Various inflammatory diseases are characterized by tissue infiltration of neutrophils. Chemokines recruit and activate leukocytes, but neutrophils are traditionally known to be restricted in their chemokine receptor (CR) expression repertoire. Neutrophils undergo phenotypic and functional changes under inflammatory conditions, but the mechanisms regulating CR expression of infiltrated neutrophils at sites of chronic inflammation are poorly defined. Here we show that infiltrated neutrophils from patients with chronic inflammatory lung diseases and rheumatoid arthritis highly express CR on their surface that are absent or only marginally expressed on circulating neutrophils, i.e., CCR1, CCR2, CCR3, CCR5, CXCR3, and CXCR4, as measured by flow cytometry, immunohistochemistry, and confocal microscopy. The induction of CR surface expression on infiltrated neutrophils was functionally relevant, because receptor activation by chemokine ligands ex vivo modulated neutrophil effector functions such as respiratory burst activity and bacterial killing. In vitro studies with isolated neutrophils demonstrated that the surface expression of CR was differentially induced in a cytokine-mediated, protein synthesis-dependent manner (CCR1, CCR3), through Toll-like (CXCR3) or NOD2 (CCR5) receptor engagement, through neutrophil apoptosis (CCR5, CXCR4), and/or via mobilization of intracellular CD63⁺ granules (CXCR3). CR activation on infiltrated neutrophils may represent a key mechanism by which the local inflammatory microenvironment fine-tunes neutrophil effector functions in situ. Since the up-regulation of CR was exclusively found on infiltrated neutrophils at inflammatory sites in situ, the targeting of these G protein-coupled receptors may have the potential to site-specifically target neutrophilic inflammation.

Background: Pregnant women usually meet their increased energy needs but do not always meet their increased micronutrient requirements. The supply of both folic acid and docosahexaenoic acid (DHA) has been related to positive pregnancy and infant outcomes. Objective: We aimed to assess whether fish-oil (FO) supplementation with or without folate from gestation week 22 to birth improves maternal and fetal n−3 long-chain polyunsaturated fatty acid (n−3 LC-PUFA) status. Design: We conducted a multicenter (Germany, Hungary, and Spain), randomized, double-blind, 2 × 2 factorial, placebo-controlled trial. From gestation week 22 until delivery, 311 pregnant women received daily a preparation with FO [0.5 g DHA and 0.15 g eicosapentaenoic acid (EPA)], 400 μg methyltetrahydrofolic acid (MTHF), FO with MTHF, or placebo. Outcome measures included maternal and cord plasma DHA and EPA contents at gestation weeks 20 and 30 and at delivery, indicators of pregnancy outcome, and fetal development. Results: FO significantly (P < 0.001) increased maternal DHA and EPA (% by wt), as shown by 3-factor repeated-measures ANOVA (ie, MTHF, FO, and time) with adjustment for maternal baseline DHA and EPA. In addition, FO significantly (P < 0.001) increased cord blood DHA (% by wt; 2-factor ANOVA). MTHF was significantly (P = 0.046) associated with increased maternal DHA (% by wt). There was no FO × MTHF interaction for the time course of DHA or EPA (P = 0.927 and 0.893). Pregnancy outcomes and fetal development did not differ significantly among the intervention groups. Conclusions: FO supplementation from gestation week 22 until delivery improves fetal n−3 LC-PUFA status and attenuates depletion of maternal stores. MTHF may further enhance maternal n−3 LC-PUFA proportions.

In past 10 years, microRNAs (miRNAs) have gained scientific attention due to their importance in the pathophysiology of allergic diseases and their potential as biomarkers in liquid biopsies. They act as master post‐transcriptional regulators that control most cellular processes. As one miRNA can target several mRNAs, often within the same pathway, dysregulated expression of miRNAs may alter particular cellular responses and contribute, or lead, to the development of various diseases. In this review, we give an overview of the current research on miRNAs in allergic diseases, including atopic dermatitis, allergic rhinitis, and asthma. Specifically, we discuss how individual miRNAs function in the regulation of immune responses in epithelial cells and specialized immune cells in response to different environmental factors and respiratory viruses. In addition, we review insights obtained from experiments with murine models of allergic airway and skin inflammation and offer an overview of studies focusing on miRNA discovery using profiling techniques and bioinformatic modeling of the network effect of multiple miRNAs. In conclusion, we highlight the importance of research into miRNA function in allergy and asthma to improve our knowledge of the molecular mechanisms involved in the pathogenesis of this heterogeneous group of diseases.