Choroid plexus-selective inactivation of adenosine A2A receptors protects against T cell infiltration and experimental autoimmune encephalomyelitis.

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.

Targeting ZDHHC9 potentiates anti-programmed death-ligand 1 immunotherapy of pancreatic cancer by modifying the tumor microenvironment.

Immune checkpoint blockade (ICB) therapy targeting the programmed death 1/programmed death-ligand 1 (PD-1/PD-L1) axis has achieved considerable success in treating a wide range of cancers. However, most patients with pancreatic cancer remain resistant to ICB. Moreover, there is a lack of optimal biomarkers for the prediction of response to this therapy. Palmitoylation is mediated by a family of 23 S-acyltransferases, termed zinc finger Asp-His-His-Cys-type palmitoyltransferases (ZDHHC), which precisely control various cancer-related protein functions and represent promising drug targets for cancer therapy. Here, we revealed that tumor cell-intrinsic ZDHHC9 was overexpressed in pancreatic cancer tissues and associated with impaired anti-tumor immunity. In syngeneic pancreatic tumor models, the knockdown of ZDHHC9 expression suppressed tumor progression and prolonged survival time of mice by modifying the immunosuppressive ('cold') to proinflammatory ('hot') tumor microenvironment. Furthermore, ZDHHC9 deficiency sensitized anti-PD-L1 immunotherapy mainly in a CD8+ T cell dependent manner. Lastly, we employed the ZDHHC9-siRNA nanoparticle system to efficiently silence ZDHHC9 in pancreatic tumors. Collectively, our findings indicate that ZDHHC9 overexpression in pancreatic tumors is a mechanism involved in the inhibition of host anti-tumor immunity and highlight the importance of inactivating ZDHHC9 as an effective immunotherapeutic strategy and booster for anti-PD-L1 therapy against pancreatic cancer.

Accumbal Adenosine A2A Receptors Enhance Cognitive Flexibility by Facilitating Strategy Shifting.

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 A2A receptors (A2ARs) 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 A2AR via the Cre-loxP strategy, we demonstrated that NAc A2AR 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 A2AR 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 A2ARs, DMS A2ARs KD neither affected visual discrimination nor improved set-shifting nor reversal learning, but promoted the effort-related motivation. Thus, NAc and DMS A2ARs exert dissociable controls of cognitive flexibility with NAc A2ARs KD selectively enhancing cognitive flexibility by facilitating strategy shifting with increased motivation/attention.

Neonatal inflammation induces reorganization in dendritic morphology of retinal ganglion cells but not their retinogeniculate projection in mice.

Perinatal inflammatory insult in preterm babies is associated with vision impairment, but the underlying cellular mechanism is still unknown. In this study, we set out to explore whether systemic inflammatory stress affects the development of retinal ganglion cells (RGCs). Neonatal inflammation was induced by single and systemic injection of lipopolysaccharide (LPS, 1 mg/kg) at postnatal day 4 (P4). Morphological changes of RGCs were investigated by using 3D neuron reconstruction technique in Thy-1 YFPH transgenic mice at P21, of which a fraction of RGCs selectively expresses the yellow fluorescent protein (YFP). Three types (Type I, II, III) of RGCs were distinguished and classified according to the characteristic features in their dendritic field area and dendrite density. Neonatal exposure to LPS did not alter the composition of the three RGC types but induced a reorganization of dendritic architecture in the RGC Type I and II (but not Type III). The average diameter, surface area and volume of dendrites in both RGC Type I and II were increased after systemic inflammation compared with those in the control group. However, soma sizes of all three RGC types were not affected by neonatal inflammation. Meanwhile, using anterograde labeling of the retinal cells, we found that neonatal exposure to LPS also did not affect the pattern of RGC projections in the dorsal lateral geniculate nucleus of the thalamus (dLGN). These results indicate that RGC dendrite reorganization induced by neonatal inflammation may contribute to the retinal cell dysfunctions associated with systemic inflammation in premature babies.

Spatiotemporal Control of GPR37 Signaling and Its Behavioral Effects by Optogenetics.

Despite the progress in deorphanization of G Protein-Coupled Receptors (GPCRs), ≈100 GPCRs are still classified as orphan receptors without identified endogenous ligands and with unknown physiological functions. The lack of endogenous ligands triggering GPCR signaling has hampered the study of orphan GPCR functions. Using GPR37 as an example, we provide here the first demonstration of the channelrhodopsin 2 (ChR2)-GPCR approach to bypass the endogenous ligand and selectively activate the orphan GPCR signal by optogenetics. Inspired by the opto-XR approach, we designed the ChR2-GPR37 chimera, in which the corresponding parts of GPR37 replaced the intracellular portions of ChR2. We showed that optogenetic activation of ChR2/opto-GPR37 elicited specific GPR37 signaling, as evidenced by reduced cAMP level, enhanced ERK phosphorylation and increased motor activity, confirming the specificity of opto-GPR37 signaling. Besides, optogenetic activation of opto-GPR37 uncovered novel aspects of GPR37 signaling (such as IP-3 signaling) and anxiety-related behavior. Optogenetic activation of opto-GPR37 permits the causal analysis of GPR37 activity in the defined cells and behavioral responses of freely moving animals. Importantly, given the evolutionarily conserved seven-helix transmembrane structures of ChR2 and orphan GPCRs, we propose that opto-GPR37 approach can be readily applied to other orphan GPCRs for their deorphanization in freely moving animals.