Proteomic analysis of extremely severe hand, foot and mouth disease infected by enterovirus 71

MicroRNA 876-5p modulates EV-A71 replication through downregulation of host antiviral factors

BACKGROUND

Human enterovirus 71 (EV-A71) is a non-enveloped virus that has a single stranded positive sense RNA genome. In a previous study, we showed that miR-876-5p upregulation was observed in the serum of patients with severe EV-A71 infection. Micro-876-5p (miR-876-5p) is a circulating miRNA that can be identified to modulate EV-A71 infections through both in vitro and in vivo studies. However, the regulatory mechanisms that involve miR-876-5p in the EV-A71 infection cycle remain unclear.

METHODS

We demonstrated that miR-876-5p facilitated EV-A71 replication and expression by overexpression and knocking-down of miR-876-5p through the transfection of miR-876-5p plasmid and miR-876-5p inhibitor. Although miR-876-5p suppressed CREB5 expression, luciferase reporter assay confirmed this. We also evaluated the role of miR-876-5p in the EV-A71 infection cycle by CREB5 mediated by transfection with an anti-miR-876-5P inhibitor or in combination with an si-CREB5 plasmid.

RESULTS

MicroR-876-5p was upregulated in EV-A71-infected neuroblastoma cells. Overexpression of miR-876-5p or knockdown of cyclic-AMP responsive element binding protein 5 (CREB5) promoted EV-A71 replication. The downregulation of miR-876-5p inhibited the accumulation of viral RNA and the production of viral proteins. Interestingly, CREB5 overexpression also suppressed EV-A71 replication. Our in vitro studies reveal that miR-876-5p directly targets CREB5. Finally, downregulation of CREB5 protein abated the inhibitory effect of anti-miR-876-5p and induced inhibitory effect of EV-A71 replication.

CONCLUSIONS

Our results suggest that intracellular miR-876-5p promotes EV-A71 replication indirectly by targeting the host CREB5 protein.

Exploration of vascular adhesion protein-1 expression in patients with conjunctivitis associated systemic lupus erythematosus using 2D-DIGE

Conjunctivitis associated systemic lupus erythematosus (caSLE) is a connective tissue autoimmune disease with a large spectrum of clinical manifestations. The disease may lead to ocular complications and in severe cases may be sight-threatening. This study investigated the expression of vascular adhesion protein-1 (VAP-1) in SLE patients with conjunctivitis and the relationship between VAP-1 and other proteins in the onset of the disease. Ten patients with caSLE (caSLE group) and 10 healthy volunteers (control group) were enrolled in the study, in order to evaluate the VAP-1 expression levels in blood. Protein expression profiling was performed with two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) and analyzed with matrix-assisted laser desorption/deionization time-of-flight (MALDI-TOF) used in tandem with mass spectrometry. In the caSLE group, 8 proteins were expressed differenty compared with the control group: C-reactive protein, hemoglobin subunit β, VAP-1, A-albumin (AFAM), enolase and immunoglobulin heavy constant mu were upregulated; interferon regulatory factor-1 and serum amyloid A2 protein were downregulated. Western blotting results are consistent with the proteomics results, showing that in caSLE group VAP-1 expression is increased in comparison to the control group. VAP-1 protein participates in the inflammatory reaction in the form of amine oxidase, copper containing 3. Bioinformatics analysis suggested that VAP-1 protein could be used as a candidate protein for further study regarding its role as a potential protein marker for screening and effectively monitoring caSLE.

Prohibitin plays a critical role in Enterovirus 71 neuropathogenesis

A close relative of poliovirus, enterovirus 71 (EV71) is regarded as an important neurotropic virus of serious public health concern. EV71 causes Hand, Foot and Mouth Disease and has been associated with neurological complications in young children. Our limited understanding of the mechanisms involved in its neuropathogenesis has hampered the development of effective therapeutic options. Here, using a two-dimensional proteomics approach combined with mass spectrometry, we have identified a unique panel of host proteins that were differentially and dynamically modulated during EV71 infection of motor-neuron NSC-34 cells, which are found at the neuromuscular junctions where EV71 is believed to enter the central nervous system. Meta-analysis with previously published proteomics studies in neuroblastoma or muscle cell lines revealed minimal overlapping which suggests unique host-pathogen interactions in NSC-34 cells. Among the candidate proteins, we focused our attention on prohibitin (PHB), a protein that is involved in multiple cellular functions and the target of anti-cancer drug Rocaglamide (Roc-A). We demonstrated that cell surface-expressed PHB is involved in EV71 entry into neuronal cells specifically, while membrane-bound mitochondrial PHB associates with the virus replication complex and facilitates viral replication. Furthermore, Roc-A treatment of EV71-infected neuronal cells reduced significantly virus yields. However, the inhibitory effect of Roc-A on PHB in NSC-34 cells was not through blocking the CRAF/MEK/ERK pathway as previously reported. Instead, Roc-A treated NSC-34 cells had lower mitochondria-associated PHB and lower ATP levels that correlated with impaired mitochondria integrity. In vivo, EV71-infected mice treated with Roc-A survived longer than the vehicle-treated animals and had significantly lower virus loads in their spinal cord and brain, whereas virus titers in their limb muscles were comparable to controls. Together, this study uncovers PHB as the first host factor that is specifically involved in EV71 neuropathogenesis and a potential drug target to limit neurological complications.

Oblongifolin M, an active compound isolated from a Chinese medical herb Garcinia oblongifolia, potently inhibits enterovirus 71 reproduction through downregulation of ERp57

There is no effective drug to treat EV71 infection yet. Traditional Chinese herbs are great resources for novel antiviral compounds. Here we showed that Oblongifolin M (OM), an active compound isolated from Garcinia oblongifolia, potently inhibited EV71 infection in a dose dependent manner. To identify its potential effectors in the host cells, we successfully identified 18 proteins from 52 differentially expressed spots by comparative proteomics studies. Further studies showed that knockdown of ERp57 inhibited viral replication through downregulating viral IRES (internal ribosome entry site) activities, whereas ectopic expression of ERp57 increased IRES activity and partly rescued the inhibitory effects of OM on viral replication. We demonstrated that OM is an effective antiviral agent; and that ERp57 is one of its cellular effectors against EV71 infection.

Elevated expression of circulating miR876-5p is a specific response to severe EV71 infections

Human enterovirus 71 (EV71) is a major causative agent of hand, foot, and, mouth disease, accounting for more than 65% of recent outbreaks. Following enteroviral infection, the host responses are crucial indicators for the development of a diagnosis regarding the clinical severity of EV71 infections. In this study, we implemented NanoString nCounter technology to characterize the responses of serum microRNA (miRNA) profiles to various EV71 infection diseases. Upon EV71 infection, 44 miRNAs were observed in patients with EV71 infections, with at least a 2-fold elevation and 133 miRNAs with a 2-fold reduction compared with the same miRNAs in healthy controls. Further detailed work with miR876-5p, a 9.5-fold change of upregulated miR-876-5p expression was observed in cases with severe EV71 symptoms, revealed that in vitro and in vivo knockdown of miR876-5p reduced viral RNA in cultured cells, and attenuated the severity of symptoms in EV71-infected mice. Altogether, we demonstrated that the elevated expression of circulating miR876-5p is a specific response to severe EV71 infections.

Proteome demonstration of alpha-1-acid glycoprotein and alpha-1-antichymotrypsin candidate biomarkers for diagnosis of enterovirus 71 infection

BACKGROUND

Human enterovirus 71 (EV71) is the major causative agents of hand-foot-and-mouth disease and frequently associated with severe complications such as encephalitis and death. Understanding the host response following enteroviral infection may facilitate the development of biomarkers for EV71 infections.

METHODS

We implemented two-dimensional gel electrophoresis technology on proteins prepared from serum obtained from 4 mild and 4 severe cases of EV71 infections and 4 healthy control children, to investigate the differentially expressed proteins. The differential expressed proteins were further identified with liquid chromatography-mass spectrometry/mass spectrometry analysis and western blotting validation.

RESULTS

A total of 27 differentially expressed proteins were picked and identified with liquid chromatography-mass spectrometry/mass spectrometry. Of the 27 identified proteins, 6 proteins were up-regulated in the mild-infected and severe EV71-infected patients in comparison to the healthy control group. Two proteins, alpha-1-acid-glycoprotein (AGP1) and alpha-antichymotrypsin (AACT), were not detected in the EV71-infected patients, but appeared in the control patient. Western blotting analysis demonstrated that AGP1 and AACT proteins were negatively associated with the clinical severity of EV71 infection. Similarly, both of the proteins were not detected in the secretion medium from the EV71-infected neuroblastoma cells, but detected in the mock-infected cells, suggesting that differentially expressed AGP1/AACT protein levels are in response to EV71 infections.

CONCLUSIONS

Two candidate proteins AGP1 and AACT, whose expression levels were reduced under the EV71 infection pathological condition, provide useful source of information for potential diagnostic biomarkers of EV71 infection in children.

Update of enterovirus 71 infection: epidemiology, pathogenesis and vaccine

Enterovirus 71 (EV71) is a neurotropic human pathogen that is the causative agent of hand foot and mouth disease (HFMD), herpangina and brain stem encephalitis. Recurrent EV71 epidemics of various scales have occurred in the Asia-Pacific region. Several specific cell surface molecules serve as the receptors for EV71. Identification of the receptors is an important step to understand EV71 disease. Cytokines, lymphocytes and monocytes contribute significantly to EV71 pathogenesis. The interaction of EV71 and receptors may be associated with the cytokines immunopathogenesis. Some animal models have been established and aim to explore the pathogenesis of EV71 infections. EV71 antibodies can neutralize or enhance infection at subneutralizing levels. These results are important for EV71 vaccine and therapeutics design. Several clinical trials of human inactivated EV71 vaccine have recently been completed. The purpose of this review is to summarize recent discoveries about the epidemiology and pathogenesis of EV71 and provide insights into human vaccine development.