Acetate-Free Biofiltration Versus Online Acetate-Free Hemodiafiltration in Patients at High Risk of Hemodialysis Intolerance

International audienceIntradialytic hypotension (IDH) is one of the most frequent and worrying issues in chronic hemodialysis. Systolic blood pressure (BP) <90 mm Hg has the strongest association with mortality in patients receiving chronic kidney replacement therapy (CKRT). IDH results from the combination of excessive ultrafiltration rate, membrane bio-incompatibility, and inappropriate hemodynamic response (heart rate and contractility, vascular tone). Modulation of the dialysate composition can improve tolerance, but standard bicarbonate dialysis remains associated with frequent IDH in patients at high risk. Online high-volume hemodiafiltration (HDF) was proposed to improve hemodynamic tolerance but was also associated with IDH in a subset of patients

Homeostasis of the gut barrier and potential biomarkers

The gut barrier plays a crucial role by spatially compartmentalizing bacteria to the lumen through the production of secreted mucus and is fortified by the production of secretory IgA (sIgA) and antimicrobial peptides and proteins. With the exception of sIgA, expression of these protective barrier factors is largely controlled by innate immune recognition of microbial molecular ligands. Several specialized adaptations and checkpoints are operating in the mucosa to scale the immune response according to the threat and prevent overreaction to the trillions of symbionts inhabiting the human intestine. A healthy microbiota plays a key role influencing epithelial barrier functions through the production of short-chain fatty acids (SCFAs) and interactions with innate pattern recognition receptors in the mucosa, driving the steady-state expression of mucus and antimicrobial factors. However, perturbation of gut barrier homeostasis can lead to increased inflammatory signaling, increased epithelial permeability, and dysbiosis of the microbiota, which are recognized to play a role in the pathophysiology of a variety of gastrointestinal disorders. Additionally, gut-brain signaling may be affected by prolonged mucosal immune activation, leading to increased afferent sensory signaling and abdominal symptoms. In turn, neuronal mechanisms can affect the intestinal barrier partly by activation of the hypothalamus-pituitary-adrenal axis and both mast cell-dependent and mast cell-independent mechanisms. The modulation of gut barrier function through nutritional interventions, including strategies to manipulate the microbiota, is considered a relevant target for novel therapeutic and preventive treatments against a range of diseases. Several biomarkers have been used to measure gut permeability and loss of barrier integrity in intestinal diseases, but there remains a need to explore their use in assessing the effect of nutritional factors on gut barrier function. Future studies should aim to establish normal ranges of available biomarkers and their predictive value for gut health in human cohorts