Endoplasmic reticulum stress mediates the myeloid-derived immune suppression associated with cancer and infectious disease.

Myeloid-derived suppressor cells (MDSCs), which are immature heterogeneous bone marrow cells, have been described as potent immune regulators in human and murine cancer models. The distribution of MDSCs varies across organs and is divided into three subpopulations: granulocytic MDSCs or polymorphonuclear MDSCs (G-MDSCs or PMN-MDSCs), monocytic MDSCs (M-MDSCs), as well as a recently identified early precursor MDSC (eMDSCs) in humans. Activated MDSCs induce the inactivation of NK cells, CD4+, and CD8+ T cells through a variety of mechanisms, thus promoting the formation of tumor immunosuppressive microenvironment. ER stress plays an important protecting role in the survival of MDSC, which aggravates the immunosuppression in tumors. In addition, ferroptosis can promote an anti-tumor immune response by reversing the immunosuppressive microenvironment. This review summarizes immune suppression by MDSCs with a focus on the role of endoplasmic reticulum stress-mediated immune suppression in cancer and infectious disease, in particular leprosy and tuberculosis.

GTSF1 gene may serve as a novel potential diagnostic biomarker for liver cancer.

The gametocyte-specific factor 1 (GTSF1) gene participates in DNA methylation and retrotransposon activation in germ cells, particularly during cell proliferation. The present study aimed to assess the level of GTSF1 gene expression in liver cancer tumor tissues, and its role in human hepatoma cell lines in vitro and in a nude mouse model in vivo. GTSF1 gene expression was detected in liver cancer tumor tissues, compared with in healthy controls, via reverse transcription quantitative polymerase chain reaction. An adeno-associated virus vector was used to study tumor stem cell proliferation in vivo. A plasmid expressing GTSF1 was constructed and transfected into various human hepatoma cell lines, in order to analyze the cellular proliferation and apoptosis of liver cancer cells using small interfering (si)RNAs in vitro. In the present study, GTSF1 gene expression was detected in 18/24 (75.0%) liver cancer tumor tissues from patients with hepatocellular carcinoma (HCC), and elevated GTSF1 expression was identified in the tissue of one of 32 healthy control samples (3.13%; P<0.05). Notably, the GTSF1 gene was expressed at a higher frequency in AFP-positive HCC samples (14/16, 87.50%) compared with in AFP-negative HCC samples (4/8, 50.0%; P=0.129). In addition, there was no statistical significance between GTSF1 expression in non-HBV-infected (71.42%) and HBV-infected HCC specimens (76.47%), as determined by a χ2 test (P=0.921). It was demonstrated that GTSF1 significantly increased the tumorigenicity of Ad-shNC-transfected (GTSF1-positive) HepG2 cells in the nude mouse xenograft model, whereas the sizes and weights of the tumors in the GTSF1-negative group were dercreased in comparison with the GTSF1-positive group (P<0.05). Reduced levels of GTSF1 mRNA, along with fewer and smaller colonies, were identified in two groups of human liver cancer cells treated with with GTSF1-targeting siRNA, when compared with cells without GTSF1 mRNA interference (P<0.05). In summary, the present study elucidated the GTSF1 mRNA expression pattern in liver cancer, and investigated the potential role of GTSF1 in tumorigenesis. The data suggest an important role for the GTSF1 gene in the molecular etiology of hepatocarcinogenesis, and indicate a potential application of GTSF1 mRNA expression in liver cancer diagnosis and therapy.

IRF3 is an important molecule in the UII/UT system and mediates immune inflammatory injury in acute liver failure.

The urotensin II/urotensin receptor (UII/UT) system can mediate inflammatory liver injury in acute liver failure (ALF); however; the related mechanism is not clear. In this study, we confirmed that lipopolysaccharide/D-galactosamine (LPS/D-GalN) induced up-regulation of liver interferon regulatory factor 3 (IRF3) in ALF mice, whereas the UT antagonist urantide inhibited the up-regulated liver IRF3. LPS stimulation induced IRF3 transcription and nuclear translocation and promoted the secretion of interleukin-6 (IL-6), interferon (IFN)-ß, and IFN-γ in Kupffer cells (KCs); these effects in LPS-stimulated KCs were inhibited by urantide. Knockdown of IRF3 using an adenovirus expressing an IRF3 shRNA inhibited IFN-ß transcription and secretion as well as tumor necrosis factor (TNF)-α and IL-1ß secretion from LPS-stimulated KCs; additionally, IL-10 transcription and secretion were promoted in response to LPS. However, LPS-stimulated TNF-α and IL-1ß mRNA was not affected in the KCs. The IRF3 shRNA also did not have a significant effect on the NF-κB p65 subunit and p38MAPK protein phosphorylation levels in the nuclei of LPS-stimulated KCs. Therefore, IRF3 expression and activation depended on the signal transduction of the UII/UT system, and played important roles in UII/UT-mediated immune inflammatory injury in the liver but did not affect NF-κB and p38 MAPK activity.

Inhibition of UII/UTR system relieves acute inflammation of liver through preventing activation of NF-κB pathway in ALF mice.

Urotensin II (UII) is implicated in immune inflammatory diseases through its specific high-affinity UT receptor (UTR). Enhanced expression of UII/UTR was recently demonstrated in the liver with acute liver failure (ALF). Here, we analysed the relationship between UII/UTR expression and ALF in lipopolysaccharide (LPS)/D-galactosamine (GalN)-challenged mice. Thereafter, we investigated the effects produced by the inhibition of UII/UTR system using urantide, a special antagonist of UTR, and the potential molecular mechanisms involved in ALF. Urantide was administered to mice treated with LPS/GalN. Expression of UII/UTR, releases of proinflammatory cytokines including tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1ß) and interferon-γ (IFN-γ), and activation of nuclear factor κB (NF-κB) signaling pathway were assessed in the lethal ALF with or without urantide pretreatment. We found that LPS/GalN-challenged mice showed high mortality and marked hepatic inflammatory infiltration and cell apoptosis as well as a significant increase of UII/UTR expression. Urantide pretreatment protected against the injury in liver following downregulation of UII/UTR expression. A close relationship between the acutely flamed hepatic injury and UII/UTR expression was observed. In addition, urantide prevented the increases of proinflammatory cytokines such as TNF-α, IL-1ß and IFN-γ, and activation of NF-κB signaling pathway induced by LPS/GalN in mice. Thus, we conclude that UII/UTR system plays a role in LPS/GalN-induced ALF. Urantide has a protective effect on the acutely inflamed injury of liver in part through preventing releases of proinflammatory cytokines and activation of NF-κB pathway.

Recurrent porphyria attacks in a Chinese patient with a heterozygous PBGD mutation.

We report here the case of a 32-year-old Chinese Han woman who presented with frequent severe abdominal pain, convulsion, numbness and confusion. She also had hypertension, hyponatremia, chronic renal failure, anemia and a high urinary δ-aminolevulinic acid concentration. We identified a heterozygous splicing mutation in intron 11 (IVS11-2A→G) of the porphobilinogen (PBG) deaminase gene (PBGD) in her genomic DNA. This mutation had previously been reported in a North American patient, but was absent from 50 healthy Chinese controls.

Characterization of the specific CD4+ T cell response against the F protein during chronic hepatitis C virus infection.

BACKGROUND: The hepatitis C virus (HCV) Alternate Reading Frame Protein (ARFP or F protein) presents a double-frame shift product of the HCV core gene. We and others have previously reported that the specific antibodies against the F protein could be raised in the sera of HCV chronically infected patients. However, the specific CD4(+) T cell responses against the F protein during HCV infection and the pathological implications remained unclear. In the current study, we screened the MHC class II-presenting epitopes of the F protein through HLA-transgenic mouse models and eventually validated the specific CD4(+) T cell responses in HCV chronically infected patients. METHODOLOGY: DNA vaccination in HLA-DR1 and-DP4 transgenic mouse models, proliferation assay to test the F protein specific T cell response, genotyping of Chronic HCV patients and testing the F-peptide stimulated T cell response in the peripheral blood mononuclear cell (PBMC) by in vitro expansion and interferon (IFN)- γ intracellular staining. PRINCIPAL FINDINGS: At least three peptides within HCV F protein were identified as HLA-DR or HLA-DP4 presenting epitopes by the proliferation assays in mouse models. Further study with human PBMCs evidenced the specific CD4(+) T cell responses against HCV F protein as well in patients chronically infected with HCV. CONCLUSION: The current study provided the evidence for the first time that HCV F protein could elicit specific CD4(+) T cell response, which may provide an insight into the immunopathogenesis during HCV chronic infection.

Assessment of specific antibodies to F protein in serum samples from Chinese hepatitis C patients treated with interferon plus ribavarin.

The hepatitis C virus (HCV) alternate reading frame protein or F protein of the HCV 1b genotype is a double-frameshift product of the HCV core protein. In order to assess the presence of antibodies specific for F protein and their clinical relevance in sera from HCV patients, we produced recombinant F protein and core protein of the HCV 1b genotype in Escherichia coli. An enzyme-linked immunosorbent assay was developed using purified recombinant HCV core, F protein, and a 99-residue synthetic F peptide (F99). The seroprevalences of anticore, anti-F protein, and anti-F99 synthetic peptide were 95%, 68%, and 36%, respectively, in 168 HCV patients. The prevalence of anti-F antibodies did not correlate with viral load, genotype, or alanine aminotransferase level. Interferon combination therapy induced a decline in the level of anti-F antibodies in 55 responders (P < 0.01). Thirteen responders (24%) lost their anti-F recombinant protein antibodies, and 17 (31%) lost their anti-F synthetic peptide antibodies, whereas no decrease was observed for the 17 nonresponders. These changes were significant between responders and nonresponders (P < 0.05). Meanwhile, no change was found in the anticore antibody titer of the 72 treated patients. The percentage of anti-F-protein-negative patients (15/15 [100%]) who achieved a sustained virological response (SVR) was higher than that of the anti-F-positive patients (70%) (P < 0.05). Based on these findings, HCV F protein elicits a specific antibody response other than the anticore protein response. Our data also suggest that the presence and level of anti-F antibody responses might be influenced by the treatment (interferon plus ribavirin) and associated with an SVR in Chinese hepatitis C patients.

Identification of a ferrochelatase mutation in a Chinese family with erythropoietic protoporphyria.

BACKGROUND/AIMS: Erythropoietic protoporphyria (EPP) is a rare autosomal dominant disorder of heme biosynthesis characterized by a partial decrease in ferrochelatase (FECH) activity leading to excessive accumulation of protoporphyrin. While a majority of EPP patients only exhibit photosensitivity, a small percentage of patients also develop liver complications and need liver transplantation. METHODS: In this study, we have sequenced the ferrochelatase gene of a Chinese EPP patient who suffered from EPP-related liver complications. RESULTS: A nonsense mutation in exon 4, 343C>T, introducing a premature stop codon at position arginine 115, was identified in the proband as well as her symptomatic mother and brother, but was absent in her father. All the family members with overt photosensitivity also carried the low-expressed allele IVS3-48c, whose prevalence in the Chinese Han population was determined to be 41.35% and which was also functional in producing an aberrant 63 bp insertion. CONCLUSION: We describe the first FECH mutation identified in the Chinese Han population and report a high frequency of the hypomorphic IVS3-48c allele in China.