Abstract
Patients with loss-of-function mutations in IL10 or IL10 receptor (IL10R) genes develop severe, medical-refractory, infantile-onset inflammatory bowel disease (IBD). We have previously reported significant alterations in innate and adaptive immune responses in these patients. Next generation sequencing platforms enable a comprehensive assessment of T cell receptor (TCR) and B cell receptor (BCR) repertoire patterns. We aimed to characterize TCR and BCR features in peripheral blood of patients with deleterious IL10 signaling defects. DNA was isolated from blood of seven patients with IL10R mutations and one with an IL10 mutation, along with eight controls, and subjected to next generation sequencing of TRB and IgH loci. A significant increase in clonality was observed in both TCR and BCR repertoires in circulating lymphocytes of IL10/IL10R-deficient patients, but to a much greater extent in T cells. Furthermore, short CDR3β length and altered hydrophobicity were demonstrated in T cells of patients, but not in B cells, secondary to lower rates of insertions of nucleotides, but not deletions, at the V-, D-, or J-junctions. We were unable to observe specific T or B clones that were limited only to the patients or among controls. Moreover, the expanded T cells clones were unique to each patient. In conclusion, next generation sequencing of the TCR and BCR is a powerful tool for characterizing the adaptive immune cell phenotype and function in immune-mediated disorders. The oligoclonality observed among IL10/IL10R-deficient patients may suggest specialization of unique clones that likely have a role in mediating tissue damage. Nevertheless, the lack of shared clones between patients provides another piece of evidence that the adaptive immune response in IBD is not triggered against common antigens. Additional studies are required to define the specific antigens that interact with the expanded IL10/IL10R-deficient clones.
Highlights
Inflammatory bowel disease (IBD), such as Crohn’s disease (CD), and ulcerative colitis (UC), are chronic, relapsing-remitting inflammatory disorders of the gastrointestinal tract
Our calculation examined clones with length of 14 amino acids for T cells, and 18 amino acids for B cells; as these were found to be the average lengths of the CDR3β and CDR3H regions, respectively
Calculation of the fraction of productive TCR sequences in each sample showed significantly lower productiveness among patients, compared with controls (78.0 ± 1.0 vs. 80.6 ± 0.7%; P ≤ 0.01, Figure 2E). These results suggest that patients with IL10/IL10 receptor (IL10R) mutations exhibit clonal expansion of specific T cell clones, which may have a role in mediating the clinical phenotype
Summary
Inflammatory bowel disease (IBD), such as Crohn’s disease (CD), and ulcerative colitis (UC), are chronic, relapsing-remitting inflammatory disorders of the gastrointestinal tract. Extensive use of advanced sequencing platforms in the last decade has facilitated identification of more than 50 different monogenic disorders that directly cause IBD [3]. Most of these patients develop IBD in the first years of life [3]. Patients with deleterious mutations in IL10 and the IL10 receptor (IL10R) were first reported in 2009 and 2010 [4,5,6] These patients develop colitis and perianal disease in the first months of life, along with arthritis and folliculitis. We have reported in two patients that anakinra, an IL1 receptor antagonist, was effective in ameliorating colitis [10] and was used as a bridge to hematopoietic stem cell transplantation (HSCT), which is the treatment of choice in these conditions [5, 9]
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