Regulation of the macrophage-hepatic stellate cell interaction by targeting macrophage peroxisome proliferator-activated receptor gamma to prevent non-alcoholic steatohepatitis progression in mice

BACKGROUND & AIMS

Macrophages display remarkable plasticity and can interact with surrounding cells to affect hepatic immunity and tissue remodelling during the progression of liver diseases. Peroxisome proliferator-activated receptor gamma (PPARγ) plays a critical role in macrophage maturation, polarization and metabolism. In this study, we investigated the role of PPARγ in macrophage-hepatic stellate cell (HSC) interaction during non-alcoholic steatohepatitis (NASH) development.

METHODS

Wild-type, Pparg^fl/fl and Pparg^ΔLyz2 mice were fed a methionine- and choline-deficient (MCD) diet to induce NASH. Depletion of macrophages was performed using an injection of gadolinium chloride intraperitoneally. PPARγ-overexpressing or PPARγ-knockout macrophages were stimulated with saturated fatty acid (SFA) and cocultured with HSCs in a conditioned medium or the transwell coculture system.

RESULTS

Depletion of macrophages inhibited HSC activation and ameliorated NASH progression in MCD diet-fed mice. Coculturing HSCs with macrophages or culturing HSCs in a macrophage-conditioned medium-facilitated HSC activation, and this effect was magnified when macrophages were metabolically activated by SFA. Moreover, the absence of PPARγ in macrophages enhanced metabolic activation, promoting the migration and activation of HSCs through IL-1β and CCL2. In contrast, overexpression of PPARγ in macrophages obtained the opposite effects. In vivo, macrophage-specific PPARγ knockout affected the phenotype of hepatic macrophages and HSCs, involving the MAPK and NLRP3/caspase-1/IL-1β signalling pathways. Infiltrating hepatic monocyte-derived macrophages became the predominant macrophages in NASH liver, especially in Pparg^ΔLyz2 mice, paralleling with aggravated inflammation and fibrosis.

CONCLUSIONS

Regulating macrophage PPARγ affected the metabolic activation of macrophages and their interaction with HSCs. Macrophage-specific PPARγ may be an attractive therapeutic target for protecting against NASH-associated inflammation and fibrosis.

[Correlation between Toxoplasma gondii infection and spontaneous abortion in pregnant women: a case-control study]

OBJECTIVE

To examine the correlation between Toxoplasma gondii infection and spontaneous abortion among pregnant women, so as to provide the evidence for the developmentofpreventivemeasuresforspontaneousabortion.

METHODS

A total of 228 serum samples collected from women with spontaneous abortion for the first time from January 2018 to December 2019 were selected as the case group, while 228 serum samples collected from pregnant women with a normal delivery and without a history of abortion during the same period were selected as the control group. The serum IgG and IgM antibodies against T. gondii were detected and compared in both groups, and the correlation between T. gondii infection and spontaneous abortion was evaluated.

RESULTS

There were no significant differences between the case and control groups in terms of age, education levels, occupation, residency and proportion of keeping cats (all P values > 0.05). The positive rate of anti-T. gondii IgM antibody was significantly higher in the case group than in the control group (adjusted χ² = 4.08, P < 0.05; OR = 8.25), while no significant difference was seen between the case and control groups (χ² = 0.42, P > 0.05).

CONCLUSIONS

Acute maternal T. gondii infection may remarkably increase the chance of spontaneous abortion. Progestational health education regarding toxoplasmosis prevention and control knowledge and detection of T. gondii infection during pregnancy should be strengthened.

The immune evasion strategies of fish viruses

Viral infection of a host rapidly triggers intracellular signaling events that induce interferon production and a cellular antiviral state. Viral diseases are important concerns in fish aquaculture. The major mechanisms of the fish antiviral immune response are suggested to be similar to those of mammals, although the specific details of the process require further studies. Throughout the process of pathogen-host coevolution, fish viruses have developed a battery of distinct strategies to overcome the biochemical and immunological defenses of the host. Such strategies include signaling interference, effector modulation, and manipulation of host apoptosis. This review provide an overview of the different mechanisms that fish viruses use to evade host immune responses. The basic mechanisms of immune evasion of fish virus are discussed, and some examples are provided to illustrate particular points.

[Coronary microvascular resistance and its relevant factors in patients with moderate coronary stenosis and chest pain]

Objective: To evaluate the impact of cardiovascular risk factors on index of microvascular resistance (IMR) and coronary flow reserve (CFR) and to explore the characteristics of IMR and CFR and the relationship between IMR and angiographic features in patients with intermediate coronary stenosis and chest pain. Methods: Fractional flow reserve (FFR), CFR, and IMR were measured in patients who underwent invasive coronary angiography with 40%-70% stenosis by visual assessment. All patients with FFR>0.75 were enrolled and grouped with the cut-off points of IMR≥25 and CFR≤2.0. Patients with IMR≥25 were group H, including two sub-groups (high IMR-low CFR, group H₁ and high IMR-high CFR, group H₂), while those with IMR<25 were group N. The thrombolysis in myocardial infarction (TIMI) frame were counted. Results: A total of 34 patients with FFR>0.75 were enrolled with 61.8%(21 cases) of males and 38.2% (13 cases) of females. The mean age was (57.3±8.1) years old. High IMR accounted for 47.1% of all cases. There was significant difference between group H and N in TIMI frame (33.0 vs. 20.8, P=0.031). There were significant differences between group H₁ and H₂ in homocysteine (17.8 µmol/L vs. 12.0 µmol/L, P=0.005) and IMR_corr (58.0 vs. 36.1, P=0.002). IMR_corr was correlated to TIMI frame (r=0.40, P=0.012) for all cases. The sensitivity and specificity of inferring IMR≥35.3 by TIMI frame were 0.75 and 0.65 (P=0.049) with TIMI frame over 40.5. Conclusions: High IMR may be one of the reasons for chest pain in patients with intermediate coronary stenosis. There is no correlation between vascular risk factors and IMR or CFR, while there is positive correlation between TIMI frame and IMR. The specificity is 65% for inferring IMR rise with TIMI frame over 40.5.

The role of liver stiffness measurement in the evaluation of liver function and esophageal varices in cirrhotic patients

OBJECTIVE

We aimed to evaluate the efficacy of liver stiffness measurement (LSM) in predicting the presence and severity of esophageal varices (EV) and investigating its association with liver function (LF) in patients with liver cirrhosis.

METHODS

Medical records of 90 cirrhotic patients who underwent LSM by transient elastography were retrospectively reviewed. The relationship between LSM and the presence and severity of EV was evaluated by esophagogastroduodenoscopy (EGD) and multislice spiral computed tomography (MSCT). Another 25 healthy individuals were included as controls.

RESULTS

LSM was significantly associated with the Child-Pugh score in cirrhotic patients, with the highest LSM in those with Child-Pugh C. Patients with clinically decompensated cirrhosis had a higher LSM than those with compensated cirrhosis (36.75 ± 16.54 kPa vs 17.65 ± 10.87 kPa, P < 0.01). However, there was no significant difference in LSM value between patients with severe EV and those with no or non-severe EV determined by endoscopy (28.18 ± 17.44 kPa vs 31.00 ± 18.44 kPa) or MSCT (29.71 ± 18.39 kPa vs 24.90 ± 14.80 kPa). The diagnostic value of LSM for predicting severe EV was low in unselected cirrhotic patients. The presence of EV examined by EGD and MSCT was similar to each other.

CONCLUSIONS

LSM could be used to evaluate the progression of liver cirrhosis continuously. However, its role in assessing EV grades in advanced cirrhosis needs further confirmation. MSCT can assess EV accurately and may serve as an alternative to endoscopy in the assessment of portal hypertension.

Riboflavin supplementation improves energy metabolism in mice exposed to acute hypoxia

This study investigated the effects of riboflavin on energy metabolism in hypoxic mice. Kunming mice were fed diets containing riboflavin at doses of 6, 12, 24 and 48 mg/kg, respectively for 2 weeks before exposure to a simulated altitude of 6000 m for 8 h. Changes of riboflavin status and energy metabolism were assessed biochemically. Simultaneously, a (1)H nuclear magnetic resonance (NMR) based metabolomic technique was used to track the changes of plasma metabolic profiling. It was found that the content of hepatic riboflavin was decreased and erythrocyte glutathione activation coefficient was elevated significantly under hypoxic condition. Meanwhile, increased plasma pyruvate, lactate, beta-hydroxybutyrate and urea, as well as decreased plasma carnitine were observed. Riboflavin supplementation improved riboflavin status remarkably in hypoxic mice and decreased plasma levels of pyruvate, free fatty acids and beta-hydroxybutyrate significantly. Plasma carnitine was increased in response to riboflavin supplementation. Results obtained from (1)H NMR analysis were basically in line with the data from biochemical assays and remarkable changes in plasma taurine, choline and some other metabolites were also indicated. It was concluded that riboflavin requirement was increased under acute hypoxic condition and riboflavin supplementation was effective in improving energy metabolism in hypoxic mice.

Effects of NF-kappaB inhibitor on titanium particulate-induced inflammation in a murine model

BACKGROUND

Activation of nuclear factor kappa B (NF-kappaB) signaling in response to implant particulates may be critical in the pathogenesis of implant loosening after joint arthroplasty. The purpose of this study was to investigate the inhibitory effects of pyrrolidine dithiocarbamate (PDTC) in a murine model of inflammation induced by titanium (Ti) particulates.

MATERIALS AND METHODS

Ti particulates were introduced into established air pouches on C57BL/6J mice. Mice were injected intraperitoneally with either high-dose PDTC (100 mg/kg) or low-dose PDTC (50 mg/kg). Mice without drug treatment, as well as mice injected with saline alone were included. Each group consisted of sixteen mice. The membranes and lavage fluid were harvested 2 d or 7 d after injection of particulate suspension for histological and molecular analysis.

RESULTS

Histologic analysis showed that PDTC reduced inflammatory responses in air pouches, that is, thinner membrane and decreased cellular infiltration. In addition, PDTC reduced the release of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in the lavage fluid or supernatant of homogenates as evaluated by ELISA.

CONCLUSION

These results suggest that PDTC inhibits Ti particulate-induced inflammatory responses in the murine model; thus it represents a promising therapeutic candidate for the prevention and treatment of implant loosening.

Proteomic analysis of human bone marrow mesenchymal stem cells transduced with human telomerase reverse transcriptase gene during proliferation

OBJECTIVES

Previous studies have reported immortalization and tumorigenicity of human mesenchymal stem cells (hMSCs) transduced with exogenous human telomerase reverse transcriptase (hTERT). We also have established a line of hMSCs transduced with hTERT (hTERT-hMSCs) and we have cultured these cells for 290 population doublings (PDs) during which they demonstrated a large proliferation potential but with no tumorigenicity. The aim of this study was to investigate the protein expression profile of hTERT-hMSCs with two-dimensional gel electrophoresis and peptide mass fingerprinting by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, to be able to analyse the effects of exogenous hTERT on protein expression in hMSCs.

MATERIALS AND METHODS

We generated proteome maps of primary hMSCs and hTERT-hMSCs at PD 95 and PD 275.

RESULTS

A total of 1543 +/- 145 protein spots in gels of primary MSCs at PD 12, 1611 +/- 186 protein spots in gels of hTERT-hMSCs at PD 95 and 1451 +/- 126 protein spots in gels of hTERT-hMSCs at 275 PD were detected. One hundred of these were successfully identified, including 20 which were differentially expressed.

CONCLUSIONS

The results suggest that sustaining levels of prohibitin and p53 expression along with differential expression of proteins in hTERT-hMSCs provide an insight into lack of transforming activity of hTERT-hMSCs during cell proliferation.

HIV-1 infection of placental cord blood monocyte-derived dendritic cells

Dendritic cells (DC), the most potent antigen-presenting cells (APC), have been implicated as the initial targets of HIV infection in skin and mucosal surfaces. DC can be generated in vitro from blood-isolated CD14(+) monocytes or CD34(+) hematopoietic progenitor cells in the presence of various cytokines. In this study, we investigated whether monocytes obtained from placental cord blood are capable of differentiation into dendritic cells when cultured with a combination of cytokines - granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-4 (IL-4), and tumor necrosis factor-alpha (TNF-alpha). We then examined HIV infection, HIV receptor (CD4, CCR5) expression, and beta-chemokine [macrophage inflammatory protein-1alpha and -1beta (MIP-1alpha, MIP-1beta)] production by placental cord monocyte-derived dendritic cells (MDDC) as compared to that of autologous cord monocyte-derived macrophages (MDM). Monocytes isolated from placental cord blood differentiate into DC after 7 days in culture with the mixture of cytokines, as demonstrated by development of characteristic DC morphology, loss of CD14 expression, and gain of CD83, a marker for mature DC. Mature cord MDDC had significantly lower susceptibility to M-tropic ADA (CCR5-dependent) envelope-pseudotyped HIV infection in comparison to autologous placental cord MDM, whereas there was no significant difference in virus replication in cord MDDC and MDM infected with murine leukemia virus envelope-pseudotyped HIV (HIV receptor-independent). This limited susceptibility of cord MDDC to M-tropic HIV infection may be due to lower expression of CD4 and CCR5 on the cell membrane and higher production of MIP-1alpha and MIP-1beta. These data provide important information toward our understanding of the biological properties of cord MDDC in relation to HIV infection.

[Effects of zinc on the free radical signals and apoptosis in liver with ischemia/ reperfusion injury]

AIM

In order to explore the preventive mechanism of zinc, the changes of free radical signals and apoptosis in hepatic ischemia/reperfusion injury (HIR) rats were observed.

METHODS

The MDA levels in serum were measured by fluorophotometry, free radical signals in liver were analyzed with electron spin resonance (ESR) method; and apoptosis was assayed by flow cytometry (FCM).

RESULTS

MDA levels in serum and free radical contents in liver were both increased in rats with HIR. After zinc supplementation, they were decreased. After HIR, the percentage of subdiploid cells was 57.72% while it was reduced to 40.85% after zinc supplementation.

CONCLUSION

Zinc may protect against HIR injury by inhibiting the production of free radicals in liver and hepatocellular apoptosis.

[Effect of acupuncture on immunologic function and histopathology of transplanted mammary cancer in mice]

This experiment mainly describes the effects of acupuncture on immunologic function and histopathology of transplanted mammary cancer in mice. The results were as follows: in acupuncture group, NK cell activity and T-lymphocyte positive rate of acid alpha-naphthyl acetate esterase (ANAE) and lymphocyte transformation rate were all increased. Compared with the control group, there was a significant difference (P < 0.01). The difference was insignificant, when compared with normal group (P > 0.05). Comparing the pathology grading of acupuncture group with control group, it showed marked difference in pathological section (P < 0.01). Adenoid structure and the degree of lymphocytic infiltration also have marked difference between acupuncture and control group (P < 0.05). Less tumour volume in acupuncture than control group were observed (P < 0.01). This indicated that acupuncture might increase the immunologic function of transplanted mammary cancer in mice and inhibit the growth of mammary cancer and enhance both differentiation level of mammary cancer cells and lymphocytic infiltration. Possibly acupuncture mightt reduce the malignancy of mammary cancer cells.

Changes in cellular immunity and nutritional status in mice after thermal injury

A 13 per cent body surface area (BSA), full skin thickness burn was inflicted on LACA male mice and the changes in cellular immunity and nutritional status were observed. The results showed that thymus, spleen and circulating lymphocytes were significantly involved. A diminished mitogen responsiveness of spleen cells and altered peritoneal macrophage function were confirmed. Ear swelling tests indicated that the cellular immunity of burned mice was most severely depressed in week 2 postburn. The present study also showed that the dramatic change in nutritional status occurred earlier than that in cellular immunity and suggested the importance of early nutritional support after thermal injury.

Detection of epoxide hydrolase in rat hepatoma cell lines and primary rat liver cells by immunoblotting

Rat epoxide hydrolase (EH) (EC 3.3.2.3) is elevated in cells of premalignant liver lesions, and variable EH activity has been reported for hepatocellular carcinomas. To facilitate detection of altered EH levels in liver cells, an immunoblotting method was devised. Rabbit antiserum specific for rat EH was prepared and used to detect EH extracted from suspensions of normal liver cells and from hepatoma cell lines. Compared with normal liver cells, 3 rat hepatoma cell lines, 7777, HTC and 17X, showed virtually undetectable EH levels by immunoblotting. The immunoblotting results rule out the possibility that very low EH enzymatic activity in the hepatoma cells results from production of normal amounts of non-functional enzyme protein.