IL-12/IL-23p40 Is Highly Expressed in Secondary Lymphoid Organs and the CNS during All Stages of EAE, but Its Deletion Does Not Affect Disease Perpetuation

Abstract

BackgroundInterleukin (IL)-12 and IL-23 are heterodimers that share the p40 subunit, and both cytokines are critical in the differentiation of T helper (Th)1 and Th17 cells, respectively. Th1 and Th17 effector cells have been implicated in the pathogenesis of experimental autoimmune encephalitis (EAE), an animal model of the human central nervous system (CNS) autoimmune demyelinating disorder multiple sclerosis (MS). However, ustekinumab, a monoclonal antibody (mAb) against p40 failed to show efficacy over placebo in a phase II clinical trial in patients with MS. The role of p40 in initial T cell priming and maintenance in secondary lymphoid tissues is not yet well understood.MethodsActive EAE was induced in the B6.129-IL12b strain of p40eYFP reporter mice (yet40 mice), and Th1 and Th17 polarized cells were adoptively transferred into p40-deficient mice. Cellular subsets were phenotyped by multi-parameter flow cytometry, and p40 tissue expression was identified by confocal microscopy.ResultsWe show that yet40 mice are susceptible to EAE, and that p40 is highly expressed in secondary lymphoid organs and the CNS during all stages of the disease. Interestingly, p40 expression in the recipient is not required for EAE induction after adoptive transfer of activated and differentiated encephalitogenic Th1 and Th17 cells into p40-deficient mice. Peripheral antagonism of T helper cell trophic factors critical for the differentiation and maintenance of Th1 and Th17 cells ameliorates EAE, indicating that p40 may play a critical role in the induction of CNS autoimmunity but not in its perpetuation.ConclusionOur data may explain why ustekinumab did not ameliorate paraclinical and clinical disease in patients with MS. In patients with already established disease, activated antigen-specific encephalitogenic CD4+ T cells are likely already differentiated, and are not dependent on p40 for maintenance. A clinical trial of longer duration with anti-p40 mAbs or other forms of pharmacological p40 antagonism, or sequential anti-p40 therapy following T cell depletion may show a benefit by affecting de novo generation of autoimmune T cells.

Peroxisome Proliferator–Activated Receptor-δ Acts within Peripheral Myeloid Cells to Limit Th Cell Priming during Experimental Autoimmune Encephalomyelitis

“…our Ab blocking studies identified IL-12p40 as the prominent DC-produced factor driving the higher Th1 and Th17 cytokine production in the LysM Cre :Ppard fl/fl CD11b + :CD4 + T cell cocultures. These findings are consistent with past studies of EAE in bicistronic mice that express Il12b and YFP that showed higher expression of IL-12p40 in CD11b + CD11c + cells compared with other DC and CD11b + subsets in both the draining lymph node and spleen (46) and with the knowledge that IL-12p40 is crucial to the development of EAE (47). The effect of IL-12p40 on Th cell priming in EAE can be mediated through a number of cytokines including IL-12(p35/p40), IL-23(p19/p40), p40 monomer, and p40 2 (48).…”

Caveolin1 Is Required for Th1 Cell Infiltration, but Not Tight Junction Remodeling, at the Blood-Brain Barrier in Autoimmune Neuroinflammation

“…After 4 days, 20 ng/ml IL-23 was added. After 3 additional days, cells were re-stimulated with 0.5 μg/ml plate-bound anti-CD3 and 0.5 μg/ml soluble anti-CD28 (Cravens et al, 2016). Th17 cultures had ~4000-fold increased production of IL-17 (Fig.…”

Treatment approaches to patients with multiple sclerosis and coexisting autoimmune disorders

“… 101 This was further corroborated in an EAE model with mice lacking the p40-ustekinumab target epitope. 102 However, the patients included in the ustekinumab study had a chronic disease course with long disease durations with low relapse activity. Furthermore, it is not clear whether the antibody can cross the blood–brain barrier effectively.…”