CD36 deficiency ameliorates drug-induced acute liver injury in mice

Background Acetaminophen (APAP) overdose causes hepatotoxicity and even acute liver failure. Recent studies indicate that sterile inflammation and innate immune cells may play important roles in damage-induced hepatocytes regeneration and liver repair. The scavenger receptor CD36 has its crucial functions in sterile inflammation. However, the roles of CD36 in APAP induced acute liver injury remain unclear and warrant further investigation. Methods WT C57BL/6 J and CD36−/− mice were intraperitoneally injected with APAP (300 mg/kg) after fasting for 16 h. Liver injury was evaluated by serum alanine aminotransferase (ALT) level and liver tissue hematoxylin and eosin (H&E) staining. Liver inflammatory factor expression was determined by real-time polymerase chain reaction (PCR). The protein adducts forming from the metabolite of APAP and the metabolism enzyme cytochrome P450 2E1 (CYP2E1) levels were measured by Western blot. Liver infiltrating macrophages and neutrophils were characterized by flow cytometry. RNA sequencing and Western blot were used to evaluate the effect of damage-associated molecular patterns (DAMP) molecule high mobility group B1 (HMGB1) on WT and CD36−/− macrophages. Moreover, PP2, a Src kinase inhibitor, blocking CD36 signaling, was applied in APAP model. Results The expression of CD36 was increased in the liver of mice after APAP treatment. Compared with WT mice, APAP treated CD36−/− mice show less liver injury. There was no significant difference in APAP protein adducts and CYP2E1 expression between these two strains. However, reduced pro-inflammatory factor mRNA expression and serum IL-1β level were observed in APAP treated CD36−/− mice as well as infiltrating macrophages and neutrophils. Moreover, CD36 deficiency impaired the activation of c-Jun N-terminal kinase (JNK) caused by APAP. Interestingly, the lack of CD36 reduced the activation of extracellular regulated protein kinases (Erk) and v-akt murine thymoma viral oncogene homolog (Akt) induced by HMGB1. RNA transcription sequencing data indicated that HMGB1 has a different effect on WT and CD36−/− macrophages. Furthermore, treatment with PP2 attenuated APAP induced mouse liver injury. Conclusion Our data demonstrated that CD36 deficiency ameliorated APAP-induced acute liver injury and inflammatory responses by decreasing JNK activation. CD36 might serve as a new target to reduce acute liver injury.

CD36 deficiency affects depressive-like behaviors possibly by modifying gut microbiota and the inflammasome pathway in mice

Both inflammatory processes and gut microbiota have been implicated in the pathophysiology of depressive disorders. The class B scavenger receptor CD36 is involved in the cytotoxicity associated with inflammation. However, its role in depression has not yet been examined. In this study, we investigated whether CD36 affects depression by modulating the microbiota-gut-inflammasome-brain axis. We used CD36−/− (knockout) mice subjected to chronic social defeat stress, and measured the expression of CD36 in these depressed mice and in patients with depression. The hippocampus of CD36−/− mice was used to investigate changes in the NLRP3 inflammasome signaling pathway. The 16S rRNA gene sequence-based approach was used to compare the cecal microbial communities in CD36−/− and WT mice. The CD36 deficiency in CD36−/− mice alleviated chronic stress-induced depression-like behaviors. CD36 was upregulated in depressed mice as well as in depressed patients. Furthermore, the NLRP3 inflammasome signaling pathway was downregulated in the hippocampus of CD36−/− mice. The Simpson Diversity Index revealed increased cecal bacterial alpha-diversity in the CD36−/− mice. Among genera, Bacteroides, Rikenella, and Alloprevotella were significantly more abundant in the CD36−/− mice, whereas Allobaculum was less abundant, consistent with the attenuated inflammation in the hippocampus of CD36−/− mice. Our findings suggest that CD36 deficiency changes the gut microbiota composition, which in turn may impact depressive-like behaviors by affecting the inflammasome pathway.

CD36 deficiency reduces chronic BBB dysfunction and scar formation and improves activity, hedonic and memory deficits in ischemic stroke

Ameliorating blood–brain barrier disruption and altering scar formation dynamics are potential strategies that may improve post-stroke recovery. CD36 is a class B scavenger receptor that plays a role in innate immunity, inflammation and vascular dysfunction and regulates post-stroke injury, neovascularization, reactive astrogliosis and scar formation. By subjecting WT and CD36KO mice to different MCAo occlusion durations to generate comparable acute lesion sizes, we addressed the role of CD36 in BBB dysfunction, scar formation and recovery. The majority of stroke recovery studies primarily focus on motor function. Here, we employed an extensive behavioral test arsenal to evaluate psychological and cognitive endpoints. While not evident during the acute phase, CD36 deficient mice displayed significantly attenuated BBB leakage and scar formation at three months after stroke compared to wild-type littermates. Assessment of motor (open field, rotarod), anxiety (plus maze, light-dark box), depression (forced swim, sucrose preference) and memory tests (water maze) revealed that CD36 deficiency ameliorated stroke-induced behavioral impairments in activity, hedonic responses and spatial learning and strategy switching. Our findings indicate that CD36 contributes to stroke-induced BBB dysfunction and scar formation in an injury-independent manner, as well as to the chronic motor and neurophysiological deficits in chronic stroke.

Type 1 cluster of differentiation 36 deficiency-related cardiomyopathy accelerates heart failure with co-existing mitral valve prolapse: a case report

Background Free fatty acid is a major energy source in the healthy heart and cluster of differentiation 36 (CD36) partially regulates the rate of myocardial fatty acid uptake. Here, we report a case of CD36 deficiency-related cardiomyopathy with a unique pathophysiology. Heart failure was accelerated by co-existing mitral valve prolapse (MVP) without a distinct phenotype of hypertrophic or dilated cardiomyopathy. Case summary A middle-aged man was aware of dyspnoea and hospitalized for heart failure with MVP. Cluster of differentiation 36 deficiency was found based on the absence of myocardial 123l-15-(p-iodophenyl)-3-(R,S)-methyl pentadecanoic acid (BMIPP) uptake by myocardial scintigraphy. Type I CD36 deficiency was further diagnosed by the lack of CD36 in both platelets and monocytes by flow cytometry. Left ventricular muscle was obtained intraoperatively, and a histological examination reflected compensative hypertrophy of cardiomyocytes with myofibrillar loss and reactive fibrosis. The microvascular structure around the cardiomyocytes was highlighted by immunohistochemical staining for CD31, while CD36 expression was absent. He had an operation of mitral valve replacement and improved heart failure. Discussion Cluster of differentiation 36 deficiency potentially mediates various pathological conditions in the heart. Incidental CD36 deficiency-related cardiomyopathy may accelerate heart failure in the presence of co-existing heart diseases. BMIPP scintigraphy might be helpful for predicting CD36 deficiency.