Vitamin D increases glucocorticoid efficacy via inhibition of mTORC1 in experimental models of multiple sclerosis

Abstract

The limited efficacy of glucocorticoids (GCs) during therapy of acute relapses in multiple sclerosis (MS) leads to long-term disability. We investigated the potential of vitamin D (VD) to enhance GC efficacy and the mechanisms underlying this VD/GC interaction. In vitro, GC receptor (GR) expression levels were quantified by ELISA and induction of T cell apoptosis served as a functional readout to assess synergistic 1,25(OH) 2 D 3 (1,25D)/GC effects. Experimental autoimmune encephalomyelitis (MOG 35–55 EAE) was induced in mice with T cell-specific GR or mTORc1 deficiency. 25(OH)D (25D) levels were determined in two independent cohorts of MS patients with stable disease or relapses either responsive or resistant to GC treatment (initial cohort: n = 110; validation cohort: n = 85). Gene expression of human CD8 + T cells was analyzed by microarray ( n = 112) and correlated with 25D serum levels. In vitro, 1,25D upregulated GR protein levels, leading to increased GC-induced T cell apoptosis. 1,25D/GC combination therapy ameliorated clinical EAE course more efficiently than respective monotherapies, which was dependent on GR expression in T cells. In MS patients from two independent cohorts, 25D deficiency was associated with GC-resistant relapses. Mechanistic studies revealed that synergistic 1,25D/GC effects on apoptosis induction were mediated by the mTOR but not JNK pathway. In line, 1,25D inhibited mTORc1 activity in murine T cells, and low 25D levels in humans were associated with a reduced expression of mTORc1 inhibiting tuberous sclerosis complex 1 in CD8 + T cells. GR upregulation by 1,25D and 1,25D/GC synergism in vitro and therapeutic efficacy in vivo were abolished in animals with a T cell-specific mTORc1 deficiency. Specific inhibition of mTORc1 by everolimus increased the efficacy of GC in EAE. 1,25D augments GC-mediated effects in vitro and in vivo in a T cell-specific, GR-dependent manner via mTORc1 inhibition. These data may have implications for improvement of anti-inflammatory GC therapy. Electronic supplementary material The online version of this article (10.1007/s00401-019-02018-8) contains supplementary material, which is available to authorized users.

Brain-homing CD4 + T cells display glucocorticoid-resistant features in MS

“…A recent study showed that low vitamin D levels are associated with GC-resistant relapses in patients with MS. 20 Although controversial results were obtained from clinical trials with respect to disease activity, increasing vitamin D levels improved GC efficacy and suppressed EAE induction in mice via Th-cell intrinsic upregulation of NR3C1 . 20 Because vitamin D also downregulates CCR6 on Th cells, 17 this steroid hormone may be exploited to enhance GC efficacy in MS by sensitizing Th17.1 cells. MDR1 activity can also be blocked by other types of steroids 44 and even by anti-CD20 antibodies.…”

“…A similar concentration is given as IV pulse therapy to dampen acute MS relapses. 20 To compare differences in proliferation, the frequencies of viable, carboxyfluorescein succinimidyl ester-negative cells were analyzed using flow cytometry. For the apoptosis assay, CD4 + cells were plated out, activated, and exposed to methylprednisolone in a similar manner as described above.…”

c-Jun N-Terminal Kinase as a Therapeutic Target in Experimental Autoimmune Encephalomyelitis

“…Active MOG 35-55 EAE was induced in 8 weeks old female C57BL/6 WT mice following our previously described MOG 35-55 EAE induction protocol [ 18 ]. Briefly, animals were immunized by subcutaneous injection of 100 µg MOG 35-55 peptide (Institute of Medical Immunology, Charité, Berlin, Germany) in phosphate-buffered saline solution (PBS; Thermo Fisher Scientific, Dreieich, Germany) emulsified in complete Freund’s adjuvant containing 100 µg mycobacterium tuberculosis (Difco, Detroit, MI, USA), followed by 200 ng pertussis toxin (Quadratech, Epsom, UK; intraperitoneal (i.p.)…”

“…injection, days 0 and 2). Animals were scored daily in a blinded manner using a 10-point EAE scale [ 18 ]. In addition to EAE scoring, body weight, which is a well-established parameter of drug side effects [ 19 ], was measured daily and a clinical assessment of side effects based on body weight and observation of the animals’ behavior was performed.…”

Functional relevance of the multi-drug transporter abcg2 on teriflunomide therapy in an animal model of multiple sclerosis

“…Chronic EAE was induced by active immunization with 100 μg myelin-oligodendrocyte-glycoprotein peptide 35-55 (MOG 35-55 ) (Charité Berlin, Germany) in complete Freund's adjuvants (CFA) and disease severity was assessed clinically using a 10-point EAE scale: 0, normal; 1, reduced tone of tail; 2, limp tail, impaired righting; 3, absent righting; 4, gait ataxia; 5, mild paraparesis of hind limbs; 6, moderate paraparesis; 7, severe paraparesis or paraplegia; 8, tetraparesis; 9, moribund; 10, death [12]. Teri (provided by Sanofi Genzyme, Cambridge, USA) was dissolved in 25 mM Tris buffer (80 %) in H 2 O (20%) at a pH of 7.5.…”