Vitamin B6 regulates IL-33 homeostasis to alleviate type 2 inflammation.

Interleukin-33 (IL-33) is a crucial nuclear cytokine that induces the type 2 immune response and maintains immune homeostasis. The fine-tuned regulation of IL-33 in tissue cells is critical to control of the type 2 immune response in airway inflammation, but the mechanism is still unclear. Here, we found that healthy individuals had higher phosphate-pyridoxal (PLP, an active form of vitamin B6) concentrations in the serum than asthma patients. Lower serum PLP concentrations in asthma patients were strongly associated with worse lung function and inflammation. In a mouse model of lung inflammation, we revealed that PLP alleviated the type 2 immune response and that this inhibitory effect relied on the activity of IL-33. A mechanistic study showed that in vivo, pyridoxal (PL) needed to be converted into PLP, which inhibited the type 2 response by regulating IL-33 stability. In mice heterozygous for pyridoxal kinase (PDXK), the conversion of PL to PLP was limited, and IL-33 levels were increased in the lungs, aggravating type 2 inflammation. Furthermore, we found that the mouse double minute 2 homolog (MDM2) protein, an E3 ubiquitin-protein ligase, could ubiquitinate the N-terminus of IL-33 and sustain IL-33 stability in epithelial cells. PLP reduced MDM2-mediated IL-33 polyubiquitination and decreased the level of IL-33 through the proteasome pathway. In addition, inhalation of PLP alleviated asthma-related effects in mouse models. In summary, our data indicate that vitamin B6 regulates MDM2-mediated IL-33 stability to constrain the type 2 response, which might help develop a potential preventive and therapeutic agent for allergy-related diseases.

Allergen protease-activated stress granule assembly and gasdermin D fragmentation control interleukin-33 secretion.

Interleukin-33 (IL-33), an epithelial cell-derived cytokine that responds rapidly to environmental insult, has a critical role in initiating airway inflammatory diseases. However, the molecular mechanism underlying IL-33 secretion following allergen exposure is not clear. Here, we found that two cell events were fundamental for IL-33 secretion after exposure to allergens. First, stress granule assembly activated by allergens licensed the nuclear-cytoplasmic transport of IL-33, but not the secretion of IL-33. Second, a neo-form murine amino-terminal p40 fragment gasdermin D (Gsdmd), whose generation was independent of inflammatory caspase-1 and caspase-11, dominated cytosolic secretion of IL-33 by forming pores in the cell membrane. Either the blockade of stress granule assembly or the abolishment of p40 production through amino acid mutation of residues 309-313 (ELRQQ) could efficiently prevent the release of IL-33 in murine epithelial cells. Our findings indicated that targeting stress granule disassembly and Gsdmd fragmentation could reduce IL-33-dependent allergic airway inflammation.

Trinickia dinghuensis sp. nov. and Trinickia fusca sp. nov., isolated from forest soil.

Two Gram-stain-negative, aerobic, non-spore forming and rod-shaped bacterial strains, designated DHOM06T and 7MK8-2T, were isolated from forest soil sampled at Dinghushan Biosphere Reserve, Guangdong Province, PR China. Strain DHOM06T grew at 12-37 °C (optimum, 28-33 °C), pH 4.5-7.5 (pH 5.5) and in the presence of 0-0.5 % NaCl (w/v); while strain 7MK8-2T grew at 12-42 °C (28-33 °C), pH 4.0-8.5 (pH 4.5-5.5) and in the presence of 0-1.0 % NaCl (w/v). Strains DHOM06T and 7MK8-2T each has a 16S rRNA gene sequence similarity of 97.1-98.9 % as well as 97.4-97.9 % to Trinickia strains, respectively. In the 16S rRNA gene sequence phylogram, both strains and all five currently described Trinickia species formed a clade but they were all distinct from each other. The average nucleotide identity and digital DNA-DNA hybridization values for strains DHOM06T and 7MK8-2T and all Trinickia species were in the range of 77.4-82.6 % and 21.7-26.2 %, respectively. The DNA G+C content of DHOM06T and 7MK8-2T was 63.2 and 63.5 mol%, respectively, based on total genome calculations. These two strains contained ubiquinone 8 as the major respiratory quinone and C16 : 0, C17 : 0cyclo, C19 : 0cyclo ω8c, summed feature 3 (C16 : 1ω7c/C16 : 1ω6c) and summed feature 8 (C18 : 1ω7c/C18 : 1ω6c) as the major cellular fatty acids. The major polar lipids of DHOM06T and 7MK8-2T were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. On the basis of phenotypic, chemotaxonomic, phylogenetic and genomic analysis data, strains DHOM06T and 7MK8-2T represent two novel species of the genus Trinickia, for which the names Trinickia dinghuensis sp. nov. (type strain DHOM06T=GDMCC 1.1280T=LMG 30259T) and Trinickia fusca sp. nov. (type strain 7MK8-2T=GDMCC 1.1449T=KCTC 62469T) are proposed.

Paraburkholderia caseinilytica sp. nov., isolated from the pine and broad-leaf mixed forest soil.

A novel Gram-stain-negative, aerobic, non-spore-forming, motile and rod-shaped bacterial strain, designated HM451T, was isolated from forest soil sampled at the Dinghushan Biosphere Reserve, Guangdong Province, PR China (112° 31' E 23° 10' N). It grew optimally at 28 °C, pH 5.0-6.0 and in the presence of 0-2.5 % (w/v) NaCl on R2A medium. Strain HM451T was closely related to Paraburkholderia mimosarum NBRC 106338T (98.6 % 16S rRNA gene sequence similarity), Paraburkholderia heleia NBRC 101817T (98.4 %) and Paraburkholderia silvatlantica SRMrh-20T (98.0 %). The 16S rRNA gene sequence analysis showed that strain HM451T and the three closely related strains formed a clade within the genus Paraburkholderia, but was clearly separated from the established species. The DNA-DNA relatedness value between strain HM451T and its phylogenetically closest relative, P. mimosarum NBRC 106338T, was much lower than 70 %. Strain HM451T contained ubiquinone 8 as the major respiratory quinone. Major fatty acids were C16 : 0, C17 : 0cyclo and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The DNA G+C content of strain HM451T was 65.4 mol%. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, two unidentified aminophospholipids, one unidentified aminolipid and a polar lipid. The phenotypic, chemotaxonomic and phylogenetic data showed that strain HM451T represents a novel species of the genus Paraburkholderia, for which the name Paraburkholderia caseinilytica sp. nov. is proposed. The type strain is HM451T (=GDMCC 1.1190T=LMG 30092T).

Dissolution enhancement of cefdinir with hydroxypropyl-ß-cyclodextrin.

The solid state properties and dissolution behavior of binary systems of cefdinir (CEF) with hydroxypropyl-ß-cyclodextrin (HP-ß-CD) were investigated. CEF-HP-ß-CD interaction in the solution state was studied by phase-solubility analysis and demonstrates the ability of HP-ß-CD to complex with CEF giving A(L) type profile with 65.28 ± 1.3 M⁻¹ stability constant. The freeze drying technique was adopted to prepare binary systems of CEF with HP-ß-CD in 1:1 molar ratio. The solid inclusion was characterized by fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRD), and scanning electron microscopy (SEM). Aqueous solubility of CEF-HP-ß-CD inclusion complex was 2.36-fold of pure CEF. The dissolution profiles of inclusion complexes were determined and compared with those of CEF alone and their physical mixtures. The dissolution rate of inclusion complex was superior than the CEF alone. These approaches indicated that CEF was able to form an inclusion complex with HP-ß-CD, and the inclusion compounds exhibited different spectroscopic features and properties.