Dendritic cells and immune kidney disease

Dendritic cells (DCs) are potent antigen presenting cells making them critical mediators of the adaptive immune response. As ‘first responders’ to foreign antigen, they also play a role in the activation of the innate immune response. With very limited knowledge of kidney DCs available prior to commencement of this thesis, these studies explore the experimental procedures for isolating them and the examination of their behaviour in different disease models. In Chapter 3 kidney DCs are shown to have an interstitial and periglomerular distribution. A technique to introduce antigen directly into the kidney parenchyma is innovated and the DC capacity to stimulate the adaptive immune response is assessed using antigen-specific transgenic T cells and confocal microscopy is examined. The importance of CD80, CD86 and PD-1 upregulation on kidney DC is revealed, but by comparison to skin DCs, kidney DCs have a dampened and delayed capacity to stimulate T cell proliferation. Chapter 4 builds on Chapter 3 and establishes and examines techniques for the isolation of kidney DCs and their detailed phenotypic analysis. Kidney digestion and enrichment by flow-activated cell sorting is refined and shown to be superior to magnetic activated cell sorting, density-based separation or combinations of these. Phenotypic analysis by flow cytometry is expanded using a broad panel of antibodies and multiple control samples and an in-vitro culture using DCs pulsed with ovalbumin and placed in culture with CFSE-labelled OT-I or OT-II T cells is optimised. Chapter 5 studies DC behaviour in the context of an innate immune response and reveals an increased number of CD11b+ DCs, a reduced number of F4/80+ DCs and an infiltration of inflammatory DCs after unilateral ureteric obstruction (UUO). Despite a heightened capacity to stimulate T cell proliferation, depletion of kidney DCs does not ameliorate kidney damage after UUO, suggesting that although DCs are activated by the inflammatory insult, this does not lead to renal fibrosis. In Chapter 6, the receptor for advanced glycation end-products (RAGE) is studied in an experimental model of crescentic glomerulonephritis. Surprisingly, no differences in major disease outcomes are identified between wild-type and RAGE-/- mice. Severe disease with high mortality in wild-type donor to RAGE-/- recipient bone-marrow chimeric mice suggests that the absence of intra-renal RAGE, potentially the anti-inflammatory soluble form of RAGE, amplifies disease. Contrary to RAGE being pro-inflammatory, this raises the possibility of a more complex pathway, involving the different RAGE transcripts, in which the secretion of local soluble RAGE may be critical in protecting the kidney from infiltrating leukocytes. Interestingly, resident kidney DCs in RAGE-/- mice incorporate significantly increased total numbers of DCs, lower expression of CD11b and fewer plasmacytoid DCs. Through the course of this thesis, important laboratory techniques are developed, which provide important tools to expand the research armamentarium available to examine kidney DCs. Experimental animal models characterised by either adaptive or immune system responses add significantly to the body of knowledge of DC behaviour in a spectrum of kidney diseases, which will hopefully provide impetus for novel therapies in the future