P-658 NLRP3 Inflammasome and polycystic ovarian syndrome – a possible novel association
Authors: Amer S , Aboeldalyl S , Tarbox R , Shawki H , Ibrahim E.M , Seyam E , Khan R 
Published: June 2022

Abstract

Study question
Is NLRP3 inflammasome expression in subcutaneous adipose tissue (SAT) and peripheral blood monocytes upregulated in women with polycystic ovarian syndrome (PCOS) compared to healthy controls?

Summary answer
NLRP3 expression was upregulated in subcutaneous adipose tissue but not in peripheral blood mononuclear cells (PBMCs) of women with PCOS compared to controls.

What is known already
Emerging evidence strongly suggests that PCOS is a chronic inflammatory condition. Inflammasomes are multiprotein complexes, which act as intracellular regulators of inflammation. It is now well established that NLRP3 inflammasome plays a central role in obesity-induced inflammation and insulin resistance. Given the close link between obesity and PCOS, it is plausible to hypothesize that the NLRP3 inflammasome may play a role in PCOS-related chronic inflammation and insulin resistance. This hypothesis has never been investigated before.

Study design, size, duration
This lab-based study involved reproductive age women (age 18–45years; BMI≤40kg/m2) who were diagnosed with PCOS (n = 24) according to the Rotterdam criteria. A healthy control group of non-PCOS women (n = 13) of similar age and BMI was included. Ethics approval was obtained, and all participants signed a written, informed consent. SAT biopsies were obtained during routine gynaecological surgery through the abdominal skin incision. Blood samples were obtained during surgery or during clinic visits.

Participants/materials, setting, methods
Blood samples were processed to separate plasma and to isolate peripheral blood mononuclear cells (PBMCs). SAT and PBMCs were analysed using qPCR and Western Blot (WB) to measure the relative gene and protein expression levels of NLRP3, CYP17, Caspase-1, IL-1β and IL-18 in both groups. ELISA was used to measure concentrations of Caspase-1, IL-1β and IL-18 in the plasma.

Main results and the role of chance
NLRP3 gene expression in SAT was significantly (p = 0.038) higher in PCOS women (2.08±3.5 (n = 12)) compared to controls (0.77±2.9 (n = 8)). Both groups were matched for age (PCOS, 29.4±3.7 vs controls, 30.3±4.0) and BMI (PCOS, 25.4±3.2 vs controls, 26.9±4.3). CYP17 expression was significantly (p = 0.001) higher in PCOS women (4.8±0.1) versus controls (1.5±1.6). There was a moderate positive correlation (r²=0.576, P &lt; 0.05) between SAT NLRP3 and CYP17 expressions.
NLRP3 gene expression in PBMCs were not significantly (p &lt; 0.05) different between non-obese PCOS (-2.64±1.55 (n = 4)), obese PCOS (-2.847±1.85 (n = 8)) and non-PCOS women (0.000±2.67 (n = 5)).
Using WB in PBMCs, NLRP3 band had a mean molecular weight of 72.59±5.43kDa with no significant difference between groups, with a trend towards higher levels in PCOS. Using ELISA in PBMCs, NLRP3 levels were not significantly (p = 0.3) different between PCOS (1.53±1.32pg/ml (n = 12)) vs controls (1.03±0.583 (n = 5)).
Gene expression levels of Caspase-1, IL-1b and IL-18 in PBMCs were not significantly (P &gt; 0.05) different between groups.
Plasma IL-1β levels were significantly (p &lt; 0.05) higher in PCOS (51.64±91.00ng/ml) vs. controls (0.47±0.93ng/ml). Plasma IL-18 concentrations were not significantly different between PCOS (3.79±0.53μg/ml) vs. controls (4.08±0.21μg/ml).

Limitations, reasons for caution
One limitation of this study is the lack of data on the protein expression of NLRP3 in the adipose tissue. There was also no data on other inflammasome components in the SAT analysis e.g. Caspase-1. However, all these data were available for the PBMCs.

Wider implications of the findings
The novel and interesting finding of an increase in NLRP3 in adipose tissue of PCOS women suggests that this inflammasome may play a central role in this common condition. Our study may therefore pave the way to further research to help understand the role of inflammation in PCOS

Trial registration number
N/A