Effects of veverimer on serum bicarbonate and physical function in women with chronic kidney disease and metabolic acidosis: a subgroup analysis from a randomised, controlled trial

Veverimer, a Nonabsorbed Gastrointestinal Tract HCl Binder, Decreases Renal Ammoniagenesis and Mitigates Nephrotoxic Serum Nephritis

Key Points

Background

Increased tubular ammoniagenesis is an adaptive response to progressive kidney disease, facilitating net acid excretion. However, excess ammonia production can also exacerbate kidney disease progression, in part, by activating the alternative complement cascade. Oral Na bicarbonate therapy can decrease the systemic H+ burden, limiting ammonia production. However, poor compliance limits bicarbonate's efficacy. Veverimer is an oral, Na+-free, nonabsorbed polymer that binds H+ within the gastrointestinal (GI) tract. This stimulates GI carbonic anhydrase-mediated bicarbonate production and systemic bicarbonate uptake. Hence, the goals of this study were to test whether GI HCl binding decreases renal tubular ammoniagenesis, to assess whether complement activation decreases, and to determine whether these changes can mitigate nephrotoxic serum (NTS) nephritis, in which complement activation may play a role.

Methods

A normal diet± veverimer (4.5% w/w) was fed to normal mice for approximately 1 week. Veverimer's effect on plasma bicarbonate; blood/urinary pH; urinary ammonia excretion; and tubular H+ transporter, NHE3, density was assessed. Additional mice were fed the normal or veverimer diet after NTS injection. Urine protein, albumin, ammonia, C5b-9 excretion, and plasma C3a levels were measured 1 week and/or 2 weeks after NTS injection. Renal histologic changes (hematoxylin and eosin stain; C5b-9, CD45 immunohistochemistry), and selected injury mediators/biomarkers (NGAL, IL-6, MCP-1, TGFβ1, and endothelin-1 mRNAs) were also assessed.

Results

Veverimer increased plasma bicarbonate/urinary pH, reduced urinary ammonia, and decreased NHE3 in normal mice. Veverimer also reduced NTS-induced proteinuria/albuminuria, urinary ammonia, and C5b-9 excretion (by approximately 60%, 75%, and 50%, respectively). Significant reductions in NTS-induced glomerular/tubulointerstitial injury, inflammatory/profibrotic gene expression, renal C5b-9 deposition, and suppressed plasma C3a levels were observed. Oral bicarbonate also conferred protection, implicating bicarbonate's role in veverimer's beneficial effect.

Conclusions

Veverimer-mediated bicarbonate generation can suppress renal ammoniagenesis and complement activation. These findings suggest a potential benefit of veverimer/bicarbonate therapy in selected complement-mediated kidney diseases.

Chronic kidney disease-induced muscle atrophy: Molecular mechanisms and promising therapies

Chronic kidney disease (CKD) is a high-risk chronic catabolic disease due to its high morbidity and mortality. CKD is accompanied by many complications, leading to a poor quality of life, and serious complications may even threaten the life of CKD patients. Muscle atrophy is a common complication of CKD. Muscle atrophy and sarcopenia in CKD patients have complex pathways that are related to multiple mechanisms and related factors. This review not only discusses the mechanisms by which inflammation, oxidative stress, mitochondrial dysfunction promote CKD-induced muscle atrophy but also explores other CKD-related complications, such as metabolic acidosis, vitamin D deficiency, anorexia, and excess angiotensin II, as well as other related factors that play a role in CKD muscle atrophy, such as insulin resistance, hormones, hemodialysis, uremic toxins, intestinal flora imbalance, and miRNA. We highlight potential treatments and drugs that can effectively treat CKD-induced muscle atrophy in terms of complication treatment, nutritional supplementation, physical exercise, and drug intervention, thereby helping to improve the prognosis and quality of life of CKD patients.