NeuroImmunology

The diagnosis of multiple sclerosis is based on neurological symptoms and signs, alongside
evidence of dissemination of CNS lesions in space and time. MRI is often sufficient
to confirm the diagnosis when characteristic lesions accompany a typical clinical
syndrome, but in some patients, further supportive information is obtained from cerebrospinal
fluid examination and neurophysiological testing. Differentiation is important from
other diseases in which demyelination is a feature (eg, neuromyelitis optica spectrum
disorder and acute disseminated encephalomyelitis) and from non-demyelinating disorders
such as chronic small vessel disease and other inflammatory, granulomatous, infective,
metabolic, and genetic causes that can mimic multiple sclerosis.

Experimental autoimmune encephalomyelitis (EAE) is the most common animal model of multiple sclerosis (MS), a chronic inflammatory autoimmune disease of the central nervous system (CNS) characterized by multifocal perivascular infiltrates that predominantly comprise lymphocytes and macrophages. During EAE, autoreactive T cells first become active in the secondary lymphoid organs upon contact with antigen presenting cells (APCs), and then gain access to CNS parenchyma, through a compromised blood–brain barrier, subsequently inducing inflammation and demyelination. Two-photon laser scanning microscopy (TPLSM) is an ideal tool for intravital imaging because of its low phototoxicity, deep tissue penetration and high resolution. In the last decade, TPLSM has been used to visualize the behavior of T cells and their contact with APCs in the lymph nodes and target tissues in several models of autoimmune diseases. The leptomeninges and cerebrospinal fluid represent particularly important points for T cell entry into the CNS and reactivation following contact with local APCs during the preclinical phase of EAE. In this review, we highlight recent findings concerning the pathogenesis of EAE and MS, emphasizing the use of TPLSM to characterize T cell activation in the lymph nodes and CNS, as well as the mechanisms of tolerance induction. Furthermore, we discuss how advanced imaging unveils disease mechanisms and helps to identify novel therapeutic strategies to treat CNS autoimmunity and inflammation.

Background. Multiple Sclerosis (MS), an autoimmune disease with neurodegeneration and inflammation, is characterized by several alterations of different T cell subsets. However, few data exist on the role of iNKT lymphocytes. Objective. To identify possible changes in the phenotype of iNKT cells in patients with different clinical forms of MS, and find alterations in their polyfunctionality (i.e., ability to produce simultaneously up to 4 cytokines such as IL-17, TNF-α, IFN-γ, IL-4). Methods. We studied a total of 165 patients, 91 with a Relapsing Remitting form [RR; 31 were treated with interferon (IFN)1-β, 25 with natalizumab (Nat), 29 with glatiramer acetate (Gla); 17 were newly-diagnosed RR without treatment, 19 not active RR without treatment]. Forty-four patients had a Progressive MS: 20 Primary Progressive (PP), 24 Secondary Progressive (SP). A total of 55 age- and sex-matched subjects represented healthy controls (CTR). Among fresh peripheral blood mononuclear cells (PBMC) iNKT cells were identified by flow cytometry. Moreover, the capability of iNKT cells to produce different cytokines (IL-17, TNF-α, IFN-γ, and IL-4) after in vitro stimulation were evaluated in 18 RR (11 treated with Nat and 7 with IFN), 4 PP, 6 SP and 16 CTR. Results. No main differences were found in iNKT cell phenotype among MS patients with different MS forms, or during different treatments. However, the polyfunctional response of iNKT cells showed Th1 and Th17 profiles. This was well evident in patients with secondary progressive form, who are characterized by high levels of inflammation and neurodegeneration, and exhibited a sustained increase in the production of Th17 cytokines. Patients treated with natalizumab displayed lower levels of iNKT cells producing IL-17, TNF-α and IFN-γ. Conclusion. Our data suggest that the progressive phase of the disease is characterized by permanent iNKT activation and a skewing towards an inflammatory phenotype. Compared to other treatments, natalizumab was able to modulate iNKT cell function.