Suppression of Allergy-Related Cytokines by Carbon Nanotubes Functionalized with Recombinant Human Surfactant Protein D: Bimodal Implications for Immune Modulation and Nanocarrier Function in Targeting Allergic Inflammation

Aims: Human Surfactant Protein D (SP-D) influences T cell activity and modulates allergic inflammation. In the context of allergen exposure, SP-D may exert regulatory effects on Peripheral Blood Mononuclear Cells (PBMCs), and this was evaluated in this study. Background: Allergic Rhinitis (AR) is a widespread condition affecting about 10–30% of adults and up to 40% of children worldwide. SP-D is a key component of the innate immune system, playing a crucial role in host defense, immune regulation, and surfactant homeostasis. Objective: To study the effect of Carbon Nanotubes (CNTs) coupled with a recombinant SP-D (CNT-rhSP-D) on Phleum Pretense (Phlp) allergen-mediated Th-2 cytokines in PBMCs. Methods: CNTs were functionalized with a recombinant SP-D using Carboxymethyl Cellulose (CMC) as a non-covalent linker. We tested the uptake of CNT-rhSP-D by activated THP-1 cells and their effects on pro-inflammatory cytokine gene expression using real-time PCR. We also studied the inhibitory effects of CNT-rhSP-D on the proliferation of Phlp allergenstimulated PBMCs and their impact on the release of allergy-related Th2 cytokines using a multiplex cytokine array. Results: Exposure of CNTs alone (10 μg/ml for 6 h) significantly increased the mRNA expression of interleukin-1 beta (IL-1β), IL-10, and tumor necrosis factor-alpha (TNF-α). Treatment with CNT-rhSP-D (10 μg/ml) significantly down-regulated the mRNA expression of these cytokines compared to the CNTs-alone group. CNT-rhSP-D (5μg/ml) significantly suppressed (P<0.0001) the Phlp allergen-stimulated proliferation of PBMCs. CNT-rhSP-D (5 μg/ml for 24 h) significantly reduced Th2 cytokine levels, with percent decreases of 29.11%, 95.61%, 86.92% and 97.03% for IL-4, IL-5, IL-9, and IL-13, respectively, compared with the Phlp alone-treated group. Conclusion: CNT-rhSP-D significantly down-regulated the expression of pro-inflammatory cytokines in immune cells and suppressed the allergen-induced PBMC proliferation. The ability of CNT-rhSP-D to attenuate Phlp-induced cytokine dysregulation positions it as a promising therapeutic agent for the treatment of allergen-induced pulmonary inflammation. Further mechanistic studies are warranted to validate its efficacy and safety in preclinical models.