Comparative effectiveness of a second-line biologic in patients with ulcerative colitis: vedolizumab followed by an anti-TNF versus anti-TNF followed by vedolizumab.

Background: Sequential drug treatment with biological agents in ulcerative colitis (UC) is becoming increasingly complex. There are few studies comparing head-to-head outcomes in second-line treatments. The study assesses whether using anti-tumour necrosis factor (anti-TNF)-α therapy following the α4ß7 integrin blocker vedolizumab (VDZ) or VDZ after an anti-TNF has more favourable clinical outcomes in UC in a real-world outpatient setting. Methods: Patients with UC who were exposed to first-line anti-TNF (adalimumab or infliximab) or VDZ who subsequently switched to the alternate class between May 2013 and August 2020 were identified by reviewing patient databases at 10 hospitals. Data were collected retrospectively using patient records. Baseline demographics, disease activity indices, biochemical markers, endoscopic Mayo score, colectomy rates, treatment persistence and urgent hospital utilisation composite endpoint (UHUC) rates were examined over a 52-week period. Results: Second-line week 52 treatment persistence was higher in the VDZ group (71/81, 89%) versus the anti-TNF group (15/34, 44%; p=0.0001), as were week 52 colectomy-free survival (VDZ: 77/80, 96%, vs anti-TNF: 26/32, 81%; p=0.009), week 52 UHUC survival (VDZ: 68/84, 81%, vs anti-TNF: 20/34, 59%; p=0.002) and week 52 corticosteroid-free clinical remission (CFCR) rates (VDZ: 22/34, 65%, vs anti-TNF: 4/20, 20%; p=0.001). Conclusion: Compared with second-line anti TNF usage, the VDZ second-line cohort had significantly higher 52-week treatment persistence, UHUC survival, higher colectomy-free survival rates and higher week 52 CFCR. These data suggest that VDZ is an effective biologic in UC as a second-line therapy after anti-TNF exposure. It highlights the effect of biological order on clinically important outcomes.

Compartment-specific immunity in the human gut: properties and functions of dendritic cells in the colon versus the ileum.

OBJECTIVE: Dendritic cells (DC) mediate intestinal immune tolerance. Despite striking differences between the colon and the ileum both in function and bacterial load, few studies distinguish between properties of immune cells in these compartments. Furthermore, information of gut DC in humans is scarce. We aimed to characterise human colonic versus ileal DC. DESIGN: Human DC from paired colonic and ileal samples were characterised by flow cytometry, electron microscopy or used to stimulate T cell responses in a mixed leucocyte reaction. RESULTS: A lower proportion of colonic DC produced pro-inflammatory cytokines (tumour necrosis factor-α and interleukin (IL)-1ß) compared with their ileal counterparts and exhibited an enhanced ability to generate CD4(+)FoxP3(+)IL-10(+) (regulatory) T cells. There were enhanced proportions of CD103(+)Sirpα(-) DC in the colon, with increased proportions of CD103(+)Sirpα(+) DC in the ileum. A greater proportion of colonic DC subsets analysed expressed the lymph-node-homing marker CCR7, alongside enhanced endocytic capacity, which was most striking in CD103(+)Sirpα(+) DC. Expression of the inhibitory receptor ILT3 was enhanced on colonic DC. Interestingly, endocytic capacity was associated with CD103(+) DC, in particular CD103(+)Sirpα(+) DC. However, expression of ILT3 was associated with CD103(-) DC. Colonic and ileal DC differentially expressed skin-homing marker CCR4 and small-bowel-homing marker CCR9, respectively, and this corresponded to their ability to imprint these homing markers on T cells. CONCLUSIONS: The regulatory properties of colonic DC may represent an evolutionary adaptation to the greater bacterial load in the colon. The colon and the ileum should be regarded as separate entities, each comprising DC with distinct roles in mucosal immunity and imprinting.

Altered human gut dendritic cell properties in ulcerative colitis are reversed by Lactobacillus plantarum extracellular encrypted peptide STp.

SCOPE: The human/microbiota cross-talk is partially mediated by bacteria-derived peptides like Serine-Threonine peptide (STp), which is resistant to gut proteolysis, is found in the human healthy colon and induces regulatory properties on gut dendritic cells (DCs); here we characterized human gut DC in ulcerative colitis (UC) patients and studied the effect of STp on their properties. METHODS AND RESULTS: Human colonic DC from healthy controls and UC patients were isolated, conditioned for 24 h +/- STp and characterized by flow cytometry, immunohistochemistry, and electron microscopy. Expression of immature DC markers DC-SIGN and ILT3, and Toll-like receptors were increased on gut UC-DC. Langerin (involved in phagocytosis), lymph node homing marker CCR7, and activation markers CD40/CD80/CD86 were decreased in UC. Gut DC had restricted stimulatory capacity for T-cells in UC. Conditioning of DC with STp in vitro reduced Toll-like receptor expression, increased CD40 and CD80 expression, and restored their stimulatory capacity. CONCLUSION: Colonic DCs display an abnormal immature phenotype in UC, which was partially restored following STp treatment. Bacteria-derived metabolites, like STp, seem to have a role in gut homeostasis that is missing in UC so they might lead a new era of probiotic products setting the basis for nondrug dietary therapy in inflammatory bowel disease.

Mechanisms of action of anti-tumor necrosis factor α agents in Crohn's disease.

Crohn's disease (CD) is characterized by inflammation that can affect any part of the gastrointestinal tract. It is a chronic destructive condition that follows a relapsing-remitting course and can lead to disability and a poor quality of life. Lifelong pharmacotherapy with systemic immunomodulator therapies remains the cornerstone of CD management. Advances in understanding of the immunopathogenic mechanisms underlying chronic gut inflammation in CD have led to the development of effective biological therapies for patients with CD. Tumor necrosis factor α (TNF-α) is a potent proinflammatory cytokine that plays a pivotal role in the development of Crohn's inflammation. Therapies designed to target this cytokine have revolutionized treatment of CD since their introduction in the late 1990s, thanks to their ability to induce and maintain remission, heal mucosa, reduce hospital admissions and surgical procedures, and restore quality of life. Despite widespread use of these therapies in CD, their precise mechanism of action remains unclear, although several different mechanisms have been proposed. This review summarizes the biology of the TNF-α cytokine and the development of biological therapies targeting TNF-α, and updates our current understanding of mechanisms of action of the commercially available anti-TNF-α therapies used in the treatment of CD.

IL-6 promotes immune responses in human ulcerative colitis and induces a skin-homing phenotype in the dendritic cells and Tcells they stimulate.

Dendritic cells (DCs) control the type and location of immune responses. Ulcerative colitis (UC) is considered a Th2 disease mediated by IL-13 where up to one third of patients can develop extraintestinal manifestations. Colonic biopsies from inflamed and noninflamed areas of UC patients were cultured in vitro and their supernatants were used to condition human blood enriched DCs from healthy controls. Levels of IL-13 in the culture supernatants were below the detection limit in most cases and the cytokine profile suggested a mixed profile rather than a Th2 cytokine profile. IL-6 was the predominant cytokine found in inflamed areas from UC patients and its concentration correlated with the Mayo endoscopic score for severity of disease. DCs conditioned with noninflamed culture supernatants acquired a regulatory phenotype with decreased stimulatory capacity. However, DCs conditioned with inflamed culture supernatants acquired a proinflammatory phenotype with increased expression of the skin-homing chemokine CCR8. These DCs did not have decreased T-cell stimulatory capacity and primed T cells with the skin-homing CLA molecule in an IL-6-dependent mechanism. Our results highlight the role of IL-6 in UC and question the concept of UC as a Th2 disease and the relevance of IL-13 in its etiology.

A dangerous combination of binge and purge.

We present a 36-year-old female diagnosed with Crohn's disease at the age of 11 years. In 2001, she underwent a total colectomy and further small bowel resection as a result of active Crohn's. Her residual anatomy consisted of 150 cm of small bowel to an end jejunostomy. Subsequently, she developed short bowel syndrome with recurrent episodes of hypomagnesaemia, hypocalcaemia, and hypokalaemia. Dietetic assessment revealed her to be severely underweight at 37 kg with a bodymass index (BMI) of 14.4 kg/m(2) . During her admission, our patient underwent psychiatric assessment and was established on home parenteral nutrition (HPN). At the time of discharge, 1 month later, her weight had increased to 44 kg (BMI = 17.7 kg/m(2) ). Over the following 12-month period, she lost weight (BMI, 15.4 mg/m(2) ; weight, 39.5 kg) and she described a high stoma output (up to 17 L) and dehydration. Assessment of her oral intake found she was consuming an estimated 14,000 kcal and 600 g protein per day. At this time, the possibility of a new form of eating disorder was discussed with the patient and she agreed that her behavior i.e., using her stoma as a purging device, fulfilled the criteria for a diagnosis of bulimia nervosa and she was referred to a specialist eating disorder unit.