Multi-target regulation of pro-inflammatory cytokine production by transcription factor Blimp-1.

OBJECTIVE: Cytokine storm syndrome is a fatal condition related to infectious and autoimmune diseases. Here, we aim to investigate the regulatory mechanisms of Blimp-1 on multiple cytokine production. METHODS: The Blimp1 shRNA was transfected into RAW264.7 macrophages, followed by Toll-like receptor (TLR) ligand stimulation. The mRNA and protein levels of cytokines were detected by real-time PCR and flow cytometric bead array. The nuclear translocation of AP-1 and NF-κB p65 was measured by immunofluorescence staining. The transcriptional activity was detected by luciferase reporter assay with 5 × NF-κB reporter or with IL6 promoter reporter. RESULTS: Blimp-1 significantly inhibited the expression and secretion of IL-1ß, IL-6, and IL-18 in macrophages during stimulation with a variety of TLR ligands. The immunofluorescence staining results showed that Blimp-1 strictly controlled the nuclear translocation of NF-κB p65 in LPS-challenged macrophages. Furthermore, Blimp-1 directly inhibited the transcriptional activity of NF-κB and the transcription of IL6 gene. CONCLUSION: Blimp-1 represses the production of multiple pro-inflammatory cytokines by directly binding the genomic region and restricting the nuclear translocation and transcriptional activity of NF-κB. This finding may provide potential therapeutic strategies for the cytokine storm-related diseases.

Weak reflectivity measurements of large-mode-area FBGs by a scale composed of a fiber Fabry-Perot interferometer.

In a previous study, we proposed a measuring method for the reflectivity of weak-reflection large-mode-area fiber Bragg gratings by using scale gratings. We experimentally found that the interference between two scale fiber Bragg gratings (FBGs) is beneficial for increasing reflectivity scales, which can improve the measurement accuracy. Therefore, in this study, we designed and fabricated FBG-based Fabry-Perot cavities (FBG-FP) in single-mode fibers by two inscription methods, namely ultraviolet (UV) laser exposure and femtosecond-laser direct writing. Then, a large-mode-area double-clad (LMA-DC) FBG of weak reflectivity was measured by these two scales, and the experimental results show that the Bragg resonance reflectivity is less than 4.28% and 1.14% ∼ 2.28%, respectively. This method of measuring the weak grating reflectivity based on FBG-FP scales is convenient, efficient, and accurate. It is also worth mentioning that the method of femtosecond-laser direct writing eliminates the period limitation of the phase mask, thereby expanding the measurement wavelength range of FBGs. In the future, with the improvement of fiber grating fabrication technology, it is expected that more accurate results can be obtained.

Method for measuring reflectivity of weak reflection large-mode-area fiber Bragg gratings using scale gratings.

Accurate fundamental-mode (FM) reflectivity measurements of FM weak reflection large-mode-area (LMA) FBGs constitute a challenging problem owing to high-order modes (HMs). In this paper, we propose a novel measurement method that uses scale gratings fabricated in a single-mode fiber. The weak reflectivity of the measured FBGs was achieved by comparing the peak reflection resonance with that of the scale gratings. The measured minimum reflectivity of the scale grating was 1.3%, giving the measurement accuracy. The accuracy can be improved further by increasing the number of reflectivity scales. A Fabry-Perot-interferometer-based scale grating was proposed, designed, and fabricated using a chirped phase mask to achieve soaring scale numbers. The minimum reflectivity of the scales decreased by 0.37%. Several LMA double-cladding FBGs with weak reflectivity were measured. The results show that this novel measurement method is convenient and efficient, does not depend on the transmission spectrum of the grating, and can circumvent the influence of HM. It is anticipated that weak reflectivity can be measured more accurately by improving grating fabrication technology.

Macrophages evoke autophagy of hepatic stellate cells to promote liver fibrosis in NAFLD mice via the PGE2/EP4 pathway.

The pathogenesis of liver fibrosis in nonalcoholic fatty liver disease (NAFLD) remains unclear and the effective treatments have not been explored yet. The activation of hepatic stellate cells (HSCs) is considered as the most critical factor in the progression of liver fibrosis and cirrhosis. Autophagy has recently been identified as a new mechanism to regulate HSC activation. Here, we found that liver macrophages were polarized toward type 2 (M2) during the progression of nonalcoholic steatohepatitis (NASH) and liver fibrosis in both patients and NAFLD mice. Using the methionine-choline-deficient (MCD) diet NAFLD murine model and the in vitro cell culture system, we identified that the M2 macrophages promoted HSC autophagy by secreting prostaglandin E2 (PGE2) and binding its receptor EP4 on the surface of HSCs, which consequently enhanced HSC activation, extracellular matrix deposition, and liver fibrosis. Mechanistically, PGE2/EP4 signals enhanced HSC autophagy through the Erk pathway. A specific PGE2/EP4 antagonist E7046 significantly inhibited M2 macrophage-mediated HSC autophagy and improved liver fibrosis and histopathology in NAFLD mice. Our study provides novel mechanistic insights into the regulation of HSC activation and liver fibrosis. Our findings suggest that the PGE2/EP4 pathway is a promising therapeutic target to prevent NASH progression into cirrhosis.

Mechanism of taurine reducing inflammation and organ injury in sepsis mice.

The fundamental basis for the pathogenesis of sepsis is an inflammatory imbalance, which is considered to be the main target for treatment. Taurine is an intracellular free amino acid that has anti-inflammatory and antioxidant effects. To investigate the protective mechanism of taurine in sepsis, we used in vitro and in vivo experiments to explore the effects of taurine on neutrophil and monocyte immune function. Metabolomic analysis showed large amounts of taurine in neutrophils and monocytes and a dramatic decrease in taurine levels after LPS exposure. Taurine supplementation decreased the expressions of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß) in LPS-challenged neutrophils and monocytes and reduced the formation of neutrophil extracellular traps by restricting reactive oxygen species. Moreover, taurine protected septic mice from death, improved tissue injuries in the lung, liver, and kidney by reducing neutrophil infiltration and TNF-α production. Our data indicate that a supplement with taurine might be a promising therapeutic strategy for sepsis to reduce hyper inflammation and improve multi-organ dysfunctions.

Hedgehog pathway inhibition causes primary follicle atresia and decreases female germline stem cell proliferation capacity or stemness.

BACKGROUND: Follicle depletion is one of the causes of premature ovarian failure (POF) and primary ovarian insufficiency (POI). Hence, maintenance of a certain number of female germline stem cells (FGSCs) is optimal to produce oocytes and replenish the primordial follicle pool. The mechanism that regulates proliferation or stemness of FGSCs could contribute to restoring ovarian function, but it remains uncharacterized in postnatal mammalian ovaries. This study aims to investigate the mechanism by which inhibiting the activity of the hedgehog (Hh) signaling pathway regulates follicle development and FGSC proliferation. METHODS AND RESULTS: To understand the role of the Hh pathway in ovarian aging, we measured Hh signaling activity at different reproductive ages and the correlation between them in physiological and pathological mice. Furthermore, we evaluated the follicle number and development and the changes in FGSC proliferation or stemness after blocking the Hh pathway in vitro and in vivo. In addition, we aimed to explain one of the mechanisms for the FGSC phenotype changes induced by treatment with the Hh pathway-specific inhibitor GANT61 via oxidative stress and apoptosis. The results show that the activity of Hh signaling is decreased in the ovaries in physiological aging and POF models, which is consistent with the trend of expression levels of the germline stem cell markers Mvh and Oct4. In vitro, blocking the Hh pathway causes follicular developmental disorders and depletes ovarian germ cells and FGSCs after treating ovaries with GANT61. The proliferation or stemness of cultured primary FGSCs is reduced when Hh activity is blocked. Our results show that the antioxidative enzyme level and the ratio of Bcl-2/Bax decrease, the expression level of caspase 3 increases, the mitochondrial membrane potential is abnormal, and ROS accumulate in this system. CONCLUSIONS: We observed that the inhibition of the Hh signaling pathway with GANT61 could reduce primordial follicle number and decrease FGSC reproductive capacity or stemness through oxidative damage and apoptosis.