Sex‐mediated elevation of the specialized pro‐resolving lipid mediator levels in a Sjögren's syndrome mouse model

Abstract

Our previous results showed that the specialized pro‐resolving mediator (SPM) Resolvin D1 (RvD1) promotes resolution of inflammation in salivary glands in non‐obese diabetic (NOD)/ShiLtJ, a mouse model for Sjögren's syndrome (SS). Additionally, mice lacking the RvD1 receptor ALX/FPR2 show defective innate and adaptive immune responses in salivary glands. Particularly, ALX/FPR2 KO mice exhibit exacerbated inflammation in their salivary glands in response to systemic LPS treatment. Moreover, female ALX/FPR2 KO mice show increased autoantibody production and loss of salivary gland function with age. Together, these studies suggest that an underlying SPM dysregulation could be contributing to SS progression. Therefore, we investigated whether SPM production is altered in NOD/ShiLtJ using metabololipidomics and enzyme‐linked immunosorbent assay (ELISA). Our results demonstrate that SPM levels were broadly elevated in plasma collected from NOD/ShiLtJ female mice after disease onset, whereas these drastic changes did not occur in male mice. Moreover, gene expression of enzymes involved in SPM biosynthesis were altered in submandibular glands (SMG) from NOD/ShiLtJ female mice after disease onset, with 5‐LOX and 12/15‐LOX being downregulated and upregulated, respectively. Despite this dysregulation, the abundances of the SPM products of these enzymes (ie, RvD1 and RvD2) were unaltered in freshly isolated SMG cells suggesting that other cell populations (eg, lymphocytes) may be responsible for the overabundance of SPMs that we observed. The elevation of SPMs noted here appeared to be sex mediated, meaning that it was observed only in one sex (females). Given that SS primarily affects females (roughly 90% of diagnosed cases), these results may provide some insights into the mechanisms underlying the observed sexual dimorphism.

The relationship between specialized pro-resolving lipid mediators, morbid obesity and weight loss after bariatric surgery

“…Serum samples stored at − 80 °C were used. Samples were extracted using protein precipitation with methanol followed by solid phase extraction (SPE) using C18 columns as described previously 16 – 19 . Before extraction, 500 pg of deuterium (d)-labeled internal standards, d5-MaR1, d4-RvE1, d8-5S-hydroxy-eicosatetraenoic acid (d8-5S-HETE), d4-LTB 4 , d5-lipoxin A 4 (d5-LXA 4 ), d5-maresin 2 (d5-MaR2), d4-PGE 2 and d5-resolvin D2 (d5-RvD2), were added to facilitate quantification of analyte recovery.…”

“…Before elution, the C18 resin was washed with 6 ml of neutral ddH2O and 6 ml hexane. Samples were eluted with 6 ml methyl formate and taken to dryness using a nitrogen stream as previously described [16][17][18][19] . The extracts were suspended in methanol/water for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses.…”

“…Liquid chromatography-tandem mass spectrometry analysis. Targeted metabololipidomics using LC-MS/MS was performed to quantify levels of the pro-resolving SPMs (D-series resolvins, E-series resolvins, protectins and maresins) and the proinflammatory eicosanoids (PGD 2 , PGE 2 and LTB 4 ) as previously described [16][17][18][19] using a QTrap 6500 mass spectrometer (Sciex) equipped with a Shimadzu Nexera XR HPLC system. An Agilent Poroshell 120 EC-C18 column (100 mm × 4.6 mm × 2.7 μm) was used with a gradient of methanol/water/acetic acid of 50:50:0.01 (volume/volume/volume) to 100:0:0.01 at 0.5-ml/min flow rate.…”

“…An Agilent Poroshell 120 EC-C18 column (100 mm × 4.6 mm × 2.7 μm) was used with a gradient of methanol/water/acetic acid of 50:50:0.01 (volume/volume/volume) to 100:0:0.01 at 0.5-ml/min flow rate. A scheduled multiple reaction monitoring (MRM) method was used to monitor and quantify the levels of each lipid mediator as we previously described 19 . The MRM detected signature ion fragments for each molecule at chromatographic retention times established by a combination of external and internal synthetic standards as previously described ( Supplementary Fig.…”

Predicting Resolvin D1 Pharmacokinetics in Humans with Physiologically‐Based Pharmacokinetic Modeling

“…25,38 The virtual human population consisted of a female to male ratio of 9:1 because of the predominance of SS in females. 10 Based on these anthropometric measurements, organ weights, volumes, and blood flows were generated using the International Commission on Radiological Protection database. 39 The physiological and drug-specific parameters used for the human salivary gland compartment are either obtained from the literature 40,41 or calculated using PK Sim ® and are provided in Table 2.The optimized NOD/ShiLtJ mouse PBPK model was extrapolated to the human model using PK Sim default human population database characteristics.…”