Relative mRNA expression signature of PBMC-derived NLRP3 inflammasomes in progression of type 2 diabetic kidney disease.

Background: NLRP3 inflammasome triggered by chronic hyperglycemia in resident pro-inflammatory leucocytes of the diabetic kidney is predominant in perpetuating chronic inflammation and renal fibrosis. This study focuses on NLRP3 expressed in circulatory immune cells, to elucidate the systemic level significance of NLRP3 inflammasome in contributing to diabetic kidney disease (DKD) progression. We therefore, aim to investigate the mRNA expression signature of genes encoding the NLRP3 inflammasome complex in circulatory immune cells and its association with severity of DKD in type 2 diabetes mellitus (T2DM) patients.

Materials & Methods: PBMCs were isolated from the blood samples of 160 T2DM patients presenting with varying grades of DKD severity. RNA extracted from the PBMCs was used for relative quantification of our target genes using SYBRGreen real-time RT-qPCR. Association of DKD progression with NLRP3 component genes' mRNA expression was analyzed statistically.

Results: Expression of NLRP3, CASP1, and IL1β mRNAs were significantly elevated in DKD; higher HSP72 mRNA expression accompanied normoalbuminuric T2DM. PBMC-derived NLRP3 mRNA levels correlated positively with circulatory monocyte population. Plasma NLRP3 protein and NLRP3 mRNA expressed in PBMCs were associated inversely with decreasing eGFR, independent of diabetes duration, age and sex. Contrastingly, HSP72 mRNA levels declined with decline in eGFR. No association between NLRP3 complex genes and HSP72 mRNA expression in PBMCs was observed, although HSP72 exhibited inverse characteristics to that of NLRP3 complex in the study.

Conclusion: A dynamic interplay exists between DKD progression and PBMC-derived mRNA expression of NLRP3 inflammasome and HSP72. At the systemic level, while NLRP3 exasperates inflammation, the protective role of HSP72 is extinguished. Their expression patterns in circulatory immune cells are associated with eGFR decline, tying systemic inflammatory state to worsening kidney disease outcomes.