Eosinophilia and Kidney Disease: More than Just an Incidental Finding?

Abstract

Peripheral blood eosinophilia (PBE), defined as 500 eosinophils or above per microliter (µL) blood, is a condition that is not uncommon but often neglected in the management of patients with chronic kidney disease (CKD), acute kidney injury (AKI), or patients on renal replacement therapy (RRT). The nature of PBE in the context of kidney diseases is predominantly secondary or reactive and has to be distinguished from primary eosinophilic disorders. Nonetheless, the finding of persistent PBE can be a useful clue for the differential diagnosis of underdiagnosed entities and overlapping syndromes, such as eosinophilic granulomatosis with polyangiitis (EGPA), IgG4-related disease (IgG4-RD), acute interstitial nephritis (AIN), or the hypereosinophilic syndrome (HES). For patients on RRT, PBE may be an indicator for bio-incompatibility of the dialysis material, acute allograft rejection, or Strongyloides hyperinfection. In a subset of patients with EGPA, eosinophils might even be the driving force in disease pathogenesis. This improved understanding is already being used to facilitate novel therapeutic options. Mepolizumab has been licensed for the management of EGPA and is applied with the aim to abrogate the underlying immunologic process by blocking interleukin-5. The current article provides an overview of different renal pathologies that are associated with PBE. Further scientific effort is required to understand the exact role and function of eosinophils in these disorders which may pave the way to improved interdisciplinary management of such patients.

Multiplex Bead Array Assay of a Panel of Circulating Cytokines and Growth Factors in Patients with Albuminuric and Non-Albuminuric Diabetic Kidney Disease

“…A prospective cohort study among US veterans demonstrated elevated peripheral blood eosinophil count in CKD cohort compared to cohort without CKD. Among patients with T2D, eosinophilia was associated with albumin excretion [72]. Eotaxin levels were elevated in the kidneys in Long-Evans rats on a high-fat diet.…”

Higher Eosinophils Predict Death-Censored Technique Failure in Peritoneal Dialysis Patients

“…The peritoneal cavity is a major reservoir of eosinophils under homeostatic and inflammatory states [18] and where eosinophils become activated and cause effects on the peritoneum. Hypersensitivity and intraperitoneal inflammatory reactions induced by PD drive the activation of Th2 cells and other inflammatory cells [19,20], releasing cytokines including IL-5, granulocytemacrophage colony-stimulating factor (GM-CSF), and IL-3, which trigger eosinophil proliferation, activation, and chemotaxis to the peritoneum [21]. There are several possible changes to the peritoneum induced by activated eosinophils.…”

The Yin and Yang of Alarmins in Regulation of Acute Kidney Injury

“…TSLP was associated with NF-κB signaling to elicit the inflammatory response. Other granule-derived peptides such as those produced by eosinophils ( 73 ), and granulysins that are secreted by cytotoxic T lymphocytes and NK cells ( 145 ), were reported in renal allograft rejection ( 76 , 77 ), and may also be linked with AKI and mortality ( 75 ).…”