Childhood idiopathic nephrotic syndrome and atopic diseases: Is there a relationship?

Nephrotic syndrome is a condition of massive proteinuria that leads to hypoalbuminaemia and oedema. In the pediatric age, the most common form of nephrotic syndrome is childhood idiopathic nephrotic syndrome (CINS). Although the etiological mechanisms underlying CINS are still unclear, the disease is considered to be immune-mediated. Several studies have previously reported a possible association between CINS and atopy, with the latter defined as abnormal immunoglobulin-E response on the background of a T-helper 2 (Th2)-driven immune system. In fact, both experimental and clinical studies have suggested that idiopathic nephrotic syndrome can be associated and/or triggered by a wide array of atopic diseases, though this remains a highly controversial topic. Exposure to inhalant-allergens (and/or introduction of food-allergens) has been previously correlated with the onset and/or the relapse of CINS in some children and a significant worse response to steroid therapy has been also described in reports of CINS associated to concomitant atopic diseases. In this review, we analyzed previous studies with the aim to clarify, basing on the existent literature, the association between atopy and idiopathic nephrotic syndrome. Additionally, we also speculated on the underlying immunological pathways that could potentially make some children prone to both CINS and atopic diseases.