# Pollen-Food Allergy Syndrome: Allergens, Clinical Insights, Diagnostic and Therapeutic Challenges
## 4 PFAS Pathogenesis
Similarly, exercise can amplify the severity of allergic reactions by increasing gastrointestinal permeability and altering blood flow dynamics, particularly to the digestive system. Physical activity accelerates the movement of allergens into the bloodstream and can lower the activation threshold for mast cells, increasing the likelihood of a systemic allergic response [35]. This phenomenon is often observed in exercise-induced anaphylaxis, where exercise acts as a trigger for severe allergic reactions, especially when combined with allergen exposure [81]. Certain medications, such as NSAIDs and proton pump inhibitors (PPIs), can also exacerbate allergic reactions. NSAIDs, by inhibiting prostaglandin synthesis, can enhance mast cell degranulation and reduce the body's ability to counteract inflammatory responses [82]. PPIs, on the other hand, alter the acidic environment of the stomach, impairing protein digestion and allowing more intact allergens to reach the immune system in the gut, thereby increasing the risk of an allergic response [79]. Other cofactors, such as stress, hormonal changes, and underlying infections, can similarly influence the severity of allergic reactions by modulating immune function or increasing the bioavailability of allergens. The interplay of these cofactors with allergen exposure is a critical aspect of managing PFAS and other allergic conditions, emphasizing the need for comprehensive patient education and individualized management strategies to minimize risks. There are other food allergy syndromes that share similar mechanisms, specifically sensitization through the airways followed by allergic reactions upon food ingestion. These syndromes underscore the importance of understanding cross-reactivity between inhalant allergens and food proteins. Pork-cat syndrome is an IgE-mediated allergic condition where individuals sensitized to cat dander, specifically the protein Fel d 2 (a serum albumin), develop allergic reactions upon consuming pork. The cross-reactivity occurs because of the high degree of homology between Fel d 2 and porcine serum albumin (Sus s 1) [83]. Serum albumins are major carrier proteins in the bloodstream and they are conserved across mammalian species to a high degree, which contributes to cross-reactivity [84]. Notably, this condition is more commonly observed in individuals with chronic exposure to cats, such as pet owners or individuals living in households with multiple cats, where repeated inhalation of Fel d 2 drives immune sensitization. Symptoms may include DAS as well as systemic reactions [85; 86]. Fungus-food allergy syndrome (FFAS) is a condition characterized by sensitization to airborne fungal spores, which subsequently leads to allergic reactions to foods containing structurally similar fungal proteins. Environmental molds such as _Alternaria alternata_, _As_pergillus fumigatus_, and _Cladosporium_ are well-documented allergens found in both outdoor and indoor environments, particularly in damp or poorly ventilated spaces [87]. Repeated inhalation of these fungal spores can prime the immune system, inducing the production of specific IgE antibodies against fungal allergens. Over time, sensitized individuals may experience allergic symptoms upon ingesting certain foods that contain fungal components or are contaminated with mold [88]. The cross-reactivity between fungal spores and food allergens is primarily attributed to shared allergenic proteins, such as enolases and thioredoxins, which are conserved across fungi and certain foods. These foods include fermented products like cheese, beer, wine, and soy sauce, as well as foods susceptible to mold contamination such as nuts, dried fruits, and grains [88,89]. _Alternaria_ and _Apergillus_ allergens are also known to exhibit cross-reactivity with proteins found in edible fungi (e.g., mushrooms) [90]. _Alternaria_-spinach syndrome has also been recently described, with Alt a 1 identified as the likely allergen involved in the reaction [91].