Oral Immunotherapy for Food Allergy-a US Regulatory Perspective.

The recent approval of Palforzia for treatment of peanut allergy by the US Food and Drug Administration (USFDA) predicts that additional products for oral immunotherapy (OIT) are on the horizon. In this article, the authors review the legal framework by which the USFDA regulates products for OIT of food allergy and the clinical data that demonstrated that the safety and effectiveness profile of Palforzia supported approval and conclude with a discussion of oral food challenge (OFC) as a clinical endpoint to demonstrate safety and effectiveness of OIT products.

Hypoxia stimulates inflammatory and fibrotic responses from nasal-polyp derived fibroblasts.

OBJECTIVES/HYPOTHESIS: Chronic sinusitis is primarily an inflammatory disorder characterized by hyperplasia of immune cells and sinus tissue. Nasal mucosal swelling or polyps can occlude the sinus ostia, decreasing the level of oxygen available to the sinus tissue. Hypoxia in many diseases results in increased recruitment of inflammatory cells and release of cytokines. The role of hypoxia in chronic sinusitis is unknown. We hypothesized that hypoxia induces production of mediators that recruit cells into the sinus tissue and are involved in remodeling of the nasal mucosa. METHODS: We compared data from unstimulated nasal-polyp derived fibroblasts with those cultured in hypoxic (10% O2) and anoxic (0% O2) environments. Changes in mRNA expression and protein levels of cytokines and chemokines were measured along with changes in cellular proliferation. RESULTS: Hypoxic conditions did not change the proliferative capacity of fibroblasts, whereas anoxia led to a 40% reduction in cellular proliferation (P < .05). Hypoxia led to increases in secretion of many cytokines including vascular endothelial growth factor and CCL11. As a marker of remodeling, procollagen and fibronectin production were significantly increased under hypoxic conditions. CONCLUSIONS: Hypoxic conditions present in the sinus tissue could increase production of proinflammatory and remodeling cytokines that contribute to the inflammation observed in sinusitis. Surgical intervention may help decrease inflammation by allowing reoxygenation of the sinus cavity and decrease the hypoxic induction of cytokines and remodeling factors.

Lysophosphatidic acid stimulates inflammatory cascade in airway epithelial cells.

Nasal polyps are benign outgrowths originating from the anterior ethmoid and maxillary sinuses. The events leading to polyp formation are unknown but evidence points to damage of the mucousal epithelium. Lysophosphatidic acid (LPA) is a water-soluble phospholipid that has been implicated in the development of allergic inflammation. We hypothesized LPA may be an important mediator in the initiation and maintenance of the inflammatory milieu of the polyp. Data was compared from unstimulated lung epithelial and when possible nasal polyp-derived epithelial cells with LPA stimulated cells. LPA receptors 1 and 2 were constitutively expressed on lung and nasal polyp-derived epithelial cells and receptor mRNA expression was decreased upon stimulation with IL-13 and IFN-gamma. When cells were treated with LPA, cellular proliferation was stimulated 2.2 fold. Supernatants from LPA stimulated cells displayed decreases in the levels of VEGF, GM-CSF, and TNF-alpha at 24h which returned to normal or increased at 48h. Our results suggest epithelial cells undergo rapid proliferation in response to LPA resulting in a transient decrease in inflammatory cytokines followed by an upregulation of these cytokines that could lead to increased inflammation.

Concordant modulation of cysteinyl leukotriene receptor expression by IL-4 and IFN-gamma on peripheral immune cells.

Arachidonic acid can be metabolized to form a group of compounds known as the cysteinyl leukotrienes (CysLT) that bind to one of two receptors to mediate their actions. On circulating cells, expression of the leukotriene receptors is low, but in inflamed tissue the receptor number is dramatically increased. We hypothesized that the cytokine milieu present during inflammation can increase receptor expression on infiltrating immune cells. Various cell populations were purified from peripheral blood and stimulated in vitro with cytokines characteristic of allergic inflammatory disorders, and CysLT receptor expression was measured using quantitative PCR analysis, Western blot, and flow cytometry. IL-4, but not IL-13, was able to significantly induce mRNA and protein levels for both CysLT receptor 1 and 2 from T cells and B cells. CysLT2 receptor expression was also significantly increased in monocytes and eosinophils after IL-4 stimulation. Surprisingly, CysLT2 receptor expression was increased in monocytes, T cells, and B cells when IFN-gamma was used as the stimulus. Factors involved in eosinophil growth and survival were tested for their ability to alter CysLT receptor expression. These results support the concept that cytokines increase expression of both receptors on lymphocytes and granulocytes, allowing these cells to be more responsive to secreted leukotrienes at sites of inflammation.

Expression of leukotriene C4 synthase and plasminogen activator inhibitor 1 gene promoter polymorphisms in sinusitis.

BACKGROUND: Studies have described polymorphisms in genes involved with both leukotriene synthesis and remodeling. Leukotriene C4 synthase (LTC4S) is the critical terminal pathway enzyme involved in regulation of cysteinyl leukotriene (CysLT) synthesis. An A-to-C base exchange in the promoter region of the LTC4S gene influences its expression. The plasminogen activator inhibitor (PAI) 1 gene is associated with tissue fibrosis. The presence of either 4G or 5G residues in the promoter region has been associated with altered transcription. The role of these polymorphisms was investigated in patients with sinusitis and polyps. We performed a prospective study of patients undergoing endoscopic sinus surgery at a university hospital between 1996 and 2004. METHODS: Demographic data and sinus tissue were collected from patients. Patients were classified into four groups: controls, chronic hyperplastic eosinophilic sinusitis (CHES), aspirin exacerbated respiratory disease (AERD), and chronic inflammatory sinusitis (CIS). DNA was analyzed for the LTC4S and the PAI-1 promoter polymorphisms using standard PCR techniques. RESULTS: There were 133 patients with 76 women and 57 men (mean age, 42 years). Sixty-six people were in the control group, 16 people were in the CIS group, 51 people were in the CHES group, and 22 people were in the AERD group. The LTC4S allelic frequencies were controls, A = 0.81 and C = 0.19; CIS, A = 0.73 and C = 0.27; CHES, A = 0.69 and C = 0.31; AERD, A = 0.67 and C = 0.33. The C allele was more frequent in CHES versus controls (p = 0.04). The PAI-1 allele frequencies were controls, 5G = 0.55 and 4G = 0.45; CIS, 5G = 0.47 and 4G = 0.53; CHES, 5G = 0.56 and 4G = 0.44; AERD, 5G = 0.54 and 4G = 0.46. Increased expression of the 4G allele of the PAI-1 gene was observed in CIS; however, this genetic variance between the four groups was not statistically different (p > 0.05). CONCLUSION: There appears to be a genetic component that contributes to nasal polyp formation in sinusitis. Although the LTC4S polymorphism has previously been associated with aspirin-sensitive asthma, this is the first demonstration that the polymorphism is associated with CHES and this is independent of aspirin sensitivity.

Characterization of interleukin-4-stimulated nasal polyp fibroblasts.

Chronic hyperplastic eosinophilic sinusitis is an inflammatory disease that results in the accumulation of eosinophils, fibroblasts, mast cells, and goblet cells at the site of injury. A common feature of this disease is the presence of nasal polyposis (NP). The current studies were designed to assess the contribution of interleukin (IL)-4 to fibroblast-mediated inflammation in chronic hyperplastic eosinophilic sinusitis/NP. In addition, we hypothesized that cysteinyl leukotrienes (CysLT) may directly influence fibroblast-mediated fibrotic and remodeling pathways in this disorder. Fibroblasts were isolated from NP tissue. All fibroblast lines expressed the IL-4 receptor. IL-4 induced changes in mRNA and protein expression of fibrotic (transforming growth factor-beta1 and -beta2) and inflammatory cytokines and chemokines (IL-6 and CCL11) by fibroblasts as measured by semiquantitative and quantitative polymerase chain reaction, RNase protection assay, and enzyme-linked immunosorbent assay. The expression of CysLT and other proinflammatory lipid receptors on fibroblasts was evaluated. CysLT1 and CysLT2 receptors were not expressed on fibroblasts; however, LPA(1) receptor was constitutively expressed and LPA(2) receptor expression was upregulated by IL-4. The metabolic cascade involved in CysLT synthesis was not expressed in fibroblasts and could not be induced by IL-4 treatment.