A peripheral lipid sensor GPR120 remotely contributes to suppression of PGD2-microglia-provoked neuroinflammation and neurodegeneration in the mouse hippocampus

Background Neuroinflammation is a key pathological component of neurodegenerative disease and is characterized by microglial activation and the secretion of proinflammatory mediators. We previously reported that a surge in prostaglandin D2 (PGD2) production and PGD2-induced microglial activation could provoke neuroinflammation. We also reported that a lipid sensor GPR120 (free fatty acid receptor 4), which is expressed in intestine, could be activated by polyunsaturated fatty acids (PUFA), thereby mediating secretion of glucagon-like peptide-1 (GLP-1). Dysfunction of GPR120 results in obesity in both mice and humans. Methods To reveal the relationship between PGD2-microglia-provoked neuroinflammation and intestinal PUFA/GPR120 signaling, we investigated neuroinflammation and neuronal function with gene and protein expression, histological, and behavioral analysis in GPR120 knockout (KO) mice. Results In the current study, we discovered notable neuroinflammation (increased PGD2 production and microglial activation) and neurodegeneration (declines in neurogenesis, hippocampal volume, and cognitive function) in GPR120 KO mice. We also found that Hematopoietic–prostaglandin D synthase (H-PGDS) was expressed in microglia, microglia were activated by PGD2, H-PGDS expression was upregulated in GPR120 KO hippocampus, and inhibition of PGD2 production attenuated this neuroinflammation. GPR120 KO mice exhibited reduced intestinal, plasma, and intracerebral GLP-1 contents. Peripheral administration of a GLP-1 analogue, liraglutide, reduced PGD2-microglia-provoked neuroinflammation and further neurodegeneration in GPR120 KO mice. Conclusions Our results suggest that neurological phenotypes in GPR120 KO mice are probably caused by dysfunction of intestinal GPR120. These observations raise the possibility that intestinal GLP-1 secretion, stimulated by intestinal GPR120, may remotely contributed to suppress PGD2-microglia-provoked neuroinflammation in the hippocampus.

Hematopoietic Prostaglandin D Synthase Inhibitor PK007 Decreases Muscle Necrosis in DMD mdx Model Mice

Duchenne muscular dystrophy (DMD) is characterized by progressive muscle weakness and wasting due to the lack of dystrophin protein. The acute phase of DMD is characterized by muscle necrosis and increased levels of the pro-inflammatory mediator, prostaglandin D2 (PGD2). Inhibiting the production of PGD2 by inhibiting hematopoietic prostaglandin D synthase (HPGDS) may alleviate inflammation and decrease muscle necrosis. We tested our novel HPGDS inhibitor, PK007, in the mdx mouse model of DMD. Our results show that hindlimb grip strength was two-fold greater in the PK007-treated mdx group, compared to untreated mdx mice, and displayed similar muscle strength to strain control mice (C57BL/10ScSn). Histological analyses showed a decreased percentage of regenerating muscle fibers (~20% less) in tibialis anterior (TA) and gastrocnemius muscles and reduced fibrosis in the TA muscle in PK007-treated mice. Lastly, we confirmed that the DMD blood biomarker, muscle creatine kinase activity, was also reduced by ~50% in PK007-treated mdx mice. We conclude that our HPGDS inhibitor, PK007, has effectively reduced muscle inflammation and fibrosis in a DMD mdx mouse model.

Discovery of a Highly Potent and Selective Degrader Targeting Hematopoietic Prostaglandin D Synthase via in Silico Design

<p>Hematopoietic prostaglandin D synthase (H-PGDS) is an attractive target for the development of therapeutic agents for Duchenne muscular dystrophy (DMD) and other H-PGDS-related diseases. We have recently developed the H-PGDS degrader <b>PROTAC(H-PGDS)-1</b>, which is a chimeric molecule in which TFC-007 (that binds to H-PGDS) and pomalidomide (that binds to cereblon [CRBN]) were conjugated to the PEG5 linker. Herein, using a docking simulation of the ternary complex of the H-PGDS degrader, H-PGDS, and CRBN, we have succeeded in developing <b>PROTAC(H-PGDS)-7, </b>a new H-PGDS degrader that does not contain a linker. <b>PROTAC(H-PGDS)-7</b> showed potent and selective degradation activity (DC₅₀ = 17.3 pM), and potent suppression of prostaglandin D₂ (PGD₂) production in KU812 cells. Additionally, in a DMD model using <i>mdx</i>mice with cardiac hypertrophy, <b>PROTAC(H-PGDS)-7</b> showed better inhibition of inflammatory cytokines than TFC-007. <b>PROTAC(H-PGDS)-7</b> is expected to be a promising candidate for the treatment of DMD and other H-PGDS-related diseases.</p>

Discovery of a Highly Potent and Selective Degrader Targeting Hematopoietic Prostaglandin D Synthase via in Silico Design

<p>Hematopoietic prostaglandin D synthase (H-PGDS) is an attractive target for the development of therapeutic agents for Duchenne muscular dystrophy (DMD) and other H-PGDS-related diseases. We have recently developed the H-PGDS degrader <b>PROTAC(H-PGDS)-1</b>, which is a chimeric molecule in which TFC-007 (that binds to H-PGDS) and pomalidomide (that binds to cereblon [CRBN]) were conjugated to the PEG5 linker. Herein, using a docking simulation of the ternary complex of the H-PGDS degrader, H-PGDS, and CRBN, we have succeeded in developing <b>PROTAC(H-PGDS)-7, </b>a new H-PGDS degrader that does not contain a linker. <b>PROTAC(H-PGDS)-7</b> showed potent and selective degradation activity (DC₅₀ = 17.3 pM), and potent suppression of prostaglandin D₂ (PGD₂) production in KU812 cells. Additionally, in a DMD model using <i>mdx</i>mice with cardiac hypertrophy, <b>PROTAC(H-PGDS)-7</b> showed better inhibition of inflammatory cytokines than TFC-007. <b>PROTAC(H-PGDS)-7</b> is expected to be a promising candidate for the treatment of DMD and other H-PGDS-related diseases.</p>

Human kidney is a target for novel severe acute respiratory syndrome coronavirus 2 infection

It is unclear whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can directly infect human kidney, thus leading to acute kidney injury (AKI). Here, we perform a retrospective analysis of clinical parameters from 85 patients with laboratory-confirmed coronavirus disease 2019 (COVID-19); moreover, kidney histopathology from six additional COVID-19 patients with post-mortem examinations was performed. We find that 27% (23/85) of patients exhibited AKI. The elderly patients and cases with comorbidities (hypertension and heart failure) are more prone to develop AKI. Haematoxylin & eosin staining shows that the kidneys from COVID-19 autopsies have moderate to severe tubular damage. In situ hybridization assays illustrate that viral RNA accumulates in tubules. Immunohistochemistry shows nucleocapsid and spike protein deposits in the tubules, and immunofluorescence double staining shows that both antigens are restricted to the angiotensin converting enzyme-II-positive tubules. SARS-CoV-2 infection triggers the expression of hypoxic damage-associated molecules, including DP2 and prostaglandin D synthase in infected tubules. Moreover, it enhances CD68+ macrophages infiltration into the tubulointerstitium, and complement C5b-9 deposition on tubules is also observed. These results suggest that SARS-CoV-2 directly infects human kidney to mediate tubular pathogenesis and AKI.

15-Deoxy-△12,14-Prostaglandin J2 Promotes Resolution of Experimentally Induced Colitis

Uncontrolled macrophage functions cause failure to resolve gut inflammation and has been implicated in the pathogenesis of inflammatory bowel disease (IBD). 15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), one of endogenous lipid mediators formed from arachidonic acid during the inflammatory process, has been reported to terminate inflammation. However, the pro-resolving effect of 15d-PGJ2 on intestinal inflammation and underlying molecular mechanisms remain largely unknown. In the present study, we examined the effects of 15d-PGJ2 on the resolution of dextran sulfate sodium (DSS)-induced murine colitis that mimics human IBD. Pharmacologic inhibition of prostaglandin D synthase (PGDS) responsible for the synthesis of 15d-PGJ2 hampered resolution of inflammation in the colonic mucosa of mice treated with DSS. Notably, intraperitoneal injection of 15d-PGJ2 accelerated the resolution of experimentally induced colitis. 15d-PGJ2 treatment reduced the number of neutrophils and M1 macrophages, while it increased the proportion of M2 macrophages. Moreover, 15d-PGJ2 treated mice exhibited the significantly reduced proportion of macrophages expressing the pro-inflammatory cytokine, IL-6 with concomitant suppression of STAT3 phosphorylation in the colonic mucosa of mice administered 2.5% DSS in drinking water. Taken together, these findings clearly indicate that 15d-PGJ2, endogenously generated from arachidonic acid by cyclooxygenase-2 and PGDS activities in inflamed tissue, promotes resolution of intestinal colitis.