Oral Adelmidrol Administration Up-Regulates Palmitoylethanolamide Production in Mice Colon and Duodenum through a PPAR-γ Independent Action

Adelmidrol is a promising palmitoylethanolamide (PEA) analog which displayed up-and-coming anti-inflammatory properties in several inflammatory conditions. Recent studies demonstrated that Adelmidrol is an in vitro enhancer of PEA endogenous production, through the so called “entourage” effect. The present study investigated the ability of Adelmidrol (1 and 10 mg/Kg per os) to increase the endogenous level of PEA in the duodenum and colon of mice after 21-day oral administration in the presence and absence of PPAR-γ inhibitor (1 mg/kg). The level of PEA was analyzed by HPLC-MS. The expression of PEA-related enzymatic machinery was evaluated by western blot and RT-PCR analysis. Our findings demonstrated that Adelmidrol significantly increased PEA levels in the duodenum and colon in a dose/time-dependent manner. We also revealed that Adelmidrol up regulated the enzymatic machinery responsible for PEA metabolism and catabolism. Interestingly, the use of the selective irreversible PPAR-γ antagonist did not affect either PEA intestinal levels or expres-sion/transcription of PEA metabolic enzymes following Adelmidrol administration. The “entourage effect” with Adelmidrol as an enhancer of PEA was thus PPAR-γ-independent. The findings suggest that Adelmidrol can maximize a PEA therapeutic-based approach in several intestinal morbidities

Ultramicronized palmitoylethanolamide inhibits NLRP3 inflammasome expression and pro-inflammatory response activated by SARS-CoV-2 spike protein in cultured murine alveolar macrophages

Despite its possible therapeutic potential against COVID-19, the exact mechanism(s) by which palmitoylethanolamide (PEA) exerts its beneficial activity is still unclear. PEA has demonstrated analgesic, anti-allergic, and anti-inflammatory activities. Most of the anti-inflammatory properties of PEA arise from its ability to antagonize nuclear factor-κB (NF-κB) signalling pathway via the selective activation of the PPARα receptors. Acting at this site, PEA can downstream several genes involved in the inflammatory response, including cytokines (TNF-α, Il-1β) and other signal mediators, such as inducible nitric oxide synthase (iNOS) and COX2. To shed light on this, we tested the anti-inflammatory and immunomodulatory activity of ultramicronized(um)-PEA, both alone and in the presence of specific peroxisome proliferator-activated receptor alpha (PPAR-α) antagonist MK886, in primary cultures of murine alveolar macrophages exposed to SARS-CoV-2 spike glycoprotein (SP). SP challenge caused a significant concentration-dependent increase in proinflammatory markers (TLR4, p-p38 MAPK, NF-κB) paralleled to a marked upregulation of inflammasome-dependent inflammatory pathways (NLRP3, Caspase-1) with IL-6, IL-1β, TNF-α over-release, compared to vehicle group. We also observed a significant concentration-dependent increase in ACE-2 following SP challenge. um-PEA concentration-dependently reduced all the analyzed proinflammatory markers fostering a parallel downregulation of ACE-2. Our data show for the first time that um-PEA, via PPAR-α, markedly inhibits the SP induced NLRP3 signalling pathway outlining a novel mechanism of action of this lipid against COVID-19

Next-Generation Probiotics for Inflammatory Bowel Disease

Engineered probiotics represent a cutting-edge therapy in intestinal inflammatory disease (IBD). Genetically modified bacteria have provided a new strategy to release therapeutically operative molecules in the intestine and have grown into promising new therapies for IBD. Current IBD treatments, such as corticosteroids and immunosuppressants, are associated with relevant side effects and a significant proportion of patients are dependent on these therapies, thus exposing them to the risk of relevant long-term side effects. Discovering new and effective therapeutic strategies is a worldwide goal in this research field and engineered probiotics could potentially provide a viable solution. This review aims at describing the proceeding of bacterial engineering and how genetically modified probiotics may represent a promising new biotechnological approach in IBD treatment

Cannabidiol inhibits SARS-Cov-2 spike (S) protein-induced cytotoxicity and inflammation through a PPARγ-dependent TLR4/NLRP3/Caspase-1 signaling suppression in Caco-2 cell line

Given the abundancy of angiotensin converting enzyme 2 (ACE-2) receptors density, beyond the lung, the intestine is considered as an alternative site of infection and replication for severe acute respiratory syndrome by coronavirus type 2 (SARS-CoV-2). Cannabidiol (CBD) has recently been proposed in the management of coronavirus disease 2019 (COVID-19) respiratory symptoms because of its anti-inflammatory and immunomodulatory activity exerted in the lung. In this study, we demonstrated the in vitro PPAR-γ-dependent efficacy of CBD (10−9-10−7 M) in preventing epithelial damage and hyperinflammatory response triggered by SARS-CoV-2 spike protein (SP) in a Caco-2 cells. Immunoblot analysis revealed that CBD was able to reduce all the analyzed proinflammatory markers triggered by SP incubation, such as tool-like receptor 4 (TLR-4), ACE-2, family members of Ras homologues A-GTPase (RhoA-GTPase), inflammasome complex (NLRP3), and Caspase-1. CBD caused a parallel inhibition of interleukin 1 beta (IL-1β), IL-6, tumor necrosis factor alpha (TNF-α), and IL-18 by enzyme-linked immunosorbent assay (ELISA) assay. By immunofluorescence analysis, we observed increased expression of tight-junction proteins and restoration of transepithelial electrical resistance (TEER) following CBD treatment, as well as the rescue of fluorescein isothiocyanate (FITC)–dextran permeability induced by SP. Our data indicate, in conclusion, that CBD is a powerful inhibitor of SP protein enterotoxicity in vitro

Sleeve Gastrectomy-Induced Body Mass Index Reduction Increases the Intensity of Taste Perception’s and Reduces Bitter-Induced Pleasantness in Severe Obesity

Background: The sense of taste is involved in food behavior and may drive food choices, likely contributing to obesity. Differences in taste preferences have been reported in normal-weight as compared to obese subjects. Changes in taste perception with an increased sweet-induced sensitivity have been reported in surgically treated obese patients, but data regarding the perception of basic tastes yielded conflicting results. We aimed to evaluate basic taste identification, induced perception, and pleasantness in normal-weight controls and obese subjects before and after bariatric surgery. Methods: Severe obese and matched normal weight subjects underwent a standardized spit test to evaluate sweet, bitter, salty, umami, and sour taste identification, induced perception, and pleasant-ness. A subset of obese subjects were also studied before and 12 months after sleeve gastrectomy. Results: No significant differences in basic taste-induced perceptions were observed, although a higher number of controls correctly identified umami than did obese subjects. Sleeve-gastrectomy-induced weight loss did not affect the overall ability to correctly identify basic tastes but was associated with a significant increase in taste intensities, with higher scores for sour and bitter, and a significantly reduced bitter-induced pleasantness. Conclusions: The perception of basic tastes is similar in normal-weight and severely obese subjects. Sleeve-gastrectomy-induced weight loss significantly increases basic taste-induced intensity, and selectively reduces bitter-related pleasantness without affecting the ability to identify the tastes. Our findings reveal that taste perception is influenced by body mass index changes, likely supporting the hypothesis that centrally mediated mechanisms modulate taste perception in severe obesity

Regional heterogeneity of cholecystokinin sensing by enteric glia.

Enteric glia are peripheral glia associated with the enteric nervous system (ENS) that function to orchestrate a variety of integrated ENS functions related to the autonomic control of gastrointestinal homeostasis. Enteric glia are also a key component of a complex gut-brain neuroepithelial circuit by which the brain quickly perceives gut sensory cues. Transcriptomics data show that enteric glia express low levels of mRNA encoding cholecystokinin (CCK) receptors A and B in the colon (35.16% and 19.36%, respectively vs P2RY1 mRNA expression, a known glia-expressed gene) and suggest that enteric glia contribute to gut-brain signalling by sensing CCK. Here, we tested the hypothesis that enteric glia detect CCK and that glial responsiveness to CCK differs among gut regions. We assessed the effects of CCK on enteric glia by using in situ Ca2+ imaging in whole-mount preparations of myenteric plexus from Sox10CreERT2::Polr2atm1[CAG-GCaMP5g,-tdTomato]Tvrd mice that express the optogenetic probe GCaMP5g in enteric glial cells. A comparable percentage of glia responded to 100µM ADP in duodenum and colon (82.4% and 89.2%, respectively; n=120 glial cells in the duodenum and n=130 in the colon), but the percentage of glia responding to 100nM CCK was higher in the colon than in the duodenum (66.4% vs 38.3%, respectively). Interestingly, blocking neuronal activity with 300nM tetrodotoxin increased the percentage of glia responding to CCK in the duodenum, but not in the colon (57.1% in the colon vs 64.8% in the duodenum). Despite higher numbers of glia responding to CCK in the colon than duodenum, CCK resulted a greater peak Ca2+ response in the duodenum than in the colon when it is compared to ADP response peak (24.8% of ADP-induced response in the colon; 33.8% of ADP-induced response in the duodenum). Glial responses to CCK in the duodenum were potentiated by blocking neuronal activity with tetrodotoxin (30% of ADP-induced response in the colon; 93.3% of ADP-induced response in the duodenum). Together, these data show that enteric glia respond to CCK and that glial responses to CCK differ in duodenum and colon. Glial sensitivity to CCK involves signalling with neurons, suggesting a possible region-specific mechanism to locally modulate gut-brain

Circuit-specific enteric glia regulate intestinal motor neurocircuits

Glia in the central nervous system exert precise spatial and temporal regulation over neural circuitry on a synapse-specific basis, but it is unclear if peripheral glia share this exquisite capacity to sense and modulate circuit activity. In the enteric nervous system (ENS), glia control gastrointestinal motility through bidirectional communication with surrounding neurons. We combined glial chemogenetics with genetically encoded calcium indicators expressed in enteric neurons and glia to study network-level activity in the intact myenteric plexus of the proximal colon. Stimulation of neural fiber tracts projecting in aboral, oral, and circumferential directions activated distinct populations of enteric glia. The majority of glia responded to both oral and aboral stimulation and circumferential pathways, while smaller subpopulations were activated only by ascending and descending pathways. Cholinergic signaling functionally specifies glia to the descending circuitry, and this network plays an important role in repressing the activity of descending neural pathways, with some degree of cross-inhibition imposed upon the ascending pathway. Glial recruitment by purinergic signaling functions to enhance activity within ascending circuit pathways and constrain activity within descending networks. Pharmacological manipulation of glial purinergic and cholinergic signaling differentially altered neuronal responses in these circuits in a sex-dependent manner. Collectively, our findings establish that the balance between purinergic and cholinergic signaling may differentially control specific circuit activity through selective signaling between networks of enteric neurons and glia. Thus, enteric glia regulate the ENS circuitry in a network-specific manner, providing profound insights into the functional breadth and versatility of peripheral glia

Functional Intraregional and Interregional Heterogeneity between Myenteric Glial Cells of the Colon and Duodenum in Mice

Enteric glia are a unique population of peripheral neuroglia that regulate homeostasis in the enteric nervous system (ENS) and intestinal functions. Despite existing in functionally diverse regions of the gastrointestinal tract, enteric glia have been approached scientifically as a homogeneous group of cells. This assumption is at odds with the functional specializations of gastrointestinal organs and recent data suggesting glial heterogeneity in the brain and ENS. Here, we used calcium imaging in transgenic mice of both sexes expressing genetically encoded calcium sensors in enteric glia and conducted contractility studies to investigate functional diversity among myenteric glia in two functionally distinct intestinal organs: the duodenum and the colon. Our data show that myenteric glia exhibit regionally distinct responses to neuromodulators that require intercellular communication with neurons to differing extents in the duodenum and colon. Glia regulate intestinal contractility in a region-specific and pathway-specific manner, which suggests regionally diverse engagement of enteric glia in local motor patterns through discrete signaling pathways. Further, functional response profiles delineate four unique subpopulations among myenteric glia that are differentially distributed between the colon and duodenum. Our findings support the conclusion that myenteric glia exhibit both intraregional and interregional heterogeneity that contributes to region-specific mechanisms that regulate digestive functions. Glial heterogeneity adds an unexpected layer of complexity in peripheral neurocircuits, and understanding the specific functions of specialized glial subtypes will provide new insight into ENS physiology and pathophysiology.SIGNIFICANCE STATEMENT Enteric glia modulate gastrointestinal functions through intercellular communication with enteric neurons. Whether heterogeneity exists among neuron-glia interactions in the digestive tract is not understood. Here, we show that myenteric glia display regional heterogeneity in their responses to neuromodulators in the duodenum and the colon, which are functionally distinct organs. Glial-mediated control of intestinal motility is region and pathway specific. Four myenteric glial subtypes are present within a given gut region that are differently distributed between gut regions. These data provide functional and regional insights into enteric circuit specificity in the adult enteric nervous system

HIV-1 Tat-induced diarrhea drives a glial inflammatory reaction to the central nervous system associated with a significant cognitive decline.

Acquired immunodeficiency syndrome (AIDS)-associated gastrointestinal and cognitive dysfunctions are complications related to HIV infection that significantly increase the morbidity and mortality1. HIV-1 Trans activating factor protein (Tat), by inducing mucosal damage, may reach the nerve part of the gut, the enteric nervous system (ENS), affecting its functions and resulting in a secretory diarrhea2. Since in the central nervous system (CNS) the glial cells are directly involved in mediating neurotoxic effects induced by HIV-1 Tat3, the possible role played by enteric glial cells (EGCs) to trigger and spread an HIV-1 Tat-induced neuroinflammatory response throughout the “gut-brain” axis was investigated.We tested our hypothesis that enteric glia is involved in HIV-1 Tat-induced diarrhea and cognitive dysfunctions to verify: (I) how the activation of the enteric glia modulates the diarrhea;(ii) if EGC-activation is localized at the intestinal level or it is associated with a signaling to the CNS; (iii) what is the pathway by which HIV-1 Tat signaling propagates from the periphery to the brain; (iv) if these events correlate with cognitive impairment. In eight-weeks-old Wistar male rats, HIV-1 Tat peptide (100 ng/ml) was injected into the lumen of the animal colon at day 1. In a subset of animals, HIV 1-Tat was administered immediately after lidocaine topic application in a single dose (0.03% w/v). In another group of animals, a single dose of bisacodyl (20 mg/Kg) was administrated orally by gavage. Animals were euthanatized at different time points (7, 12, 14 and 21 days) depending upon the scheduled experimental plan, and colon, thoracic and cervical spinal cord and brain were isolated to perform immunofluorescence, in situ hybridization and biochemical/molecular analyses.  Finally, we investigated the memory skills of treated rats by the object recognition test. Our study demonstrates that a single colonic application of HIV-1 Tat induces an acute diarrhea that is at least partially modulated by the activation of glia cells in the submucosal plexus. This local response is able to trigger and activate glia cells in the spinal cord and brain cortex through the expression of Cx43, that results in an inflammatory reaction in the brain and that is associated with a significant cognitive decline in treated rats

LPAR1 regulates enteric nervous system function through glial signaling and contributes to chronic intestinal pseudo-obstruction

Gastrointestinal motility disorders involve alterations to the structure and/or function of the enteric nervous system (ENS) but the causal mechanisms remain unresolved in most cases. Homeostasis and disease in the ENS are processes that are regulated by enteric glia. Signaling mediated through type I lysophosphatidic acid receptors (LPAR1) has recently emerged as an important mechanism that contributes to disease, in part, through effects on peripheral glial survival and function. Enteric glia express LPAR1 but its role in ENS function and motility disorders is unknown. We used a combination of genetic, immunohistochemical, calcium imaging, and in vivo pharmacological approaches to investigate the role of LPAR1 in enteric glia. LPAR1 was enriched in enteric glia in mice and humans and LPA stimulated intracellular calcium responses in enteric glia, subsequently recruiting activity in a subpopulation of myenteric neurons. Blocking LPAR1 in vivo with AM966 attenuated gastrointestinal motility in mice and produced marked enteric neuro- and gliopathy. Samples from humans with chronic intestinal pseudo-obstruction (CIPO), a severe motility disorder, showed reduced glial LPAR1 expression in the colon and ileum. These data suggest that enteric glial LPAR1 signaling regulates gastrointestinal motility through enteric glia and could contribute to severe motility disorders in humans such as CIPO