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Abstract: TH-PO943

NLRP3 Inflammasome Is Activated in Skeletal Muscle of Patients with CKD

Session Information

Category: CKD (Non-Dialysis)

  • 1903 CKD (Non-Dialysis): Mechanisms

Authors

  • Verzola, Daniela, DiMI University of Genoa, Genoa, Italy
  • Milanesi, Samantha, DiMI University of Genoa, Genoa, Italy
  • Barisione, Chiara, University of Genova, Genova, Italy
  • Garibaldi, Silvano, DiMI University of Genoa, Genoa, Italy
  • Saio, Michela, DiMI University of Genoa, Genoa, Italy
  • Picciotto, Daniela, DiMI University of Genoa, Genoa, Italy
  • Murugavel, Abitha, DiMI University of Genoa, Genoa, Italy
  • Costigliolo, Francesca, DiMI University of Genoa, Genoa, Italy
  • Brunori, Giuliano, Ospedale S. Chiara, Trento - Italy, Trento TN, Italy
  • Venturelli, Chiara, APSS TRENTO, Trento, Italy
  • Garibotto, Giacomo, DiMI University of Genoa, Genoa, Italy
Background

Inflammation in skeletal muscle is implicated in the pathogenesis of insulin resistance and cachexia but why uremia upregulates muscle pro inflammatory cytokines is not completely understood.The NOD-like receptors (NLRs) are a group of pattern recognition receptors which activate the inflammasome platform. Aim of this study was to investigate the NLP3 role in skeletal muscle of CKD patients and the effects of uremic milieu on the NLRP3 pathway and mitochondria homeostasis.

Methods

Rectus abdominis muscle biopsies were collected from CKD5 patients (n= 25, 18M/7F, age 69±10 yrs, ,eGFR 8±1mL/min 1,73m2) and from 10 controls (C) (age 68±11 7M/3F, eGFR 100±4mL/min 1,73m2). NLRP3, IL1β expression was studied by immunohistochemistry, mRNA (NLRP3,IL1β,PGC1α,MFN2, NRF2) by rt-PCR. To assess the effects of uremic milieu, C2C12 myotubes were exposed to 10% normal serum (NS) or Uremic (US) Serum for 5-48 hours (h). NLRP3,IL1β,PGC1α,MFN2,NRF2 were studied by rtPCR, caspase1 by western blot and mitochondria damage by JC1 staining.

Results

In CKD, NLRP3 mRNA and protein were overexpressed (by 16-2 folds, p<0.05-0.025). IL1β mRNA was upregulated (p=0.02). In vitro, 5 hour US treatment upregulated NLRP3 and IL1β mRNAs (by 71-12 folds p<0.01) and caspase1 (+30% p<0.05). TAK 242 (1µM) a TLR4 antagonist prevented these effects. In CKD muscle, PGC1α (a mitochondrial biogenesis regulator), MFN2 (involved in mitochondrial fusion and in the mitochondrial network maintenance) and Nrf2 (a player in supporting the mitochondria structural and functional integrity) were significantly elevated (0.05-0.01) respect to C. Moreover, US upregulated PGC1α, MFN2 and Nrf2 (by 2-26 folds p<0.05-0.001) and altered mitochondrial membrane potential (p<0.05).These effects were partially blocked by TAK 242.

Conclusion

Our data show that NLRP3 inflammasome is activated and mitochondria dysregulated in CKD 5 skeletal muscle. These effects are rescued by TLR4 block, showing a link between TLR4 and inflammasome. TLR4/NLRP3/IL-1β blockade offers a novel method for reducing inflammation in muscle of CKD patients.