B‐cell clonal diversification and gut‐lymph node trafficking in ulcerative colitis revealed using lineage tree analysis

Abstract

In studies of inflammatory bowel diseases (IBD), research has so far focused mainly on the role of T cells. Despite evidence suggesting that B cells and the production of autoantibodies may play a significant role in IBD pathogenesis, the role of B cells in gut inflammation has not yet been thoroughly investigated. In the present study we used the new approach of lineage tree analysis for studying immunoglobulin variable region gene diversification in B cells found in the inflamed intestinal tissue of two ulcerative colitis patients as well as B cells from mucosa-associated lymph nodes (LN) in the same patients. Healthy intestinal tissue of three patients with carcinoma of the colon was used as normal control. Lineage tree shapes revealed active immune clonal diversification processes occurring in ulcerative colitis patients, which were quantitatively similar to those in healthy controls. B cells from intestinal tissues and the associated LN are shown here to be clonally related, thus supplying the first direct evidence supporting B-cell trafficking between gut and associated LN in IBD and control tissues. IntroductionUlcerative colitis (UC), one of the idiopathic inflammatory bowel diseases (IBD), is a chronic relapsing inflammatory disorder that may lead to significant impairment of gastrointestinal structure and function. UC usually involves the large intestine and extends proximally from the rectum upwards in a continuous fashion. Histologically, inflammation is usually limited to the mucosal layer and may involve ulceration and crypt abscess formation. UC has also been linked to an increased risk of gastrointestinal malignancy [1].Despite recent progress in IBD research, in human subjects as well as a wide variety of experimental animal models, many questions concerning the immunological and genetic basis of the disease remain unanswered. The mucosa-associated lymphoid 2600tissue of the gastrointestinal tract has the important tasks of, on the one hand, recognizing harmful pathogens and antigens within the gut and mounting an appropriate immune response against them and, on the other hand, knowing when and how to dampen or suppress that response once the assault has been cleared or when commensal flora or self-antigens are encountered [2]. The pathogenesis of IBD appears to be related to a disruption of that finely tuned and regulated balance which exists within the mucosa-associated lymphoid tissue, resulting in deregulated and exaggerated local immune responses. This imbalance is most probably a result of complex genetic, environmental, and immunological susceptibility factors [3].Experimental models of intestinal inflammation indicate that mucosal inflammation is probably mediated either by excessive effector T-cell function or deficient regulatory T-cell function. Exaggerated T helper 1 cell response associated with increased secretion of IL-12, IFN-g and/or TNF results in a Crohn's Disease (CD)-like colitis in these experimental models, and exaggerated T helper 2 cell response associated with increas...

Ectopic GC in the thymus of myasthenia gravis patients show characteristics of normal GC

“…This is in accordance with the previous findings where GC founder B cells were found to migrate between distinct secondary lymphoid tissues via the peripheral blood [40,41]. B-cell trafficking has been reported to occur between different follicles in follicular lymphoma [42][43][44] and between the gut and the associated lymph node in ulcerative colitis [45]. Circulating GC founder B cells were detected in the peripheral blood in primary Sjögren's syndrome and rheumatoid arthritis, although once seeded in the GC they no longer circulated [40].…”

“…Mutations were enumerated and analyzed using IgTree r [49] and additional programs incorporated into IgTree r that perform mutation targeting motif, aa replacement and R:S analyses [45], as explained in the following paragraphs. Thus, the results are subject to the tree structure as created by the IgTree r program.…”

Aging affects B‐cell antigen receptor repertoire diversity in primary and secondary lymphoid tissues

“…Mutations were counted per tree, as described in [32,43]. All trees were measured using our program MTree C , quantifying the graphical properties of the trees [20].…”

“…Furthermore, the small amounts of DNA we could extract and the inability to isolate and clone specific B or plasma cells have necessitated a slightly nonstandard procedure in order to confirm there are no primer-induced biases (this paper) or that the results are equivalent to those obtained from, e.g. frozen samples [32]. However, limitations of the methodology would apply to all samples in our tissue analysis, so it is noteworthy that we observe agerelated differences between B-cell repertoires from old and young individuals.…”

Lineage tree analysis of high throughput immunoglobulin sequencing clarifies B cell maturation pathways

“…Previous studies demonstrated the usefulness of this method and resulted in new insights regarding differences in GC dynamics in aging or between different tissues [35]- [37],in autoimmune diseases [38], chronic inflammation [39], lymphomas [40], and chronic gastritis and gastric lymphomas [41]. This method was also used to determine clonal relationships of Ig genes from different tissues [39] [42].…”