[Update on celiac disease]. / Neues zur Zöliakie.

Celiac disease is a T-cell-mediated autoimmune disorder. It is relevant to us for two very different reasons. Firstly, it has a prevalence of 1 % in the European population. Thus, a huge number of celiac patients remains undiagnosed. Secondly, the celiac trigger, gluten, functions as a "switch", that has the potential to selectively activate celiac immune pathology, thereby allowing us to uncover previously unknown immune conditions. This again contributes to new celiac treatment modalities that will presumably alleviate the future fate of celiac disease patients. In 2022, the German guidelines for celiac disease are published by the Deutsche Gesellschaft für Verdauungs- und Stoffwechselkrankheiten (DGVS). We have summarized some of the recommendations published therein.

Results from the German registry for refractory celiac disease.

Refractory celiac disease (RCD) refers to a rare subgroup of patients with celiac disease who show clinical signs of malabsorption despite a gluten-free diet. RCD is divided into an autoimmune phenotype (RCD type I) and pre-lymphoma (RCD type II). To reflect the clinical reality in managing this disease in Germany, a national register was established based on a questionnaire developed specifically for this purpose. Between 2014 and 2020, a total of 53 patients were registered. The diagnosis of RCD was confirmed in 46 cases (87%). This included 27 patients (59%) with RCD type I and 19 patients (41%) with RCD type II. A wide range of diagnostic and therapeutic measures was used. Therapeutically, budesonide was used in 59% of the RCD patients regardless of the subtype. Nutritional therapy was used in only 5 patients (11%). Overall mortality was 26% (12 patients) with a clear dominance in patients with RCD type II (9 patients, 47%). In summary, RCD needs to become a focus of national guidelines to increase awareness, establish standards, and thus enable the treating physician to make the correct diagnosis in a timely manner. Moreover, we concluded that when treating such patients, contacting a specialized center is recommended to ensure sufficient management.

Histone deacetylase 5 regulates the inflammatory response of macrophages.

Modifying the chromatin structure and interacting with non-histone proteins, histone deacetylases (HDAC) are involved in vital cellular processes at different levels. We here specifically investigated the direct effects of HDAC5 in macrophage activation in response to bacterial or cytokine stimuli. Using murine and human macrophage cell lines, we studied the expression profile and the immunological function of HDAC5 at transcription and protein level in over-expression as well as RNA interference experiments. Toll-like receptor-mediated stimulation of murine RAW264.7 cells significantly reduced HDAC5 mRNA within 7 hrs but presented baseline levels after 24 hrs, a mechanism that was also found for Interferon-γ treatment. If treated with lipopolysaccharide, RAW264.7 cells transfected for over-expression only of full-length but not of mutant HDAC5, significantly elevated secretion of tumour necrosis factor α and of the monocyte chemotactic protein-1. These effects were accompanied by increased nuclear factor-κB activity. Accordingly, knock down of HDAC5-mRNA expression using specific siRNA significantly reduced the production of these cytokines in RAW264.7 or human U937 cells. Taken together, our results suggest a strong regulatory function of HDAC5 in the pro-inflammatory response of macrophages.