Differential Modulation by Delta9-Tetrahydrocannabinol (∆9-THC) of CD40 Ligand (CD40L) Expression in Activated Mouse Splenic CD4+ T cells

Abstract

The anti-inflammatory activity of cannabinoids has been widely demonstrated in experimental animal models and in humans. CD40-CD40-ligand (L) interactions are among the most crucial initiators of inflammation. This study investigated the effects of Δ9-THC on CD40L expression in mouse splenic T cells after activation with various stimuli. Time course studies demonstrated that peak surface expression of CD40L by CD4+ T cells after anti-CD3/CD28 or phorbol ester plus calcium ionophore (PMA/Io) occurred 8 h post activation. Peak CD40L mRNA levels were observed at 2 h post PMA/Io treatment and at 4 h post anti-CD3/CD28 treatment. Pretreatment with Δ9-THC significantly impaired the upregulation of CD40L induced by anti-CD3/CD28 at both the protein and mRNA level. By contrast, Δ9-THC did not affect PMA/Io-induced surface CD40L expression on CD4+ T cells. Additionally, Δ9-THC also attenuated anti-CD3/CD28-induced CD40L expression on CD4+ T cells derived from CB1−/−/CB2−/− mice. We investigated whether the mechanism by which Δ9-THC suppressed CD40L expression involved putative cannabinoid activation of the glucocorticoid receptor (GR). Although activation of GR resulted in suppression of CD40L induction by anti-CD3/CD28, no interaction between Δ9-THC and GR was observed by a glucocorticoid response element (GRE) luciferase reporter assay in HEK293T cells. Collectively, these results suggest that Δ9-THC targets proximal T cell receptor-associated signaling in a cannabinoid receptor- and glucocorticoid receptor-independent manner. These findings identify suppression of CD40L expression as a novel part of the mechanism by which Δ9-THC exerts anti-inflammatory activity.

Impaired NFAT and NFκB activation are involved in suppression of CD40 ligand expression by Δ9-tetrahydrocannabinol in human CD4+ T cells

“…Consistent with our previous study demonstrating the suppression of CD40L upregulation by Δ 9 -THC in mouse splenic T cells (Ngaotepprutaram et al , 2012), Δ 9 -THC attenuated anti-CD3/CD28-induced CD40L expression by human T cells. It is noteworthy that the decrease of surface CD40L expression by Δ 9 -THC could be the result of increasing the generation of soluble CD40L by proteolysis in the microsome (Pietravalle et al ., 1996); however, this possibility is unlikely in light of the concomitant decrease in the CD40L mRNA levels by Δ 9 -THC treatment.…”

“…Based on our previous finding that Δ 9 -THC attenuated the upregulation of CD40L expression in activated mouse splenic T cells (Ngaotepprutaram et al ., 2012), the effect of Δ 9 -THC on anti-CD3/CD28-induced CD40L expression by activated primary human T cells was investigated. Human PBMCs were activated with anti-CD3/CD28 in the presence or absence of Δ 9 -THC, and peak expression of CD40L occurred between 36–48 h (Fig.…”

“…Our previous study using mouse splenocytes suggested that Δ 9 -THC affected the proximal signaling of TCR based on the fact that Δ 9 -THC-mediated suppression of CD40L expression occurred following T cell activation by anti-CD3/CD28 antibodies, but not phorbol ester/ionomycin (Ngaotepprutaram et al ., 2012). Concordantly, a study reported by Borner and coworkers demonstrated that the T-cell inhibitory effect of Δ 9 -THC is, partly, due to the impairment of proximal TCR signaling cascades (Borner et al, 2009).…”

“…Specifically, our laboratory has shown that Δ 9 -THC impairs production of cytokines such as interleukin 2, expression of costimulatory molecules such as inducible costimulatory molecules (ICOS) and CD40L by activated mouse splenic T cells (Springs et al ., 2008; Lu et al ., 2009b; Ngaotepprutaram et al ., 2012). With the increased use of marijuana recreationally and medically, the potential impact on immune competence is a concern, especially when used by patients whose immune system has already been compromised.…”

Effects of Cannabinoids on T-cell Function and Resistance to Infection

“…For in vivo administration of Δ 9 -THC, it is also possible that the immunosuppression is not due to a direct effect of the drug on cells of the immune system, but is indirect via other suppressive mechanisms such as release of cortisone. Further exploration of the role of Δ 9 -THC and the cannabinoid receptors in modulating T-cell CD40L expression was carried out by the Kaminski laboratory (Ngaotepprutaram et al 2012). CD40L is expressed by T-cells and binds to its cognate molecule, CD40, on antigen presenting cells and B-cells, resulting in T-cell activation.…”