Linkage between Toll-like receptor (TLR) 2 promotor and intron polymorphisms: functional effects and relevance to sarcoidosis

doi:10.1111/j.1365-2249.2007.03428.x

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Wiley InterScience

Clinical & Experimental Immunology

Volume 149 Issue 3, Pages 453 - 462

Published Online: 12 Jun 2007

An Official Journal of the British Society for Immunology

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ORIGINAL ARTICLE

Linkage between Toll-like receptor (TLR) 2 promotor and intron polymorphisms: functional effects and relevance to sarcoidosis

M. Veltkamp,* P. A. H. M. Wijnen, ^† C. H. M. van Moorsel,*^‡ G. T. Rijkers, ^§ H. J. T. Ruven, ^‡ M. Heron,* O. Bekers, ^† A. M. E. Claessen, ^§ M. Drent, ^¶ J. M. M. van den Bosch* and J. C. Grutters*

*Heart Lung Center Utrecht, Department of Pulmonology, St. Antonius Hospital, Nieuwegein, the Netherlands, ^† Department of Clinical Chemistry, ILD Care Team, University Hospital Maastricht, the Netherlands, ^‡ Department of Clinical Chemistry, St Antonius Hospital, Nieuwegein, the Netherlands, ^§ Department of Medical Microbiology and Immunology, St Antonius Hospital, Nieuwegein, the Netherlands, and ^¶ Department of Respiratory Medicine, ILD Care Team, University Hospital Maastricht, the Netherlands

Correspondence to M. Veltkamp, MD, St Antonius Hospital, Department of Pulmonology, PO Box 2500, 3430 EM Nieuwegein, the Netherlands.
E-mail: veltkamp76@hotmail.com

KEYWORDS

linkage • polymorphisms • sarcoidosis • Toll-like receptor 2

Summary

The intracellular pathogens Propionibacterium acnes and Mycobacterium tuberculosis have been leading suspects as the cause of sarcoidosis, a systemic disorder characterized by the formation of non-caseating granulomas. Toll-like receptor (TLR) 2 is important in the innate immune response against both pathogens, and is therefore of interest in sarcoidosis research. In the present study, three single nucleotide polymorphisms and one dinucleotide repeat polymorphism in the TLR-2 gene were genotyped in 419 sarcoidosis patients, divided into a study cohort and a validation cohort, and 196 healthy controls. In the study cohort we found a significant increase in prevalence of the AA-genotype at promotor location −16934 in patients with chronic disease compared to patients with acute/self-remitting sarcoidosis (34·5% versus 15·9%, respectively, P = 0·006, P_c = 0·019). These results could not be confirmed in our validation cohort, implicating a possible role for TLR-2 genetics in only a small percentage of sarcoidosis patients. Furthermore, linkage was found between the promotor polymorphism −16934 A/T and the number of GT repeats in intron 1 (P < 0·0001). After in vitro stimulation of peripheral blood mononuclear cells (PMBCs) with different TLR-2 agonists, a correlation between induction of TNF-α (P = 0·008), interleukin (IL)-12 (P = 0·008) as well as IL-6 (P = 0·02), and the number of GT repeats was observed. In conclusion, the data show that polymorphisms in TLR-2 might be important in a small group of sarcoidosis patients and that their functional consequences explain partly some of the variance in cytokine pattern observed in different clinical phenotypes of this disease.