Scope The cathelicidin antimicrobial peptide (CAMP) gene is induced by 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3), lithocholic acid, curcumin, nicotinamide and butyrate. Discovering additional small molecules that regulate its expression will identify new molecular mechanisms involved in CAMP regulation and increase understanding of how diet and nutrition can improve immune function. Methods and results We discovered that two stilbenoids, resveratrol and pterostilbene, induced CAMP promoter-luciferase expression. Synergistic activation was observed when either stilbenoid was combined with 1α,25(OH)2D3. Both stilbenoids increased CAMP mRNA and protein levels in the monocyte cell line U937 and synergy was observed in both U937 and the keratinocyte cell line, HaCaT. Inhibition of resveratrol targets sirtuin-1, cyclic AMP production and the c-Jun N-terminal, phophoinositide 3 and AMP-activated kinases did not block induction of CAMP by resveratrol or synergy with 1α,25(OH)2D3. Nevertheless, inhibition of the extracellular signal-regulated 1/2 and p38 mitogen-activated protein kinases, increased CAMP gene expression in combination with 1α,25(OH)2D3 suggesting that inhibition of these kinases by resveratrol may explain, in part, its synergy with vitamin D. Conclusions Our findings demonstrate for the first time that stilbenoid compounds may have the potential to boost the innate immune response by increasing CAMP gene expression particularly in combination with 1α,25(OH)2D3.

Neonatal CD4+ T cells have traditionally been viewed as deficient in their capacity to produce Th-1 cytokines in response to polyclonal or antigen specific stimuli. Thus, defining unique aspects of CD4+ T cell activation and development into Th-1 effector cells in neonates is essential to the successful development of novel vaccines and immunotherapies to protect infants from intracellular pathogens. Using highly purified naïve CD4+ T cells derived from cord and adult peripheral blood, we compared the impact of anti-CD3 stimulation plus co-stimulation through TLR-2 performed in the absence of APC, on CD4+ T cell cytokine production, proliferation, and expression of activation markers. In both age groups, TLR-2 co-stimulation elicited activation of naïve CD4+ T cells, characterized by robust production of IL-2 as well as key Th-1 type cytokines IFN-γ and TNF-α. TLR-2 co-stimulation also dramatically reduced naïve T cell production of the immunosuppressive cytokine IL-10. We observed that neonatal naïve CD4+ T cells are uniquely sensitive to TLR-2 mediated co-stimulation, which enabled them to produce equivalent amounts of IFN-γ and more IL-2 when compared to adult responses. Thus, neonatal CD4+ T cells have a distinctive propensity to utilize TLR-2 mediated co-stimulation for development into pro-inflammatory Th-1 effectors, and interventions that target CD4+ T cell TLR-2 mediated responses may be exploited to enhance neonatal adaptive immunity.

Background: Functional Toll like receptors (TLR) are found on human T cells. Neonatal antigen presenting cells (APC) have altered responses to TLR ligands; it is unknown if neonatal CD4+ T cell TLR responses are comparable to adult. Objective: Comparison of TLR-2 expression and responsiveness to TLR-2 direct co-stimulation among total and naïve CD4+ T cell subsets from neonates and adults. Methods: T cell subsets (CD3+CD4+ or CD3+CD4+CD45RA+) were isolated from cord and adult peripheral blood mononuclear cells by flow sorting ( >99.5% purity) and cultured in an APC-free model with α-CD3 ± α -CD28 ± TLR-2 ligand Pam3CYS4. Quantitative PCR and ELISA determined TLR-2 expression and cytokine production. Results: Neonatal CD4+ T cells are predominately naïve (97.2% CD45RA+) but express 5-fold more TLR-2 mRNA than adult CD4+ T cells. Pam3CYS4 provides direct co-stimulation in the presence of α-CD3 to adult and neonatal total CD4+ T cells resulting in IL-2, TNF-α, and IFN-γ production; provision of additional co-stimulation (α-CD28) further enhances cytokine production. When comparing total CD4+ T cell populations, neonatal cells generate significantly less cytokines than adult. When naïve neonatal and adult T cells are compared, neonatal cells generate more cytokines in response to TLR-2 mediated co-stimulation. Conclusions: Naïve neonatal CD4+ T cells have enhanced TLR-2 expression and increased sensitivity to direct TLR-2 co-stimulation as compared to naïve adult cells.