The CNS-penetrant soluble guanylate cyclase stimulator CYR119 attenuates markers of inflammation in the central nervous system

Abstract

Background Inflammation in the central nervous system (CNS) is observed in many neurological disorders. Nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate (NO–sGC–cGMP) signaling plays an essential role in modulating neuroinflammation. CYR119 is a CNS-penetrant sGC stimulator that amplifies endogenous NO–sGC–cGMP signaling. We evaluated target engagement and the effects of CYR119 on markers of neuroinflammation in vitro in mouse microglial cells and in vivo in quinolinic acid (QA)-induced and high-fat diet-induced rodent neuroinflammation models. Methods Target engagement was verified in human embryonic kidney (HEK) cells, rat primary neurons, mouse SIM-A9 cells, and in rats by measuring changes in cGMP and downstream targets of sGC signaling [phosphorylated vasodilator-stimulated phosphoprotein (pVASP), phosphorylated cAMP-response element binding (pCREB)]. In SIM-A9 cells stimulated with lipopolysaccharides (LPS), markers of inflammation were measured when cells were treated with or without CYR119. In rats, microinjections of QA and vehicle were administered into the right and left hemispheres of striatum, respectively, and then rats were dosed daily with either CYR119 (10 mg/kg) or vehicle for 7 days. The activation of microglia [ionized calcium binding adaptor molecule 1 (Iba1)] and astrocytes [glial fibrillary acidic protein (GFAP)] was measured by immunohistochemistry. Diet-induced obese (DIO) mice were treated daily with CYR119 (10 mg/kg) for 6 weeks, after which inflammatory genetic markers were analyzed in the prefrontal cortex. Results In vitro, CYR119 synergized with exogenous NO to increase the production of cGMP in HEK cells and in primary rat neuronal cell cultures. In primary neurons, CYR119 stimulated sGC, resulting in accumulation of cGMP and phosphorylation of CREB, likely through the activation of protein kinase G (PKG). CYR119 attenuated LPS-induced elevation of interleukin 6 (IL-6) and tumor necrosis factor (TNF) in mouse microglial cells. Following oral dosing in rats, CYR119 crossed the blood–brain barrier (BBB) and stimulated an increase in cGMP levels in the cerebral spinal fluid (CSF). In addition, levels of proinflammatory markers associated with QA administration or high-fat diet feeding were lower in rodents treated with CYR119 than in those treated with vehicle. Conclusions These data suggest that sGC stimulation could provide neuroprotective effects by attenuating inflammatory responses in nonclinical models of neuroinflammation.

The Interplay between cGMP and Calcium Signaling in Alzheimer’s Disease

“…This process requires RhoA-GTPase to be phosphorylated, and thus inhibited, by cGK [101]. Although this is the most commonly described role of cGMP in astrocytes, there are also studies showing a decrease in GFAP expression upon administration of NO-GC stimulators [103]. Next to the signaling via NO, this pathway can also be triggered by ANP, since astrocytes contain pGC-A [45].…”

“…Indeed, stimulation of microglial cells with ANP reduces LPS-induced microglial activation [114]. Nevertheless, several publications revealed microglial sensitivity to the manipulations of the NO-GC signaling [103,115]. For example, in the scratch wound in vitro models, as well as under acute spinal cord injury conditions in vivo, the application of the NO-GC inhibitor ODQ significantly reduced microglial motility [116][117][118][119].…”

“…In the case of traumatic brain injury, the application of a PDE inhibitor leads to a reduction in the number of amoeboid microglia around the site of injury, together with a decrease in the expression of the ionized Ca 2+ -binding adaptor molecule 1 (Iba-1) and Cd11b [102]. It was shown that cGMP can reduce the inflammatory response to LPS stimulation, as shown by the reduced expression of proinflammatory genes [103,114]. On the other hand, there are also reports of increased Iba-1, iNOS, Cd11, MHC class II, and proinflammatory cytokine expression (i.e., increased inflammation) upon cGMP accumulation [99,120,121].…”

“…Recently, brain penetrant NO-GC stimulators have been developed as targets for AD treatment [103,211]. In vitro and in vivo studies with CYR119 revealed anti-inflammatory effects in murine microglia cell culture and the intact brain [103].…”

“…Recently, brain penetrant NO-GC stimulators have been developed as targets for AD treatment [103,211]. In vitro and in vivo studies with CYR119 revealed anti-inflammatory effects in murine microglia cell culture and the intact brain [103]. Furthermore, the BBB penetrant NO-GC stimulator CY6463 improved LTP in a Huntington's disease mouse model and reduced loss of neuronal spines in a mouse model of AD (APP/PS1 mice).…”