TSLP rather than IL33 drives food allergy following epicutaneous sensitization to food allergen

BACKGROUND

A major route of sensitization to food allergen is through an impaired skin barrier. IL33 and TSLP have both been implicated in epicutaneous sensitization and food allergy, albeit in different murine models.

OBJECTIVE

We assessed the respective contributions of TSLP and IL33 to the development of atopic dermatitis (AD) and subsequent food allergy in TSLP and IL33 receptor (ST2) deficient mice using an AD model that does not require tape stripping.

METHOD

TSLPR^-/-, ST2^-/- and BALB/cJ control mice were exposed to 3 weekly epicutaneous skin patches of either saline, OVA, or a combination of OVA and Aspergillus fumigatus (ASP), followed by repeated intragastric OVA challenges and development of food allergy.

RESULTS

ASP(+/-OVA)-patched, but not OVA-patched, BALB/cJ mice developed an AD-like skin phenotype. However, epicutaneous OVA sensitization occurred in OVA-patched mice and was decreased in ST2^-/- mice resulting in lower intestinal mast cell degranulation, accumulation and OVA-induced diarrhea occurrences upon intragastric OVA challenges. In TSLPR^-/- mice, intestinal MC accumulation was abrogated, and no diarrhea was observed. AD was significantly milder in OVA+ASP-patched TSLPR^-/- mice compared to wild type and ST2^-/- mice. Accordingly, intestinal mast cell accumulation and degranulation were impaired in OVA+ASP-patched TSLPR^-/- mice compared to wild type and ST2^-/- mice, protecting TSLPR^-/- mice from developing allergic diarrhea.

CONCLUSION

Epicutaneous sensitization to food allergen and development of food allergy can occur without skin inflammation and is partly mediated by TSLP, suggesting that prophylactic targeting of TSLP may be useful in mitigating the development of atopic dermatitis and food allergy early in life in at-risk infants.

Alveolar injury and regeneration following deletion of ABCA3

Adaptation to air breathing after birth is dependent upon the synthesis and secretion of pulmonary surfactant by alveolar type 2 (AT2) cells. Surfactant, a complex mixture of phospholipids and proteins, is secreted into the alveolus, where it reduces collapsing forces at the air-liquid interface to maintain lung volumes during the ventilatory cycle. ABCA3, an ATP-dependent Walker domain containing transport protein, is required for surfactant synthesis and lung function at birth. Mutations in ABCA3 cause severe surfactant deficiency and respiratory failure in newborn infants. We conditionally deleted the Abca3 gene in AT2 cells in the mature mouse lung. Loss of ABCA3 caused alveolar cell injury and respiratory failure. ABCA3-related lung dysfunction was associated with surfactant deficiency, inflammation, and alveolar-capillary leak. Extensive but incomplete deletion of ABCA3 caused alveolar injury and inflammation, and it initiated proliferation of progenitor cells, restoring ABCA3 expression, lung structure, and function. M2-like macrophages were recruited to sites of AT2 cell proliferation during the regenerative process and were present in lung tissue from patients with severe lung disease caused by mutations in ABCA3. The remarkable and selective regeneration of ABCA3-sufficient AT2 progenitor cells provides plausible approaches for future correction of ABCA3 and other genetic disorders associated with surfactant deficiency and acute interstitial lung disease.