Direct effects of HP Acthar Gel® on human B lymphocyte activation in vitro

Abstract

IntroductionBoth clinical experience and experimental evidence have suggested that Adrenocorticotropic hormone (ACTH) might directly exert immunomodulatory effects not dependent on adrenal steroidogenesis.MethodsThe direct effects of H.P. Acthar Gel® (Acthar), a repository preparation containing a porcine ACTH analogue, on human B lymphocyte function were studied in vitro using peripheral blood B cells isolated using anti-CD19 coated magnetic beads and activated by interleukin 4 (IL-4) and CD40 ligand (CD40L). Analysis of expression of messenger RNA (mRNA) encoding activation-induced cytidine deaminase (AICDA) was carried out by quantitative real-time polymerase chain reaction (PCR). Cellular proliferation was assessed by a flow cytometric technique using intracellular staining with carboxyfluorescein succinimidyl ester (CFSE). Immunoglobulin G (IgG) production was measured in cell supernatants using an immunoassay.ResultsActhar was found to exert acute, dose-dependent inhibitory effects on IL-4/CD40L–mediated induction of the expression of activation-induced cytidine deaminase (AICDA) after 24 hours, as well as sustained inhibition of B cell proliferation and IgG production during five more days of culture, without deleterious effects on B cell viability.ConclusionsThese experiments demonstrate that Acthar can exert direct effects on the humoral immune system independent of any role in the regulation of adrenal steroidogenesis. Although the impact of these findings on clinical disease was not evaluated in this study, these data support the therapeutic potential of Acthar for the management of autoimmune diseases characterized by B cell activation and aberrant humoral immune function.

Repository corticotrophin injection exerts direct acute effects on human B cell gene expression distinct from the actions of glucocorticoids

“…We found evidence for dose-dependent alterations in specific B cell mRNAs that are largely consistent with our previous observations of suppressive effects of the RCI preparation on B cell function in vitro [7]. Our experiments were carried out under conditions in vitro that activate B cells to undergo late steps of differentiation leading to active IgG secretion.…”

“…The central components of this group, MAP kinase 11, MAP kinase 13 and myocyte enhancer factor 2C (MEF2C) have been demonstrated to regulate the cellular proliferation required in the terminal differentiation of antibody-secreting cells [45]. The proliferative arrest induced by RCI action on IL-4/ CD40L-activated B cells [7] was observed after several days in culture. As no proliferative response has yet occurred in control IL-4/CD40L-activated cells at the early time-point (19)(20)(21)(22)(23)(24) h) of the current study, it seems possible that inhibition of the p38 MAP kinases and/or MEF2C expression might be central to suppressive effect of RCI gel on the function of activated B cells.…”

“…RCI or placebo gel (provided in blinded fashion; Mallinckrodt Pharmaceuticals, St Louis, MO, USA) was added to replicate cultures at estimated ACTH analogue concentrations of 0Á124, 1Á24 and 2Á49 mM (or equal volumes of placebo gel), to replicate the conditions under which RCI exerted biological effects in our prior studies [7]. The ages of the subjects ranged from 24 to 65 years and averaged 41Á9 6 3Á6 years.…”

“…The first reports of anti-inflammatory properties of such glucocorticoids in 1950 led directly to the use of corticotrophin as a therapeutic with the intention of augmenting endogenous glucocorticoid production [2]. However, subsequent clinical and experimental observations (including the recognition that cells of the immune system express receptors for corticotrophin and related peptides [3][4][5][6] and that corticotrophin exerts direct effects on immune cells under conditions in which steroidogenesis cannot take place [7,8]) have suggested that augmentation of endogenously produced glucocorticoid levels might not be the sole mechanism underlying the therapeutic efficacy of repository corticotrophin injection (RCI).…”

“…Our previously reported experiments demonstrated that RCI exerts dose-dependent inhibitory effects on the functions of interleukin (IL)-4 1 CD40 ligand (CD40L)stimulated human B lymphocytes in vitro [7]. Acthar V R gel), a corticotrophin therapeutic approved by the Food and Drug Administration (FDA) for the treatment of multiple autoimmune and inflammatory disorders, might exert direct immunomodulatory effects independent of any action on the adrenal glands.…”