Tissue localization of complement component 3 receptor-bearing cells in lymphoid tissue after injection with complete Freund adjuvant

In-Depth Characterization of Somatic and Orofacial Sensitive Dysfunctions and Interfering-Symptoms in a Relapsing-Remitting Experimental Autoimmune Encephalomyelitis Mouse Model

Among the many symptoms (motor, sensory, and cognitive) associated with multiple sclerosis (MS), chronic pain is a common disabling condition. In particular, neuropathic pain symptoms are very prevalent and debilitating, even in early stages of the disease. Unfortunately, chronic pain still lacks efficient therapeutic agents. Progress is needed (i) clinically by better characterizing pain symptoms in MS and understanding the underlying mechanisms, and (ii) preclinically by developing a more closely dedicated model to identify new therapeutic targets and evaluate new drugs. In this setting, new variants of experimental autoimmune encephalomyelitis (EAE) are currently developed in mice to exhibit less severe motor impairments, thereby avoiding confounding factors in assessing pain behaviors over the disease course. Among these, the optimized relapsing-remitting EAE (QuilA-EAE) mouse model, induced using myelin oligodendrocyte glycoprotein peptide fragment (35–55), pertussis toxin, and quillaja bark saponin, seems very promising. Our study sought (i) to better define sensitive dysfunctions and (ii) to extend behavioral characterization to interfering symptoms often associated with pain during MS, such as mood disturbances, fatigue, and cognitive impairment, in this optimized QuilA-EAE model. We made an in-depth characterization of this optimized QuilA-EAE model, describing for the first time somatic thermal hyperalgesia associated with mechanical and cold allodynia. Evaluation of orofacial pain sensitivity showed no mechanical or thermal allodynia. Detailed evaluation of motor behaviors highlighted slight defects in fine motor coordination in the QuilA-EAE mice but without impact on pain evaluation. Finally, no anxiety-related or cognitive impairment was observed during the peak of sensitive symptoms. Pharmacologically, as previously described, we found that pregabalin, a treatment commonly used in neuropathic pain patients, induced an analgesic effect on mechanical allodynia. In addition, we showed an anti-hyperalgesic thermal effect on this model. Our results demonstrate that this QuilA-EAE model is clearly of interest for studying pain symptom development and so could be used to identify and evaluate new therapeutic targets. The presence of interfering symptoms still needs to be further characterized.

A model of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice for the characterisation of intervention therapies

Multiple sclerosis (MS) and its different forms are studied in the animal model experimental autoimmune encephalomyelitis (EAE). Relapsing-remitting MS, the most common form of the disease can be induced in mice where clinical symptoms fluctuate in severity over time. However, the animal model does not experience periods of recovery where clinical signs are absent, unlike the human disease. We have developed a novel model of relapsing-remitting EAE in C57BL/6 mice immunised with myelin oligodendrocyte glycoprotein (MOG) peptide and Quil A as adjuvant. These animals have relapses that are followed by periods of recovery, during which time the animals do not exhibit illness. Furthermore, administration of the PPARgamma agonist pioglitazone prior to a predicted relapse prevents the expected development of symptoms in a dose-dependent fashion. Immune cell infiltration into white matter of the CNS and decreased production of inflammatory cytokine IFN-gamma in treated animals were also observed. Our model will be a valuable tool in assessing intervention therapies for RR-MS sufferers.