IL-17A Facilitates Entry of Autoreactive T-Cells and Granulocytes into the CNS During EAE

Harnessing monocyte dynamics for treatment of multiple sclerosis; insights from experimental model studies

Monocytes are central to the innate immune system's response to infection or injury. In murine, these cells are classified into distinct subsets: classical monocytes, defined by elevated Ly6C expression (Ly6Chi), intermediate monocytes (Ly6Cint), and non-classical inflammatory monocytes, characterized by low Ly6C expression (Ly6Clow). Monocytes recruited to tissues differentiate into macrophages, which can be pro-inflammatory or anti-inflammatory, thereby influencing disease processes and outcomes. The principal function of classical monocytes is the mediation of pro-inflammatory reactions, whereas non-classical monocytes are associated with repair and anti-inflammatory processes, patrolling the lumen of the vessels. Growing evidence highlights the importance of monocytes in multiple sclerosis (MS), an autoimmune and neurodegenerative disease of the central nervous system (CNS). Recent studies indicate that modulation of the innate immune system, focusing specifically on the shift from Ly6Chi to Ly6Clow monocytes, is an effective therapeutic strategy for neurodegenerative diseases, such as Alzheimer's and MS. This transition is crucial for switching the immune response from inflammation to tissue repair and inflammation resolution, emphasizing the plasticity of monocytes and their potential as targets in MS. This review differs from prior studies in that it focuses solely on animal models of MS, which either directly perturb or study monocytes, or where therapeutic approaches mediate their protective effects through monocytes. Such details permit a subtle comprehension of monocyte dynamics in the context of MS.

Delimiting MOGAD as a disease entity using translational imaging

The first formal consensus diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) were recently proposed. Yet, the distinction of MOGAD-defining characteristics from characteristics of its important differential diagnoses such as multiple sclerosis (MS) and aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorder (NMOSD) is still obstructed. In preclinical research, MOG antibody-based animal models were used for decades to derive knowledge about MS. In clinical research, people with MOGAD have been combined into cohorts with other diagnoses. Thus, it remains unclear to which extent the generated knowledge is specifically applicable to MOGAD. Translational research can contribute to identifying MOGAD characteristic features by establishing imaging methods and outcome parameters on proven pathophysiological grounds. This article reviews suitable animal models for translational MOGAD research and the current state and prospect of translational imaging in MOGAD.

The β2-adrenergic receptor agonist terbutaline upregulates T helper-17 cells in a protein kinase A-dependent manner

BACKGROUND

T helper 17 (Th17) cells produce IL-17A cytokine and can exacerbate autoimmune diseases and asthma. The β2 adrenergic receptor is a g protein-coupled receptor that induces cAMP second messenger pathways. We tested the hypothesis that terbutaline, a β2-adrenergic receptor-specific agonist, promotes IL-17 secretion by memory Th17 cells in a cAMP and PKA-dependent manner.

METHODS

Venous peripheral blood mononuclear cells (PBMC) from healthy human participants were activated with anti-CD3 and anti-CD28 antibodies. Secreted IL-17A was measured by enzyme linked immunosorbent assay, intracellular IL-17A, and RORγ were measured using flow cytometry, and RORC by qPCR. Memory CD3+CD4+CD45RA-CD45RO+ T cells were obtained by immunomagnetic negative selection and activated with tri-antibody complex CD3/CD28/CD2. Secreted IL-17A, intracellular IL-17A, RORC were measured, and phosphorylated-serine133-CREB was measured by western blotting memory Th cells.

RESULTS

Terbutaline increased IL-17A (p < 0.001), IL-17A+ cells (p < 0.05), and RORC in activated PBMC and memory Th cells. The PKA inhibitors H89 (p < 0.001) and Rp-cAMP (p < 0.01) abrogated the effects of terbutaline on IL-17A secretion in PBMC and memory T cells. Rolipram increased IL-17A (p < 0.01) to a similar extent as terbutaline. P-Ser133-CREB was increased by terbutaline (p < 0.05) in memory T cells.

CONCLUSION

Terbutaline augments memory Th17 cells in lymphocytes from healthy participants. This could exacerbate autoimmune diseases or asthma, in cases where Th17 cells are considered to be pro-inflammatory.