Gut Homeostasis, Microbial Dysbiosis, and Opioids

Gut-Brain Axis a Key Player to Control Gut Dysbiosis in Neurological Diseases

Parkinson's disease is a chronic neuropathy characterised by the formation of Lewy bodies (misfolded alpha-synuclein) in dopaminergic neurons of the substantia nigra and other parts of the brain. Dopaminergic neurons play a vital role in generating both motor and non-motor symptoms. Finding therapeutic targets for Parkinson's disease (PD) is hindered due to an incomplete understanding of the disease's pathophysiology. Existing evidence suggests that the gut microbiota participates in the pathogenesis of PD via immunological, neuroendocrine, and direct neural mechanisms. Gut microbial dysbiosis triggers the loss of dopaminergic neurons via mitochondrial dysfunction. Gut dysbiosis triggers bacterial overgrowth in the small intestine, which increases the permeability barrier and induces systemic inflammation. It results in excessive stimulation of the innate immune system. In addition to that, activation of enteric neurons and enteric glial cells initiates the aggregation of alpha-synuclein. This alpha-synucleinopathy thus affects all levels of the brain-gut axis, including the central, autonomic, and enteric nervous systems. Though the neurobiological signaling cascade between the gut microbiome and the central nervous system is poorly understood, gut microbial metabolites may serve as a promising therapeutic strategy for PD. This article summarises all the known possible ways of bidirectional signal communication, i.e., the "gut-brain axis," where microbes from the middle gut interact with the brain and vice versa, and highlights a unique way to treat neurodegenerative diseases by maintaining homeostasis. The tenth cranial nerve (vagus nerve) plays a significant part in this signal communication. However, the leading regulatory factor for this axis is a diet that helps with microbial colonisation and brain function. Short-chain fatty acids (SCFAs), derived from microbially fermented dietary fibres, link host nutrition to maintain intestinal homeostasis. In addition to that, probiotics modulate cognitive function and the metabolic and behavioural conditions of the body. As technology advances, new techniques will emerge to study the tie-up between gut microbes and neuronal diseases.

Gut dysbiosis was inevitable, but tolerance was not: temporal responses of the murine microbiota that maintain its capacity for butyrate production correlate with sustained antinociception to chronic morphine

The therapeutic benefits of opioids are compromised by the development of analgesic tolerance, which necessitates higher dosing for pain management thereby increasing the liability for drug dependence and addiction. Rodent models indicate opposing roles of the gut microbiota in tolerance: morphine-induced gut dysbiosis exacerbates tolerance, whereas probiotics ameliorate tolerance. Not all individuals develop tolerance which could be influenced by differences in microbiota, and yet no study design has capitalized upon this natural variation. We leveraged natural behavioral variation in a murine model of voluntary oral morphine self-administration to elucidate the mechanisms by which microbiota influences tolerance. Although all mice shared similar morphine-driven microbiota changes that largely masked informative associations with variability in tolerance, our high-resolution temporal analyses revealed a divergence in the progression of dysbiosis that best explained sustained antinociception. Mice that did not develop tolerance maintained a higher capacity for production of the short-chain fatty acid (SCFA) butyrate known to bolster intestinal barriers and promote neuronal homeostasis. Both fecal microbial transplantation (FMT) from donor mice that did not develop tolerance and dietary butyrate supplementation significantly reduced the development of tolerance independently of suppression of systemic inflammation. These findings could inform immediate therapies to extend the analgesic efficacy of opioids.

Molecular Insights Into β-Glucuronidase Inhibition by Alhagi Graecorum Flavonoids: A Computational and Experimental Approach

In this study, we aimed to investigate the inhibitory mechanisms of β-glucuronidase by flavonoids derived from Alhagi graecorum through both experimental and computational approaches. The activity of β-glucuronidase was assessed using an in vitro enzyme inhibition assay, where myricetin and chrysoeriol were identified as potent inhibitors based on their low IC50 values. Kinetic studies were conducted to determine the inhibition type, revealing that both compounds exhibit noncompetitive inhibition of β-glucuronidase-catalyzed hydrolysis of PNPG. Molecular docking was employed to explore the binding affinities of the flavonoids, showing that myricetin formed the highest number of polar interactions with the enzyme. Additionally, molecular dynamics (MD) simulations were performed to evaluate the stability of the enzyme-inhibitor complexes, demonstrating consistent trajectory behavior for both compounds, with significant energy stabilization. Interaction energy analyses highlighted the dominant role of electrostatic forces in myricetin's inhibition mechanism, while Van der Waals forces were more prominent for chrysoeriol. The MM/PBSA method was used to calculate the binding free energies, with myricetin and chrysoeriol exhibiting the lowest values. Potential energy landscape analysis further revealed that β-glucuronidase adopts a more closed conformation when bound to these inhibitors, limiting substrate access. These findings suggest that flavonoids from Alhagi graecorum hold promise for clinical applications, particularly in managing drug-induced enteropathy.

Intestinal organ chips for disease modelling and personalized medicine

Alterations in intestinal structure, mechanics and physiology underlie acute and chronic intestinal conditions, many of which are influenced by dysregulation of microbiome, peristalsis, stroma or immune responses. Studying human intestinal physiology or pathophysiology is difficult in preclinical animal models because their microbiomes and immune systems differ from those of humans. Although advances in organoid culture partially overcome this challenge, intestinal organoids still lack crucial features that are necessary to study functions central to intestinal health and disease, such as digestion or fluid flow, as well as contributions from long-term effects of living microbiome, peristalsis and immune cells. Here, we review developments in organ-on-a-chip (organ chip) microfluidic culture models of the human intestine that are lined by epithelial cells and interfaced with other tissues (such as stroma or endothelium), which can experience both fluid flow and peristalsis-like motions. Organ chips offer powerful ways to model intestinal physiology and disease states for various human populations and individual patients, and can be used to gain new insight into underlying molecular and biophysical mechanisms of disease. They can also be used as preclinical tools to discover new drugs and then validate their therapeutic efficacy and safety in the same human-relevant model.

Design, synthesis and activity screening of cedrol derivatives as small molecule JAK3 inhibitors

The JAK-STAT signalling pathway is considered to be a significant role involved in the regulation of inflammatory diseases and immune responses, which indicate that specific inhibition of JAK-STAT pathway would be a potential key strategy for RA (Rheumatoid arthritis) treatment. Cedrol (CE), found from ginger by our group earlier, has been proven to play an excellent role in ameliorating RA via acting on JAK3. In this study, 27 new (1, 3-28), along with one known (2) derivatives of CE were synthesized by using chloroacetic acid and acryloyl chloride as intermediate ligands. In vitro, the inhibition effect on JAK kinases were performed using HTRF (Homogenous Time-Resolved Fluorescence) detection technology, which is more convenient and stable than traditional methods. The results compared with the secretion of LPS-induced p-JAK3 can better reflect the true kinase-selective effect of the compounds. Compound 22 was identified as a potent inhibitor to reduce the secretion of LPS-induced p-JAK3 with a dose-dependent manner. Given these results, compound 22 could serve as a favourable inhibitor of JAK3 for further research.

Clinical sequelae of gut microbiome development and disruption in hospitalized preterm infants

Aberrant preterm infant gut microbiota assembly predisposes to early-life disorders and persistent health problems. Here, we characterize gut microbiome dynamics over the first 3 months of life in 236 preterm infants hospitalized in three neonatal intensive care units using shotgun metagenomics of 2,512 stools and metatranscriptomics of 1,381 stools. Strain tracking, taxonomic and functional profiling, and comprehensive clinical metadata identify Enterobacteriaceae, enterococci, and staphylococci as primarily exploiting available niches to populate the gut microbiome. Clostridioides difficile lineages persist between individuals in single centers, and Staphylococcus epidermidis lineages persist within and, unexpectedly, between centers. Collectively, antibiotic and non-antibiotic medications influence gut microbiome composition to greater extents than maternal or baseline variables. Finally, we identify a persistent low-diversity gut microbiome in neonates who develop necrotizing enterocolitis after day of life 40. Overall, we comprehensively describe gut microbiome dynamics in response to medical interventions in preterm, hospitalized neonates.

Understanding the impact of the gut microbiome on opioid use disorder: Pathways, mechanisms, and treatment insights

The widespread use of opioids for chronic pain management not only poses a significant public health issue but also contributes to the risk of tolerance, dependence, and addiction, leading to opioid use disorder (OUD), which affects millions globally each year. Recent research has highlighted a potential bidirectional relationship between the gut microbiome and OUD. This emerging perspective is critical, especially as the opioid epidemic intensifies, emphasizing the need to investigate how OUD may alter gut microbiome dynamics and vice versa. Understanding these interactions could reveal new insights into the mechanisms of addiction and tolerance, as well as provide novel approaches for managing and potentially mitigating OUD impacts. This comprehensive review explores the intricate bidirectional link through the gut-brain axis, focusing on how opiates influence microbial composition, functional changes, and gut mucosal integrity. By synthesizing current findings, the review aims to inspire new strategies to combat the opioid crisis and leverage microbiome-centred interventions for preventing and treating OUD.

Opioids and the Gastrointestinal Tract: The Role of Peripherally Active µ-Opioid Receptor Antagonists in Modulating Intestinal Permeability

Opioid receptors are found throughout the gastrointestinal tract, including the large intestine. Many patients treated with opioids experience opioid-induced constipation (OIC). Laxatives are not effective in most patients, and in those who do initially respond, the efficacy of laxatives generally diminishes over time. In addition, OIC does not spontaneously resolve for most patients. However, complications of opioids extend far beyond simply slowing gastrointestinal transit. Opioid use can affect intestinal permeability through a variety of mechanisms. Toll-like receptors are a crucial component of innate immunity and are tightly regulated within the gut epithelium. Pathologic µ-opioid receptor (MOR) and toll-like receptor signaling, resulting from chronic opioid exposure, disrupts intestinal permeability leading to potentially harmful bacterial translocation, elevated levels of bacterial toxins, immune activation, and increased cytokine production. Peripherally active MOR antagonists, including methylnaltrexone, are effective at treating OIC. Benefits extend beyond simply blocking the MOR; these agents also act to ameliorate opioid-induced disrupted intestinal permeability. In this review, we briefly describe the physiology of the gastrointestinal epithelial border and discuss the impact of opioids on gastrointestinal function. Finally, we consider the use of peripherally active MOR antagonists to treat disrupted intestinal permeability resulting from opioid use and discuss the potential for improved morbidity and mortality in patients treated with methylnaltrexone for opioid-induced bowel disorders.

Deciphering molecular mechanisms underlying the inhibition of β-glucuronidase by xanthones from Centaurium spicatum

Herein, we scrutinized the inhibitory potential of five xanthones and a flavonoid, sourced from Centaurium spicatum, against β-glucuronidase activity. The results showed that gentisin and azaleatin emerged as the most potent inhibitors, with significantly lower IC50 values of 0.96 ± 0.10 and 0.57 ± 0.04 μM, respectively. The evaluation of enzyme kinetics unveiled that the isolated xanthones manifested inhibition of β-glucuronidase through a mixed inhibition mode, whereas azaleatin exhibited a noncompetitive inhibition mechanism. The findings from molecular docking analysis unveiled that the compounds under investigation, particularly azaleatin, displayed comparatively diminished binding affinities towards β-glucuronidase. Furthermore, the tested drugs were shown to occupy a common binding site as the employed reference drug. Our comprehensive Molecular Dynamics (MD) simulations analysis revealed consistent trajectories for the investigated drugs, wherein azaleatin and gentisin demonstrated notable stabilization of energy levels. Analysis of various MD parameters revealed that drugs with the lowest IC50 values maintained relatively stable interactions with β-glucuronidase. These drugs were shown to exert notable alterations in their conformation or flexibility upon complexation with the target enzyme. Conversely, the flexibility and accessibility of β-glucuronidase was reduced upon drug binding, particularly with azaleatin and gentisin, underscoring the stability of the drug-enzyme complexes. Analysis of Coul-SR and LJ-SR interaction energies unveiled consistent and stable interactions between certain isolated drugs and β-glucuronidase. Azaleatin notably displayed the lowest average Coul-SR interaction energy, suggesting strong electrostatic interactions with the enzyme's active site and significant conformational variability during simulation. Remarkably, LJ-SR interaction energies across different xanthones complexes were more negative than their Coul-SR counterparts, emphasizing the predominant role of van der Waals interactions, encompassing attractive dispersion and repulsive forces, in stabilizing the drug-enzyme complexes rather than electrostatic interactions.

Sex differences in opioid response: a role for the gut microbiome?

Opioid drugs have been long known to induce different responses in males compared to females, however, the molecular mechanisms underlying these effects are yet to be fully characterized. Recent studies have established a link between the gut microbiome and behavioral responses to opioids. Chronic opioid use is associated with gut dysbiosis, or microbiome disruptions, which is thought to contribute to altered opioid analgesia and reward processing. Gut microbiome composition and functioning have also been demonstrated to be influenced by sex hormones. Despite this, there is currently very little work investigating whether sex differences in the gut microbiome mediate sex-dependent responses to opioids, highlighting a critical gap in the literature. Here, we briefly review the supporting evidence implicating a potential role for the gut microbiome in regulating sexually dimorphic opioid response and identify areas for future research.

Pancreatic Cancer: A Review of Risk Factors

Pancreatic adenocarcinoma is one of the most lethal types of gastrointestinal cancer despite the latest medical advances. Its incidence has continuously increased in recent years in developed countries. The location of the pancreas can result in the initial symptoms of neoplasia being overlooked, which can lead to a delayed diagnosis and a subsequent reduction in the spectrum of available therapeutic options. The role of modifiable risk factors in pancreatic cancer has been extensively studied in recent years, with smoking and alcohol consumption identified as key contributors. However, the few screening programs that have been developed focus exclusively on genetic factors, without considering the potential impact of modifiable factors on disease occurrence. Thus, fully understanding and detecting the risk factors for pancreatic cancer represents an important step in the prevention and early diagnosis of this type of neoplasia. This review reports the available evidence on different risk factors and identifies the areas that could benefit the most from additional studies.

Gut Microbiota and Symptom Expression and Severity in Neonatal Abstinence Syndrome

Problem: Neonatal abstinence syndrome (NAS) affecting neonates with fetal exposure to opioids, is defined by expression and severity of symptoms. The pathophysiology behind symptoms variability is lacking. The study aims were to examine (a) differences in gut microbiota of neonates with and without NAS, (b) the relationships between gut microbiota and symptom expression and NAS severity, and (c) the changes in the neonate gut microbiota diversity during the course of NAS treatment. Methods: A cross-sectional observational design was used to examine differences in microbiota and a longitudinal, repeated measures approach was used to determine relationships between gut microbiota and NAS symptoms. Symptom data were collected using the Finnegan Neonatal Abstinence Scoring Tool and the Neonatal Pain Agitation and Sedation Scale. Stool samples were collected for microbiome analyses with 16S rRNA microbiome sequencing. Results: Differences in alpha and beta diversity between neonates with and without NAS were seen. Relative abundance results revealed 18 taxa were different in neonates with NAS compared to neonates without NAS. No differences were found in alpha or beta diversity in neonates with NAS between enrollment and hospital discharge. There was increased abundance of Escherichia-Shigella and Bacteriodes genera related to higher symptom scores. Discussion: Differences in alpha and beta diversity between neonates with and without NAS may be due to differences in birth mode and type of feeding. The findings of specific increased bacteria related to increased symptoms in the neonates with NAS may also be influenced by birth mode and type of feeding.

Impact of opioid analgesics on survival in cancer patients receiving immune checkpoint inhibitors

PURPOSE

This study aimed to assess the effects of concurrent opioid analgesic (OA) use with immune checkpoint inhibitors (ICIs) on progression-free survival (PFS) and overall survival (OS).

METHODS

In this observational retrospective study, we included advanced cancer patients who received ICIs at Hacettepe University Hospital's Department of Medical Oncology between June 2018 and January 2023.

RESULTS

Our study included 375 recurrent or metastatic cancer patients treated with ICIs in the first, second line, or beyond. There were no significant differences between the OA-treated and OA-untreated groups regarding median age, age group, gender, primary tumor location, ICI type, or the presence of baseline liver and lung metastases. However, the OA-treated group exhibited a significantly higher proportion of patients who had received three or more prior treatments before initiating ICIs (p = 0.015). OA-Untreatment was significantly correlated with prolonged mPFS (6.83 vs. 4.30 months, HR 0.59, 95% CI 0.44-0.79, p < 0.001) and mOS (17.05 vs. 7.68 months, HR 0.60, 95% CI 0.45-0.80, p < 0.001).

CONCLUSIONS

Our study demonstrates an association between the concurrent use of OAs and reduced OS and PFS in patients treated with ICIs. While OA treatment serves as a surrogate marker for higher disease burden, it may also suggest a potential biological relationship between opioids and immunotherapy efficacy.

The interplay between the microbiota and opioid in the treatment of neuropathic pain

Neuropathic pain (NP) is characterized by its complex and multifactorial nature and limited responses to opioid therapy; NP is associated with risks of drug resistance, addiction, difficulty in treatment cessation, and psychological disorders. Emerging research on gut microbiota and their metabolites has demonstrated their effectiveness in alleviating NP and augmenting opioid-based pain management, concurrently mitigating the adverse effects of opioids. This review addresses the following key points: (1) the current advances in gut microbiota research and the challenges in using opioids to treat NP, (2) the reciprocal effects and benefits of gut microbiota on NP, and (3) the interaction between opioids with gut microbiota, as well as the benefits of gut microbiota in opioid-based treatment of NP. Through various intricate mechanisms, gut microbiota influences the onset and progression of NP, ultimately enhancing the efficacy of opioids in the management of NP. These insights pave the way for further pragmatic clinical research, ultimately enhancing the efficacy of opioid-based pain management.

Injection Drug Use Alters Plasma Regulation of the B Cell Response

The opioid epidemic continues to be a major public health issue that includes millions of people who inject drugs (PWID). PWID have increased incidence of serious infections, including HIV as well as metabolic and inflammatory sequelae. We sought to discern the extent of systemic alterations in humoral immunity associated with injection drug use, including alterations in the plasma proteome and its regulation of B cell responsiveness. Comprehensive plasma proteomics analysis of HIV negative/hepatitis C negative individuals with a history of recent injection heroin use was performed using mass spectrometry and ELISA. The effects of plasma from PWID and healthy controls on the in vitro proliferation and transcriptional profile of B cell responses to stimulation were determined by flow cytometry and RNA-Seq. The plasma proteome of PWID was distinct from healthy control individuals, with numerous immune-related analytes significantly altered in PWID, including complement (C3, C5, C9), immunoglobulin (IgD, IgM, kappa light chain), and other inflammatory mediators (CXCL4, LPS binding protein, C-reactive protein). The plasma of PWID suppressed the in vitro proliferation of B cells. Transcriptome analysis indicated that PWID plasma treatment increased B cell receptor and CD40 signaling and shifted B cell differentiation from plasma cell-like toward germinal center B cell-like transcriptional profiles. These results indicate that the systemic inflammatory milieu is substantially altered in PWID and may impact their B cell responses.

Long access heroin self-administration significantly alters gut microbiome composition and structure

Introduction

It is well known that chronic opioid use disorder is associated with alterations in gastrointestinal (GI) function that include constipation, reduced motility, and increased bacterial translocation due to compromised gut barrier function. These signs of disrupted GI function can be associated with alterations in the gut microbiome. However, it is not known if long-access opioid self-administration has effects on the gut microbiome.

Methods

We used 16S rRNA gene sequencing to investigate the gut microbiome in three independent cohorts (N=40 for each) of NIH heterogeneous stock rats before onset of long-access heroin self-administration (i.e., naïve status), at the end of a 15-day period of self-administration, and after post-extinction reinstatement. Measures of microbial α- and β-diversity were evaluated for all phases. High-dimensional class comparisons were carried out with MaAsLin2. PICRUSt2 was used for predicting functional pathways impacted by heroin based on marker gene sequences.

Results

Community α-diversity was not altered by heroin at any of the three phases by comparison to saline-yoked controls. Analyses of β-diversity showed that the heroin and saline-yoked groups clustered significantly apart from each other using the Bray-Curtis (community structure) index. Heroin caused significant alterations at the ASV level at the self-administration and extinction phases. At the phylum level, the relative abundance of Firmicutes was increased at the self-administration phase. Deferribacteres was decreased in heroin whereas Patescibacteria was increased in heroin at the extinction phase. Potential biomarkers for heroin emerged from the MaAsLin2 analysis. Bacterial metabolomic pathways relating to degradation of carboxylic acids, nucleotides, nucleosides, carbohydrates, and glycogen were increased by heroin while pathways relating to biosynthesis of vitamins, propionic acid, fatty acids, and lipids were decreased.

Discussion

These findings support the view that long access heroin self-administration significantly alters the structure of the gut microbiome by comparison to saline-yoked controls. Inferred metabolic pathway alterations suggest the development of a microbial imbalance favoring gut inflammation and energy expenditure. Potential microbial biomarkers and related functional pathways likely invoked by heroin self-administration could be targets for therapeutic intervention.

Opioids and Immunosuppression: Clinical Evidence, Mechanisms of Action, and Potential Therapies

Background

In addition to the more well-known adverse effects of opioids, such as constipation, mounting evidence supports underlying immunosuppressive effects as well.

Methods

In this study, we provide a narrative review of preclinical and clinical evidence of opioid suppression of the immune system as well as possible considerations for therapies.

Results

In vitro and animal studies have shown clear effects of opioids on inflammatory cytokine expression, immune cell activity, and pathogen susceptibility. Observational data in humans have so far supported preclinical findings, with multiple reports of increased rates of infections in various settings of opioid use. However, the extent to which this risk is due to the impact of opioids on the immune system compared with other risk factors associated with opioid use remains uncertain. Considering the data showing immunosuppression and increased risk of infection with opioid use, measures are needed to mitigate this risk in patients who require ongoing treatment with opioids. In preclinical studies, administration of opioid receptor antagonists blocked the immunomodulatory effects of opioids.

Conclusions

As selective antagonists of peripheral opioid receptors, peripherally acting mu-opioid receptor (MOR) antagonists may be able to protect against immune impairment while still allowing for opioid analgesia. Future research is warranted to further investigate the relationship between opioids and infection risk as well as the potential application of peripherally acting MOR antagonists to counteract these risks.

Prescription opioids induced microbial dysbiosis worsens severity of chronic pancreatitis and drives pain hypersensitivity

Opioids, such as morphine and oxycodone, are widely used for pain management associated with chronic pancreatitis (CP); however, their impact on the progression and pain sensitivity of CP has never been evaluated. This report investigates the impact of opioid use on the severity of CP, pain sensitivity, and the gut microbiome. C57BL/6 mice were divided into control, CP, CP with morphine/oxycodone, and either morphine or oxycodone alone groups. CP was induced by administration of caerulein (50ug/kg/h, i.p. hourly x7, twice a week for 10 weeks). The mouse-to-pancreas weight ratio, histology, and Sirius red staining were performed to measure CP severity. Tail flick and paw pressure assays were used to measure thermal and mechanical pain. DNA was extracted from the fecal samples and subjected to whole-genome shotgun sequencing. Germ-free mice were used to validate the role of gut microbiome in sensitizing acute pancreatic inflammation. Opioid treatment exacerbates CP by increasing pancreatic necrosis, fibrosis, and immune-cell infiltration. Opioid-treated CP mice exhibited enhanced pain hypersensitivity and showed distinct clustering of the gut microbiome compared to untreated CP mice, with severely compromised gut barrier integrity. Fecal microbiota transplantation (FMT) from opioid-treated CP mice into germ-free mice resulted in pancreatic inflammation in response to a suboptimal caerulein dose. Together, these analyses revealed that opioids worsen the severity of CP and induce significant alterations in pain sensitivity and the gut microbiome in a caerulein CP mouse model. Microbial dysbiosis plays an important role in sensitizing the host to pancreatic inflammation.

Opioid trail: Tracking contributions to opioid use disorder from host genetics to the gut microbiome

Opioid use disorder (OUD) is a worldwide public health crisis with few effective treatment options. Traditional genetics and neuroscience approaches have provided knowledge about biological mechanisms that contribute to OUD-related phenotypes, but the complexity and magnitude of effects in the brain and body remain poorly understood. The gut-brain axis has emerged as a promising target for future therapeutics for several psychiatric conditions, so characterizing the relationship between host genetics and the gut microbiome in the context of OUD will be essential for development of novel treatments. In this review, we describe evidence that interactions between host genetics, the gut microbiome, and immune signaling likely play a key role in mediating opioid-related phenotypes. Studies in humans and model organisms consistently demonstrated that genetic background is a major determinant of gut microbiome composition. Furthermore, the gut microbiome is susceptible to environmental influences such as opioid exposure. Additional work focused on gene by microbiome interactions will be necessary to gain improved understanding of their effects on OUD-related behaviors.

Multi-omics analysis revealing the interplay between gut microbiome and the host following opioid use

Opioid crisis is an ongoing epidemic since the past several decades in the United States. Opioid use-associated microbial dysbiosis is emerging as a key regulator of intestinal homeostasis and behavioral responses to opioid. However, the mechanistic insight into the role of microbial community in modulating host response is unavailable. To uncover the role of opioid-induced dysbiosis in disrupting intestinal homeostasis we utilized whole genome sequencing, untargeted metabolomics, and mRNA sequencing to identify changes in microbiome, metabolome, and host transcriptome respectively. Morphine treatment resulted in significant expansion of Parasuterella excrementihominis, Burkholderiales bacterium 1_1_47, Enterococcus faecalis, Enterorhabdus caecimuris and depletion of Lactobacillus johnsonii. These changes correlated with alterations in lipid metabolites and flavonoids. Significant alteration in microbial metabolism (metabolism of lipids, amino acids, vitamins and cofactors) and increased expression of virulence factors and biosynthesis of lipopolysaccharides (LPS) and lipoteichoic acid (LTA) were observed in microbiome of morphine-treated animals. In concurrence with changes in microbiome and metabolome extensive changes in innate and adaptive immune response, lipid metabolism, and gut barrier dysfunction were observed in the host transcriptome. Microbiome depleted mice displayed lower levels of inflammation, immune response and tissue destruction compared to mice harboring a dysbiotic microbiome in response to morphine treatment, thus establishing dysbiotic microbiome as mediator of morphine gut pathophysiology. Integrative analysis of multi-omics data highlighted the associations between Parasutterella excrementihominis, Burkholderiales bacterium 1_1_47, Enterococcus faecalis, Enterorhabdus caecimuris and altered levels of riboflavin, flavonoids, and lipid metabolites including phosphocholines, carnitines, bile acids, and ethanolamines with host gene expression changes involved in inflammation and barrier integrity of intestine. Omic analysis also highlighted the role of probiotic bacteria Lactobacillus johnsonii, metabolites flavonoids and riboflavin that were depleted with morphine as important factors for intestinal homeostasis. This study presents for the first time ever an interactive view of morphine-induced changes in microbial metabolism, strain level gut microbiome analysis and comprehensive view of changes in gut transcriptome. We also identified areas of potential therapeutic interventions to limit microbial dysbiosis and present a unique resource to the opioid research community.

Molecular mechanisms of alcohol's effects on the human body: A review and update

Alcohol consumption has been linked to numerous negative health outcomes although it has some beneficial effects on moderate dosages, the most severe of which being alcohol-induced hepatitis. The number of people dying from this liver illness has been shown to climb steadily over time, and its prevalence has been increasing. Researchers have found that alcohol consumption primarily affects the brain, leading to a wide range of neurological and psychological diseases. High-alcohol-consumption addicts not only experienced seizures, but also ataxia, aggression, social anxiety, and variceal hemorrhage that ultimately resulted in death, ascites, and schizophrenia. Drugs treating this liver condition are limited and can cause serious side effects like depression. Serine-threonine kinases, cAMP protein kinases, protein kinase C, ERK, RACK 1, Homer 2, and more have all been observed to have their signaling pathways disrupted by alcohol, and alcohol has also been linked to epigenetic changes. In addition, alcohol consumption induces dysbiosis by changing the composition of the microbiome found in the gastrointestinal tract. Although more studies are needed, those that have been done suggest that probiotics aid in keeping the various microbiota concentrations stable. It has been argued that reducing one's alcohol intake may seem less harmful because excessive drinking is a lifestyle disorder.

The temporal relationship between antibiotic and opioid prescription on the risk of developing an opioid use disorder: A national database study

Background: Previously, we discovered that subjects co-prescribed both antibiotics and opioids on the same day in a hospital setting displayed an increased risk of developing an opioid use disorder (OUD) 12 months following hospital discharge. The goal of this study was to examine whether prescribing antibiotics in the inpatient or emergency department setting at various time points before or after an opioid prescription impacted the risk OUD.Methods: A propensity score matched cohort study was conducted to identify subjects (18-65 years old) with no previous history of OUD. Two cohorts were defined: subjects who were prescribed antibiotics 0-1, 2-4, 5-7, 8-10, 11-12 months before or after the date of an opioid prescription while in the emergency department or inpatient setting, from the years 2010-2019. The diagnosis of an Opioid Related Disorder (F11.10-F11.20) 12 months following discharge from the emergency department or inpatient unit was then observed.Results: Primary analysis showed that subjects prescribed an antibiotic 0-1 month or 8-10 months before an opioid prescription showed a modest risk of developing an OUD 12 months following an opioid prescription (0.04% and 0.20%, respectively). Similarly, subjects prescribed an antibiotic 0-1 month, 5-7 months, or 8-10 months after an opioid prescription displayed a modest risk of developing OUD 12 months after an opioid prescription (0.02% risk, 0.14% risk, and 0.16% risk, respectively).Conclusions: These findings suggest that there is little to no effect on the risk of developing OUD when antibiotics are prescribed at various time points before or after opioid prescription.

Changes in gut microbiota composition after 12 weeks of a home-based lifestyle intervention in breast cancer survivors during the COVID-19 lockdown

Background

Breast cancer (BC) is the second-leading cause of cancer-related death worldwide. This study aimed to investigate the effects of a 12-week home-based lifestyle intervention (based on nutrition and exercise) on gut microbial composition in twenty BC survivors of the MoviS clinical trial (protocol: NCT04818359).

Methods

Gut microbiota analysis through 16S rRNA gene sequencing, anthropometrics, Mediterranean Diet (MD) adherence, and cardiometabolic parameters were evaluated before (Pre) and after (Post) the lifestyle intervention (LI).

Results

Beneficial effects of the LI were observed on MD adherence, and cardiometabolic parameters (pre vs post). A robust reduction of Proteobacteria was observed after LI, which is able to reshape the gut microbiota by modulating microorganisms capable of decreasing inflammation and others involved in improving the lipid and glycemic assets of the host. A significant negative correlation between fasting glucose and Clostridia_vadinBB60 (r = -0.62), insulin and homeostatic model assessment (HOMA) index and Butyricicoccus genera (r = -0.72 and -0.66, respectively), and HDL cholesterol and Escherichia/Shigella (r = -0.59) have been reported. Moreover, positive correlations were found between MD adherence and Lachnospiraceae_ND3007 (r = 0.50), Faecalibacterium (r = 0.38) and Butyricimonas (r = 0.39).

Conclusion

These data suggest that adopting a healthy lifestyle, may contribute to ameliorate several biological parameters that could be involved in the prevention of cancer relapses through the modulation of gut microbiota.

The role of the gut microbiome and microbial metabolism in mediating opioid-induced changes in the epigenome

The current opioid pandemic is a major public health crisis in the United States, affecting millions of people and imposing significant health and socioeconomic burdens. Preclinical and clinical research over the past few decades has delineated certain molecular mechanisms and identified various genetic, epigenetic, and environmental factors responsible for the pathophysiology and comorbidities associated with opioid use. Opioid use-induced epigenetic modifications have been identified as one of the important factors that mediate genetic changes in brain regions that control reward and drug-seeking behavior and are also implicated in the development of tolerance. Recently, it has been shown that opioid use results in microbial dysbiosis, leading to gut barrier disruption, which drives systemic inflammation, impacting the perception of pain, the development of analgesic tolerance, and behavioral outcomes. In this review, we highlight the potential role of microbiota and microbial metabolites in mediating the epigenetic modifications induced by opioid use.

Immunological mechanisms of inflammatory diseases caused by gut microbiota dysbiosis: A review

The gut microbiota is indispensable for maintaining host health by enhancing the host's digestive capacity, safeguarding the intestinal epithelial barrier, and preventing pathogen invasion. Additionally, the gut microbiota exhibits a bidirectional interaction with the host immune system and promotes the immune system of the host to mature. Dysbiosis of the gut microbiota, primarily caused by factors such as host genetic susceptibility, age, BMI, diet, and drug abuse, is a significant contributor to inflammatory diseases. However, the mechanisms underlying inflammatory diseases resulting from gut microbiota dysbiosis lack systematic categorization. In this study, we summarize the normal physiological functions of symbiotic microbiota in a healthy state and demonstrate that when dysbiosis occurs due to various external factors, the normal physiological functions of the gut microbiota are lost, leading to pathological damage to the intestinal lining, metabolic disorders, and intestinal barrier damage. This, in turn, triggers immune system disorders and eventually causes inflammatory diseases in various systems. These discoveries provide fresh perspectives on how to diagnose and treat inflammatory diseases. However, the unrecognized variables that might affect the link between inflammatory illnesses and gut microbiota, need further studies and extensive basic and clinical research will still be required to investigate this relationship in the future.

Morphine use induces gastric microbial dysbiosis driving gastric inflammation through TLR2 signalling which is attenuated by proton pump inhibition

BACKGROUND AND PURPOSE

Opioids are the standard drug for pain management; however, their effects on gastric dysfunction are relatively understudied. Opioid users have a higher incidence of gastric pathology leading to increased hospitalization. Herein, we investigated the consequences of morphine use on gastric pathology and the underlying mechanisms. We further investigated the therapeutic benefit of proton pump inhibition to overcome morphine-mediated gastric inflammation.

EXPERIMENTAL APPROACH

Mice were implanted with 25 mg slow-release morphine and placebo pellets. Gastric microbiome analyses were performed. Gastric damage was assayed. Gastric pH was measured. Germ-free and TLR2KO mice were used to investigate the mechanisms. Gastroprotective studies were performed with the proton pump inhibitor (PPI) omeprazole.

KEY RESULTS

Chronic morphine treatment alters gastric microbial composition and induces preferential expansion of pathogenic bacterial communities such as Streptococcus and Pseudomonas. Morphine causes disruption of the gastric mucosal layer, increases apoptosis, and elevates inflammatory cytokines. Moreover, morphine-mediated gastric pathology was significantly attenuated in germ-free mice, and reconstitution of morphine gastric microbiome in germ-free mice resulted gastric inflammation. In addition, morphine-mediated gastric inflammation was attenuated in TLR2KO mice. Morphine causes a decrease in gastric pH, which contributes to gastric dysbiosis leads to gastric inflammation. Omeprazole treatment inhibits gastric acidity, rescuing morphine-induced gastric dysbiosis and preventing inflammation.

CONCLUSION AND IMPLICATIONS

This study attributes morphine-induced gastric acidity as a driver of gastric dysbiosis and pathology and proposes the therapeutic use of PPI as an inexpensive approach for the clinical management of morphine-associated pathophysiology.

Oral and fecal microbiota perturbance in cocaine users: Can rTMS-induced cocaine abstinence support eubiosis restoration?

The effects of cocaine on microbiota have been scarcely explored. Here, we investigated the gut (GM) and oral (OM) microbiota composition of cocaine use disorder (CUD) patients and the effects of repetitive transcranial magnetic stimulation (rTMS). 16S rRNA sequencing was used to characterize GM and OM, whereas PICRUST2 assessed functional changes in microbial communities, and gas-chromatography was used to evaluate fecal short and medium chain fatty acids. CUD patients reported a significant decrease in alpha diversity and modification of the abundances of several taxa in both GM and OM. Furthermore, many predicted metabolic pathways were differentially expressed in CUD patients' stool and saliva samples, as well as reduced levels of butyric acid that appear restored to normal amounts after rTMS treatment. In conclusion, CUD patients showed a profound dysbiotic fecal and oral microbiota composition and function and rTMS-induced cocaine abstinence determined the restoration of eubiotic microbiota.

HIV, opioid use, and alterations to the gut microbiome: elucidating independent and synergistic effects

Background

The microbiome is essential to immune development, defense against pathogens, and modulation of inflammation. Microbial dysbiosis has been reported in various diseases including human immunodeficiency virus (HIV) and opioid use disorder (OUD). Notably, people living with HIV (PLWH) have been reported to both have higher rates of OUD and use opioids at higher rates than the general public. Thus, studying gut microbial alterations in people living with HIV and with OUD could elucidate mechanisms pertaining to how these conditions both shape and are shaped by the microbiome. However, to date few studies have investigated how HIV and OUD in combination impact the microbiome.

Aim of review

Here, we review previous studies outlining interactions between HIV, opioid use, and microbial dysbiosis and describe attempts to treat this dysbiosis with fecal microbial transplantation, probiotics, and dietary changes.

Key scientific concepts of review

While the limited number of studies prevent overgeneralizations; accumulating data suggest that HIV and opioid use together induce distinct alterations in the gut microbiome. Among the three existing preclinical studies of HIV and opioid use, two studies reported a decrease in Lachnospiraceae and Ruminococcaceae, and one study reported a decrease in Muribaculaceae in the combined HIV and opioid group relative to HIV-alone, opioid-alone, or control groups. These bacteria are known to modulate immune function, decrease colonic inflammation, and maintain gut epithelial barrier integrity in healthy individuals. Accordingly, modulation of the gut microbiome to restore gut homeostasis may be attempted to improve both conditions. While mixed results exist regarding treating dysbiosis with microbial restoration in PLWH or in those with opioid dependency, larger well-defined studies that can improve microbial engraftment in hosts hold much promise and should still be explored.

Role of the gut-brain axis in HIV and drug abuse-mediated neuroinflammation

Drug abuse and related disorders are a global public health crisis affecting millions, but to date, limited treatment options are available. Abused drugs include but are not limited to opioids, cocaine, nicotine, methamphetamine, and alcohol. Drug abuse and human immunodeficiency virus-1/acquired immune deficiency syndrome (HIV-1/AIDS) are inextricably linked. Extensive research has been done to understand the effect of prolonged drug use on neuronal signaling networks and gut microbiota. Recently, there has been rising interest in exploring the interactions between the central nervous system and the gut microbiome. This review summarizes the existing research that points toward the potential role of the gut microbiome in the pathogenesis of HIV-1-linked drug abuse and subsequent neuroinflammation and neurodegenerative disorders. Preclinical data about gut dysbiosis as a consequence of drug abuse in the context of HIV-1 has been discussed in detail, along with its implications in various neurodegenerative disorders. Understanding this interplay will help elucidate the etiology and progression of drug abuse-induced neurodegenerative disorders. This will consequently be beneficial in developing possible interventions and therapeutic options for these drug abuse-related disorders.

The Microbiome and Mental Health Across the Lifespan

INTRODUCTION

The combined genetic material of the microorganisms in the human body, known as the microbiome, is being increasingly recognized as a major determinant of human health and disease. Although located predominantly on mucosal surfaces, these microorganisms have profound effects on brain functioning through the gut-brain axis.

METHOD

The content of the chapter is based on a study group session at the annual meeting of the American College of Neuropsychopharmacology (ACNP). The objective was to discuss the emerging relationship between the human microbiome and mental health as relevant to ACNP's interests in developing and evaluating novel neuropsychiatric treatment strategies. The focus is on specific brain disorders, such as schizophrenia, substance use, and Alzheimer's disease, as well as on broader clinical issues such as suicidality, loneliness and wisdom in old age, and longevity.

RESULTS

Studies of schizophrenia indicate that the microbiome of individuals with this disorder differs from that of non-psychiatric comparison groups in terms of diversity and composition. Differences are also found in microbial metabolic pathways. An early study in substance use disorders found that individuals with this disorder have lower levels of beta diversity in their oral microbiome than a comparison group. This measure, along with others, was used to distinguish individuals with substance use disorders from controls. In terms of suicidality, there is preliminary evidence that persons who have made a suicide attempt differ from psychiatric and non-psychiatric comparison groups in measures of beta diversity. Exploratory studies in Alzheimer's disease indicate that gut microbes may contribute to disease pathogenesis by regulating innate immunity and neuroinflammation and thus influencing brain function. In another study looking at the microbiome in older adults, positive associations were found between wisdom and alpha diversity and negative associations with subjective loneliness. In other studies of older adults, here with a focus on longevity, individuals with healthy aging and unusually long lives had an abundance of specific microorganisms which distinguished them from other individuals.

DISCUSSION

Future studies would benefit from standardizing methods of sample collection, processing, and analysis. There is also a need for the standardized collection of relevant demographic and clinical data, including diet, medications, cigarette smoking, and other potentially confounding factors. While still in its infancy, research to date indicates a role for the microbiome in mental health disorders and conditions. Interventions are available which can modulate the microbiome and lead to clinical improvements. These include microbiome-altering medications as well as probiotic microorganisms capable of modulating the inflammation in the brain through the gut-brain axis. This research holds great promise in terms of developing new methods for the prevention and treatment of a range of human brain disorders.

Interactions between NSAIDs, opioids and the gut microbiota - Future perspectives in the management of inflammation and pain

The composition of intestinal microbiota is influenced by a number of factors, including medications, which may have a substantial impact on host physiology. Nonsteroidal anti-inflammatory drugs (NSAIDs) and opioid analgesics are among those widely used medications that have been shown to alter microbiota composition in both animals and humans. Although much effort has been devoted to identify microbiota signatures associated with these medications, much less is known about the underlying mechanisms. Mucosal inflammation, changes in intestinal motility, luminal pH and bile acid metabolism, or direct drug-induced inhibitory effect on bacterial growth are all potential contributors to NSAID- and opioid-induced dysbiosis, however, only a few studies have addressed directly these issues. In addition, there is a notable overlap between the microbiota signatures of these drugs and certain diseases in which they are used, such as spondyloarthritis (SpA), rheumatoid arthritis (RA) and neuropathic pain associated with type 2 diabetes (T2D). The aims of the present review are threefold. First, we aim to provide a comprehensive up-to-date summary on the bacterial alterations caused by NSAIDs and opioids. Second, we critically review the available data on the possible underlying mechanisms of dysbiosis. Third, we review the current knowledge on gut dysbiosis associated with SpA, RA and neuropathic pain in T2D, and highlight the similarities between them and those caused by NSAIDs and opioids. We posit that drug-induced dysbiosis may contribute to the persistence of these diseases, and may potentially limit the therapeutic effect of these medications by long-term use. In this context, we will review the available literature data on the effect of probiotic supplementation and fecal microbiota transplantation on the therapeutic efficacy of NSAIDs and opioids in these diseases.

Multi-omics gut microbiome signatures in obese women: role of diet and uncontrolled eating behavior

BACKGROUND

Obesity and related co-morbidities represent a major health challenge nowadays, with a rapidly increasing incidence worldwide. The gut microbiome has recently emerged as a key modifier of human health that can affect the development and progression of obesity, largely due to its involvement in the regulation of food intake and metabolism. However, there are still few studies that have in-depth explored the functionality of the human gut microbiome in obesity and even fewer that have examined its relationship to eating behaviors.

METHODS

In an attempt to advance our knowledge of the gut-microbiome-brain axis in the obese phenotype, we thoroughly characterized the gut microbiome signatures of obesity in a well-phenotyped Italian female cohort from the NeuroFAST and MyNewGut EU FP7 projects. Fecal samples were collected from 63 overweight/obese and 37 normal-weight women and analyzed via a multi-omics approach combining 16S rRNA amplicon sequencing, metagenomics, metatranscriptomics, and lipidomics. Associations with anthropometric, clinical, biochemical, and nutritional data were then sought, with particular attention to cognitive and behavioral domains of eating.

RESULTS

We identified four compositional clusters of the gut microbiome in our cohort that, although not distinctly associated with weight status, correlated differently with eating habits and behaviors. These clusters also differed in functional features, i.e., transcriptional activity and fecal metabolites. In particular, obese women with uncontrolled eating behavior were mostly characterized by low-diversity microbial steady states, with few and poorly interconnected species (e.g., Ruminococcus torques and Bifidobacterium spp.), which exhibited low transcriptional activity, especially of genes involved in secondary bile acid biosynthesis and neuroendocrine signaling (i.e., production of neurotransmitters, indoles and ligands for cannabinoid receptors). Consistently, high amounts of primary bile acids as well as sterols were found in their feces.

CONCLUSIONS

By finding peculiar gut microbiome profiles associated with eating patterns, we laid the foundation for elucidating gut-brain axis communication in the obese phenotype. Subject to confirmation of the hypotheses herein generated, our work could help guide the design of microbiome-based precision interventions, aimed at rewiring microbial networks to support a healthy diet-microbiome-gut-brain axis, thus counteracting obesity and related complications.

Modeling mucus physiology and pathophysiology in human organs-on-chips

The surfaces of human internal organs are lined by a mucus layer that ensures symbiotic relationships with commensal microbiome while protecting against potentially injurious environmental chemicals, toxins, and pathogens, and disruption of this layer can contribute to disease development. Studying mucus biology has been challenging due to the lack of physiologically relevant human in vitro models. Here we review recent progress that has been made in the development of human organ-on-a-chip microfluidic culture models that reconstitute epithelial tissue barriers and physiologically relevant mucus layers with a focus on lung, colon, small intestine, cervix and vagina. These organ-on-a-chip models that incorporate dynamic fluid flow, air-liquid interfaces, and physiologically relevant mechanical cues can be used to study mucus composition, mechanics, and structure, as well as investigate its contributions to human health and disease with a level of biomimicry not possible in the past.

Methadone use is associated with increased levels of sCD14, immune activation, and inflammation during suppressed HIV infection

Opioid use has negative effects on immune responses and may impair immune reconstitution in persons living with HIV (PLWH) infection undergoing antiretroviral treatment (ART). The effects of treatment with μ opioid receptor (MOR) agonists (e.g., methadone, MET) and antagonists (e.g., naltrexone, NTX) on immune reconstitution and immune activation in ART-suppressed PLWH have not been assessed in-depth. We studied the effects of methadone or naltrexone on measures of immune reconstitution and immune activation in a cross-sectional community cohort of 30 HIV-infected individuals receiving suppressive ART and medications for opioid use disorder (MOUD) (12 MET, 8 NTX and 10 controls). Plasma markers of inflammation and immune activation were measured using ELISA, Luminex, or Simoa. Plasma IgG glycosylation was assessed using capillary electrophoresis. Cell subsets and activation were studied using whole blood flow cytometry. Individuals in the MET group, but no in the NTX group, had higher plasma levels of inflammation and immune activation markers than controls. These markers include soluble CD14 (an independent predictor of morbidity and mortality during HIV infection), proinflammatory cytokines, and proinflammatory IgG glycans. This effect was independent of time on treatment. Our results indicate that methadone-based MOUD regimens may sustain immune activation and inflammation in ART-treated HIV-infected individuals. Our pilot study provides the foundation and rationale for future longitudinal functional studies of the impact of MOUD regimens on immune reconstitution and residual activation after ART-mediated suppression.

Neonatal Morphine Results in Long-Lasting Alterations to the Gut Microbiome in Adolescence and Adulthood in a Murine Model

Despite the many advancements in the field of pain management, the use of intravenous opioids, such as morphine, in neonates is still a challenge for clinicians and researchers, as the available evidence concerning the long-term consequences of such an early exposure is limited. In particular, little is known concerning the long-term consequences of neonatal morphine exposure on the gut microbiome, which has been identified as a key modulator of health and diseases. Consequently, the purpose of this study was to investigate those long-term consequences of neonatal morphine on the gut microbiome. Newborn mice were exposed to either morphine (5 mg/kg/day) or saline for a duration of 7 ± 2 days. Fecal samples were collected during adolescence and adulthood to longitudinally assess the gut microbiome. DNA extracted from the stool samples were sent out for 16s rRNA sequencing. During adolescence, neonatal morphine resulted in a significant increase of α-diversity and an overall decrease in the abundance of several commensal genera. During adulthood, β-diversity revealed a significantly different microbial composition of the neonatally morphine-exposed mice than that of the controls. The results demonstrate that morphine exposure during this critical developmental period resulted in long-lasting changes, particularly a reduction in several commensal bacteria. Thus, an adjunct therapeutic intervention with probiotics could potentially be used along with opioids to manage pain while attenuating the long-term co-morbidities of neonatal morphine later in life.

Food-Specific IgG4 Antibody-Guided Exclusion Diet Improves Conditions of Patients with Chronic Pain

INTRODUCTION

Chronic pain is related to gastrointestinal (GI) functions because food components affect inflammation and pain through their action on the GI immune and/or neural system and because many analgesics interact with the gut to alter its structure and function. Immunoglobulin G4 (IgG4) are food-specific antibodies resulting from exposure of the gut immune system to nutrients. High IgG4 levels have been found to be associated with inflammation.

METHODS

IgG4 were determined (both with the rapid test and enzyme-linked immunosorbent assay, ELISA) in men and women outpatients with chronic pain. All subjects were asked to exclude for 4 weeks all foods to which they had high blood levels of IgG4 antibodies. Pain and quality of life questionnaires were administered before (visit 1) and after (visit 2) the personalized exclusion diet period. Visual analogue scale (VAS), Italian Pain Questionnaire (QUID) and Margolis (MA) questionnaires were administered to determine pain intensity, pain features and pain extent, while Short Form Health Survey (SF-36) and Profile of Mood States (POMS) were used to test the quality of life and mood state. The nutritional status was evaluated in all subjects. Subject groups were women of reproductive age (pre-MW), women in menopause for at least 1 year (MW) and men.

RESULTS

Fifty-four subjects with chronic pain (n = 12 neuropathic, n = 14 diffuse pain, n = 11 headache, n = 17 low back pain) completed the two visits and the 1-month exclusion diet. At visit 1, 47 (87%) subjects showed medium/high levels of IgG4 to at least one food. The foods showing the highest IgG4 values were eggs, dairy products, cereals and dried fruit. At visit 2, IgG4 levels were decreased, increased or unchanged. In all groups, the 4-week exclusion diet resulted in a significant reduction in all pain measures and an improvement of quality of life parameters. In particular, at visit 2, the VAS score determined in the morning decreased by more than 50%.

CONCLUSIONS

A food elimination diet based on IgG4 antibody levels may be effective in reducing pain and improving quality of life in patients with chronic pain.

Machine learning for infection risk prediction in postoperative patients with non-mechanical ventilation and intravenous neurotargeted drugs

Drug efficacy can be improved by understanding the effects of anesthesia on the neurovascular system. In this study, we used machine learning algorithms to predict the risk of infection in postoperative intensive care unit (ICU) patients who are on non-mechanical ventilation and are receiving hydromorphone analgesia. In this retrospective study, 130 patients were divided into high and low dose groups of hydromorphone analgesic pump patients admitted after surgery. The white blood cells (WBC) count and incidence rate of infection was significantly higher in the high hydromorphone dosage group compared to the low hydromorphone dosage groups (p < 0.05). Furthermore, significant differences in age (P = 0.006), body mass index (BMI) (P = 0.001), WBC count (P = 0.019), C-reactive protein (CRP) (P = 0.038), hydromorphone dosage (P = 0.014), and biological sex (P = 0.024) were seen between the infected and non-infected groups. The infected group also had a longer hospital stay and an extended stay in the intensive care unit compared to the non-infected group. We identified important risk factors for the development of postoperative infections by using machine learning algorithms, including hydromorphone dosage, age, biological sex, BMI, and WBC count. Logistic regression analysis was applied to incorporate these variables to construct infection prediction models and nomograms. The area under curves (AUC) of the model were 0.835, 0.747, and 0.818 in the training group, validation group, and overall pairwise column group, respectively. Therefore, we determined that hydromorphone dosage, age, biological sex, BMI, WBC count, and CRP are significant risk factors in developing postoperative infections.

Opioid Use in Murine Model Results in Severe Gastric Pathology that May Be Attenuated by Proton Pump Inhibition

Opioids are the gold standard for chronic and acute pain management; however, their consequence on gastric function is relatively understudied. Opioid users have a higher incidence of gastric dysfunction, worse quality of life, increased hospitalizations, and increased use of antiemetic and pain modulator medications. The current study shows that morphine treatment in the murine model results in greater disruption of gastric epithelial cell morphology, increased gastric cell apoptosis, elevated inflammatory cytokines, and matrix metallopeptidase-9 secretion. Morphine treatment also increases gastric acid secretion and causes delays in gastric emptying. Moreover, morphine treatment causes an increase in systemic IL-6 level, which plays an important role in morphine-induced delayed gastric emptying and gastric damage. IL-6 knockout mice show a significant level of reduction in morphine-induced gastric delaying, acid retention, and gastric damage. Thus, morphine-mediated gastric damage is a consequence of the accumulation of acid in the stomach due to increased gastric acid secretion and delayed gastric emptying. Treatment with a proton pump inhibitor resulted in a significant reduction in morphine-induced gastric inflammation, gastric delaying, and improved morphine tolerance. Hence, these studies attribute morphine-mediated induction in gastric acidity and inflammatory cytokines as drivers for morphine-associated gastric pathology and show the therapeutic use of proton pump inhibitors as an inexpensive approach for clinical management of morphine-associated pathophysiology and analgesic tolerance.

Pain and Opioid-Induced Gut Microbial Dysbiosis

Opioid-induced dysbiosis (OID) is a specific condition describing the consequences of opioid use on the bacterial composition of the gut. Opioids have been shown to affect the epithelial barrier in the gut and modulate inflammatory pathways, possibly mediating opioid tolerance or opioid-induced hyperalgesia; in combination, these allow the invasion and proliferation of non-native bacterial colonies. There is also evidence that the gut-brain axis is linked to the emotional and cognitive aspects of the brain with intestinal function, which can be a factor that affects mental health. For example, Mycobacterium, Escherichia coli and Clostridium difficile are linked to Irritable Bowel Disease; Lactobacillaceae and Enterococcacae have associations with Parkinson’s disease, and Alistipes has increased prevalence in depression. However, changes to the gut microbiome can be therapeutically influenced with treatments such as faecal microbiota transplantation, targeted antibiotic therapy and probiotics. There is also evidence of emerging therapies to combat OID. This review has collated evidence that shows that there are correlations between OID and depression, Parkinson’s Disease, infection, and more. Specifically, in pain management, targeting OID deserves specific investigations.

Ginsenoside Rg1 mitigates morphine dependence via regulation of gut microbiota, tryptophan metabolism, and serotonergic system function

BACKGROUND

Morphine dependence, a devastating neuropsychiatric condition, may be closely associated with gut microbiota dysbiosis. Ginsenoside Rg1 (Rg1), an active ingredient extracted from the roots of Panax ginseng C.A. Meyer, has potential health-promoting effects on the nervous system. However, its role in substance use disorders remains unclear. Here, we explored the potential modulatory roles of Rg1 in protection against morphine dependence.

METHODS

Conditioned place preference (CPP) was used for establishing a murine model of morphine dependence. 16S rRNA gene sequencing and metabolomics were performed for microbial and metabolite analysis. Molecular analysis was tested for evaluating the host serum and brain responses.

RESULTS

Rg1 prevented morphine-induced CPP in mice. The 16S rRNA gene-based microbiota analysis demonstrated that Rg1 ameliorated morphine-induced gut microbiota dysbiosis, specifically for Bacteroidetes. Moreover, Rg1 also inhibited gut microbiota-derived tryptophan metabolism and reduced the serotonin, 5-hydroxytryptamine receptor 1B (5-HTR1B), and 5-hydroxytryptamine receptor 2 A (5-HTR2A) levels. However, the Rg1-induced amelioration of CPP was not observed in mice when their gut microbiome was depleted by non-absorbable antibiotics. Subsequently, gavage with Bacteroides vulgatus increased the abundance of Bacteroidetes. B. vulgatus supplementation synergistically enhanced Rg1-alleviated morphine-induced CPP in mice with microbiome knockdown. Co-treatment with B. vulgatus and Rg1 produced suppressive effects against morphine dependency by inhibiting tryptophan metabolism and reducing the serotonin and 5-HTR1B/5-HTR2A levels.

CONCLUSIONS

The gut microbiota-tryptophan metabolism-serotonin plays an important role in gut-brain signaling in morphine disorders, which may represent a novel approach for drug dependence treatment via manipulation of the gut microbial composition and tryptophan metabolite.

Drugs and Bugs: The Gut-Brain Axis and Substance Use Disorders

Substance use disorders (SUDs) represent a significant public health crisis. Worldwide, 5.4% of the global disease burden is attributed to SUDs and alcohol use, and many more use psychoactive substances recreationally. Often associated with comorbidities, SUDs result in changes to both brain function and physiological responses. Mounting evidence calls for a precision approach for the treatment and diagnosis of SUDs, and the gut microbiome is emerging as a contributor to such disorders. Over the last few centuries, modern lifestyles, diets, and medical care have altered the health of the microbes that live in and on our bodies; as we develop, our diets and lifestyle dictate which microbes flourish and which microbes vanish. An increase in antibiotic treatments, with many antibiotic interventions occurring early in life during the microbiome's normal development, transforms developing microbial communities. Links have been made between the microbiome and SUDs, and the microbiome and conditions that are often comorbid with SUDs such as anxiety, depression, pain, and stress. A better understanding of the mechanisms influencing behavioral changes and drug use is critical in developing novel treatments for SUDSs. Targeting the microbiome as a therapeutic and diagnostic tool is a promising avenue of exploration. This review will provide an overview of the role of the gut-brain axis in a wide range of SUDs, discuss host and microbe pathways that mediate changes in the brain's response to drugs, and the microbes and related metabolites that impact behavior and health within the gut-brain axis.

Dose- and Sex-Dependent Bidirectional Relationship between Intravenous Fentanyl Self-Administration and Gut Microbiota

Gut bacteria influence neural circuits in addiction-related behaviors. Given the association between opioid use, gastrointestinal distress, and microbial dysbiosis in humans and mice, we test the hypothesis that interactions between gut bacteria and the brain mediate the rewarding and reinforcing properties of fentanyl. We implant rats with intravenous catheters in preparation for fentanyl intravenous self-administration (IVSA) on an escalating schedule of reinforcement to determine factors that influence fentanyl intake, including sex, dose, and gut microbiota. Our data show the impact of fentanyl IVSA on gut microbiota diversity, as well as the role of gut microbiota on fentanyl IVSA, in Sprague Dawley rats in a sex- and dose-dependent manner (n = 10–16/group). We found that the diversity of gut microbiota within females dose-dependently predicts progressive but not fixed ratio schedules of fentanyl IVSA. Depending on sex and fentanyl dose, alpha diversity (richness and evenness measured with Shannon index) is either increased or decreased following fentanyl IVSA and predicts progressive ratio breakpoint. Our findings collectively suggest a role of gut bacteria in drug-related behavior, including motivation and reinforcement. This work provides feasibility for an intravenous fentanyl self-administration model and uncovers potential factors mediating drug use, which may lead to the development of effective addiction interventions.

Effect of Concomitant Use of Analgesics on Prognosis in Patients Treated With Immune Checkpoint Inhibitors: A Systematic Review and Meta-Analysis

Background

Drug–drug interactions (DDIs) pose new challenges beyond traditional pharmacodynamics in the context of optimizing the treatment options with immune checkpoint inhibitors (ICIs). To alleviate cancer-related pain, analgesics are of absolute vital importance as chronic medications used by cancer patients. However, the possible outcome of ICI treatment concomitant with analgesics remains unclear.

Methods

Original articles describing the possible influence of analgesics use on ICI treatment published before December 1, 2021 were retrieved from PubMed, Embase, and the Cochrane Library. Odds ratio (OR) with 95% confidence interval (CI) for objective response rate (ORR), hazard ratio (HR) with 95% CI for progression-free survival (PFS), and overall survival (OS) were calculated using the random-effects or fixed-effects model, and heterogeneity was assessed using the χ²-based Q-test. Publication bias was examined by funnel plot analysis.

Results

A total of 11 studies involving 4,404 patients were included. The pooled OR showed that opioid use decreased the response of opioid users to ICIs compared to non-opioid users (OR = 0.49, 95% CI = 0.37–0.65, p < 0.001). Compared to patients who did not receive opioids, opioid users had an increased risk of progression and mortality (HR = 1.61, 95% CI = 1.37–1.89, p < 0.001; HR = 1.67, 95% CI =1.30–2.14, p < 0.001, respectively). Furthermore, the concomitant use of non-steroidal anti-inflammatory drugs (NSAIDs) was not significantly associated with differences in ORR, PFS, and OS in patients treated with ICIs (OR = 1.40, 95% CI = 0.84–2.32, p = 0.190; HR = 0.90, 95% CI = 0.77–1.06, p = 0.186; HR = 0.90, 95% CI = 0.71–1.14, p = 0.384, respectively).

Conclusion

The concomitant use of opioids during ICI treatment has an adverse effect on patient prognosis, while the use of NSAIDs is not significantly associated with the prognosis in patients treated with ICIs.

The role of key gut microbial metabolites in the development and treatment of cancer

In recent years, the role of gut microbial metabolites on the inhibition and progression of cancer has gained significant interest in anticancer research. It has been established that the gut microbiome plays a pivotal role in the development, treatment and prognosis of different cancer types which is often mediated through the gut microbial metabolites. For instance, gut microbial metabolites including bacteriocins, short-chain fatty acids and phenylpropanoid-derived metabolites have displayed direct and indirect anticancer activities through different molecular mechanisms. Despite the reported anticancer activity, some gut microbial metabolites including secondary bile acids have exhibited pro-carcinogenic properties. This review draws a critical summary and assessment of the current studies demonstrating the carcinogenic and anticancer activity of gut microbial metabolites and emphasises the need to further investigate the interactions of these metabolites with the immune system as well as the tumour microenvironment in molecular mechanistic and clinical studies.

Gut Microbiota and Bone Diseases: A Growing Partnership

Gut microbiota is key to human health and disease. Convincing studies have demonstrated that dysbiosis in the commensal gut microbiota is associated with intestinal and extra-intestinal diseases. Recent explorations have significantly contributed to the understanding of the relationship between gut microbiota and bone diseases (osteoporosis, osteoarthritis, rheumatoid arthritis, and bone cancer). Gut microbiota and its metabolites may become associated with the development and progression of bone disorders owing to their critical role in nutrient absorption, immunomodulation, and the gut–brain–bone axis (regulation hormones). In this work, we review the recent developments addressing the effect of gut microbiota modulation on skeletal diseases and explore a feasible preventive approach and therapy for bone diseases.

Impact of illicit opioid use on markers of monocyte activation and systemic inflammation in people living with HIV

INTRODUCTION

We hypothesize that illicit opioid use increases bacterial translocation from the gut, which intensifies systemic inflammation.

OBJECTIVE

To investigate the association between opioid use and plasma soluble CD14 [sCD14], interleukin-6 [IL-6] and D-dimer in people living with HIV (PLWH).

METHODS

We analyzed data from the Russia ARCH study-an observational cohort of 351 ART-naive PLWH in St. Petersburg, Russia. Plasma levels of sCD14 (primary outcome), IL-6 and D-dimer (secondary outcomes) were evaluated at baseline, 12, and 24 months. Participants were categorized into three groups based on illicit opioid use: current, prior, and never opioid use. Linear mixed effects models were used to evaluate associations.

RESULTS

Compared to never opioid use, sCD14 levels were significantly higher for participants with current opioid use (AMD = 197.8 ng/ml [11.4, 384.2], p = 0.04). IL-6 levels were also higher for participants with current vs. never opioid use (ARM = 2.10 [1.56, 2.83], p <0.001). D-dimer levels were higher for current (ARM = 1.95 [1.43, 2.64], p <0.001) and prior (ARM = 1.57 [1.17, 2.09], p = 0.004) compared to never opioid use.

CONCLUSIONS

Among PLWH, current opioid use compared to never use is associated with increased monocyte activation and systemic inflammation.

The Underestimated and Overlooked Burden of Diarrhea and Constipation in Cancer Patients

PURPOSE OF REVIEW

This review aims to summarize and discuss the diverse causes of two major gastrointestinal dysfunction symptoms, diarrhea and constipation, in cancer patients. We also discuss short- and long-term clinical, economic, and humanistic consequences, including the impact on cancer treatment regimens and patient quality of life, highlighting the limitations of the literature.

RECENT FINDINGS

Diarrhea and constipation as a result of cancer and its treatment can risk the success of anti-cancer therapies by requiring treatment delay or withdrawal, and imposes a substantial humanistic burden in patients with cancer. Despite its importance and frequency, gastrointestinal side effects may be overlooked due to the focus on cancer treatment, and the impact on patients may be underestimated. Additionally, the burden reported may not fully reflect current cancer management, particularly the true impact of economic consequences. A full understanding of the burden of diarrhea and constipation in patients with cancer is required, including broad evaluation of clinical considerations, the patient experience, and an updated assessment of economic burden. This would improve caregivers' appreciation of the impact of gastrointestinal dysfunction and aid the prioritization of future research efforts.

Morphine Exacerbates Experimental Colitis-Induced Depression of Nesting in Mice

Opioids and non-steroidal anti-inflammatory drugs (NSAIDs) are excellent analgesics, but recent clinical evidence suggests that these drugs might worsen disease severity in Crohn's disease patients, limiting their clinical utility for treating Inflammatory Bowel Disease (IBD). One indicator of change in well-being from conditions such as IBD is behavioral depression and disruption to activities of daily living. Preclinical measures of behavioral depression can provide an indicator of changes in quality of life and subsequent modification by candidate analgesics. In mice, nesting is an adaptive unconditioned behavior that is susceptible to disruption by noxious stimuli, and some types of pain related nesting depression are responsive to opioid and NSAID analgesics. Here we show that a 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) model of experimental colitis depresses nesting behavior in mice, and we evaluated effects of morphine, an opioid, and ketoprofen, a NSAID, on TNBS-induced nesting depression. In Swiss Webster mice, TNBS significantly reduced nesting that peaked on Day 3 and recovered in a time-dependent manner with complete recovery by Day 7. In the absence of colonic inflammation, daily treatment with morphine (1-10 mg/kg) did not decrease nesting except at 10mg/kg/day. However, in TNBS-treated mice 3.2 mg/kg/day morphine significantly exacerbated TNBS-induced nesting depression and delayed recovery. While 3.2 mg/kg/day morphine alone did not alter locomotor activity and TNBS-induced depression of locomotion recovered, the combination of TNBS and 3.2 mg/kg/day morphine significantly attenuated locomotion and prevented recovery. Daily treatment with 3.2 or 10 mg/kg ketoprofen in TNBS-treated mice did not prevent depression of nesting. These data suggest that opioid analgesics but not NSAIDS worsen colonic inflammation-induced behavioral depression. Furthermore, these findings highlight the importance of evaluating analgesic effects in models of colonic inflammation induced depression of behavior.