Polypharmacy of osteoarthritis: the perfect intestinal storm

Assessing causality between osteoarthritis and gastrointestinal disorders: a Mendelian randomization study

The association between osteoarthritis (OA) and gastrointestinal disorders was found in observational studies. However, the causality is still elusive. A bidirectional Mendelian randomization (MR) analysis using genome wide association studies data was conducted to assess the causal association between OA and gastrointestinal diseases [including peptic ulcer disease (PUD), gastroesophageal reflux disease (GORD), and inflammatory bowel disease (IBD)]. A two-step MR (TSMR) was conducted between OA, gastrointestinal diseases and drugs to explore the mediating effects of non-steroidal anti-inflammatory drugs (NSAIDs) and opioids use. We used multivariable MR (MVMR) analysis to further validate the impact of prescription history on diseases. Results had statistical significance at a Bonferroni corrected P-value below 0.008. We observed that genetically predicted OA had a significant positive association with GORD [odds ratio (OR) = 1.26, P = 5e-05], but not with PUD or IBD. Regarding the other direction, gastrointestinal disorders as exposure had a null association with OA. Using TSMR, OA patients tended to increase the use of NSAIDs (OR = 1.45, P = 0.001) and opioids (OR = 1.77, P = 2e-05), but only the use of opioids increased the risk of GORD (OR = 1.43, P = 5e-09). Further MVMR analysis showed that the adverse effect of OA on GORD was significantly reduced after adjusting for opioids use (OR = 1.20, P = 0.038). This study provides evidence for the causal association between OA and increased risk of GORD, which is partly attributed to opioids use in OA patients but not NSAIDs.

M378 exhibits anti-inflammatory activities through NLRP3 signaling pathway

Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used drugs due to their values in attenuating pain, fever and inflammation. Unfortunately, conspicuous adverse effects, such as gastrointestinal (GI) damage and/or cardiovascular events have impeded their application in clinic. M378 is a novel hydrogen sulfide-releasing NSAIDs with uncompromised potency and negligible toxicity compared to the existing NSAIDs. However, its anti-inflammatory activity and mechanism are still an enigma. Here we investigated the effect of M378 on the NLRP3 inflammasome signaling pathway and addressed the underlying molecular mechanism. Our data in vitro showed that M378 dose-dependently inhibited the cleavage of Caspase-1 and the secretion of active IL-1β and blocked NLRP3-dependent pyroptosis in LPS-primed J774A.1 macrophages. Furthermore, M378 remarkably inhibited upstream ASC oligomerization and ROS production regarding the process of NLRP3 inflammasome assembly. Our data in vivo demonstrated that M378 protected mice from acute liver injury, reducing the levels of ALT/AST and IL-1β and improving hepatic pathological damages. Immunoblot analysis revealed that M378 inhibited the expressions of Caspase-1 and IL-1β in liver tissues of ALI mice. We also showed that M378 alleviated IL-1β secretion and peritoneal neutrophils infiltration in MSU-elicited acute peritonitis mice. In conclusion, M378 exerted its anti-inflammatory effect both in vitro and in vivo and its mechanisms are at least connected to its inhibitory performance on the generation of ASC oligomers and ROS production. These findings give an insight. into the molecular mechanism of hydrogen sulfide-releasing NSAIDs and support a potent therapeutic role of M378 in the treatment of NLRP3-driven inflammatory diseases.

Comorbidity phenotypes and risk of mortality in patients with osteoarthritis in the UK: a latent class analysis

BACKGROUND

Osteoarthritis (OA) is a common chronic condition but its association with other chronic conditions and mortality is largely unknown. This study aimed to use latent class analysis (LCA) of 30 comorbidities in patients with OA and matched controls without OA to identify clusters of comorbidities and examine the associations between the clusters, opioid use, and mortality.

METHODS

A matched cohort analysis of patients derived from the IQVIA Medical Research Data (IMRD-UK) database between 2000 and 2019. 418,329 patients with newly diagnosed OA were matched to 243,170 patients without OA to identify comorbidity phenotypes. Further analysis investigated the effect of opioid use on mortality in individuals with OA and their matched controls.

RESULTS

The median (interquartile range (IQR)) number of comorbidities was 2 (1-4) and 1 (0-3) in the OA and control groups respectively. LCA identified six comorbidity phenotypes in individuals with and without OA. Clusters with a high prevalence of comorbidities were characterised by hypertension, circulatory, and metabolic diseases. We identified a comorbidity cluster with the aforementioned comorbidities plus a high prevalence of chronic kidney disease, which was associated with twice the hazard of mortality in hand OA with a hazard ratio (HR) (95% CI) of 2.53 (2.05-3.13) compared to the hazard observed in hip/knee OA subtype 1.33 (1.24-1.42). The impact of opioid use in the first 12 months on hazards of mortality was significantly greater for weak opioids and strong opioids across all groups HR (95% CI) ranging from 1.11 (1.07-11.6) to 1.80 (1.69-1.92)). There was however no evidence of association between NSAID use and altered risk of mortality.

CONCLUSION

This study identified six comorbidity clusters in individuals with OA and matched controls within this cohort. Opioid use and comorbidity clusters were differentially associated with the risk of mortality. The analyses may help shape the development of future interventions or health services that take into account the impact of these comorbidity clusters.

The Role of Medicinal and Aromatic Plants against Obesity and Arthritis: A Review

Obesity is a significant health concern, as it causes a massive cascade of chronic inflammations and multiple morbidities. Rheumatoid arthritis and osteoarthritis are chronic inflammatory conditions and often manifest as comorbidities of obesity. Adipose tissues serve as a reservoir of energy as well as releasing several inflammatory cytokines (including IL-6, IFN-γ, and TNF-α) that stimulate low-grade chronic inflammatory conditions such as rheumatoid arthritis, osteoarthritis, diabetes, hypertension, cardiovascular disorders, fatty liver disease, oxidative stress, and chronic kidney diseases. Dietary intake, low physical activity, unhealthy lifestyle, smoking, alcohol consumption, and genetic and environmental factors can influence obesity and arthritis. Current arthritis management using modern medicines produces various adverse reactions. Medicinal plants have been a significant part of traditional medicine, and various plants and phytochemicals have shown effectiveness against arthritis and obesity; however, scientifically, this traditional plant-based treatment option needs validation through proper clinical trials and toxicity tests. In addition, essential oils obtained from aromatic plants are being widely used as for complementary therapy (e.g., aromatherapy, smelling, spicing, and consumption with food) against arthritis and obesity; scientific evidence is necessary to support their effectiveness. This review is an attempt to understand the pathophysiological connections between obesity and arthritis, and describes treatment options derived from medicinal, spice, and aromatic plants.

Probiotics for pain of osteoarthritis; An N-of-1 trial of individual effects

OBJECTIVE

This study aimed to investigate the safety and effectiveness of probiotics in osteoarthritic pain for one individual.

METHODS

The study was an N-of-1 trial design, divided into 3 blocks of 10 weeks. Each block included one pair of randomized interventions (AB), separated by a washout period. The trial took place in a private naturopathic practice in Sydney, Australia. The participant was a 67 year old female with osteoarthritis in her lower back and right ankle. The active intervention was two daily capsules that contained Lactobacillus rhamnosus (LGG®), Saccharomyces cerevisiae (boulardii) and Bifidobacterium animalis ssp lactis. The placebo was an identical capsule that did not contain probiotics. The primary outcome was daily pain scores, measured by the participant on a Visual Analogue Scale (VAS). Secondary outcome measures included patient preference (of intervention), General Health Questionnaire (GHQ-12), Patient Specific Functional Scale (PSFS), Comprehensive Digestive Stool Analysis (CDSA) and rescue medication usage. A dependent t-test analysed mean pain scores for the last week of each intervention across the three blocks of the study.

RESULTS

The probiotic intervention was associated with lower pain scores and was the preferred intervention chosen by the participant. The mean pain score on the VAS was 4.9 ± 2.2 in the placebo condition compared to 4.0 ± 1.7 in the probiotic condition (t(20) = 2.2, p =  0.04, difference = 0.9, 95 % CI [0.04, 1.77]).

CONCLUSIONS

The reduction in pain scores associated with the probiotic intervention was small but clinically significant for this patient. A holistic view of the patient focusing on digestive integrity and function may be crucial for clinical applications of interventions such as probiotics. N-of-1 trial designs allow for the measurement of a holistic approach to an individual, which is aligned with naturopathic practice. Further trials are required to generate data to enable reliable estimation of population effects.

COMPARING OF FAECAL CALPROTECTIN LEVELS IN PATIENTS WITH OSTEOARTHRITIS TAKING NSAID TREATMENT AND PATIENTS WITHOUT NSAIDS THERAPY

Faecal calprotectin (FC) level can be increased in several conditions, which are characterised by neutrophilic inflammation. Some medications, particularly NSAIDs, can elevate its level as well. NSAIDs are taken by patients in many chronic conditions, including osteoarthritis (OA). On the other hand, there is growing evidence that osteoarthritis is not only a degenerative disease, but it has a significant inflammatory component. The role of systemic inflammation is well-known in inflammatory joint diseases, but there is some evidence that it can play an essential role in the OA as well. It can suggest that in the OA, the inflammatory changes could be found in the different organs and systems. The aim of this study was to investigate the FC level in patients with osteoarthritis depending on the NSAIDs intake and to compare it to the FC levels in healthy adults. Materials and methods. In this small observational study, we evaluated the FC levels in patients suffering from OA (36 persons), divided them into two groups depending on their NSAIDs intake, and compared it to FC levels in healthy participants (12 persons). We compared the FC levels depending on the selectivity of the NSAIDs taken by our participants, as well. Results. The median calprotectin level in our patients was 72.57 (IQR 20.55-221.57) mg/kg, 95 %CI 26,18-109.01. OA patients had higher levels than the healthy group (p<0.001). OA patients who took NSAIDs had the highest FC levels – 221.57 (IQR 91.56-448.61) – higher, than those who did not take it – 72.57 (IQR 35.26-164.79) (p=0.03) and than healthy participants, who has normal FC levels (p<0.001); the FC levels of patients who did not take NSAIDs also exceeds healthy subject’s levels (p<0.001). The FC levels in the collective group have a sufficient positive correlation with the duration of NSAIDs intake, VAS score and strong correlation with Lequesne index values. We found that both NSAIDs groups have a significantly greater prevalence of elevated or high FC levels than the control group (p<0.001) and that NSAIDs patients significantly more often have high FC levels than those who do not take NSAIDs (p=0.035). When comparing FC levels in patients depending on the type of NSAIDs they take, we found that those who take non-selective NSAIDs has significantly higher FC levels than those who do not take NSAIDs – 264.1 (IQR 89.72-464.67) to 25.65 (IQR 19.5-75.33) (p=0.0003). The FC levels of who take selective NSAIDs – 98.53 (91.56-105.5) – did not differ significantly to non-selective NSAIDs taker’s group values and non-selective NSAIDs taker’s values (p>0.05). Conclusions. Patients who suffer from OA have higher FC levels than healthy individuals, and patients with OA who take NSAIDs regularly have higher FC levels than those who do not. The intake of non-selective NSAIDs is associated with higher FC levels, than the intake of high-selective NSAIDs. FC levels of those who take high-selective NSAIDs do not differ statistically from those who do not intake NSAIDs. Further research is needed in this area.

A proof-of-concept, Phase 2 clinical trial of the gastrointestinal safety of a hydrogen sulfide-releasing anti-inflammatory drug

BACKGROUND AND PURPOSE

ATB-346 is a hydrogen sulfide (H2 S)-releasing anti-inflammatory and analgesic drug. Animal studies demonstrated negligible gastrointestinal (GI) damage despite marked inhibition of COX activity and significant analgesic and anti-inflammatory effects. In humans, ATB-346 (250 mg once daily) was found to inhibit COX to the same extent as naproxen (550 mg twice daily).

EXPERIMENTAL APPROACH

Two hundred forty-four healthy volunteers completed a 2-week, double-blind study, taking either ATB-346 (250 mg once daily) or naproxen (550 mg twice daily), with upper GI ulceration being examined endoscopically.

KEY RESULTS

Forty-two per cent of the subjects taking naproxen developed at least one ulcer (≥3-mm diameter), while only 3% of the subjects taking ATB-346 developed at least one ulcer. The two drugs produced comparable and substantial (>94%) suppression of COX activity. Subjects in the naproxen group developed more ulcers per subject than ATB-346-treated subjects and a greater incidence of larger ulcers (≥5-mm diameter). The incidence of dyspepsia, abdominal pain, gastro-oesophageal reflux, and nausea was lower with ATB-346 than with naproxen. Subjects treated with ATB-346 had significantly higher plasma levels of H2 S than those treated with naproxen.

CONCLUSIONS AND IMPLICATIONS

This Phase 2B study provides unequivocal evidence for a marked reduction of GI toxicity of the H2 S-releasing analgesic/anti-inflammatory drug, ATB-346, as compared to the conventional dose of naproxen that produced equivalent suppression of COX.

LINKED ARTICLES

This article is part of a themed section on Hydrogen Sulfide in Biology & Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.4/issuetoc.

Eicosanoids in the gastrointestinal tract

Eicosanoids play important roles in modulating inflammation throughout the body. The gastrointestinal (GI) tract, in part because of its intimate relationship with the gut microbiota, is in a constant state of low-grade inflammation. Eicosanoids like PGs, lipoxins and leukotrienes play essential roles in maintenance of mucosal integrity. On the other hand, in some circumstances, these mediators can become major drivers of inflammatory processes when the lining of the GI tract is breached. Drugs such as nonsteroidal anti-inflammatories, by altering the production of various eicosanoids, can dramatically impact the ability of the GI tract to respond appropriately to injury. Disorders such as inflammatory bowel disease appear to be driven in part by altered production of eicosanoids. Several classes of drugs have been developed that target eicosanoids. LINKED ARTICLES: This article is part of a themed section on Eicosanoids 35 years from the 1982 Nobel: where are we now? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.8/issuetoc.

Iron Dysregulation and Dormant Microbes as Causative Agents for Impaired Blood Rheology and Pathological Clotting in Alzheimer's Type Dementia

Alzheimer’s disease and other similar dementias are debilitating neurodegenerative disorders whose etiology and pathogenesis remain largely unknown, even after decades of research. With the anticipated increase in prevalence of Alzheimer’s type dementias among the more susceptible aging population, the need for disease-modifying treatments is urgent. While various hypotheses have been put forward over the last few decades, we suggest that Alzheimer’s type dementias are triggered by external environmental factors, co-expressing in individuals with specific genetic susceptibilities. These external stressors are defined in the Iron Dysregulation and Dormant Microbes (IDDM) hypothesis, previously put forward. This hypothesis is consistent with current literature in which serum ferritin levels of individuals diagnosed with Alzheimer’s disease are significantly higher compared those of age- and gender-matched controls. While iron dysregulation contributes to oxidative stress, it also causes microbial reactivation and virulence of the so-called dormant blood (and tissue) microbiome. Dysbiosis (changes in the microbiome) or previous infections can contribute to the dormant blood microbiome (atopobiosis¹), and also directly promotes systemic inflammation via the amyloidogenic formation and shedding of potent inflammagens such as lipopolysaccharides. The simultaneous iron dysregulation and microbial aberrations affect the hematological system, promoting fibrin amylodiogenesis, and pathological clotting. Systemic inflammation and oxidative stress can contribute to blood brain barrier permeability and the ensuing neuro-inflammation, characteristic of Alzheimer’s type dementias. While large inter-individual variability exists, especially concerning disease pathogenesis, the IDDM hypothesis acknowledges primary causative factors which can be targeted for early diagnosis and/or for prevention of disease progression.

The Clinical Efficacy and Safety of Gumiganghwal-Tang in Knee Osteoarthritis: A Phase II Randomized Double Blind Placebo Controlled Study

Background

Gumiganghwal-tang (GMGHT) is a traditional herbal medicine consisting of nine different herbs. GMGHT inhibits the mRNA expression and production of inflammatory cytokines tumor necrosis factor-α (TNF- α), interleukin-6 (IL-6), and TNF- β on lipopolysaccharide- (LPS-) stimulated peritoneal macrophages in a dose-dependent manner. It is empirically used for the treatment of inflammatory disease, but there are few reports of clinical trials that investigate its efficacy and safety. The current study aimed to investigate the clinical efficacy and safety of GMGHT in patients with knee osteoarthritis (OA).

Methods

This was a multicenter, two-armed, double-blinded, randomized, placebo controlled study of GMGHT over 6 weeks. Eligible patients who fulfilled the American College of Rheumatology criteria for OA were randomized to receive either GMGHT or the placebo. Clinical assessments included measurement of knee pain and function using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), patient global assessment (PGA), and knee pain scores every 2 weeks.

Results

A total of 128 patients were enrolled (91.4% female; mean age, 58.7 ± 8.1 years). At baseline, pain visual analogue score (VAS) was 67.2 ± 1.4, resp. 71.3 ± 1.6 (treatment, resp. placebo group, p=0.84), and total WOMAC score was 55.2 ± 1.6, resp. 55.6 ± 1.5 (p = 0.84). After 6 weeks, the pain VAS was 43.0 ± 2.5, resp. 61.6 ± 2.5 (p < 0.01) and the total WOMAC score was 34.1 ± 2.4, resp. 46.9 ± 1.8 (p < 0.01). No patients withdrew because of treatment emergent adverse events. Expected adverse events including dyspepsia, liver function abnormality, and lower extremity edema were comparable between both groups.

Conclusions

Treatment with GMGHT resulted in significant improvement in pain, function, and global assessment, and it was generally safe and well tolerated in patients with OA.

Hydrogen Sulfide-Releasing Therapeutics: Translation to the Clinic

SIGNIFICANCE

Shortly after the discovery of the role of hydrogen sulfide (H₂S) in many physiological and pathological processes, attempts were made to develop novel pharmaceuticals that may be of benefit for treatment or prevention of a wide range of disorders. The promise of H₂S-based therapeutics is now being demonstrated in clinical trials. Recent Advances: H₂S-releasing drugs, such as SG1002 for cardiovascular disorders, and ATB-346 for arthritis, have progressed into clinical trials and have shown considerable promise. Some older drugs, such as zofenopril, have now been recognized to produce at least some of the beneficial effects through release of H₂S.

CRITICAL ISSUES

There remains a need to better understand the underlying mechanisms for some of the observed effects of H₂S-releasing drugs in a clinical setting, such as the marked increase in analgesic potency that has been observed with ATB-346.

FUTURE DIRECTIONS

The proof-of-concept clinical studies reviewed herein pave the way for examination, in a clinical setting, of several other potential applications of H₂S-based drugs in a wide range of disorders, including diabetes, hypertension, and cancer chemoprevention. Antioxid. Redox Signal. 28, 1533-1540.

The Challenges of Treating Sciatica Pain in Older Adults

Sciatica is a debilitating condition affecting approximately 25 % of the population. Typically, the patient will complain of lower limb pain that is more severe than pain in the lower back, usually accompanied by numbness and motor weakness. Most international guidelines recommend pharmacological management for the pain relief of sciatica, including paracetamol, non-steroidal anti-inflammatory drugs, opioid analgesics, anticonvulsants, and corticosteroids, among others. However, the evidence for most of these pharmacological options is scarce, and the majority of clinical trials exclude older patients. There is overall very limited information on the efficacy, safety, and tolerability of these medicines in older patients with sciatica. This review presents a critical appraisal of the existing evidence for the pharmacological treatment of sciatica, with a special focus on the older adult. The age-related changes in the health of older patients, as well as their impact on the response to pharmacological treatment, including polypharmacy, drug interactions, and drug-disease interactions, is also discussed.

Polypharmacy and Multimorbidity Among Medicaid Enrollees: A Multistate Analysis

The purpose of this study is to explore the associations between polypharmacy and multimorbidity using conventional and novel measures of polypharmacy. In this cross-sectional study, data on fee-for-service (FFS) Medicaid enrollees with at least 1 chronic condition and aged 18-64 years (N = 38,329) were derived from the 2010 Medicaid Analytic eXtract (MAX) files of Maryland and West Virginia. Polypharmacy, by the authors' novel definition, was determined as simultaneous use of ≥5 drugs for a consecutive period of 60 days. Multimorbidity was defined as having ≥2 chronic conditions based on the US Department of Health and Human Services framework. The association between multimorbidity and polypharmacy was examined with chi-square tests and logistic regression. Polypharmacy prevalence was estimated at 50.9% using the novel definition, as compared to 16.7% and 64.9% for the 2 commonly used conventional measures, respectively. For all 3 definitions, individuals with multimorbidity were more likely to have polypharmacy than those without multimorbidity (P < 0.001). The authors also consistently found, using all definitions, that those who were older, female, white, and eligible for Medicaid because of cash assistance were more likely to have polypharmacy (all P < 0.001). Polypharmacy was highly prevalent and significantly associated with multimorbidity among Medicaid FFS enrollees irrespective of the definitions used. The new measure may provide a more comprehensive and accurate estimation of polypharmacy than the conventional measures. These findings suggest the need for a paradigm shift from disease-specific care to patient-centered collaborative care to manage patients with multimorbidity and polypharmacy.

Polypharmacy and Health-Related Quality of Life Among US Adults With Arthritis, Medical Expenditure Panel Survey, 2010-2012

INTRODUCTION

Our objective was to determine the relationship between polypharmacy (treatment with prescription drugs from 6 or more drug classes concurrently) and health-related quality of life (HRQoL) among US adults with arthritis.

METHODS

We conducted a retrospective cohort study that used 2-year longitudinal data from the Medical Expenditure Panel Survey to analyze a cohort of 6,132 adults aged over 21 years with arthritis. Measures of HRQoL were the summary scores from the mental component summary (MCS) and physical component summary (PCS) of the 12-item short-form health survey. Unadjusted and adjusted regression models were used to evaluate the association between polypharmacy and HRQoL measures. We used SAS, version 9.4, (SAS Institute Inc) to conduct all analyses.

RESULTS

In unadjusted analyses, adults with arthritis taking prescription drugs from 6 or more drug classes concurrently had significantly lower MCS and PCS scores (β, -3.11, P < .001 and β, -10.26, P < .001, respectively) than adults taking prescription drugs from fewer than 6. After controlling for the demographic characteristics, number of mental and physical chronic conditions, and baseline MCS and PCS scores, adults taking prescription drugs from 6 or more drug classes concurrently had significantly lower PCS scores (β, -1.68, P < .001), than those taking prescription drugs from fewer than 6. However, no significant difference in MCS scores was found between adults taking prescription drugs from 6 or more drug classes concurrently and those taking prescription drugs from fewer than 6 (β, -0.27, P = .46).

CONCLUSION

Polypharmacy is significantly associated with lower PCS scores among adults with arthritis. Because polypharmacy can lead to drug-drug and drug-disease interactions, health care providers need to consider the risk and adopt a cautious approach in prescribing multiple drugs to manage chronic conditions and in choosing therapies to improve HRQoL among adults with arthritis.

Clinical importance of nonsteroidal anti-inflammatory drug enteropathy: the relevance of tumor necrosis factor as a promising target

The pathogenesis of nonsteroidal anti-inflammatory drug (NSAID) enteropathy is still unclear, and consequently, there is no approved therapeutic strategy for ameliorating such damage. On the other hand, molecular treatment strategies targeting tumor necrosis factor (TNF) exerts beneficial effects on NSAID-induced intestinal lesions in rodents and rheumatoid arthritis patients. Thus, TNF appears to be a potential therapeutic target for both the prevention and treatment of NSAID enteropathy. However, the causative relationship between TNF and NSAID enteropathy is largely unknown. Currently approved anti-TNF agents are highly expensive and exhibit numerous side effects. Hence, in this review, the pivotal role of TNF in NSAID enteropathy has been summarized and plant-derived polyphenols have been suggested as useful alternative anti-TNF agents because of their ability to suppress TNF activated inflammatory pathways both in vitro and in vivo.

Hydrogen sulfide-releasing anti-inflammatory drugs for chemoprevention and treatment of cancer

For many years it has been recognized that inhibition of cyclooxygenase enzymes is effective in reducing the incidence of many types of cancer, but the adverse effects of these drug, particularly in the gastrointestinal and cardiovascular systems, limits their utility. Recently developed hydrogen sulfide-releasing anti-inflammatory drugs may be a promising option for cancer chemoprevention. In this paper we review evidence suggesting that these novel compounds are effective in a range of animal models of various types of cancer, while exhibiting greatly reduced toxicity relative to currently marketed non-steroidal anti-inflammatory drugs. Some of the possible mechanisms of action of hydrogen sulfide-releasing anti-inflammatory drugs are also discussed.

Profound Chemopreventative Effects of a Hydrogen Sulfide-Releasing NSAID in the APCMin/+ Mouse Model of Intestinal Tumorigenesis

Nonsteroidal anti-inflammatory drugs have been shown to reduce the incidence of gastrointestinal cancers, but the propensity of these drugs to cause ulcers and bleeding limits their use. H₂S has been shown to be a powerful cytoprotective and anti-inflammatory substance in the digestive system. This study explored the possibility that a H₂S-releasing nonsteroidal anti-inflammatory drug (ATB-346) would be effective in a murine model of hereditary intestinal cancer (APC^Min+ mouse) and investigated potential mechanisms of action via transcriptomics analysis. Daily treatment with ATB-346 was significantly more effective at preventing intestinal polyp formation than naproxen. Significant beneficial effects were seen with a treatment period of only 3–7 days, and reversal of existing polyps was observed in the colon. ATB-346, but not naproxen, significantly decreased expression of intestinal cancer-associated signaling molecules (cMyc, β-catenin). Transcriptomic analysis identified 20 genes that were up-regulated in APC^Min+ mice, 18 of which were reduced to wild-type levels by one week of treatment with ATB-346. ATB-346 is a novel, gastrointestinal-sparing anti-inflammatory drug that potently and rapidly prevents and reverses the development of pre-cancerous lesions in a mouse model of hereditary intestinal tumorigenesis. These effects may be related to the combined effects of suppression of cyclooxygenase and release of H₂S, and correction of most of the APC^Min+-associated alterations in the transcriptome. ATB-346 may represent a promising agent for chemoprevention of tumorigenesis in the GI tract and elsewhere.

Toward More GI-Friendly Anti-Inflammatory Medications

OPINION STATEMENT

Despite the introduction 20-30 years ago of potent inhibitors of gastric acid secretion and anti-inflammatory drugs that preferentially inhibit cyclo-oxygenase (COX)-2, the GI adverse effects of nonsteroidal anti-inflammatory drugs (NSAIDs) remain a significant clinical concern and a considerable economic burden. Inhibitors of acid secretion and selective COX-2 inhibitors reduce damage only in the proximal GI tract (stomach and proximal duodenum), but NSAIDs produce injury and bleeding throughout the GI tract. The small intestinal damage caused by NSAIDs is common, difficult to diagnose, and there are no proven-effective preventative or curative therapies. There is also emerging evidence that proton pump inhibitors (PPIs) and histamine H2-receptor antagonists (H2RAs) exacerbate NSAID-induced small intestinal injury. A new approach to solve this clinical problem is to deliver an endogenous, cytoprotective "rescue molecule" together with a COX inhibitor. Hydrogen sulfide (H2S) is a naturally produced, potent protective agent in the GI tract. H2S-releasing NSAIDs have been synthesized and extensively tested in laboratory animals and humans. They exhibit improved anti-inflammatory activity over the parent NSAID, while causing negligible damage in the GI tract.

Safety and efficacy of paracetamol and NSAIDs in osteoarthritis: which drug to recommend?

INTRODUCTION

Osteoarthritis (OA) is the most common form of arthritis and is a major cause of disability, especially in people ≥ 45 years old. Several international societies recommend the use of both acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs) to alleviate OA pain. However, patients with OA often have comorbidities, notably cardiovascular risk factors, which may hamper the use of these analgesics.

AREAS COVERED

This paper reviews the safety of both acetaminophen and NSAIDs in OA. Recent data have pointed to a gastrointestinal and cardiovascular toxicity of acetaminophen, which has been neglected for a long time. In addition, several meta-analyses revealed that acetaminophen is a poor analgesic in OA. Traditional NSAIDs and cyclooxygenase 2 inhibitors (coxibs) have similar analgesic effects but vary greatly in their potential gastrointestinal and cardiovascular toxicity.

EXPERT OPINION

Given the putative gastrointestinal and cardiovascular toxicity and poor analgesic properties of acetaminophen in OA, its use in patients with risk factors is questionable. Acetaminophen should be used at the lowest effective dosage and for the shortest time in all OA patients. Given the different safety profiles, the choice of NSAIDs, traditional or coxibs, should be based on individual patient risk factors. A good knowledge of the different strategies to decrease the gastrointestinal and cardiovascular toxic effects of NSAIDs is key to the management of OA.

Gaseous mediators in resolution of inflammation

There are numerous gaseous substances that can act as signaling molecules, but the best characterized of these are nitric oxide, hydrogen sulfide and carbon monoxide. Each has been shown to play important roles in many physiological and pathophysiological processes. This article is focused on the effects of these gasotransmitters in the context of inflammation. There is considerable overlap in the actions of nitric oxide, hydrogen sulfide and carbon monoxide with respect to inflammation, and these mediators appear to act primarily as anti-inflammatory substances, promoting resolution of inflammatory processes. They also have protective and pro-healing effects in some tissues, such as the gastrointestinal tract and lung. Over the past two decades, significant progress has been made in the development of novel anti-inflammatory and cytoprotective drugs that release of one or more of these gaseous mediators.

Deciphering the pathogenesis of NSAID enteropathy using proton pump inhibitors and a hydrogen sulfide-releasing NSAID

The small intestine is a significant site of ulceration and bleeding induced by nonsteroidal anti-inflammatory drugs (NSAIDs). The pathogenesis is poorly understood. The present study explored the roles of bile, bacteria, and enterohepatic circulation to NSAID enteropathy, using both a conventional NSAID (naproxen) and a gastrointestinal-safe naproxen derivative (ATB-346), as well as proton pump inhibitors (PPIs). Rats were treated orally with naproxen or equimolar doses of ATB-346 over a 5-day period, with or without PPI administration, and intestinal damage was quantified. The cytotoxicity of bile from the rats was evaluated in vitro. Biliary excretion of naproxen and ATB-346 was determined. The impact of the NSAIDs and of PPIs on the composition of the intestinal microbiota was examined by deep sequencing of 16s rRNA. Naproxen caused significant intestinal damage and inflammation, whereas ATB-346 did not. Naproxen, but not ATB-346, dose dependently increased the cytotoxicity of bile, and it was further increased by PPI coadministration. Whereas biliary excretion of naproxen was significant in naproxen-treated rats, it was greatly reduced in rats treated with ATB-346. The enteric microbiota of naproxen-treated rats was distinct from that in vehicle- or ATB-346-treated rats, and PPI administration caused significant intestinal dysbiosis. The increase in cytotoxicity of bile induced by naproxen and PPIs may contribute significantly to intestinal ulceration and bleeding. Some of these effects may occur secondary to significant changes in the jejunal microbiota induced by both naproxen and PPIs.

Hydrogen sulfide-based therapeutics: exploiting a unique but ubiquitous gasotransmitter

Hydrogen sulfide (H2S) has become recognized as an important signalling molecule throughout the body, contributing to many physiological and pathological processes. In recent years, improved methods for measuring H2S levels and the availability of a wider range of H2S donors and more selective inhibitors of H2S synthesis have helped to more accurately identify the many biological effects of this highly reactive gaseous mediator. Animal studies of several H2S-releasing drugs have demonstrated considerable promise for the safe treatment of a wide range of disorders. Several such drugs are now in clinical trials.

NSAID enteropathy and bacteria: a complicated relationship

The clinical significance of small intestinal damage caused by nonsteroidal anti-inflammatory drugs (NSAIDs) remains under-appreciated. It occurs with greater frequency than the damage caused by these drugs in the upper gastrointestinal tract, but is much more difficult to diagnose and treat. Although the pathogenesis of NSAID enteropathy remains incompletely understood, it is clear that bacteria, bile, and the enterohepatic circulation of NSAIDs are all important factors. However, they are also interrelated with one another. Bacterial enzymes can affect the cytotoxicity of bile and are essential for enterohepatic circulation of NSAIDs. Gram-negative bacteria appear to be particularly important in the pathogenesis of NSAID enteropathy, possibly through release of endotoxin. Inhibitors of gastric acid secretion significantly aggravate NSAID enteropathy, and this effect is due to significant changes in the intestinal microbiome. Treatment with antibiotics can, in some circumstances, reduce the severity of NSAID enteropathy, but published results are inconsistent. Specific antibiotic-induced changes in the microbiota have not been causally linked to prevention of intestinal damage. Treatment with probiotics, particularly Bifidobacterium, Lactobacillus, and Faecalibacteriaum prausnitzii, has shown promising effects in animal models. Our studies suggest that these beneficial effects are due to colonization by the bacteria, rather than to products released by the bacteria.

Anti-inflammatory and cytoprotective actions of hydrogen sulfide: translation to therapeutics

SIGNIFICANCE

There is a rapidly expanding body of evidence for important roles of hydrogen sulfide in protecting against tissue injury, reducing inflammation, and promoting repair. There is also growing evidence that H2S can be successfully exploited in drug development.

RECENT ADVANCES

H2S synthesis and degradation are regulated in circumstances of inflammation and injury so as to promote repair and re-establish homeostasis. Novel H2S-releasing drugs exhibit enhanced anti-inflammatory and pro-restorative effects, while having reduced adverse effects in many tissues.

CRITICAL ISSUES

H2S is a pleiotropic mediator, having effects on many elements in the inflammatory cascade and promoting the resolution of inflammation and injury. It also contributes significantly to mucosal defence in the gastrointestinal tract, and in host defence against infection. There is strong evidence that novel, H2S-based therapeutics are safe and effective in animal models, and several are progressing through human trials.

FUTURE DIRECTIONS

A better understanding of the physiological and pathophysiological roles of H2S continues to be restrained by the lack of simple, reliable methods for measurement of H2S synthesis, and the paucity of highly selective inhibitors of enzymes that participate in endogenous H2S synthesis. On the other hand, H2S donors show promise as therapeutics for several important indications.

Anti-inflammatory and cytoprotective properties of hydrogen sulfide

Hydrogen sulfide is an endogenous gaseous mediator that plays important roles in many physiological processes in microbes, plants, and animals. This chapter focuses on the important roles of hydrogen sulfide in protecting tissues against injury, promoting the repair of damage, and downregulating the inflammatory responses. The chapter focuses largely, but not exclusively, on these roles of hydrogen sulfide in the gastrointestinal tract. Hydrogen sulfide is produced throughout the gastrointestinal tract, and it contributes to maintenance of mucosal integrity. Suppression of hydrogen sulfide synthesis renders the tissue more susceptible to injury and it impairs repair. In contrast, administration of hydrogen sulfide donors can increase resistance to injury and accelerate repair. Hydrogen sulfide synthesis is rapidly and dramatically enhanced in the gastrointestinal tract after injury is induced. These increases occur specifically at the site of tissue injury. Hydrogen sulfide also plays an important role in promoting resolution of inflammation, and restoration of normal tissue function. In recent years, these beneficial actions of hydrogen sulfide have provided the basis for development of novel hydrogen sulfide-releasing drugs. Nonsteroidal anti-inflammatory drugs that release small amounts of hydrogen sulfide are among the most advanced of the hydrogen sulfide-based drugs. Unlike the parent drugs, these modified drugs do not cause injury in the gastrointestinal tract, and do not interfere with healing of preexisting damage. Because of the increased safety profile of these drugs, they can be used in circumstances in which the toxicity of the parent drug would normally limit their use, such as in chemoprevention of cancer.

Nonsteroidal anti-inflammatory drugs, proton pump inhibitors, and gastrointestinal injury: contrasting interactions in the stomach and small intestine

Nonsteroidal anti-inflammatory drugs (NSAIDs) and proton pump inhibitors (PPIs) are among the most frequently prescribed groups of drugs worldwide. The use of NSAIDs is associated with a high number of significant adverse effects. Recently, the safety of PPIs has also been challenged. Capsule endoscopy studies reveal that even low-dose NSAIDs are responsible for gut mucosal injury and numerous clinical adverse effects, for example, bleeding and anemia, that might be difficult to diagnose. The frequent use of PPIs can exacerbate NSAID-induced small intestinal injury by altering intestinal microbiota. Thus, the use of PPI is considered to be an independent risk factor associated with NSAID-associated enteropathy. In this review, we discuss this important clinical problem and review relevant aspects of epidemiology, pathophysiology, and management. We also present the hypothesis that even minor and subclinical injury to the intestinal mucosa can result in significant, though delayed, metabolic consequences, which may seriously affect the health of an individual. PubMed was searched using the following key words (each key word alone and in combination): gut microbiota, microbiome, non-steroidal anti inflammatory drugs, proton pump inhibitors, enteropathy, probiotic, antibiotic, mucosal injury, enteroscopy, and capsule endoscopy. Google engine search was also carried out to identify additional relevant articles. Both original and review articles published in English were reviewed.

Hydrogen sulphide protects against NSAID-enteropathy through modulation of bile and the microbiota

BACKGROUND AND PURPOSE

Hydrogen sulphide is an important mediator of gastrointestinal mucosal defence. The use of non-steroidal anti-inflammatory drugs (NSAIDs) is significantly limited by their toxicity in the gastrointestinal tract. Particularly concerning is the lack of effective preventative or curative treatments for NSAID-induced intestinal damage and bleeding. We evaluated the ability of a hydrogen sulphide donor to protect against NSAID-induced enteropathy.

EXPERIMENTAL APPROACH

Intestinal ulceration and bleeding were induced in Wistar rats by oral administration of naproxen. The effects of suppression of endogenous hydrogen sulphide synthesis or administration of a hydrogen sulphide donor (diallyl disulphide) on naproxen-induced enteropathy was examined. Effects of diallyl disulphide on small intestinal inflammation and intestinal microbiota were also assessed. Bile collected after in vivo naproxen and diallyl disulphide administration was evaluated for cytotoxicity in vitro using cultured intestinal epithelial cells.

KEY RESULTS

Suppression of endogenous hydrogen sulphide synthesis by β-cyano-L-alanine exacerbated naproxen-induced enteropathy. Diallyl disulphide co-administration dose-dependently reduced the severity of naproxen-induced small intestinal damage, inflammation and bleeding. Diallyl disulphide administration attenuated naproxen-induced increases in the cytotoxicity of bile on cultured enterocytes, and prevented or reversed naproxen-induced changes in the intestinal microbiota.

CONCLUSIONS AND IMPLICATIONS

Hydrogen sulphide protects against NSAID-enteropathy in rats, in part reducing the cytotoxicity of bile and preventing NSAID-induced dysbiosis.

H2S-releasing drugs: anti-inflammatory, cytoprotective and chemopreventative potential

Hydrogen sulfide exerts a number of cytoprotective and anti-inflammatory effects in many organ systems. In an effort to exploit these potent and beneficial effects, a number of hydrogen sulfide-releasing derivatives of existing drugs have been developed and extensively tested in pre-clinical models. In particular, efforts have been made by several groups to develop hydrogen sulfide-releasing derivatives of a number of nonsteroidal anti-inflammatory drugs. The main goal of this approach is to reduce the gastrointestinal ulceration and bleeding caused by this class of drugs, particularly when used chronically such as in the treatment of arthritis. However, these drugs may also have utility for prevention of various types of cancer. This paper provides an overview of some of the mechanisms underlying the anti-inflammatory and cytoprotective actions of hydrogen sulfide. It also gives some examples of hydrogen sulfide-releasing anti-inflammatory drugs, and their actions in terms of reducing inflammation and attenuating the development of cancer in experimental models.

NSAID-gastroenteropathy: new aspects of pathogenesis and prevention

Nonsteroidal anti-inflammatory drugs (NSAIDs) remain among the most commonly used medications because of their effectiveness in reducing pain and inflammation. Inhibitors of gastric acid secretion can substantially reduce the damaging effects of NSAIDs in the stomach and duodenum. However, there are no proven effective preventative or curative treatments for NSAID-induced enteropathy. In recent years, substantial progress has been made in better understanding the pathogenesis of NSAID-enteropathy, and in particular the interplay of enteric bacteria, bile and the enterohepatic recirculation of the NSAIDs. Moreover, it is becoming clear that suppression of gastric acid secretion significantly worsens NSAID-enteropathy.

Drug-drug interaction between NSAIDS and low-dose aspirin: a focus on cardiovascular and GI toxicity

INTRODUCTION

The aging of the population in the US and other countries means that a large number of people will likely take NSAIDs for the relief of pain and low-dose aspirin (LD-ASA) for cardioprotection. However, the cardioprotective value of LD-ASA can be compromised in patients who take NSAIDs concomitantly, because some NSAIDs competitively bind to critical amino-acid residues on cyclooxygenase (COX) enzymes and interfere with the mechanism of antiplatelet activity of LD-ASA.

AREAS COVERED

A review of the literature was conducted to provide an overview of current issues surrounding the concomitant use of NSAIDs and LD-ASA, to explore potential mechanisms for this drug-drug interaction and to consider current and future treatment options that may mitigate the risk associated with their concomitant use.

EXPERT OPINION

NSAIDs offer effective pain relief for the most common forms of pain, such as low back pain, musculoskeletal pain associated with arthritis, postsurgical pain, headache, acute pain syndromes, menstrual pain and dental pain. The development of NSAID formulations that offer effective pain control with fewer or less serious adverse effects due to interference with ASA would be a valuable medical advance. Several promising treatment options and regimens may be available in the future.