Mesencephalic Astrocyte-derived Neurotrophic Factor Supports Hepatitis B Virus-induced Immunotolerance.

BACKGROUND & AIMS: The immune tolerance induced by hepatitis B virus (HBV) is a major challenge for achieving effective viral clearance, and the mechanisms involved are not well-understood. One potential factor involved in modulating immune responses is mesencephalic astrocyte-derived neurotrophic factor (MANF), which has been reported to be increased in patients with chronic hepatitis B. In this study, our objective is to examine the role of MANF in regulating immune responses to HBV. METHODS: We utilized a commonly used HBV-harboring mouse model, where mice were hydrodynamically injected with the pAAV/HBV1.2 plasmid. We assessed the HBV load by measuring the levels of various markers including hepatitis B surface antigen, hepatitis B envelope antigen, hepatitis B core antigen, HBV DNA, and HBV RNA. RESULTS: Our study revealed that following HBV infection, both myeloid cells and hepatocytes exhibited increased expression of MANF. Moreover, we observed that mice with myeloid-specific MANF knockout (ManfMye-/-) displayed reduced HBV load and improved HBV-specific T cell responses. The decreased HBV-induced tolerance in ManfMye-/- mice was associated with reduced accumulation of myeloid-derived suppressor cells (MDSCs) in the liver. Restoring MDSC levels in ManfMye-/- mice through MDSC adoptive transfer reinstated HBV-induced tolerance. Mechanistically, we found that MANF promoted MDSC expansion by activating the IL-6/STAT3 pathway. Importantly, our study demonstrated the effectiveness of a combination therapy involving an hepatitis B surface antigen vaccine and nanoparticle-encapsulated MANF siRNA in effectively clearing HBV in HBV-carrier mice. CONCLUSION: The current study reveals that MANF plays a previously unrecognized regulatory role in liver tolerance by expanding MDSCs in the liver through IL-6/STAT3 signaling, leading to MDSC-mediated CD8+ T cell exhaustion.

CaMK4: Structure, physiological functions, and therapeutic potential.

Calcium/calmodulin-dependent protein kinase IV (CaMK4) is a versatile serine/threonine kinase involved in various cellular functions. It regulates T-cell differentiation, podocyte function, tumor cell proliferation/apoptosis, ß cell mass, and insulin sensitivity. However, the underlying molecular mechanisms are complex and remain incompletely understood. The aims of this review are to highlight the latest advances in the regulatory mechanisms of CaMK4 underlying T-cell imbalance and parenchymal cell mass in multiple diseases. The structural motifs and activation of CaMK4, as well as the potential role of CaMK4 as a novel therapeutic target are also discussed.

Emerging trophic activities of mesencephalic astrocyte-derived neurotrophic factor in tissue repair and regeneration.

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a soluble endoplasmic reticulum (ER) luminal protein and its expression and secretion can be induced by ER stress. Despite initially being classified as a neurotrophic factor, MANF has been demonstrated to have restorative and protective effects in many different cell types such as neurons, liver cells, retinal cells, cardiac myocytes, and pancreatic ß cells. However, underlying molecular mechanisms are complex and remain incompletely understood. The aims of this review are to highlight the latest advances in the understanding of the trophic activities of MANF in tissue repair and regeneration as well as underlying molecular mechanisms. The structural motifs and immune modulation of MANF are also described. We therefore propose that MANF might be a promising therapeutic target for tissue repair.

Berberine and Cisplatin Exhibit Synergistic Anticancer Effects on Osteosarcoma MG-63 Cells by Inhibiting the MAPK Pathway.

Berberine (BBR) has been reported to have potent anticancer activity and can increase the anticancer effects of chemotherapy drugs. The present study aims to investigate whether BBR and cisplatin (DDP) exert synergistic effects on the osteosarcoma (OS) MG-63 cell line. In the present study, MG-63 cells were treated with BBR and DDP alone or in combination. The effects of these therapeutics on cell viability, colony formation, migration, invasion, nuclear morphology, apoptosis, and the cell cycle, as well as their role in regulating the expression of proteins related to apoptosis, the cell cycle, and the mitogen-activated protein kinase (MAPK) pathway, were determined. The results demonstrated that BBR or DDP significantly inhibited the proliferation of MG-63 cells in a dose- and time-dependent manner. The combination treatment of BBR and DDP exerted a prominent inhibitory effect on proliferation and colony formation. Furthermore, the results showed that the combination treatment of BBR and DDP enhanced the inhibition of cell migration and invasion and reversed the changes in nuclear morphology. The results showed that the combination treatment of BBR and DDP induced apoptosis and cell cycle arrest in the G0/G1 phase. Mechanistically, the combination treatment of BBR and DDP inhibited the expression of MMP-2/9, Bcl-2, CyclinD1, and CDK4, enhanced the expression of Bax and regulated the activity of the MAPK pathway. Collectively, our data suggest that the combination therapy of BBR and DDP markedly enhanced OS cell death.

Susceptibility factor RTP1 negatively regulates Phytophthora parasitica resistance via modulating UPR regulators bZIP60 and bZIP28.

The unfolded protein response (UPR) is a conserved stress adaptive signaling pathway in eukaryotic organisms activated by the accumulation of misfolded proteins in the endoplasmic reticulum (ER). UPR can be elicited in the course of plant defense, playing important roles in plant-microbe interactions. The major signaling pathways of plant UPR rely on the transcriptional activity of activated forms of ER membrane-associated stress sensors bZIP60 and bZIP28, which are transcription factors that modulate expression of UPR genes. In this study, we report the plant susceptibility factor Resistance to Phytophthora parasitica 1 (RTP1) is involved in ER stress sensing and rtp1-mediated resistance against P. parasitica is synergistically regulated with UPR, as demonstrated by the simultaneous strong induction of UPR and ER stress-associated immune genes in Arabidopsis thaliana rtp1 mutant plants during the infection by P. parasitica. We further demonstrate RTP1 contributes to stabilization of the ER membrane-associated bZIP60 and bZIP28 through manipulating the bifunctional protein kinase/ribonuclease IRE1-mediated bZIP60 splicing activity and interacting with bZIP28. Consequently, we find rtp1bzip60 and rtp1bzip28 mutant plants exhibit compromised resistance accompanied with attenuated induction of ER stress-responsive immune genes and reduction of callose deposition in response to P. parasitica infection. Taken together, we demonstrate RTP1 may exert negative modulating roles in the activation of key UPR regulators bZIP60 and bZIP28, which are required for rtp1-mediated plant resistance to P. parasitica. This facilitates our understanding of the important roles of stress adaptive UPR and ER stress in plant immunity.

Genome-wide identification and characterization of HD-ZIP genes in potato.

HD-ZIP (Homeodomain leucine zipper) transcription factors play an important regulatory role in stress resistance in plants. The purpose of this study was to analyze the characteristics of the HD-ZIP genes/proteins and to study their expression profiles under high and low temperature conditions in potato (Solanum tuberosum L.). A strict homology search was used to find 43 HD-ZIP genes located on potato chromosomes 1-12. Exons/introns, protein features and conserved motifs were analyzed, and six segment duplications were identified from 43 HD-ZIP genes. Then, we analyzed the data from the PGSC (Potato Genome Sequencing Consortium) database regarding the expression of 43 HD-ZIP genes that were induced by biotic and abiotic stresses and phytohormone treatments and conducted an expression analysis for these genes across all potato life stages. Additionally, the expression levels of 13 HD-ZIP genes were analyzed under high temperature (37 °C) and low temperature (4 °C) conditions. The results showed that the transcript levels of all 13 genes changed, which indicated that these genes respond to heat and cold in plants. Especially for StHOX20, the expression significantly upregulated in roots at 37 °C and 4 °C. Our findings laid the foundation and provided clues for understanding the biological functions of HD-ZIP family genes.

Time-resolved spectra of single-bubble sonoluminescence in sulfuric acid with a streak camera.

The time-resolved spectra of single-bubble sonoluminescence (SBSL) in sulfuric acid have been observed with a streak camera after a spectrograph. The spectral center evolves from infrared to ultraviolet gradually within a SBSL duration, which corresponds to an increase of temperature. The peak temperature within one sonoluminescence (SL) duration is 5-9 times higher than the average temperature based on the average spectrum in our experiment. Furthermore, the ratio of the peak temperature to average temperature increases with the increase of driving pressure. The SBSL flash dies out after a dramatic heating-up, and there is no cooling procedure observed at the time resolution of 110 SL duration, which is incompatible with the radius-related adiabatic heating model as the mechanism of SBSL.

Composition and its evolution inside a sonoluminescing bubble by line spectra.

The line emissions of OH*, Na, Na-Ar*, and Ar are observed in stable and bright single bubble sonoluminescence (SBSL), which shows that the composition of the bubble consists of at least three parts: the vapor, droplets of the host liquid, and the gas dissolved in the host liquid. The observation of line emissions in SBSL demonstrates that it shares exactly the same spectra with multibubble sonoluminescences (MBSL). The experiments indicate that noble gas plays an important role in all line emissions of both SBSL and MBSL. The time resolved spectra of SBSL show that there is significant mass exchange between the inside and outside of the bubble. The time scale of the mass exchange ranges from less than 1/10 s to tens of seconds. The SBSL in sulfuric acid supports the argon rectification theory. Because stable SBSL in sulfuric acid can just be achieved within a narrow parameter range, only weak rectification is observed in our experiments.

The evolution of the cavitation bubble driven by different sound pressure.

In this paper, the relation between the ambient radius R(0) of the acoustic cavitation bubble and its driving pressure was investigated by an improved method. The evolution of the bubble was gained with a long-distance microscope and a bundle of 532 nm laser switched by an acousto-optic modulator. The ambient radius R(0) was determined by fitting the numerical calculation based on Rayleigh-Plesset equation to the experimental data. The results showed that as the sound pressure increased R(0) decreased at beginning and increased after the pressure reached to about 1.2 atm. Although the same rule was gotten from the relation between the maximum radius R(m) and the sound pressure, the ratio R(m)/R(0) varied monotonously with the sound pressure. It indicates that enhancing the sound pressure can increase the compression ratio of the bubble even if the mass inside the bubble is also increased.