ePoster Presentation 49th Annual Scientific Meeting of the Australian and New Zealand Society for Immunology 2021

Functional evaluation of common NOD2 gene variants in patients with antibody deficiency and gastrointestinal complications (#181)

Ebony G Blight 1 , Emily SJ Edwards 1 2 , Julian J Bosco 2 3 , Samar Ojaimi 2 4 5 6 , Pei M Aui 1 2 , Robyn E O'Hehir 1 2 3 , Menno C van Zelm 1 2 3
  1. Department of Immunology and Pathology, Central Clinical School, Monash University and The Alfred Hospital, Melbourne, VIC, Australia
  2. The Jeffrey Modell Diagnostic and Research Centre for Primary Immunodeficiencies, Melbourne, VIC, Australia
  3. Allergy, Asthma and Clinical Immunology Service, Department of Respiratory, Allergy and Clinical Immunology (Research), The Alfred Hospital, Melbourne, VIC, Australia
  4. Department of Infectious Diseases, Monash Health, Clayton, VIC, Australia
  5. Immunology Laboratory , Monash Health, Clayton, VIC, Australia
  6. Department of Allergy and Immunology, Monash Health, Clayton, VIC, Australia

Background: Predominantly antibody deficiency (PAD) is the most common inherited immunodeficiency and is presumed to be caused by rare genetic mutations. Despite genomic advances, >70% remain genetically undiagnosed. Approximately 20% of PAD patients suffer from gastrointestinal disease. Common genetic variants (minor allele frequency >1%) in the NOD2 gene (R702W, G908R, and L1007fsX1008) are the three major risk alleles for gastrointestinal disease. NOD2 is a pattern recognition receptor that recognises peptidoglycan fragment muramyl dipeptide (MDP) and is critical for defence against bacteria. In this study, we examined whether NOD2 variants are associated with PAD and whether these impact NOD2 function.

Methods: Carriership for three NOD2 variants (R702W, G908R, and L1007fsX1008) was determined in 75 PAD patients from whole-exome sequencing data, and using Sanger sequencing in 75 healthy adult controls. NOD2 function was determined through in vitro stimulation of peripheral blood mononuclear cells with L18-MDP and detection of intracellular TNFα by flow cytometry. Stimulation with LPS and media only were used as positive and negative controls, respectively.

Results: The R702W variant was detected in 8 controls and 8 patients, G908R in 2 controls and 1 patient, L1007fsX1008 in 2 patients. No homozygotes were detected. Monocytes from healthy adults with and without the R702W showed similar TNFα production (medians)(P=0.43) in L18-MDP-induced TNFa production in individuals with or without R702W.

Conclusion: Our PAD cohort did not display increased presence of NOD2 variants. The R702W does not impact on NOD2 function in healthy controls. In ongoing studies, NOD2 signalling will be examined in PAD patients with the R702W and L1007fsX1008 variants. This will give new insights into the functional consequences of NOD2 variants and their association with gastrointestinal disease in PAD. If an effect is confirmed, this would provide a rationale for the use of anti-TNF therapies in these patients.