Oxidized low-density lipoprotein antigen transport induces autoimmunity in the renal tubulointerstitium

Chronic kidney disease involves inflammation/oxidative stress, which contributes to progressive kidney injury.

Male Sprague-Dawley rats underwent 5/6 nephrectomy (Nx) or sham Nx and were sacrificed after 2 days, 2 weeks and 4 weeks. Microarray analysis expression sets over time suggested the evolution of renal lymphocyte infiltration and antigen-presenting cell (APC) activation after 5/6Nx. RT-PCR analysis also confirmed the migration and activation of lymphocytes and APCs through the upregulation of CD3, CXCR3/CXCL10 and CCR7/CCL19 mRNA in remnant kidney (RK). Purified T lymphocytes from spleen and unilateral ureteral obstruction (UUO) kidney were incubated with oxidized low-density lipoprotein (Ox-LDL)-treated major histocompatibility complex class II (MHC II)-expressing APCs. Culture supernatant was collected for mouse IFN-γ ELISA and cell proliferation was measured.

Ox-LDL deposited predominantly in renal tubulointerstitial areas of RK, increased over time, and co-stained with lectin-like Ox-LDL receptor in affected renal tubular cells. Both Ox-LDL and renal-specific glycoprotein Tamm-Horsfall protein were identified in renal lymph nodes. Cells co-staining for major MHC II and Ox-LDL were observed in RK and draining renal lymph nodes after 5/6Nx. Similarly, Ox-LDL was also present in tubules after UUO, CD3-positive T cells were present in the interstitium, and Ox-LDL-treated MHC II-expressing APCs induced proliferation and IFN-γ production in renal tubulointerstitial T lymphocytes isolated from kidneys after UUO.

These data demonstrate that the tubulointerstitial inflammatory infiltrate that accompanies chronic kidney disease reflects, at least in part, the development of autoimmunity to novel antigens generated during renal injury.