Dietary zinc is a key environmental modifier in the progression of IgA nephropathy

PLoS One. 2014 Feb 28;9(2):e90558. doi: 10.1371/journal.pone.0090558. eCollection 2014.

Abstract

IgA nephropathy (IgAN) shows diverse epidemiological characteristics, resulting from both genetic and acquired (e.g., environmental) causes. Environmental factors, such as diet or exposure to exogenous antigens, may prescribe the progression or prognosis of IgAN. It remains unclear as to how diet and infection influence susceptibility to IgAN. A relationship, such as Toll-like receptors (TLRs), especially TLR9 and TLR4, was demonstrated between IgAN and pathogen-recognition molecules. Recently, zinc (Zn) was discovered to be involved in various immune-related diseases, affecting B, T, and dendritic cells (DCs). This study investigates the relationship between dietary Zn and IgAN development in IgAN-prone mice. Seven-week-old IgAN-prone mice were divided into low, normal, and high Zn diet groups. To assess exogenous pathogen-mediated immune responses, lipopolysaccharide (LPS) was nasally administered. The activity of IgAN was biochemically and pathologically evaluated during the disease course. We also examined in vitro IgA production in spleen cells or in combinations of cocultured B, T, and DCs under various Zn conditions with or without LPS. Dietary conditioning with Zn affected serum immunoglobulins and urinary albumin levels, and mesangial deposition of IgA and IgG. Zn deficiency is associated with IgAN progression through the activation of the TLR4/TIR-domain-containing adapter-inducing interferon-β (TRIF), but not the TLR9, in DCs. Zn supplementation prevented disease aggravation. Our findings indicate that immune conditioning with dietary Zn alters nephritogenic IgA production after mucosal infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Vesicular Transport / genetics
  • Adaptor Proteins, Vesicular Transport / immunology
  • Albuminuria / immunology
  • Animals
  • Body Weight / drug effects
  • Body Weight / immunology
  • Cells, Cultured
  • Dietary Supplements*
  • Disease Progression
  • Female
  • Gene Expression / immunology
  • Glomerular Mesangium / immunology
  • Glomerular Mesangium / metabolism
  • Glomerulonephritis, IGA / genetics
  • Glomerulonephritis, IGA / immunology*
  • Glomerulonephritis, IGA / metabolism
  • Immunoglobulin A / immunology
  • Immunoglobulin A / metabolism
  • Immunoglobulin G / immunology
  • Immunoglobulin G / metabolism
  • Interferon-beta
  • Lipopolysaccharides / administration & dosage
  • Lipopolysaccharides / immunology*
  • Mice
  • Microscopy, Confocal
  • Myeloid Differentiation Factor 88 / genetics
  • Myeloid Differentiation Factor 88 / immunology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Spleen / immunology
  • Spleen / metabolism
  • Time Factors
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / immunology
  • Zinc / administration & dosage
  • Zinc / blood
  • Zinc / immunology*

Substances

  • Adaptor Proteins, Vesicular Transport
  • Immunoglobulin A
  • Immunoglobulin G
  • Lipopolysaccharides
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • TICAM-1 protein, mouse
  • Toll-Like Receptor 4
  • Interferon-beta
  • Zinc

Grant support

This study was supported in part by a Grant-in-Aid for Progressive Renal Diseases Research, Research on Intractable Disease, from the Ministry of Health, Labour and Welfare of Japan, by JSPS KAKENHI Grant Number 23790957, by Strategic International Research Cooperative Program, Japan Science and Technology Agency (JST), and by a research grant from the Study Group on IgAN in Japan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.