Adipocytes orchestrate the formation of tertiary lymphoid organs in the creeping fat of Crohn's disease affected mesentery.

The formation of tertiary lymphoid organs (TLOs) is orchestrated by the stromal cells of tissues chronically submitted to inflammatory stimuli, in order to uphold specific adaptive immune responses. We have recently shown that the smooth muscle cells of the arterial wall orchestrate the formation of the TLOs associated with atherosclerosis in response to the local release of TNF-α. Observational studies have recently documented the presence of structures resembling TLOs the creeping fat that develops in the mesentery of patients with Crohn's disease (CD), an inflammatory condition combining a complex and as yet not elucidated infectious and autoimmune responses. We have performed a comprehensive analysis of the TLO structures in order to decipher the mechanism leading to their formation in the mesentery of CD patients, and assessed the effect of infectious and/or inflammatory inducers on the potential TLO-organizer functions of adipocytes. Quantitative analysis showed that both T and B memory cells, as well as plasma cells, are enriched in the CD-affected mesentery, as compared with tissue from control subjects. Immunohistochemistry revealed that these cells are concentrated within the creeping fat of CD patients, in the vicinity of transmural lesions; that T and B cells are compartmentalized in clearly distinct areas; that they are supplied by post-capillary high endothelial venules and drained by lymphatic vessels indicating that these nodules are fully mature TLOs. Organ culture showed that mesenteric tissue samples from CD patients contained greater amounts of adipocyte-derived chemokines and the use of the conditioned medium from these cultures in functional assays was able to actively recruit T and B lymphocytes. Finally, the production of chemokines involved in TLO formation by 3T3-L1 adipocytes was directly elicited by a combination of TNF-α and LPS in vitro. We therefore propose a mechanism in which mesenteric adipocyte, through their production of key chemokines in response to inflammatory/bacterial stimuli, may orchestrate the formation of functional TLOs developing in CD-affected mesentery.

Liver function test abnormalities are associated with a poorer prognosis in Covid-19 patients: Results of a French cohort.

AIM: To assess the impact of liver function test (LFT) abnormalities on the prognosis of patients with coronavirus disease 2019 (COVID-19) in a French cohort of hospitalized patients. PATIENTS AND METHOD: From March 13 to April 22, 2020, we collected on a computerized and anonymized database, medical records, laboratory data and clinical outcomes of patients hospitalized for confirmed cases of COVID-19 infection (RT-PCR and/or CT-scan). Patients were followed up until April 22, 2020 or until death or discharge. We have considered for statistical analysis, LFT abnormalities with levels greater than two times the upper limit of normal. Composite endpoint included admission to ICU, mechanical ventilation, severe radiologic injury and death to define disease severity. RESULTS: Among 281 patients (median age 60 years) with COVID-19, 102 (36.3%) had abnormal LFT. Hypertension (45.6%) and diabetes (29.5%) were the main comorbidities. 20.2% were taken liver-toxic drugs at the admission and 27.4% were given drugs known to induce hepatic cytolysis during hospitalization. Patients with elevated levels of ALT or AST were significantly more severe with a higher rate of admission to ICU (40.0% vs 6.0%, p< 0.0001), and global mortality (26.7% vs 12.1%, p= 0.03). In multivariate analysis, obesity and cytolytic profil were associated with the composite endpoint (respectively 2.37 [1.21; 4.64], p= 0.01 and OR 6.20, 95% confidence interval [1.84, 20.95], p-value 0.003) CONCLUSION: Most of liver injuries are mild and transient during COVID-19. LFT abnormalities are associated with a poorer prognosis and could be a relevant biomarker for early detection of severe infection.

Negative Screening Does Not Rule Out the Risk of Tuberculosis in Patients with Inflammatory Bowel Disease Undergoing Anti-TNF Treatment: A Descriptive Study on the GETAID Cohort.

AIM: to describe the characteristics of incident cases of tuberculosis [TB] despite negative TB screening tests, in patients with inflammatory bowel disease [IBD] undergoing anti-TNF treatment, and to identify the risk factors involved. METHODS: A retrospective descriptive study was conducted at GETAID centers on all IBD patients undergoing anti-TNF treatment who developed TB even though their initial screening test results were negative. The following data were collected using a standardized anonymous questionnaire: IBD, and TB characteristics and evolution, initial screening methods and results, and time before anti-TNF treatment was restarted. RESULTS: A total of 44 IBD patients [including 23 men; median age 37 years] were identified at 20 French and Swiss centers at which TB screening was performed [before starting anti-TNF treatment] based on Tuberculin Skin Tests [n = 25], Interferon Gamma Release Assays [n = 12], or both [n = 7]. The median interval from the start of anti-TNF treatment to TB diagnosis was 14.5 months (interquartile range [IQR] 25-75: 4.9-43.3). Pulmonary TB involvement was observed in 25 [57%] patients, and 40 [91%] had at least one extrapulmonary location. One TB patient died as the result of cardiac tamponade. Mycobacterium tuberculosis exposure was thought to be a possible cause of TB in 14 cases [32%]: 7 patients [including 6 health care workers] were exposed to occupational risks, and 7 had travelled to endemic countries. Biotherapy was restarted on 27 patients after a median period of 11.2 months [IQR 25-75: 4.4-15.2] after TB diagnosis without any recurrence of the infection. CONCLUSION: Tuberculosis can occur in IBD patients undergoing anti-TNF treatment, even if their initial screening results were negative. In the present population, TB was mostly extrapulmonary and disseminated. TB screening tests should be repeated on people exposed to occupational risks and/or travelers to endemic countries. Restarting anti-TNF treatment seems to be safe.