TILRR (Toll-like Interleukin-1 Receptor Regulator), an Important Modulator of Inflammatory Responsive Genes, is Circulating in the Blood

Abstract

Mohammad Abul Kashem,1– 4 Xin-Yong Yuan,4 Lin Li,2 Joshua Kimani,5 Francis Plummer1 ,† Ma Luo1,2,4 1Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada; 2JC Wilt Infectious Diseases Research Centre, Winnipeg, Mb, Canada; 3Department of Microbiology and Veterinary Public Health, Chittagong Veterinary and Animal Sciences University, Chittagong, Bangladesh; 4National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada; 5Institute for Tropical and Infectious Diseases, University of Nairobi, Nairobi, Kenya†In memoriam (passed away on February 4, 2020).Correspondence: Ma LuoDepartment of Medical Microbiology, University of Manitoba, Winnipeg, MB, CanadaTel [phone]Fax [phone]Email [email protected]; [email protected]: TILRR (Toll-like interleukin-1 receptor regulator), a variant of FREM1 (Fras-related extracellular matrix 1), is a modulator of many genes in NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) signaling and inflammatory responses. It enhanced the expression of multiple genes in the NF-κB signaling pathway and promoted the production of multiple pro-inflammatory cytokines/chemokines. TILRR is an extracellular matrix protein and expressed in cells and tissues, and has never been considered to exist in the blood. The study aimed to identify circulating TILRR protein in human plasma as a biomarker of systemic inflammation.Methods and Results: We developed a multiplex bead array method (Bio-Plex) using 4 monoclonal antibodies targeting different protein domains of FREM1/TILRR to investigate whether TILRR can be detected in blood plasma. The results of the multiplex bead array method were validated by Western blot analysis of affinity-purified TILRR from patient plasma samples. We subsequently analyzed 640 plasma samples from women enrolled in the Pumwani Sex Worker cohort (PSWC) (Nairobi, Kenya). Our study showed that TILRR exists in all patient plasma samples, but its quantities vary greatly among the patients, ranging from 2.38 ng/mL to 5196.79 ng/mL. The plasma TILRR below 2.38 ng/mL can only be detected by affinity purification and Western blot analysis.Conclusion: Our in-house developed multiplex bead array method can successfully quantify TILRR protein in plasma samples. Because TILRR is an important modulator of many inflammation-responsive genes, it may be an inflammation biomarker in blood and play a role in modulating systemic inflammation.Keywords: TILRR, soluble biomarker, human plasma, mouse anti-FREM1 mAbs, multiplex bead array method, Western blot analysis

Keywords

• tilrr
• soluble biomarker
• human plasma
• mouse anti-frem1 mabs
• multiplex bead array method
• western blot analysis.