Richard Aranda

Systemic activation and antigen-driven oligoclonal expansion of T cells in a mouse model of colitis.

Transfer of CD4+CD45RBhigh T cells into immunodeficient mice results in both the expansion of the transferred T cells and colitis. Here we show that colitis pathogenesis requires expression of MHC class II molecules by the immune-deficient host. Analysis of the TCRβ repertoire of the cells found in the large intestine of diseased mice revealed a population with restricted TCR diversity. Furthermore, nucleotide sequence analysis demonstrated the selection for particular CDR3β amino acid sequence motifs. Collectively, these data indicate that the expansion of T cells in the intestine and colitis pathogenesis are likely to require the activation of Ag-specific T cells, as opposed to nonspecific or superantigen-mediated events. There is relatively little overlap, however, when the TCR repertoires of different individuals are compared, suggesting that a number of Ags can contribute to T cell expansion and the generation of a T cell population in the intestine. Surprisingly, many of the expanded clones found in the large intestine also were found in the spleen and elsewhere, although inflammation is localized to the colon. Additionally, donor-derived T cells appear to be activated in both the intestine and the spleen at early time points after cell transfer. Together, these results strongly suggest that disease induction in this model involves either the early and systemic activation of antigen-specific T cells or the rapid dispersal of T cells activated at a particular site.

Noninvasive quantification of bowel inflammation through positron emission tomography imaging of 2-deoxy-2-[18F]fluoro-D-glucose-labeled white blood cells.

Treatment of inflammatory bowel disease (IBD) generally relies on long-term use of anti-inflammatory and immunosuppressive agents. The adverse effects of those drugs make it important to prescribe the minimal regimen that is effective. An objective method for noninvasively quantifying severity of bowel inflammation would thus be valuable in guiding inflammatory bowel disease therapy. Using positron emission tomography (PET), we show that white blood cells (WBCs) labeled with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) can serve as a quantitative marker for identifying the presence and severity of intestinal inflammation. In both murine and human subjects, PET images of FDG-labeled WBCs demonstrated little tracer uptake in healthy gastrointestinal and urinary tracts, where physiologic distribution of FDG images of glucose metabolism often compromises abdominopelvic PET imaging of intestinal pathology. Intestinal foci of FDG-labeled WBCs were confirmed to represent inflamed bowel through histopathologic or colonoscopic analysis, and intensity of foci measured in PET images correlated well with histopathologic measures of degree of inflammation. FDG-labeled WBCs, in conjunction with PET, can be used to provide quantitative assessment of bowel inflammation noninvasively, accurately, and rapidly.

β7 Integrin expression is not required for the localization of T cells to the intestine and colitis pathogenesis

β7 Integrins have been shown to have an important role in the localization of T cells to the intestine. Utilizing two different experimental mouse models of inflammatory bowel disease (IBD), this study was undertaken to determine if β7 integrin expression is critical for T cell localization to the intestine and colitis pathogenesis. Transfer of CD4+ CD45RBhigh cells into immunodeficient mice results in colitis. To examine the role of β7 integrins, donor cells were obtained from β7 integrin gene‐deficient animals and disease induction was examined following transfer into severe combined immunodeficiency (SCID) mice. Additionally, β7 integrin gene‐deficient animals were crossed to IL‐2‐deficient mice and the onset of spontaneous colitis that normally occurs in IL‐2‐deficient animals was examined. No differences in the onset or severity of spontaneous colitis was noted in animals that were deficient in both β7 integrin and IL‐2. In contrast, the onset of colitis in recipients of T cells from β7 integrin‐deficient donors was delayed significantly. In mice receiving β7 integrin negative cells, the initial lack of colitis appeared to correlate with fewer numbers of CD3+β7 integrin –/– donor lymphocytes present in the host colon. The eventual development of disease, however, was associated with increased numbers of donor β7 integrin –/– lymphocytes. These results show that β7 integrin expression is not absolutely required for T cell localization to the intestine and colitis pathogenesis.

Abatacept in subjects who switch from intravenous to subcutaneous therapy: results from the phase IIIb ATTUNE study

Objective To assess safety, immunogenicity and efficacy in rheumatoid arthritis (RA) patients switched from long-term intravenous to subcutaneous (SC) abatacept. Methods In this phase IIIb, open-label, single-arm trial, patients who completed ≥4 years of intravenous abatacept (in long-term extensions of two phase III studies) were enrolled to receive SC abatacept (125 mg/week). The primary objective was safety during the first 3 months after switching from intravenous therapy. Results 123 patients entered the study (mean Disease Activity Score 28 (based on C reactive protein) and HAQ-DI of 3.4 and 0.94, respectively). At month 3, 120 (97.6%) patients were continuing to receive SC abatacept; no patients discontinued due to lack of efficacy. Adverse events (AEs) were reported in 49 (39.8%) patients through month 3. One patient (0.8%) discontinued due to an AE and one patient (0.8%) experienced a serious AE. Two (1.6%) patients had SC injection site reactions (erythema, pain), both with mild intensity. Clinical efficacy was maintained throughout. Limited impact on immunogenicity was observed when switching routes of administration. Conclusion These data demonstrate that patients can switch from long-term monthly intravenous abatacept to a weekly fixed dose of 125 mg SC abatacept with no increased safety concerns. This study further supports SC abatacept as an alternative treatment option for patients with RA.

Lymphocyte—Epithelial Cross-Talk in the Intestine: Do Nonclassical Class I Molecules Have a Big Part in the Dialogue?

Publisher Summary This chapter focuses on the behavior and properties of nonclassical class I molecules expressed by mouse intestinal epithelial cells, and the possible role these molecules may have in the development and function of mouse intestinal intraepithelial lymphocytes (IEL). IEL have a phenotype that is distinct from other T-cell populations, and these lymphocytes may be the product of a separate, thymus-independent lineage. If such a lineage exists, it would be likely that the intestinal epithelium plays a major role in its development. It is also possible, however, that some IEL are derived from thymus-derived T cells. This is evidenced by the ability of conventional CD4+ cells to home to the gut epithelium in scid mice, and to acquire characteristics of the T cells that normally reside in the intestine. This chapter shows that nonpolymorphic class I molecules expressed in the intestine have unique properties, most notably, their lack of a requirement for TAP in order to be expressed on the cell surface. This lack of a TAP requirement may provide some insight into the specialized function of the TL antigen and mCDl in the mucosal immune system. This chapter further demonstrates that mCDl can function as an antigen-presenting molecule, and that it presents peptide antigens distinct from those presented by classical class I molecules.

P-106 Examination of an Alternative Definition for Clinical Remission in UC: Results from TOUCHSTONE, a Randomized, Double-Blind, Placebo-Controlled Trial of Ozanimod

Background:The Mayo score has been used to assess UC disease activity and to establish the efficacy of medications approved for the treatment of UC for over 2 decades. The definition of clinical remission used for approval of biologic agents since infliximab has been a Mayo score ⩽2 with no subscore >1, which is being scrutinized by the FDA due to its lack of formal validation and inclusion of the poorly-defined physician global assessment subscore (PGA). An alternative definition of clinical remission using the Mayo scoring system without the PGA, has been proposed that requires a rectal bleeding subscore (RBS) = 0, an endoscopy subscore (ES) of ⩽1 and a stool frequency subscore (SFS) ⩽1 with improvement ≥1. We have explored this alternative definition of remission in a post hoc analysis of the data from the TOUCHSTONE study. Methods:TOUCHSTONE was a randomized, double-blind, placebo-controlled trial designed to evaluate efficacy and safety of 0.5 mg (low dose, LD) and 1 mg (high dose, HD) ozanimod, an oral, selective sphingosine 1-phosphate (S1P) 1 and 5 receptor modulator, in comparison to placebo (PBO), in patients with moderate to severe UC. A total of 197 patients were randomized (1:1:1) and treated once daily with PBO (n = 65), LD (n = 65) or HD (n = 67). The patients who achieved clinical response at week 8 continued into the maintenance period (MP) with their original treatment for an additional 24 weeks. Using the data from TOUCHSTONE, we calculated clinical remission rates at weeks 8 and 32 applying the alternative definition of clinical remission, which excludes the PGA. Results:Of 197 patients in the IP, 103 (52.3%) continued in the MP and 91/103 (88.3%) completed. At week 8 using the original definition (Mayo score ⩽2 with no subscore >1) clinical remission occurred in 16.4% for HD (P = 0.0482 versus PBO), 13.8% for LD (P = 0.1422), and 6.2% for PBO while the alternate definition (RBS = 0, SFS ⩽1 with improvement ≥1, ES ⩽1), clinical remission occurred in 23.9%, HD (P = 0.0154 versus PBO), 16.9%, LD (P = 0.2099), and 9.2%, PBO. At week 32, using the original definition, clinical remission occurred in 20.9%, HD (P = 0.0108 versus PBO), 26.2%, LD (P = 0.0021), and 6.2%, PBO while using the alternative definition clinical remission occurred in 26.9%, HD (P = 0.0025 versus PBO), 26.2%, LD (P = 0.0053), and 7.7%, PBO. Conclusions:Using this alternative definition of clinical remission, a greater difference between HD and PBO was observed. An endpoint that excludes the PGA but maintains the other components of the Mayo score (RBS, ES, SFS) is able to demonstrate a treatment effect and could be one of the endpoints in clinical trials of UC. Further, the analysis confirms that patients with moderate to severe UC treated with ozanimod HD were more likely to both achieve and maintain clinical remission.

Systemic activation and antigen-driven oligoclonal expansion of T cells in a mouse model of colitis

Transfer of CD4+CD45RBhigh T cells into immunodeficient mice results in both the expansion of the transferred T cells and colitis. Here we show that colitis pathogenesis requires expression of MHC class II molecules by the immune-deficient host. Analysis of the TCRbeta repertoire of the cells found in the large intestine of diseased mice revealed a population with restricted TCR diversity. Furthermore, nucleotide sequence analysis demonstrated the selection for particular CDR3beta amino acid sequence motifs. Collectively, these data indicate that the expansion of T cells in the intestine and colitis pathogenesis are likely to require the activation of Ag-specific T cells, as opposed to nonspecific or superantigen-mediated events. There is relatively little overlap, however, when the TCR repertoires of different individuals are compared, suggesting that a number of Ags can contribute to T cell expansion and the generation of a T cell population in the intestine. Surprisingly, many of the expanded clones found in the large intestine also were found in the spleen and elsewhere, although inflammation is localized to the colon. Additionally, donor-derived T cells appear to be activated in both the intestine and the spleen at early time points after cell transfer. Together, these results strongly suggest that disease induction in this model involves either the early and systemic activation of antigen-specific T cells or the rapid dispersal of T cells activated at a particular site.