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Platelet-Activating Factor Receptors in the Airways
Published in Devendra K. Agrawal, Robert G. Townley, Inflammatory Cells and Mediators in Bronchial Asthma, 2020
An increased concentration of lyso-PAF has been found in the plasma of patients with late asthmatic response.163 In addition, PAF-acether inactivator activity in plasma decreased in parallel to the increase in plasma lyso-PAF levels. This suggests that PAF-acether may be one of the mediators involved in the late-phase reaction in asthma. Recently, a deficiency of serum PAF acetylhydrolase activity has been observed in asthmatic children.164 Deficiency in serum PAF acetylhydrolase appeared to be transmitted by autosomal recessive heredity among five Japanese families. This deficiency correlated with the severity of asthma.164 This study suggests that PAF-acether may be released into the blood of asthmatics, and an increase in PAF-acether levels may cause more severe respiratory symptoms in asthmatic children.
Recognition, treatment, and prevention of systemic allergic reactions and anaphylaxis *
Published in Richard F. Lockey, Dennis K. Ledford, Allergens and Allergen Immunotherapy, 2020
Emma Westermann-Clark, Stephen F. Kemp, Richard D. deShazo
The roles of PAF and PAF acetylhydrolase, the enzyme that inactivates PAF, appear to be important in human anaphylaxis. In a prospective controlled study, serum PAF levels directly correlated and PAF acetylhydrolase levels inversely correlated with anaphylaxis severity [43]. Retrospective analysis demonstrates that PAF acetylhydrolase activity is significantly lower in subjects experiencing fatal peanut anaphylaxis than for five control groups. Similarly, PAF levels correlated with the severity of acute allergic reactions in 41 patients who presented to an emergency room for treatment, more so than blood levels of histamine or tryptase [44].
Fertility issues in men with spinal cord injury
Published in Jacques Corcos, David Ginsberg, Gilles Karsenty, Textbook of the Neurogenic Bladder, 2015
Jeanne Perrin, Blandine Courbiere, Vincent Achard, Catherine Metzler-Guillemain
The high level of platelet-activating factor (PAF) acetylhydrolase observed in the seminal fluid of SCI patients inactivates PAF and contributes to the impairment of sperm motility, capacitation, and fertilization ability.40 Indeed, PAF is an important phospholipid mediator that stimulates sperm motility, improves sperm capacitation and fertilization. As stated for insufficient antioxidant activity, this mechanism could be associated to a dysfunction of seminal vesicles.
Inhibition of platelet-activating factor (PAF)-induced platelet aggregation by fatty acids from human saliva
Published in Platelets, 2022
Interest in cis-unsaturated FAs is being maintained since some of their properties have led to the belief that dietary enrichment with PUFA, for example EPA in fish oils, and other ω-3 unsaturated FAs that are not metabolized to eicosanoids, might protect against thrombosis, atherosclerosis, and a range of inflammatory diseases [36–40]. Although PAF has been implicated in a variety of different inflammatory states and may be a critical mediator in shock, sepsis, and trauma [41], its etiological role has yet to be conclusively established in many cell types. The presence in saliva of PAF and a potent inhibitor of PAF-induced PA raises questions concerning the possible involvement of this phospholipid in oral inflammatory disorders. PAF levels in saliva and fluid from inflamed gingiva are significantly increased during periodontitis and mucositis with levels correlating with disease severity [42,43]. These observations suggest that PAF has a role in the pathophysiology of oral inflammatory disorders and, in the almost total absence of PAF acetylhydrolase in saliva, cis-unsaturated FA inhibitors of PAF may constitute an important anti-inflammatory control mechanism in the oral cavity.
The clinical evidence of second-generation H1-antihistamines in the treatment of allergic rhinitis and urticaria in children over 2 years with a special focus on rupatadine
Published in Expert Opinion on Pharmacotherapy, 2021
Antonio Nieto, María Nieto, Ángel Mazón
Although histamine is the main mediator in the pathophysiology of allergic rhinitis and chronic urticaria, it is clearly not the only mediator involved in these processes. In recent years, the role of platelet activating factor (PAF) as a key mediator involved in the allergic hypersensitivity reaction has gained recognition. PAF is an endogenous phospholipid synthesized in inflammatory cells such as mast cells, eosinophils, basophils, neutrophils, macrophages, and platelets, which is released during allergic or inflammatory reactions. In allergic rhinitis, these reactions are associated with increased vascular permeability, eosinophil chemoattraction, and airway hyperresponsiveness. Increased plasma levels of PAF have been reported in patients with urticaria compared with healthy controls [12–17]. Additionally, recent findings in CSU patients, particularly those with sgAH refractoriness, showed significant increases in serum PAF levels and decreases in PAF-AH. Therapies modulating PAF and PAF-acetylhydrolase (PAF-AH), which is responsible for PAF degradation. PAF-AH levels could be effective in patients with CSU refractory to antihistamines [18].
Evaluation of maternal plasma platelet activating factor acetylhydrolase activity and mRNA expression in pre-eclampsia: a case control study
Published in Journal of Obstetrics and Gynaecology, 2021
Preeti Gupta, Rachna Agarwal, Sruthi Bhaskaran, Seema Garg, Mohit Mehndiratta, Gita Radhakrishnan, Alpana Singh, Richa Agarwal, Divya Narang
PAF acetylhydrolase (PAF-AH) hydrolyses and inactivates PAF and PAF-like oxidised phospholipids. Higher PAF-AH activity results in a lower plasma PAF level and ultimately resulting in vasoconstriction, increased vascular resistance and diminished refractoriness to various pressor agents that lead to hypertension (Fan et al. 2012). Though many studies have shown increased PAF-AH activity in PE (Benedetto et al. 1989; Maki et al. 1993; Kobayashi et al. 1994; Fan et al. 2012), similar studies in the Indian population are lacking. We conducted this study to determine PAF-AH activity in maternal plasma of PE patients versus normotensives and PAF-AH mRNA expression to know the aberration of PAF-AH activity at the level of the gene, in the Indian population.