Dual Immuno-Barrier Effects of Black Shallot and Aloe Vera Gel in DNFB-Induced Allergic Dermatitis

Allergic dermatitis arises from a self-amplifying interplay between immune-driven inflammation and epidermal barrier disruption, so therapies targeting only one axis may provide incomplete benefit. This study aimed to evaluate the dual immuno-barrier effects of topical black shallot extract and Aloe vera gel, alone and in combination, in a 2,4-dinitrofluorobenzene (DNFB)-induced mouse model. Male Swiss albino mice were assigned to the normal control, DNFB model, DNFB + black shallot, DNFB + Aloe vera, and DNFB + combination groups (n = 8 per group). Treatments were applied once daily from Day 5 to Day 14, and clinical scores, skin thickness, H&E histopathology, and ELISA-based cytokines were assessed. DNFB markedly increased the severity of dermatitis, epidermal thickness, dermal infiltration, and TNF-α, IL-6, and IL-4 levels. Black shallot preferentially reduced inflammatory cytokines and dermal edema, whereas Aloe vera mainly improved epidermal architecture and hyperkeratosis. The combination produced the strongest response, reducing TNF-α from 120.13 ± 8.05 to 45.56 ± 4.33 pg/mg protein, IL-6 from 110.39 ± 8.09 to 40.45 ± 4.16 pg/mg protein, IL-4 from 55.26 ± 5.14 to 20.00 ± 3.00 pg/mg protein, and epidermal thickness from 120.37 ± 8.17 to 50.69 ± 6.27 µm versus DNFB. These findings indicate that black shallot and Aloe vera act through complementary immune-modulating and barrier-restorative mechanisms, supporting a rational dual-axis topical strategy for allergic dermatitis.