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2022 ◽  
Vol 15 ◽  
Luoziyi Wang ◽  
Yiwen Qian ◽  
Xin Che ◽  
Jing Jiang ◽  
Jinshan Suo ◽  

Microglia, the primary resident immunocytes in the retina, continuously function as immune system supervisors in sustaining intraocular homeostasis. Microglia relate to many diseases, such as diabetic retinopathy, glaucoma, and optic nerve injury. To further investigate their morphology and functions in vitro, a reliable culture procedure of primary human retinal microglia is necessary. However, the culture condition of microglia from the adult retina is unclear. Researchers created several protocols, but most of them were carried out on rodents and newborns. This study describes a protocol to isolate and characterize human primary retinal microglia from human post-mortem eyes. The whole procedure started with removing the retinal vessels, mechanical separation and enzymatic dissociation, filtration, and centrifugation. Then, we cultured the cell suspensions on a T-75 flask for 18 days and then shook retinal microglia from other retinal cells. We found numerous retinal microglia grow and attach to Müller cells 10 days after seeding and increase rapidly on days 14–18. Iba1 and P2RY12 were used to qualify microglia through immunofluorescence. Moreover, CD11b and P2RY12 were positive in flow cytometry, which helps to discriminate microglia from other cells and macrophages. We also observed a robust response of retinal microglia in lipopolysaccharide (LPS) treatment with proinflammatory cytokines. In conclusion, this study provides an effective way to isolate and culture retinal microglia from adult human eyes, which may be critical for future functional investigations.

2022 ◽  
Vol 2022 ◽  
pp. 1-13
Jindong Zhao ◽  
Lili Liu ◽  
Ling Xin ◽  
Yunxia Lu ◽  
Xiaojun Yang ◽  

Objective. The aim of this study was to evaluate the effects of a modified Xiaohua Funing decoction (Xfd) on acute liver failure (ALF) and determine whether the protective mechanisms are related to alterations in the gut microbiota. Methods. An animal model of ALF was induced by intraperitoneal injection of D-galactosamine (D-Gal, 0.5 g/kg) and lipopolysaccharide (LPS, 100 μg/kg). Male BALB/c mice were randomly divided into the following 4 groups: the control group (saline, Con), model group (D-Gal/LPS, Mod), silymarin pretreatment group (200 mg/kg, Sil), and modified Xfd pretreatment group (650 mg/kg, Xfd). The Sil and Xfd groups received the respective intervention orally for 14 days and 2 h before D-Gal/LPS treatment. The liver injury markers included alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and liver histology. 16S rRNA gene sequencing was performed to assess the effects on the caecum content. Results. D-Gal/LPS treatment caused severe ALF, illustrating that the ALF model was successfully established. The administration of Sil and Xfd greatly reduced the serum ALT and AST levels and improved the pathological signs of liver injury. However, no significant difference was found between the two groups. In contrast to the Mod group, the Sil and Xfd groups showed a shift toward the Con group in terms of the gut microbiota structure. The abundances of Firmicutes and Bacteroidetes and the Bacteroidetes/Firmicutes ratio in the Mod group significantly differed from those in the Con group. The Sil and Xfd groups showed restoration of the disordered microbiota. Significantly increased relative abundances of Lachnospiraceae_NK4A136_group and Candidatus_Saccharimonas and a markedly decreased Muribaculaceae abundance were found in the Sil and Xfd mice compared with those in the Mod mice ( P < 0.01 , P < 0.05 ). Interestingly, a negative correlation was observed between the abundances of the gut microbiota constituents, specifically Clostridia_UCG-014, and ALT and AST levels. Conclusion. In summary, our results indicate that Xfd may protect the liver and modify the gut microbiota in ALF mice.

Li Jin ◽  
Juan Li ◽  
ShuJuan Yang ◽  
Rou Zhang ◽  
Chunhua Hu ◽  

Background: In the past, hepatic stellate cells (HSCs) were considered to be noninflammatory cells and contribute to liver fibrosis by producing extracellular matrix. Recently, it was found that HSCs can also secrete cytokines and chemokines and therefore participate in hepatic inflammation. Autophagy participates in many immune response processes in immune cells. It is unclear whether autophagy is involved in inflammatory cytokine induction in HSCs. Methods: MAPK p38, Ulk1 phosphorylation and the Ulk1-Atg13 complex were analyzed in HSC-T6 cells after LPS treatment. The relationship between autophagy inhibition and inflammation was investigated in primary rat HSCs. Results: We discovered that LPS inhibited autophagy through MAPK p38. The activation of MAPK p38 induced Ulk1 phosphorylation, which disrupted the Ulk1-Atg13 complex and therefore inhibited autophagy. Furthermore, in primary rat HSCs, we demonstrated that autophagy inhibition regulated IL-1β induction, which depended on the MAPK p38/Ulk1 pathway. Conclusions: Our results reveal a continuous signaling pathway, MAPK p38-Ulk1 phosphorylation-Ulk1/Atg13 disruption, which inhibits autophagy and induces IL-1β expression in HSCs.

2022 ◽  
Lei Zhao ◽  
Xiaosong Liu ◽  
Jiankai Yang ◽  
Xiaoliang Wang ◽  
Xiaomeng Liu ◽  

Abstract Background Microglia are important immune cells, which can be induced by lipopolysaccharide (LPS) into M1 phenotype that express pro-inflammatory cytokines. Some studies have shown that microRNAs play critical roles in microglial activation. Objective This study was designed to investigate the role of miR-200c-3p in regulating inflammatory responses of LPS-treated BV2 cells. Methods The expression of miR-200c-3p in BV2 cells was detected by real-time PCR. Receptor-interacting protein 2 (RIP2) was predicted as a target gene of miR-200c-3p. Their relationship was verified by dual-luciferase reporter assay. The function of miR-200c-3p and RIP2 in microglial polarization and NF-κB signaling was further evaluated. Results LPS treatment reduced miR-200c-3p expression in a dose-dependent and time-dependent manner in BV2 cells. LPS treatment increased the expression of M1 phenotype markers inducible nitric oxide synthase (iNOS) and major histocompatibility complex class (MHC)-II, promoted the release of pro-inflammatory cytokines interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, and enhanced the nuclear translocation and phosphorylation of nuclear factor-kappaB (NF-κB) p65. Reversely, miR-200c-3p mimics down-regulated the levels of these inflammatory factors. Furthermore, RIP2 was identified to be a direct target of miR-200c-3p. RIP2 knockdown had a similar effect to miR-200c-3p mimics. Overexpression of RIP2 eliminated the inhibitory effect of miR-200c-3p on LPS-induced M1 polarization and NF-κB activation in BV2 cells. Conclusions MiR-200c-3p mimics suppressed LPS-induced microglial M1 polarization and NF-κB activation by targeting RIP2. MiR-200c-3p/RIP2 might be a potential therapeutic target for the treatment of neuroinflammation-associated diseases.

Leif D. Nelin ◽  
Yi Jin ◽  
Bernadette Chen ◽  
Yusen Liu ◽  
Lynette K. Rogers ◽  

Many lung diseases are caused by an excessive inflammatory response, and inflammatory lung diseases are often modeled using lipopolysaccharide (LPS) in mice. Cyclooxygenase-2 (COX-2) encoded by the Ptgs2 gene is induced in response to inflammatory stimuli including lipopolysaccharide (LPS). The objective of this study was to test the hypothesis that mice deficient in COX-2 (Ptgs2-/-) will be protected from LPS-induced lung injury. Wild type (WT, CD1 mice) and Ptgs2-/- mice (on a CD1 background) were treated with LPS or vehicle for 24 hours. LPS-treatment resulted in histological evidence of lung injury, which was attenuated in the Ptgs2-/- mice. LPS-treatment increased the mRNA levels for tumor necrosis factor (TNF)-α, interleukin (IL)-10, and monocyte chemoattractant protein (MCP)-1 in the lungs of WT mice, and the LPS-induced increases in these levels were attenuated in the Ptgs2-/- mice. The protein levels of active caspase-3 and caspase-9 were lower in the LPS-treated lungs of Ptgs2-/- mice than in LPS-treated WT mice, as were the number of TUNEL positive cells in lung sections. LPS exposure resulted in greater lung wet-to-dry weight ratio (W/D) in WT mice, suggestive of pulmonary edema; while in LPS-treated Ptgs2-/- mice the W/D was not different from controls and less than in LPS-treated WT mice. These results demonstrate that COX-2 is involved in the inflammatory response to LPS, and suggest that COX-2 not only acts as a downstream participant in the inflammatory response, but also acts as a regulator of the inflammatory response likely through a feed-forward mechanism following LPS stimulation.

Anita Patel ◽  
Henriette Frikke-Schmidt ◽  
Olivier Bezy ◽  
Paul V Sabatini ◽  
Nikolaj Rittig ◽  

Growth differentiation factor 15 (GDF15), a TGFβ superfamily cytokine, acts through its receptor, GDNF-family receptor α-like (GFRAL), to suppress food intake and promote nausea. GDF15 is broadly expressed at low levels but increases in states of disease such as cancer, cachexia, and sepsis. Whether GDF15 is necessary for inducing sepsis associated anorexia and body weight loss is currently unclear. To test this we used a model of moderate systemic infection in GDF15KO and GFRALKO mice with lipopolysaccharide (LPS) treatment to define the role of GDF15 signaling in infection-mediated physiologic responses. Since physiologic responses to LPS depend on housing temperature, we tested the effects of subthermoneutral and thermoneutral conditions on eliciting anorexia and inducing GDF15. Our data demonstrate a conserved LPS-mediated increase in circulating GDF15 levels in mouse, rat and human. However, we did not detect differences in LPS induced anorexia between WT and GDF15KO or GFRALKO mice. Further, there were no differences in anorexia or circulating GDF15 levels at either thermoneutral or subthermoneutral housing conditions in LPS treated mice. These data demonstrate that GDF15 is not necessary to drive food intake suppression in response to moderate doses of LPS.

2021 ◽  
Vol 12 ◽  
Jianbo Lai ◽  
Peifen Zhang ◽  
Jiajun Jiang ◽  
Tingting Mou ◽  
Yifan Li ◽  

Tetratricopeptide repeat and ankyrin repeat containing 1 (TRANK1) is a robust risk gene of bipolar disorder (BD). However, little is known on the role of TRANK1 in the pathogenesis of BD and whether the gut microbiota is capable of regulating TRANK1 expression. In this study, we first investigated the serum mRNA level of TRANK1 in medication-free patients with a depressive episode of BD, then a mice model was constructed by fecal microbiota transplantation (FMT) to explore the effects of gut microbiota on brain TRANK1 expression and neuroinflammation, which was further verified by in vitro Lipopolysaccharide (LPS) treatment in BV-2 microglial cells and neurons. 22 patients with a depressive episode and 28 healthy individuals were recruited. Serum level of TRANK1 mRNA was higher in depressed patients than that of healthy controls. Mice harboring ‘BD microbiota’ following FMT presented depression-like phenotype. mRNA levels of inflammatory cytokines and TRANK1 were elevated in mice hippocampus and prefrontal cortex. In vitro, LPS treatment activated the secretion of pro-inflammatory factors in BV-2 cells, which was capable of upregulating the neuronal expression of TRANK1 mRNA. Moreover, primary cortical neurons transfected with plasmid Cytomegalovirus DNA (pcDNA3.1(+)) vector encoding human TRANK1 showed decreased dendritic spine density. Together, these findings add new evidence to the microbiota-gut-brain regulation in BD, indicating that microbiota is possibly involved in the neuropathogenesis of BD by modulating the expression of TRANK1.

Biomedicines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1946
Ying Wang ◽  
Pedro Andrade ◽  
Asla Pitkänen

Peripheral infections occur in up to 28% of patients with traumatic brain injury (TBI), which is a major etiology for structural epilepsies. We hypothesized that infection occurring after TBI acts as a “second hit” and facilitates post-traumatic epileptogenesis. Adult male Sprague–Dawley rats were subjected to lateral fluid-percussion injury or sham-operation. At 8 weeks post-injury, rats were treated with lipopolysaccharide (LPS, 5 mg/kg) to mimic Gram-negative peripheral infection. T2-weighted magnetic resonance imaging was used to detect the cortical lesion type (small focal inflammatory [TBIFI] vs. large cavity-forming [TBICF]). Spontaneous seizures were detected with video-electroencephalography, and seizure susceptibility was determined by the pentylenetetrazole (PTZ) test. Post-PTZ neuronal activation was assessed using c-Fos immunohistochemistry. LPS treatment increased the percentage of rats with PTZ-induced seizures among animals with TBIFI lesions (p < 0.05). It also increased the cumulative duration of PTZ-induced seizures (p < 0.01), particularly in the TBIFI group (p < 0.05). The number of c-Fos immunopositive cells was higher in the perilesional cortex of injured animals compared with sham-operated animals (p < 0.05), particularly in the TBI-LPS group (p < 0.05). LPS treatment increased the percentage of injured rats with bilateral c-Fos staining in the dentate gyrus (p < 0.05), particularly in the TBIFI group (p < 0.05). Our findings demonstrate that peripheral infection after TBI increases PTZ-induced seizure susceptibility and neuronal activation in the perilesional cortex and bilaterally in the dentate gyrus, particularly in animals with prolonged perilesional T2 enhancement. Our data suggest that treatment of infections and reduction of post-injury neuro-inflammation are important components of the treatment regimen aiming at preventing epileptogenesis after TBI.

Biology ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1300
Felix Kretzschmar ◽  
Robin Piecha ◽  
Jannik Jahn ◽  
Phani Sankar Potru ◽  
Björn Spittau

As resident innate immune cells of the CNS, microglia play important essential roles during physiological and pathological situations. Recent reports have described the expression of Lilrb4 in disease-associated and aged microglia. Here, we characterized the expression of Lilrb4 in microglia in vitro and in vivo in comparison with bone marrow-derived monocytes and peritoneal macrophages in mice. Using BV2 cells, primary microglia cultures as well as ex vivo isolated microglia and myeloid cells in combination with qPCR and flow cytometry, we were able to provide a comprehensive characterization of Lilrb4 expression in distinct mouse myeloid cells. Whereas microglia in vivo display low expression of Lilrb4, primary microglia cultures present high levels of surface LILRB4. Among the analyzed peripheral myeloid cells, peritoneal macrophages showed the highest expression levels of Lilrb4. Moreover, LPS treatment and inhibition of microglial TGFβ signaling resulted in significant increases of LILRB4 cell surface levels. Taken together, our data indicate that LILRB4 is a reliable surface marker for activated microglia and further demonstrate that microglial TGFβ signaling is involved in the regulation of Lilrb4 expression during LPS-induced microglia activation.

2021 ◽  
Vol 12 ◽  
Atsushi Murao ◽  
Chuyi Tan ◽  
Alok Jha ◽  
Ping Wang ◽  
Monowar Aziz

Extracellular cold-inducible RNA-binding protein (eCIRP) is an important damage-associated molecular pattern (DAMP). Despite our understanding of the potentially harmful effects of eCIRP in sepsis, how eCIRP is released from cells remains elusive. Exosomes are endosome-derived extracellular vesicles, which carry proteins, lipids, and nucleic acids to facilitate intercellular communication and several extracellular functions. We hypothesized that eCIRP is released via exosomes to induce inflammation in sepsis. Exosomes isolated from the supernatants of LPS-treated macrophage culture and serum of endotoxemia and polymicrobial sepsis mice showed high purity, as revealed by their unique median sizes ranging between 70 and 126 nm in diameter. eCIRP levels of the exosomes were significantly increased after LPS treatment in the supernatants of macrophage culture, mouse serum, and cecal ligation and puncture (CLP)-induced sepsis mouse serum. Protease protection assay demonstrated the majority of eCIRP was present on the surface of exosomes. Treatment of WT macrophages and mice with exosomes isolated from LPS-treated WT mice serum increased TNFα and IL-6 production. However, treatment with CIRP−/- mice serum exosomes significantly decreased these levels compared with WT exosome-treated conditions. CIRP−/- mice serum exosomes significantly decreased neutrophil migration in vitro compared with WT exosomes. Treatment of mice with serum exosomes isolated from CIRP−/- mice significantly reduced neutrophil infiltration into the peritoneal cavity. Our data suggest that eCIRP can be released via exosomes to induce cytokine production and neutrophil migration. Thus, exosomal eCIRP could be a potential target to inhibit inflammation.

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