Zonulin, iron status, and anemia in kidney transplant recipients: are they related?

Background: In patients after kidney transplantation, anemia is relatively common and is associated with impaired kidney function, subclinical inflammatory state, and immunosuppressive treatment. Zonulin-prehaptoglobin-2, a newly discovered protein, is necessary for integrity of intracellular tight junctions in the gut. Taking into consideration iron metabolism, including its absorption in the gut, we designed a cross-sectional study to look for the possible interactions among zonulin, iron status, and anemia in kidney transplant recipients.
Methods: The study was performed on 72 stable kidney transplant recipients and 22 healthy volunteers. Zonulin, iron status, and inflammatory markers were assessed with the use of commercially available kits.
Results: Zonulin was significantly lower in kidney allograft recipients than in healthy volunteers (P < .001). Zonulin correlated with systolic blood pressure (r = -0.33; P < .05), thyroid-binding globulin (r = 0.24; P < .05), hematocrit (r = 0.28; P < .005), hemoglobin (r = 0.32; P < .01), total protein (r = -0.33; P < .01), erythrocyte count (r = 0.26; P < .05), and fasting glucose (r = -0.25; P < .05). Zonulin was not affected by sex, type of immunosuppressive therapy, presence of diabetes, coronary artery disease, heart failure, hypertension, or cause of end-stage renal disease. Zonulin was not related to any of the iron parameters studied. In multiple regression analysis, predictors of zonulin were total protein and thyroglobulin-binding protein, explaining 46% of variation.
Conclusions: Zonulin, with its poorly defined function, does not seem to play a role in the anemia in kidney allograft recipients; however, it seems to be related to the absorption process in the gut.