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Basophils have been erroneously considered as minor relatives of mast cells, due to some phenotypic similarity between them. While recent studies have revealed non-redundant roles for basophils in various immune responses, basophil-derived effector molecules, including lipid mediators, remain poorly characterized, compared to mast cell-derived ones. Here we analyzed and compared eicosanoids produced by mouse basophils and mast cells when stimulated with IgE plus allergens. The production of 5-LOX metabolites such as LTB4 and 5-HETE was detected as early as 0.5 h post-stimulation in both cell types, even though their amounts were much smaller in basophils than in mast cells. In contrast, basophils and mast cells showed distinct time course in the production of COX metabolites, including PGD2, PGE2 and 11-HETE. Their production by mast cells was detected at both 0.5 and 6 h post-stimulation while that by basophils was detectable only at 6 h. Of note, mast cells showed 8–9 times higher levels of COX-1 than did basophils at the resting status. In contrast to unaltered COX-1 expression with or without stimulation, COX-2 expression was up-regulated in both cell types upon activation. Importantly, when activated, basophils expressed 4–5 times higher levels of COX-2 than did mast cells. In accordance with these findings, the late-phase production of the COX metabolites by basophils was completely ablated by COX-2 inhibitor whereas the early-phase production by mast cells was blocked by COX-1 but not COX-2 inhibitor. Thus, the production of COX metabolites is differentially regulated by COX-1 and COX-2 in basophils and mast cells.

Background and AimLipids play important roles in inflammation and may be involved in the pathophysiology of inflammatory bowel disease (IBD). Here, we evaluated the characteristics of the plasma lipid profile in patients with IBD.MethodsPlasma samples were collected from 20 patients with Crohn's disease (CD), 20 patients with ulcerative colitis (UC), and 10 healthy volunteers (HVs) after overnight fasting. The subjects were men between 20 and 49 years of age with no history of hyperlipidemia. A total of 698 molecular species in 22 lipid classes were analyzed by ultra‐performance liquid chromatography‐electrospray ionization‐tandem mass spectrometry.ResultsLipid classes of lysophosphatidic acid, lysophosphatidylserine (LPS), phosphatidylserine (PS), and shingosine‐1‐phosphate (S1P) were significantly increased in UC patients compared with the HV. The LPS, PS, and S1P levels were significantly increased, while those of lysophosphatidylinositol and phosphatidylcholine were significantly decreased in CD patients compared with HV. Among PS species, the levels of PSacyl (PSa) 40:3, PSa 38:3, and PSa 42:4 were significantly higher in CD patients, both active and remissive stage, than in HV. The LPS 18:0 level was significantly higher in CD and UC patients compared with HV. PSa 40:3 and PSa 38:3 levels positively correlated with the Crohn's Disease Activity Index, erythrocyte sedimentation rate, and platelet count and negatively correlated with hemoglobin, hematocrit, and albumin levels in CD patients.ConclusionThe lipid profile in IBD patients exhibits significant alterations, and PS levels are associated with clinical disease activity in CD patients.

A 25 kDa fragment of beta-type troponin T (beta-TnT) was expressed in Escherichia coli, and its function as a component of the regulatory system for actomyosin ATPase was compared with that of the authentic counterpart, the full length alpha-TnT. The expressed species, designated as beta-TnT(N'-208), consists of 208 residues. It lacks the entire variable region at the amino-terminus and, near the carboxyl-terminus, a segment of 14 residues is changed from the alpha-type to the beta-type sequence. Functional tests indicated that the truncated beta-TnT was not distinguishable from the full length alpha-TnT, suggesting that neither deletion of the variable N-terminal region nor alteration of the type has a significant effect on the regulatory action of TnT.

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There is increasing evidence that hepoxilins are novel inflammatory mediators. In vitro studies have shown that hepoxilins cause the mobilization of intracellular calcium in human neutrophils, induce plasma leakage, and potently stimulate the chemotaxis of human neutrophils. In vivo, the hepoxilin pathway is activated in conditions with inflammation, for example, pathogen infection, psoriasis, and arthritis, and hepoxilins promote inflammatory hyperalgesia and allodynia. 1 The "hepox" comes from hydroxy-epoxy, and the "ilin" comes from hepoxilins' activity as an insulin secretagogue (albeit an activity whose physiological significance remains unconfirmed). AbstractPsoriasis is a common skin disorder that is characterized by hyperkeratosis, epidermal hyperplasia, T-cell and neutrophil recruitment, and changes in the vascular endothelial system. The several upregulated variable lipid mediators, including the eicosanoids, in psoriatic keratinocytes were described previously, although some results were contradictory. Since hepoxilin is less stable than other eicosanoids such as hydroxyeicosatetraenoic acid (HETE), the measurement of hepoxilin is difficult. In this study, to clarify the relationship between hepoxilin/hepoxilin-related fatty acid derivatives and psoriasis vulgaris, we evaluated the amount of production of lipid mediators including hepoxilins in skin tissues of patients with psoriasis vulgaris in comparison with normal controls by high-performance liquid chromatography/mass spectrometry. Most of the hepoxilins and related lipids evaluated in this study tended to be more abundant in the lesional skin from the psoriasis patient group (PPG) than in the skin from controls. Interestingly, 12R-HETE was markedly higher in the skin samples from the PPG. In addition, the lipids produced in the lipoxygenase pathway, including hepoxilin, were elevated in the skin lesions of the PPG compared with those of normal controls, whereas the lipids produced in the cyclooxygenase pathway were decreased in the skin lesions from the PPG. Our results suggest that an imbalance between the lipoxygenase and cyclooxygenase pathways may contribute to psoriatic pathomechanisms. K E Y W O R D S cyclooxygenase, hepoxilin, lipoxygenase, psoriasis vulgaris, psoriatic arthritis How to cite this article: Takeichi T, Kinoshita F, Tanaka H, et al. The lipoxygenase-hepoxilin pathway is activated in cutaneous plaque lesions of psoriasis. J Cutan Immunol Allergy. 2019;2:15-24. https://doi.