PGE2, Kidney Disease, and Cardiovascular Risk: Beyond Hypertension and Diabetes

An important measure of cardiovascular health is obtained by evaluating the global cardiovascular risk, which comprises a number of factors, including hypertension and type 2 diabetes, the leading causes of illness and death in the world, as well as the metabolic syndrome. Altered immunity, inflammation, and oxidative stress underlie many of the changes associated with cardiovascular disease, diabetes, and the metabolic syndrome, and recent efforts have begun to elucidate the contribution of PGE2 in these events. This review summarizes the role of PGE2 in kidney disease outcomes that accelerate cardiovascular disease, highlights the role of cyclooxygenase-2/microsomal PGE synthase 1/PGE2 signaling in hypertension and diabetes, and outlines the contribution of PGE2 to other aspects of the metabolic syndrome, particularly abdominal adiposity, dyslipidemia, and atherogenesis. A clearer understanding of the role of PGE2 could lead to new avenues to improve therapeutic options and disease management strategies.

Chronic kidney disease: targeting prostaglandin E2 receptors

Chronic kidney disease is a leading cause of morbidity and mortality in the world. A better understanding of disease mechanisms has been gained in recent years, but the current management strategies are ineffective at preventing disease progression. A widespread focus of research is placed on elucidating the specific processes implicated to find more effective therapeutic options. PGE2, acting on its four EP receptors, regulates many renal disease processes; thus EP receptors could prove to be important targets for kidney disease intervention strategies. This review summarizes the major pathogenic mechanisms contributing to initiation and progression of chronic kidney disease, emphasizing the role of hyperglycemia, hypertension, inflammation, and oxidative stress. We have long recognized the multifaceted role of PGs in both the initiation and progression of chronic kidney disease, yet studies are only now seriously contemplating specific EP receptors as targets for therapy. Given the plethora of renal complications attributed to PG involvement in the kidney, this review highlights these pathogenic events and emphasizes the PGE2 receptor targets as options available to complement current therapeutic strategies.

Gut Microbiota Modulation and Fecal Transplantation: An Overview on Innovative Strategies for Hepatic Encephalopathy Treatment

Hepatic encephalopathy (HE) is a major complication of cirrhosis, which is associated with gut microbial composition and functional alterations. Current treatments largely focus on gut microbiota using lactulose, rifaximin and other agents. However, despite these treatments, patients with HE have a high rate of readmission, morbidity and cognitive impairment. Fecal microbiota transplant (FMT) involves introduction of a donor microbiota into a recipient and is currently mainly used for recurrent C. difficile infection (rCDI). The role of FMT in cirrhosis and HE is evolving. There have been two randomized clinical trials (RCT) and several case reports/series in cirrhosis. Both RCTs were safety-focused phase 1 trials. One involved pre-FMT antibiotics and FMT enema versus standard of care, while the other involved 15 FMT capsules versus placebo without pre-FMT antibiotics. There was evidence of safety in both trials and the FMT group demonstrated reduction in hospitalizations compared to the non-FMT group. Changes in microbial function centered around short-chain fatty acids, bile acids and brain function showed improvement in the FMT groups. Long-term follow-up demonstrated continued safety and reduction in the antibiotic-resistance gene carriage. However, larger trials of FMT in HE are needed that can refine the dose, duration and route of FMT administration.

PGE2 receptor EP3 inhibits water reabsorption and contributes to polyuria and kidney injury in a streptozotocin-induced mouse model of diabetes

AIMS/HYPOTHESIS

The first clinical manifestation of diabetes is polyuria. The prostaglandin E2 (PGE2) receptor EP3 antagonises arginine vasopressin (AVP)-mediated water reabsorption and its expression is increased in the diabetic kidney. The purpose of this work was to study the contribution of EP3 to diabetic polyuria and renal injury.

METHODS

Male Ep 3 (-/-) (also known as Ptger3 (-/-)) mice were treated with streptozotocin (STZ) to generate a mouse model of diabetes and renal function was evaluated after 12 weeks. Isolated collecting ducts (CDs) were microperfused to study the contribution of EP3 to AVP-mediated fluid reabsorption.

RESULTS

Ep 3 (-/-)-STZ mice exhibited attenuated polyuria and increased urine osmolality compared with wild-type STZ (WT-STZ) mice, suggesting enhanced water reabsorption. Compared with WT-STZ mice, Ep 3 (-/-)-STZ mice also had increased protein expression of aquaporin-1, aquaporin-2, and urea transporter A1, and reduced urinary AVP excretion, but increased medullary V2 receptors. In vitro microperfusion studies indicated that Ep 3 (-/-) and WT-STZ CDs responded to AVP stimulation similarly to those of wild-type mice, with a 60% increase in fluid reabsorption. In WT non-injected and WT-STZ mice, EP3 activation with sulprostone (PGE2 analogue) abrogated AVP-mediated water reabsorption; this effect was absent in mice lacking EP3. A major finding of this work is that Ep 3 (-/-)-STZ mice showed blunted renal cyclooxygenase-2 protein expression, reduced renal hypertrophy, reduced hyperfiltration and reduced albuminuria, as well as diminished tubular dilation and nuclear cysts.

CONCLUSIONS/INTERPRETATION

Taken together, the data suggest that EP3 contributes to diabetic polyuria by inhibiting expression of aquaporins and that it promotes renal injury during diabetes. EP3 may prove to be a promising target for more selective management of diabetic kidney disease.

Severe Vitamin B12 Deficiency Mimicking Microangiopathic Hemolytic Anemia

Most individuals with vitamin B12 deficiency present with anemia, fatigue, and neurologic disturbances such as paresthesia and loss of sensory function if chronic. However, in severe states, it may manifest as hemolytic anemia, thrombocytopenia, schistocytosis, elevated lactate dehydrogenase, and low reticulocyte production. This phenomenon is known as pseudo-thrombotic microangiopathy (TMA), and is most commonly due to pernicious anemia. The overlap in clinical presentation with primary TMA creates a challenge in the diagnosis and management of pseudo-TMA. Primary TMA, particularly thrombotic thrombocytopenic purpura, is emergently managed with plasma exchange and may require admission to an intensive care unit due to high risk of mortality. In contrast, pseudo-TMA does not respond to plasma exchange and instead is treated with vitamin B12 supplementation. Patients with this atypical presentation of B12 deficiency may receive unnecessary, costly, and potentially harmful therapy. We present the case of a patient with pseudo-TMA in the setting of pernicious anemia.

Bowel Movement Frequency Is Not Linked With Cognitive Function in Cirrhosis

The spectrum of hepatic encephalopathy (HE) ranges from overt HE (OHE) to cognitive impairment (ie, covert) HE (CHE).¹ The first-line therapy is lactulose, which is titrated to achieve ~2-3 soft/loose daily bowel movements (BM). This metric is considered dogma for practitioners despite erratic results, GI adverse events, and poor tolerance in Western countries.¹ There are logistic barriers for the widespread uptake of rifaximin, the second-line therapy. Moreover, although BM frequency-directed dose titration of lactulose is the usual practice, its impact on objective cognitive performance is unclear. Our aim is to determine the impact of BM frequency on cognition in patients with/without prior OHE.

Glomerular filtration rate early after liver transplantation independently predicts atherosclerotic events

Cardiovascular disease (CVD) is an important cause of mortality among liver transplantation (LT) recipients; however, the data on CVD risk stratification following LT are limited. Thus, the primary aim of this study was to evaluate the association between decline in renal function early after LT and atherosclerotic events. This retrospective study included all patients receiving LT between 2007 and 2019. Early renal function was quantified as estimated glomerular filtration rate (GFR) 6 months after LT. The primary endpoint for the study was a composite atherosclerotic cardiovascular event of three-point major adverse cardiovascular events (MACEs), which includes nonfatal myocardial infarction (MI), nonfatal stroke, or death from CVD. A total of 553 LT recipients met entry criteria. After a median follow-up of 74 months (interquartile range 46-111), 94 (17%) LT recipients died and CVD-associated death occurred in 20 patients. MACE-3 occurred in 66 (12%) patients, with nonfatal MI being the most common event (n = 30). A strong inverse relationship between early GFR and MACE-3 was noted in unadjusted analysis with hazard ratio (HR) 0.96 (95% confidence interval [CI] 0.95-0.98; p = 0.0001) and remained significant even after accounting for age, sex, coronary artery disease, diabetes mellitus, hypertension, calcineurin inhibitor use, and Framingham Risk Score (FRS; HR 0.96, 95% CI 0.95-0.97; p = 0.0001 per unit increase in GFR). Furthermore, an independent interaction between GFR, FRS, and likelihood of developing an MACE-3 was noted. GFR 6 months following LT is a strong predictor of developing atherosclerotic events. This relationship is independent of traditional CVD risk stratification models (e.g. FRS) and thus has the potential to be incorporated into CVD risk assessment after LT but requires further validation.

Performance of Vibration-Controlled Transient Elastography and Clinical Prediction Models In Liver Transplant Recipients

Hepatic fibrosis is a strong predictor of clinical outcomes following liver transplantation (LT).1 Despite the centrality of hepatic fibrosis in clinical outcomes, the published literature with noninvasive fibrosis assessment in LT recipients is limited and liver biopsy, despite its invasive nature, remains the reference standard. Vibration-controlled transient elastography (VCTE) and clinical prediction models (CPM) are point-of-care tests that can provide noninvasive assessment of hepatic fibrosis2-4; however, the data comparing the diagnostic performance of VCTE and CPM in LT recipients are lacking. The current study evaluated the diagnostic performance of VCTE and CPM in LT recipients using best practices in regulatory sciences for biomarker development.

Impact of Liver Transplantation on Adipose Tissue Compartments and Its Association With Metabolic Sequela

BACKGROUND

Loss of skeletal muscle can be accompanied by an increase in adipose tissue leading to sarcopenic obesity. There are limited data on how liver transplantation (LT) might impact adipose tissue compartments, particularly among patients with metabolically active disease, such as nonalcoholic steatohepatitis (NASH) and subsequent metabolic sequela.

METHODS

Skeletal muscle, visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) were measured using cross-sectional imaging performed in 190 patients pre-LT, 6 mo post-LT and 12 mo post-LT. Changes in adipose tissue and their impact on metabolic diseases were determined in patients transplanted for NASH versus non-NASH.

RESULTS

Skeletal muscle, VAT, and SAT were similar in patients with NASH and non-NASH pre-LT despite a higher burden of metabolic diseases in patients with NASH. Following LT, no significant differences between skeletal muscle and SAT were observed in the entire cohort and among patients with NASH (versus non-NASH). LT recipients with the highest muscle mass pre-LT were at the greatest risk for muscle loss post-LT. A time-dependent increase in VAT was noted post-LT, which was more robust among patients with a history of NASH cirrhosis. In adjusted multivariate analysis, NASH versus non-NASH was a strong predictor of post-LT increase in VAT (β-coefficient 3.00, P  = 0.04). Pre-LT VAT was an independent predictor of post-LT serum triglycerides (β-coefficient 5.49 ± 2.78, P  = 0.05) and low-density lipoprotein cholesterol (β-coefficient 1.80 ± 0.75, P  = 0.02). A trend between pre-LT VAT and diabetes was noted but did not reach statistical significance.

CONCLUSIONS

VAT but not SAT increases rapidly after LT, especially among patients transplanted for NASH cirrhosis and predicts future metabolic burden.

Is Next-Generation Sequencing Appropriate for the Clinic?

Next-generation sequencing (NGS) has ignited a revolution in genomic medicine by eliminating the inherent limitations of conventional sequencing methods. Due to its high throughput and low-cost, clinics can use NGS to perform targeted and genome sequencing to make diagnoses or pre-screen for risk to future disease. Despite its clinical uses, many challenges exist before NGS becomes a mainstay in the clinic. There is a lack of understanding of the impact of genetic variants on health and disease and how to best apply genetic information to patient care. Nevertheless, the translation of base pair reads to clinical applications has truly begun.

Real-world effectiveness of COVID-19 vaccination in liver cirrhosis: a systematic review with meta-analysis of 51,834 patients

SARS-CoV-2 vaccinations were found to be highly effective in phase 3 clinical trials. However, these trials have not reported data regarding the subgroup of liver disease or excluded patients with liver disease. The effectiveness of COVID-19 vaccines among liver cirrhosis (LC) patients is unclear. We conducted this meta-analysis to assess the effectiveness of SARS-CoV-2 vaccination in LC patients. A comprehensive literature search was conducted to include all the relevant studies that compared the outcomes of LC patients who received SARS-CoV-2 vaccines vs. unvaccinated patients. Pooled risk ratios (RRs) with 95% confidence intervals (CIs) were calculated by the Mantel-Haenszel method within a random-effect model. Four studies with 51,834 LC patients (20,689 patients received at least one dose vs 31,145 were unvaccinated) were included. COVID-19-related complications, including hospitalization (RR 0.73, 95% CI 0.59-0.91, P = 0.004), mortality (RR 0.29, 95% CI 0.16-0.55, P = 0.0001), and need for invasive mechanical ventilation (RR 0.29, 95% CI 0.11-0.77, P = 0.01), were significantly lower in the vaccinated group compared to the unvaccinated group. SARS-CoV-2 vaccination in LC patients reduced COVID-19-related mortality, intubation, and hospitalization. SARS-CoV-2 vaccination is highly effective in LC. Further prospective studies, preferably randomized controlled trials, are necessary to validate our findings and determine which vaccine is superior in patients with LC.

"Wet Heparin" and "Wet Saline" EUS-Guided Liver Biopsy Techniques Both Provide High Rates of Specimen Adequacy for Benign Parenchymal Liver Disease

BACKGROUND

Endoscopic ultrasound-guided liver biopsy (EUS-LB) has emerged as a viable mean to obtain core tissue, but the optimal tools and techniques are still an area of active investigation.

AIMS

(1) To compare tissue adequacy using "wet saline" (WS) vs. "wet heparin" (WH) technique (2) To compare post-procedure pain between EUS-LB and percutaneous liver biopsy (PLB).

METHODS

Retrospective review of consecutive patients who underwent EUS-LB and PLB for benign parenchymal liver disease between May 2017 to October 2019 at a single tertiary veterans affairs medical center.

RESULTS

About 257 biopsies from 217 patients were included. Among the 102 EUS-LB specimens, 53 were obtained using WS technique and 49 were obtained using WH technique. Specimen adequacy was similar in both groups. Median Aggregate Specimen Length (ASL) and length of longest piece did not differ significantly between WS and WH groups. Clots were present more frequently in the WS group. Among patients who underwent EUS-LB of both right and left liver lobes, an adequate biopsy was obtained in 85% of patients in the WS group and 96% of patients in the WH group. The percentage of patients experiencing immediate post-procedure pain was higher with PLB compared to EUS-LB, but these results were not statistically significant.

CONCLUSIONS

Both WS and WH EUS-LB techniques can offer high rates of specimen adequacy with low rates of pain and other post-procedure complications.

CELLULITIS: A mnemonic to increase accuracy of cellulitis diagnosis

Cellulitis, a bacterial infection of the skin and subcutaneous tissue, is often misdiagnosed. Cellulitis accounts for a large number of all infectious disease-related hospitalizations in the U.S. Cellulitis can be challenging to diagnose since it lacks pathognomonic findings. We reviewed all articles on cellulitis within the last 20 years that included a statistical analysis, with odds ratios (OR), of specific clinical features of cellulitis. We then constructed a mnemonic encompassing the features with the highest odds ratios. Our mnemonic is CELLULITIS for cellulitis history, edema, local warmth, lymphangitis, unilateral, leukocytosis, injury, tender, instant onset, and systemic signs. The first characteristic has the highest OR and may be the easiest to recall: past episode(s) of cellulitis.

Risk factors for biliary strictures and leaks after living-donor liver transplantation: a systematic review and meta-analysis

BACKGROUND

Liver transplantation is the only curative treatment of end-stage liver disease. Unfortunately, a significant number of patients on the organ waitlist die waiting for an organ. Living-donor liver transplantation (LDLT) is an approach that has been used to expand organ availability. Although LDLT has excellent outcomes, biliary complications remain a significant drawback. This meta-analysis aimed to precisely assess the predictors of biliary stricture and leak after LDLT.

METHODS

PubMed, Embase, and Web of Science databases were searched from inception to January 2024. Only studies that used a multivariate model to assess risk factors for post-LDLT biliary stricture or leak in adult participants were included. Studies reporting unadjusted risk factors were excluded. Pooled adjusted odds ratios (ORs) and pooled hazard ratios (HRs) with 95% CIs for risk factors reported in ≥2 studies were obtained within a random-effects model.

RESULTS

Overall, 22 studies with 9442 patients who underwent LDLT were included. The post-LDLT biliary stricture rate was 22%, whereas the post-LDLT biliary leak rate was 14%. In addition, 13 unique risk factors were analyzed. Postoperative bile leak (OR, 4.10 [95% CI, 2.88-5.83]; HR, 3.88 [95% CI, 2.15-6.99]) was the most significant predictor of biliary stricture after LDLT. Other significant predictors of biliary stricture after LDLT were right lobe graft (OR, 2.56; 95% CI, 1.23-5.32), multiple ducts for anastomosis (OR, 1.62; 95% CI, 1.08-2.43), ductoplasty (OR, 2.07; 95% CI, 1.36-3.13), ABO incompatibility (OR, 1.45; 95% CI, 1.16-1.81), and acute cellular rejection (OR, 4.10; 95% CI, 2.88-5.83). Donor bile duct size (HR, 0.82; 95% CI, 0.74-0.91; P = .001, I2 = 0%) was found to be significantly associated with reduced risk of post-LDLT biliary stricture. Donor age, recipient age, recipient male sex, and duct-to-duct anastomosis were not associated with an increased risk of post-LDLT biliary strictures. Multiple ducts for anastomosis (OR, 1.86; 95% CI, 1.43-2.43) was a significant predictor of post-LDLT biliary leak. Recipient age, warm ischemia time, and duct-to-duct anastomosis were not associated with an increased risk of post-LDLT biliary leak.

CONCLUSION

In this meta-analysis, 7 unique risk factors were shown to be predictive of post-LDLT biliary stricture, one of which was associated with both post-LDLT biliary stricture and leak. Donor bile duct size was found to be protective against post-LDLT biliary strictures. Identifying reliable predictors is crucial for recognizing high-risk patients. This approach can facilitate the implementation of preventive measures, surveillance protocols, and targeted interventions to reduce the incidence of biliary strictures after LDLT.