Mechanisms Governing Anaphylaxis: Inflammatory Cells, Mediators, Endothelial Gap Junctions and Beyond

Anaphylaxis is a severe, acute, life-threatening multisystem allergic reaction resulting from the release of a plethora of mediators from mast cells culminating in serious respiratory, cardiovascular and mucocutaneous manifestations that can be fatal. Medications, foods, latex, exercise, hormones (progesterone), and clonal mast cell disorders may be responsible. More recently, novel syndromes such as delayed reactions to red meat and hereditary alpha tryptasemia have been described. Anaphylaxis manifests as sudden onset urticaria, pruritus, flushing, erythema, angioedema (lips, tongue, airways, periphery), myocardial dysfunction (hypovolemia, distributive or mixed shock and arrhythmias), rhinitis, wheezing and stridor. Vomiting, diarrhea, scrotal edema, uterine cramps, vaginal bleeding, urinary incontinence, dizziness, seizures, confusion, and syncope may occur. The traditional (or classical) pathway is mediated via T cells, Th2 cytokines (such as IL-4 and 5), B cell production of IgE and subsequent crosslinking of the high affinity IgE receptor (FcεRI) on mast cells and basophils by IgE-antigen complexes, culminating in mast cell and basophil degranulation. Degranulation results in the release of preformed mediators (histamine, heparin, tryptase, chymase, carboxypeptidase, cathepsin G and tumor necrosis factor alpha (TNF-α), and of de novo synthesized ones such as lipid mediators (cysteinyl leukotrienes), platelet activating factor (PAF), cytokines and growth factors such as vascular endothelial growth factor (VEGF). Of these, histamine, tryptase, cathepsin G, TNF-α, LTC₄, PAF and VEGF can increase vascular permeability. Recent data suggest that mast cell-derived histamine and PAF can activate nitric oxide production from endothelium and set into motion a signaling cascade that leads to dilatation of blood vessels and dysfunction of the endothelial barrier. The latter, characterized by the opening of adherens junctions, leads to increased capillary permeability and fluid extravasation. These changes contribute to airway edema, hypovolemia, and distributive shock, with potentially fatal consequences. In this review, besides mechanisms (endotypes) underlying IgE-mediated anaphylaxis, we also provide a brief overview of IgG-, complement-, contact system-, cytokine- and mast cell-mediated reactions that can result in phenotypes resembling IgE-mediated anaphylaxis. Such classifications can lead the way to precision medicine approaches to the management of this complex disease.

Impact of Lactoferrin Supplementation on Respiratory Tract Infections in Older Nursing Home Residents: A Protocol for a Randomized Control Trial

Objectives

To evaluate the impact of a dietary supplement within an elderly population who reside in a Community Living Center (CLC; VA Nursing Home), on the number of respiratory tract infections (RTIs) during a 90-day study period.

Methods

This is a randomized, double-blind, placebo-controlled study to evaluate the impact of bovine Lactoferrin (bLf) on RTIs in an elderly nursing home population in the US. Subjects will be residents of the CLC and screened within 21 days prior to starting study supplementation. Eligible participants were at least 55 years of age, able to eat and drink and expected to reside at the CLC for the duration of the study. Consent was obtained from the study participant or their legally recognized representative decision maker. Participants will be excluded if: receiving tube feeds or specialized diets for eating disorders; immunocompromised; have a life expectancy of less than six months; or allergic to study products.

Results

Subjects will be randomized in a ratio of 1:1 to either investigational (600 mg of bLf) or (placebo arms. All participants will take study supplement by mouth daily for 90 days. Subjects will be assessed daily for RTI symptoms. Blood and saliva will be collected at 45 and 90 days. Ad hoc assessments and a nasal sample will take place if a subject develops a protocol-defined RTI.

Conclusions

The primary outcome will be number of RTIs over the 90-day study period. Secondary outcomes include severity and duration of RTI symptoms, symptoms associated with RTIs, number of RTI complications, and nasopharyngeal swab at onset of RTI, Other secondary outcomes include the following, all measured at baseline, day 45 and day 90: quality of life by questionnaire, weight, saliva markers, laboratory testing and immunological markers. An exploratory endpoint is vaccine specific inflammatory panel (influenza and Sars-Cov2) measured upon vaccination during supplement period. RTI number, severity, duration and complications and medically confirmed adverse events will be compared between the placebo and investigational groups.

Funding Sources

RB/Mead Johnson & Company.

The Effect of Broccoli Sprout Extract on Seasonal Grass Pollen-Induced Allergic Rhinitis

Patients exposed to pollutants are more likely to suffer from allergic rhinitis and may benefit from antioxidant treatment. Our study determined if patients diagnosed with grass-induced allergic rhinitis could benefit from broccoli sprout extract (BSE) supplementation. In total, 47 patients were confirmed with grass-induced allergic rhinitis and randomized to one of four groups: group 1 (nasal steroid spray + BSE), group 2 (nasal steroid spray + placebo tablet), group 3 (saline nasal spray + BSE) and group 4 (saline nasal spray + placebo tablet). Peak Nasal Inspiratory Flow (PNIF), Total Nasal Symptoms Scores (TNSS) and nasal mucus cytokine levels were analyzed in samples collected before and after the 3-week intervention. Comparing before and after the intervention, PNIF improved significantly when comparing Groups 1 and 2, vs. placebo, at various time points (p ≤ 0.05 at 5, 15, 60 and 240 min) following nasal challenge, while TNSS was only statistically significant at 5 (p = 0.03), 15 (p = 0.057) and 30 (p = 0.05) minutes. There were no statistically significant differences in various cytokine markers before and after the intervention. Combining nasal corticosteroid with BSE led to the most significant improvement in objective measures.

Thrombotic thrombocytopenia purpura in a patient with systemic sclerosis

Thrombotic thrombocytopenic purpura (TTP) has been associated with scleroderma renal crises (SRC) in the past. However such reports markedly diminished after the onset of ACE inhibitor use. Recently, reports again have surfaced that describe scleroderma patients presenting with clinical evidence of TTP. We describe a 50-year-old female with longstanding limited cutaneous scleroderma who presented with hematochezia and thrombocytopenia along with other findings suggesting TTP. A colon biopsy revealed thrombi within the lumen. Her course was complicated by renal failure and hypertension that did not respond to ACE inhibitor therapy alone. She improved after a course of plasma exchange. She was discharged home only to return 2 months later with grand mal seizures and hypertension. During her course she developed adult respiratory distress syndrome. She again responded to plasma exchange and she was discharged home. She has remained stable for 2 years. This report emphasizes the importance of fully evaluating patients with longstanding limited cutaneous scleroderma who present with renal failure, hypertension, and thrombocytopenia in association with multiorgan complications. All possible etiologies, including SRC, TTP, vasculitis, and sepsis should be considered. Tissue biopsies (in this case, a colon biopsy revealed thrombi within the vessel lumen) may prove beneficial in assisting with the diagnosis. For such patients who fail treatment with ACE inhibitors, plasma exchange may be considered.