Beta adrenergic signaling as a therapeutic target for autoimmunity

Abstract

Multiple sclerosis (MS) is an inflammatory demyelinating disorder of the central nervous system (CNS) characterized by an autoimmune response where both T-lymphocytes and proinflammatory interleukin 17A (IL-17A) are implicated in the pathogenesis of the disease. We recently identified a molecular mechanism involving beta-adrenergic 1 and 2 receptors (β1/2) in the polarization of T_H17 lymphocytes. Pharmacological and genetic inhibition of these receptors in combination, but not separately, impaired the ability of T-lymphocytes to produce IL-17A and instead promoted the differentiation of protective T_reg cells that secrete anti-inflammatory interleukin-10 (IL-10). However, it remained unclear whether this regulatory mechanism could serve as a novel therapeutic approach for autoimmune disorders mediated by IL-17A-producing T-lymphocytes, like MS. Using an animal model of MS, termed experimental autoimmune encephalomyelitis (EAE), we addressed the impact of beta adrenergic receptor blockade (genetically and pharmacologically) on EAE disease progression, severity, and T_H17/T_reg balance. Genetic deletion β1/2 receptors, either systemically or specifically on T-lymphocytes, significantly attenuated EAE disease severity and animal weight loss. Therapeutic pharmacological blockade of β1/2 receptors with either propranolol (lipophilic) or nadolol (aqueous) limited disease severity and weight loss similar to the genetic models, with combination therapy with anti-IL-17A antibodies showing the greatest disease remission. All models showed degrees of shifted T_H17/T_reg balance and decreased T-lymphocyte IL-17A production. Our data depict a novel role for β1/2 adrenergic signaling in the control of T_H17/T_reg cells in EAE, and provide new insight into the disease progression as well as offer a potential new pharmacological therapy for IL-17A-related autoimmune diseases.

Keywords: Autonomic; EAE; IL-17 A; Propranolol; T-lymphocyte.

Figure 1.. β1/2 adrenergic blockade attenuates clinical EAE score and EAE-induced weight loss.

EAE was induced in WT, β1/2^−/−, or adoptively transferred Rag2^−/− mice and were clinically scored and weighed daily. (A-B) Whole body β1/2^−/− animals versus WT (n=31). (C-D) Adoptive transfer of β1/2^−/− T-lymphocytes vs WT T-lymphocytes into immunodeficient Rag2^−/− mice (n=13). (E-F) Pharmacological adrenergic blockade using propranolol (lipophilic β1/2 antagonist) (n=41) or (G-H) nadolol (aqueous β1/2 antagonist) (n=34). Statistics by 2-way ANOVA with Bonferroni post-hoc.

Figure 2.. β1/2 signaling alters the T_H17/T_reg balance in EAE.

EAE was induced in WT, β1/2^−/−, or adoptively transferred Rag2^−/− mice. Mice were sacrificed at maximal disease severity (day 14-21 depending on model), and spleens and inguinal lymph nodes harvested for T-lymphocyte immunophenotyping. Whole body β1/2^−/− animals versus WT splenic T_H17 (A), splenic T_regs (B), lymph node T_H17 (C), and lymph node T_regs (D). Adoptive transfer of β1/2^−/− T-lymphocytes vs WT T-lymphocytes into immunodeficient Rag2^−/− mice splenic T_H17 (E), splenic T_regs (F), lymph node T_H17 (G), and lymph node T_regs (H). Pharmacological adrenergic blockade using propranolol (lipophilic β1/2 antagonist) or nadolol (aqueous β1/2 antagonist) splenic T_H17 (I), splenic T_regs (J), lymph node T_H17 (K), and lymph node T_regs (L). Statistics by Student’s t-test (A-H) and 1-way ANOVA with Dunnett’s post-hoc (I-L).

Figure 3.. β1/2 adrenergic blockade inhibits T-lymphocyte IL-17A.

EAE was induced in WT, β1/2^−/−, or adoptively transferred Rag2^−/− mice. Mice were sacrificed at maximal disease severity (day 14-21 depending on model). Plasma was harvested for circulating cytokine analysis. Spleens and inguinal lymph nodes harvested for T-lymphocyte recall with 10 μg/mL of MOG peptide for 72 hours. Whole body β1/2^−/− animals versus WT plasma IL-17A (A), splenocyte recall (B), lymph node recall (C). Adoptive transfer of β1/2^−/− T-lymphocytes vs WT T-lymphocytes into immunodeficient Rag2^−/− mice plasma IL-17A (D), splenocyte recall (E), lymph node recall (F). Pharmacological adrenergic blockade using propranolol (lipophilic β1/2 antagonist) or nadolol (aqueous β1/2 antagonist) plasma IL-17A (G), splenocyte recall (H), lymph node recall (I). Statistics by Student’s t-test (A-F) and 1-way ANOVA with Dunnett’s post-hoc (G-I).

Figure 4.. β1/2 adrenergic antagonism as an adjuvant therapy limit EAE.

EAE was induced in WT mice with pharmacological therapy induced 7 days after immunization. Mice were clinically scored and weighed daily (n=40). Mice were sacrificed at 14 days for cellular analyses or 28 days for disease progression analysis. Plasma was harvested for circulating cytokine analysis. Spleens and inguinal lymph nodes harvested for T-lymphocyte recall with 10 μg/mL of MOG peptide for 72 hours. Clinical scores and weights (A-B), splenic T_H17 (C), splenic T_regs (D), lymph node T_H17 (E), lymph node T_regs (F), plasma IL-17A (G), splenocyte antigen recall (H), and lymph node antigen recall (I). Statistics by 2-way ANOVA with Bonferroni post-hoc (A-B) and 1-way ANOVA with Dunnett’s post-hoc (C-I).