Background Multiple sclerosis (MS) is one of the most common autoimmune disorders characterized by the infiltration of immune cells into the brain and demyelination. The unwanted immunosuppressive side effect of therapeutically successful natalizumab led us to focus on the choroid plexus (CP), a key site for the first wave of immune cell infiltration in experimental autoimmune encephalomyelitis (EAE), for the control of immune cells trafficking. Adenosine A2A receptor (A2AR) is emerging as a potential pharmacological target to control EAE pathogenesis. However, the cellular basis for the A2AR-mediated protection remains undetermined. Methods In the EAE model, we assessed A2AR expression and leukocyte trafficking determinants in the CP by immunohistochemistry and qPCR analyses. We determined the effect of the A2AR antagonist KW6002 treatment at days 8–12 or 8–14 post-immunization on T cell infiltration across the CP and EAE pathology. We determined the critical role of the CP-A2AR on T cell infiltration and EAE pathology by focal knock-down of CP-A2AR via intracerebroventricular injection of CRE-TAT recombinase into the A2ARflox/flox mice. In the cultured CP epithelium, we also evaluated the effect of overexpression of A2ARs or the A2AR agonist CGS21680 treatment on the CP permeability and lymphocytes migration. Results We found the specific upregulation of A2AR in the CP associated with enhanced CP gateway activity peaked at day 12 post-immunization in EAE mice. Furthermore, the KW6002 treatment at days 8–12 or 8–14 post-immunization reduced T cell trafficking across the CP and attenuated EAE pathology. Importantly, focal CP-A2AR knock-down attenuated the pathogenic infiltration of Th17+ cells across the CP via inhibiting the CCR6–CCL20 axis through NFκB/STAT3 pathway and protected against EAE pathology. Lastly, activation of A2AR in the cultured epithelium by A2AR overexpression or CGS21680 treatment increased the permeability of the CP epithelium and facilitated lymphocytes migration. Conclusion These findings define the CP niche as one of the primary sites of A2AR action, whereby A2AR antagonists confer protection against EAE pathology. Thus, pharmacological targeting of the CP-A2AR represents a novel therapeutic strategy for MS by controlling immune cell trafficking across CP.

The endogenous metabolite itaconate and its cell-permeable derivative dimethyl itaconate (DI) have been identified as anti-inflammatory regulators of macrophages; however, their contribution to inflammasome-mediated pyroptosis remains unknown. The present study examined the molecular mechanism of DI on NLR family pyrin domain-containing 3 (NLRP3) inflammasome assembly and NLRP3 inflammasome-dependent pyroptosis in microglia. Lipopolysaccharide (LPS) and ATP were used to induce microglia pyroptosis in vitro; this process was confirmed by TUNEL assay, lactate dehydrogenase (LDH) detection and gasdermin D (GSDMD) expression analysis. The regulation of microglia polarization and inflammatory cytokine expression was assessed by immunofluorescence assays and ELISA. To investigate the associated mechanism of action, the expression levels of the nuclear factor erythroid 2-related factor 2 (Nrf-2)/heme oxygenase-1 (HO-1) pathway proteins were analyzed by western blotting. Finally, the regulatory effect of DI on autophagy and its association with inflammation was determined by western blotting. The present study demonstrated that DI administration inhibited NLRP3 assembly, LDH release and GSDMD cleavage. Cotreatment of DI with LPS and ATP facilitated the transition from M1 to M2, reduced inflammatory mediator expression and impeded NF-κB phosphorylation. In addition, DI effectively reduced reactive oxygen species production through the Nrf-2/HO-1 pathway. Moreover, DI induced cellular autophagy, whereas inhibition of autophagy with 3-methyladenine markedly reversed its inhibitory effect on NLRP3-dependent pyroptosis. Taken together, the present study suggested that DI participated in the Nrf-2/HO-1 pathway and served a key role in microglia inflammation and NLRP3 inflammasome-mediated pyroptosis via induction of autophagy.

The deficits of cognitive flexibility (including attentional set-shifting and reversal learning) concomitant with dysfunction of the striatum are observed in several neuropsychiatric disorders. Rodent and human studies have identified the striatum [particularly the dorsomedial striatum (DMS) and nucleus accumbens (NAc)] as the critical locus for control of cognitive flexibility, but the effective neuromodulator and pharmacological control of cognitive flexibility remains to be determined. The adenosine A 2A receptors (A 2A Rs) are highly enriched in the striatopallidal neurons where they integrate dopamine and glutamate signals to modulate several cognitive behaviors, but their contribution to cognitive flexibility control is unclear. In this study, by coupling an automated operant cognitive flexibility task with striatal subregional knockdown (KD) of the A 2A R via the Cre-loxP strategy, we demonstrated that NAc A 2A R KD improved cognitive flexibility with enhanced attentional set-shifting and reversal learning by decreasing regressive and perseverative errors, respectively. This facilitation was not attributed to mnemonic process or motor activity as NAc A 2A R KD did not affect the visual discrimination, lever-pressing acquisition, and locomotor activity, but was associated with increased attention and motivation as evident by the progressive ratio test (PRT). In contrast to NAc A 2A Rs, DMS A 2A Rs KD neither affected visual discrimination nor improved set-shifting nor reversal learning, but promoted the effort-related motivation. Thus, NAc and DMS A 2A Rs exert dissociable controls of cognitive flexibility with NAc A 2A Rs KD selectively enhancing cognitive flexibility by facilitating strategy shifting with increased motivation/attention.

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Background: Multiple sclerosis (MS) is one of the most common autoimmune disorders characterized by the infiltration of immune cells into the brain and demyelination. The unwanted immunosuppressive side effect of therapeutically successful natalizumab led us to focus on choroid plexus (CP), a key site for the first wave of immune cell infiltration in experimental autoimmune encephalomyelitis (EAE), for the control of immune cells trafficking. Adenosine A2A receptor (A2AR) is emerging as a potential pharmacological target to control EAE pathogenesis; however, the cellular basis for the A2AR-mediated protection remains undetermined. Methods: In EAE model, we assessed A2AR expression and leukocyte trafficking determinants in CP by immunohistochemistry and qPCR analyses. We determined the effect of the A2AR antagonist KW6002 treatment at days 8-12 or 8-14 post-immunization on T cell infiltration across CP and EAE pathology. We determined the critical role of the CP-A2AR on T cell infiltration and EAE pathology by focal knockdown the CP-A2AR with intracerebroventricular injection of CRE-TAT recombinase into the A2ARflox/flox mice. In cultured CP epithelium, we also evaluated the effect of overexpression of A2ARs or the A2AR agonist CGS21680 treatment on CP permeability and lymphocytes migration. Results: We found the specific upregulation of A2AR in CP in association with enhanced CP gateway activity peaked at day 12 post-immunization in EAE mice. Furthermore, the KW6002 treatment at days 8-12 or 8-14 post-immunization reduced T-cell trafficking across CP and attenuated EAE pathology. Importantly, focal CP-A2AR knockdown attenuated pathogenic infiltration of Th17+ cells across CP via inhibiting CCR6-CCL20 axis through NFκB / STAT3 pathway and protected against EAE pathology. Lastly, activation of A2AR in cultured epithelium by A2AR overexpression or CGS21680 treatment increased the permeability of CP epithelium and facilitated lymphocytes migration. Conclusion: These findings define the CP niche as one of the primary sites of A2AR action whereby A2AR antagonists confer protection against EAE pathology. Thus, pharmacological targeting of the CP-A2AR represents a novel therapeutic strategy for MS by controlling immune cell trafficking across CP.