cell cycle progression, senescence, caspase-3 activity, autophagy and migration in a cell-specific manner. In particular, in HDF it induces cell cycle arrest in G2 and senescence, but not autophagy; in the U343 cells, berberine leads to cell cycle arrest in G2 and induces both senescence and autophagy; in MIA PaCa-2 cells, the alkaloid induces arrest in G1, senescence, autophagy, it increases caspase-3 activity and impairs migration/invasion. As demonstrated by decreased citrate synthase activity, the three cell lines show mitochondrial dysfunction following berberine exposure. Finally, we observed that berberine modulates the expression profile of genes involved in different pathways of tumorigenesis in a cell line-specific manner. These findings have valuable implications for understanding the complex functional interactions between berberine and specific cell types.