Toll‐like receptors (TLR) represent an ancient front‐line defence system that enables the host organism to sense the presence of microbial components within minutes. As inducers of inflammation, TLR act as important triggers of distinct entities such as sepsis or autoimmune disease exacerbation. We report here that vitamin D3 [1α,25‐dihydroxycholecalciferol, 1,25(OH)₂D3] suppresses the expression of TLR2 and TLR4 protein and mRNA in human monocytes in a time‐ and dose‐dependent fashion. Despite 1,25(OH)₂D3‐induced up‐regulation of CD14, challenge of human monocytes with either LPS or lipoteichoic acid resulted in impaired TNF‐α and procoagulatory tissue factor (CD142) production, emphasizing the critical role of TLR in the induction of inflammation. Moreover, reduced TLR levels in 1,25(OH)₂D3‐treated phagocytes were accompanied by impaired NF‐κB/RelA translocation to the nucleus and by reduced p38 and p42/44 (extracellular signal‐regulated kinase 1/2) phosphorylation upon TLR‐ligand engagement. Both TLR down‐regulation and CD14 up‐regulation were substantially inhibited by the vitamin D receptor (VDR) antagonist ZK 159222, indicating that the immunomodulatory effect of 1,25(OH)₂D3 on innate immunity receptors requires VDR transcription factor activation. Our data provide strong evidence that 1,25(OH)₂D3 primes monocytes to respond less effectively to bacterial cell wall components in a VDR‐dependent mechanism, most likely due to decreased levels of TLR2 and TLR4.

Type 1 diabetes is characterized by the destruction of pancreatic β cells, and generating new insulin-producing cells from other cell types is a major aim of regenerative medicine. One promising approach is transdifferentiation of developmentally related pancreatic cell types, including glucagon-producing α cells. In a genetic model, loss of the master regulatory transcription factor Arx is sufficient to induce the conversion of α cells to functional β-like cells. Here, we identify artemisinins as small molecules that functionally repress Arx by causing its translocation to the cytoplasm. We show that the protein gephyrin is the mammalian target of these antimalarial drugs and that the mechanism of action of these molecules depends on the enhancement of GABA_A receptor signaling. Our results in zebrafish, rodents, and primary human pancreatic islets identify gephyrin as a druggable target for the regeneration of pancreatic β cell mass from α cells.

Background: Single-center trials have shown that monocytic HLA-DR is a good marker for monitoring the severity of temporary immunodepression after trauma, major surgery, or sepsis. A new test for measuring monocytic HLA-DR is now available. Methods: We evaluated a new test reagent set for monocytic HLA-DR expression (BD Quantibrite™ HLA-DR/Monocyte reagent; Becton Dickinson) in single-laboratory and interlaboratory experiments, assessing preanalytical handling, lyse-no-wash (LNW) vs lyse-wash (LW) values, reference values, and the effect of use of different flow cytometers and different instrument settings on test variance. Results: For preanalytical handling, EDTA anticoagulation, storage on ice as soon as possible, and staining within 4 h after blood collection gave results comparable to values obtained for samples analyzed immediately after collection (mean increase of ∼4% in monocytic HLA-DR). Comparison of LNW and LW revealed slightly higher results for LNW (∼18% higher for LNW compared with LW; r = 0.982). Comparison of different flow cytometers and instrument settings gave CVs <4%, demonstrating the independence of the test from these variables and suggesting that this method qualifies as a standardized test. CV values from the interlaboratory comparison ranged from 15% (blood sample unprocessed before transport) to 25% (stained and fixed before transport). Conclusions: For the BD Quantibrite HLA-DR/Monocyte test, preanalytical handling is standardized. Single-laboratory results demonstrated the independence of this test from flow cytometer and instrument settings. Interlaboratory results showed greater variance than single-laboratory values. This interlaboratory variance was partly attributable to the influence of transport and can be reduced by optimization of transport conditions.

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The impaired infection control related to the functional immaturity of the neonatal immune system is an important cause of infection in preterm newbo