Homeostatic function and inflammatory activation of ileal CD8+ tissue-resident T cells is dependent on mucosal location

Background & Aims: Tissue-resident memory T (Trm) cells, both of the CD4 and CD8 lineage, have been implicated in disease flares in inflammatory bowel disease. However, data are conflicting regarding the profile of human CD8 + Trm cells, with studies suggesting both proinflammatory and regulatory functions. It is crucial to understand the functional profile of these cells in the context of (new) therapeutic strategies targeting (trafficking of) gut Trm cells. Methods: Here, we performed imaging mass cytometry, flow cytometry, and RNA-sequencing to compare lamina propria and intraepithelial CD103 +/–CD69 +CD8 + Trm cells in healthy control subjects and patients with active ileal Crohn's disease. Results: Our data revealed that lamina propria CD103 +CD69 +CD8 + T cells have a classical Trm cell profile with active pathways for regulating cell survival/death and cytokine signaling, whereas intraepithelial CD103 +CD69 +CD8 + T cells display tightly regulated innate-like cytotoxic profile. Furthermore, within lamina propria CD8 +CD103 – Trm cells, an Itgb2 +GzmK +KLRG1 + population distinct from CD103 + CD8 + Trm cells is found. During chronic inflammation, especially intraepithelial CD103 +CD69 +CD8 + T cells displayed an innate proinflammatory profile with concurrent loss of homeostatic functions. Conclusions: Altogether, these compartmental and inflammation-induced differences indicate that therapeutic strategies could have a different impact on the same immune cells depending on the local compartment and presence of an inflammatory milieu, and should be taken into account when investigating short- and long-term effects of new gut T cell–targeting drugs

Development of Mucosal PNAd+ and MAdCAM-1+ Venules during Disease Course in Ulcerative Colitis

PNAd and MAdCAM-1 addressins on venules are of importance in T-cell homing and potential therapeutic targets in ulcerative colitis (UC). Normally, PNAd+ high endothelial venules (HEVs) are only present in lymphoid organs, whereas small numbers of MAdCAM-1+ venules can be seen in non-lymphoid tissue. We aimed to study their presence in the intestinal mucosa of UC patients at diagnosis and during follow-up, and their correlation with disease activity. Colonic biopsy specimens of 378 UC patients were analyzed by immunohistochemistry for CD3, CD20, ERG, MECA-79 (PNAd) and MECA-376 (MAdCAM-1) and compared to healthy controls (HC). The proportion of PNAd+HEVs in UC at diagnosis was 4.9% (IQR 2.0%-8.3%), while none were detected in HC. During follow-up, PNAd+HEVs completely disappeared in remission (n = 93), whereas the proportion in active disease was similar to baseline (n = 285, p = 0.39). The proportion of MAdCAM-1+venules in UC at baseline was 5.8% (IQR 2.6-10.0). During follow-up, the proportion in remission was comparable to diagnosis, but upregulated (7.5% (IQR 4.4-10.9), p = 0.001) in active disease. In conclusion, PNAd+HEVs appear in UC during active inflammation which could thus serve as a marker for disease activity, whereas MAdCAM-1+venules remain present after inflammation is resolved and increase after subsequent flares, reflecting chronicity and potentially serving as a therapeutic target

The complexity of alpha E beta 7 blockade in Inflammatory Bowel Diseases

Monoclonal antibodies targeting integrins are emerging as new treatment option in Inflammatory Bowel Diseases. Integrins are molecules involved in cell adhesion and signalling. After the successful introduction of anti-α4β7, currently anti-β7 is under evaluation in a phase three trial. Anti-β7 blocks both α4β7/MAdCAM-1 and αEβ7/E-cadherin interaction, targeting both the homing to and the retention in the gut of potential pathological T cells. Since the physiological and potential pathological role of immune cells expressing αEβ7 is less distinct than of those expressing α4β7. An overview of the current state of knowledge on αEβ7 in mice and human is presented here in both health and Inflammatory Bowel Diseases, also addressing the potential consequences of anti-β7 treatment

Intestinal T cell profiling in inflammatory bowel disease : Linking T cell subsets to disease activity and disease course

Introduction: A dysregulated intestinal T cell response is presumed in patients with inflammatory bowel disease [IBD]. In this longitudinal study, we investigated the changes in intestinal T lymphocyte subsets in IBD at first presentation and over time during endoscopic active or inactive disease, and relate them to disease activity and outcome. Methods: We included 129 newly diagnosed patients (87 Crohn's disease [CD], 42 ulcerative colitis [UC]) and 19 healthy controls [HC]. Follow-up biopsy specimens were analysed from 70 IBD patients. Immunophenotyping of specimens was performed by flow cytometry identifying lymphocyte subpopulations. Results: IBD patients at diagnosis displayed higher percentages of CD4 T+ cells, Tregs, and central memory T cells [TCM] and with lower percentages of CD8 and CD103 T lymphocytes than HC. Follow-up specimens of patients with endoscopic inactive disease showed T cell subset recovery comparable to HC. Endoscopic active disease at follow-up coincided with T cell subsets similar to those at diagnosis. In UC, lower baseline percentages of CD3 cells was associated with milder disease course without the need of an immunomodulator, whereas in CD, higher baseline percentages of CD4 and Tregs were associated with complicated disease course. Conclusions: The intestinal T cell infiltrate in IBD patients with active endoscopic disease is composed of increased percentages of CD4+ T cells, Tregs, and TCM, with lower percentages of CD8+ T cells and CD103+ T cells, compared with HC and endoscopic inactive IBD. Baseline percentages of CD3, CD4, and Tregs were associated with disease outcome. Further research is needed to demonstrate the predictive value of these lymphocyte subsets

Candidate serum markers in early Crohn's disease : Predictors of disease course

Background and Aims: More than half of patients with Crohn's disease [CD] develop disease complications requiring aggressive medical therapy or surgery over time. However, predicting disease course and treatment response remains difficult. We therefore identified distinctive serum analytes associated with disease activity and course in newly diagnosed, untreated patients at presentation and during their follow-up. Methods: In a pilot study, a multiplex immunoassay analysis on 36 markers was performed on serum from 20 CD patients at the time of primary diagnosis following endoscopic evaluation. The 12 most potent markers associated with disease activity, phenotype and course were analysed in a consecutive cohort of 66 CD patients at diagnosis and follow-up [n = 39]. A healthy control group [n = 20] was included as a reference. Results: CD patients had higher baseline levels of sTNF-R2 [p = 0.001], sIL-2R [p = 0.0001], and MMP-1 [p = 0.001] compared with healthy controls. Serial measurements revealed that these three analytes dropped statistically significantly from baseline level during remission and were high during exacerbation. Great decline of sTNF-R1 levels was found during remission, with 6.7-fold lower levels than in healthy controls [p = 0.015]. Patients who did not respond to initial prednisone treatment had higher baseline levels of sTNF-R2 [p = 0.001]. Patients experiencing relapses during follow-up had lower baseline sTNF-R2 and VCAM levels compared with patients with long-lasting remission. Conclusions: In a large cohort of newly diagnosed untreated CD patients, we identified candidate serum markers [sTNF-R1, sTNF-R2, sIL-2R, and MMP-1] associated with disease activity. Furthermore, sTNF-R2 was associated with prednisone response and, together with VCAM, with long-lasting remission

Candidate serum markers in early Crohn's disease : Predictors of disease course

Background and Aims: More than half of patients with Crohn's disease [CD] develop disease complications requiring aggressive medical therapy or surgery over time. However, predicting disease course and treatment response remains difficult. We therefore identified distinctive serum analytes associated with disease activity and course in newly diagnosed, untreated patients at presentation and during their follow-up. Methods: In a pilot study, a multiplex immunoassay analysis on 36 markers was performed on serum from 20 CD patients at the time of primary diagnosis following endoscopic evaluation. The 12 most potent markers associated with disease activity, phenotype and course were analysed in a consecutive cohort of 66 CD patients at diagnosis and follow-up [n = 39]. A healthy control group [n = 20] was included as a reference. Results: CD patients had higher baseline levels of sTNF-R2 [p = 0.001], sIL-2R [p = 0.0001], and MMP-1 [p = 0.001] compared with healthy controls. Serial measurements revealed that these three analytes dropped statistically significantly from baseline level during remission and were high during exacerbation. Great decline of sTNF-R1 levels was found during remission, with 6.7-fold lower levels than in healthy controls [p = 0.015]. Patients who did not respond to initial prednisone treatment had higher baseline levels of sTNF-R2 [p = 0.001]. Patients experiencing relapses during follow-up had lower baseline sTNF-R2 and VCAM levels compared with patients with long-lasting remission. Conclusions: In a large cohort of newly diagnosed untreated CD patients, we identified candidate serum markers [sTNF-R1, sTNF-R2, sIL-2R, and MMP-1] associated with disease activity. Furthermore, sTNF-R2 was associated with prednisone response and, together with VCAM, with long-lasting remission

Flow cytometric analysis of the Vβ repertoire in healthy controls

Background: Analysis of the T-cell receptor (TCR)-Vβ repertoire has been used for studying selective T-cell responses in autoimmune disease, alloreactivity in transplantation, and protective immunity against microbial and tumor antigens. For the interpretation of these studies, we need information about the Vβ repertoire usage in healthy individuals. Methods: We analyzed blood T-lymphocyte (sub)populations of 36 healthy controls (age range: from neonates to 86 years) with a carefully selected most complete panel of 22 Vβ monoclonal antibodies, which together recognized 70-75% of all blood TCRαβ+ T lymphocytes. Subsequently, we developed a six-tube test kit with selected Vβ antibody combinations for easy and rapid detection of single ('clonal') Vβ domain usage in large T-cell expansions. Results: The mean values of the Vβ repertoire usage were stable during aging in blood TCRαβ+ T lymphocytes as well as in the CD4+ and CD8+ T-cell subsets, although the standard deviations increased in the elderly. The increased standard deviations were caused by the occurrence of oligoclonal T-cell expansions in the elderly, mainly consisting of CD8+ T lymphocytes. The 15 detected T-cell expansions did not reach 40% of total TCRαβ+ T lymphocytes and represented less than 0.4 x 109 cells per liter in our study. Vβ usage of the CD4+ and CD8+ subsets was comparable for most tested Vβ domains, but significant differences (P &lt; 0.01) between the two subsets were found for Vβ2, Vβ5.1, Vβ6.7, Vβ9.1, and Vβ22 (higher in CD4+), as well as for Vβ1, Vβ7.1, Vβ14, and Vβ23 (higher in CD8+). Finally, single Vβ domain expression in large T-cell expansions can indeed be detected by the six-tube test kit. Conclusions: The results of our study can now be used as reference values in studies on distortions of the Vβ repertoire in disease states. The six-tube test kit can be used for detection of single Vβ domain expression in large T-cell expansions (&gt;2.0 x 109/l), which are clinically suspicious of T-cell leukemia. (C) 2000 Wiley-Liss, Inc.</p

Development of Mucosal PNAd+ and MAdCAM-1+ Venules during Disease Course in Ulcerative Colitis

PNAd and MAdCAM-1 addressins on venules are of importance in T-cell homing and potential therapeutic targets in ulcerative colitis (UC). Normally, PNAd+ high endothelial venules (HEVs) are only present in lymphoid organs, whereas small numbers of MAdCAM-1+ venules can be seen in non-lymphoid tissue. We aimed to study their presence in the intestinal mucosa of UC patients at diagnosis and during follow-up, and their correlation with disease activity. Colonic biopsy specimens of 378 UC patients were analyzed by immunohistochemistry for CD3, CD20, ERG, MECA-79 (PNAd) and MECA-376 (MAdCAM-1) and compared to healthy controls (HC). The proportion of PNAd+HEVs in UC at diagnosis was 4.9% (IQR 2.0%&ndash;8.3%), while none were detected in HC. During follow-up, PNAd+HEVs completely disappeared in remission (n = 93), whereas the proportion in active disease was similar to baseline (n = 285, p = 0.39). The proportion of MAdCAM-1+venules in UC at baseline was 5.8% (IQR 2.6&ndash;10.0). During follow-up, the proportion in remission was comparable to diagnosis, but upregulated (7.5% (IQR 4.4&ndash;10.9), p = 0.001) in active disease. In conclusion, PNAd+HEVs appear in UC during active inflammation which could thus serve as a marker for disease activity, whereas MAdCAM-1+venules remain present after inflammation is resolved and increase after subsequent flares, reflecting chronicity and potentially serving as a therapeutic target