Ignacio Quevedo Romero¹, Andrea Carrasco², LAURA HURTADO NAVARRO³, PABLO PELEGRIN VIVANCOS³, SANTIAGO CUEVAS GONZÁLEZ³

(1) dep. cirugia digestiva, endocrina y transplante de organos abdominales. unidad de inflamación. IMIB, 30204, España (Región de Murcia)
(2) BioMedical Research Institute of Murcia (IMIB-Arrixaca), España (Región de Murcia)
(3) CIRUGÍA DIGESTIVA, ENDOCRINA Y TRASPLANTE DE ÓRGANOS ABDOMINALES, IMIB-Arrixaca, España

Kidney diseases remain a worldwide public health problem characterized by sustained inflammation. Inflammasome has recently emerged as crucial regulators of renal inflammation. In particular, the NLRP3 inflammasome, is involved in the activation of caspase-1 and the maturation of IL-1β and IL-18, which have been strongly associated with diabetic nephropathy. DJ-1 is a redox-sensitive chaperone with reported antioxidant and anti-inflammatory properties in the kidney, in part due to the regulation of transcription factor Nrf2, which regulates the expression of several antioxidant genes. The 20 amino acid (aa) peptide ND-13, is a new experimental treatment that consists of 13 highly conserved aa from the DJ-1 sequence and a TAT-derived 7 aa sequence that helps in cell penetration.

In this study, we determined NLRP3 inflammasome activation in mouse bone marrow macrophages and peripheral blood mononuclear cells (PBMCs) of diabetic nephropathy patients and the capacity of Nrf2 inducers to attenuate inflammasome activation. Mouse bone marrow macrophages were stimulated with LPS/ATP and treated with Bardoxolone (1µM), an Nrf2 inducer, and ND-13 (1µM) for 24 hours. PBMCs isolated from the blood of controls patients, patients with diabetes, and patients with diabetes and renal disease were cultured in vitro and stimulated with LPS/ATP.

The IL-1β concentration in the medium increased by the stimulation of the NLRP3 inflammasome by LPS/ATP, and decreased in macrophages pre-treated with Bardoxolone (65.07±26%,n=4, P<0.05) but not in macrophages pre-treated with ND-13. Concentration-response curve demonstrates the capacity of Bardoxolone to inhibit NLRP3 inflammasome activation by LPS/ATP. Additionally, in presence of H2O2 (100nM), ND-13 (1µM) significantly decreased IL-1β release after NLRP3 activation (88.6±1.2%, n=4, P<0.05), suggesting the capacity of the ND-13 peptide to reduce NLRP3 inflammasome activity under pathological conditions. Compared to controls and diabetic individuals, patients with diabetic nephropathy presented a trend to increase IL-1β release.

All these data point out that inflammasome pre-activation could have a role in the pathogenesis of diabetic nephropathy, that Nrf2 pathway stimulation is a promising approach to decrease immune cells inflammasome pre-activation, and ND-13 could be a new approach to protect the renal damage associated to inflammasome over-activation in renal diseases.