Upregulation of interleukin-1 by Epstein-Barr virus latent membrane protein 1 and its possible role in nasopharyngeal carcinoma cell growth

Deciphering the Role of Epstein-Barr Virus Latent Membrane Protein 1 in Immune Modulation: A Multifaced Signalling Perspective

The disruption of antiviral sensors and the evasion of immune defences by various tactics are hallmarks of EBV infection. One of the EBV latent gene products, LMP1, was shown to induce the activation of signalling pathways, such as NF-κB, MAPK (JNK, ERK1/2, p38), JAK/STAT and PI3K/Akt, via three subdomains of its C-terminal domain, regulating the expression of several cytokines responsible for modulation of the immune response and therefore promoting viral persistence. The aim of this review is to summarise the current knowledge on the EBV-mediated induction of immunomodulatory molecules by the activation of signal transduction pathways with a particular focus on LMP1-mediated mechanisms. A more detailed understanding of the cytokine biology molecular landscape in EBV infections could contribute to the more complete understanding of diseases associated with this virus.

Epstein-Barr Virus and Innate Immunity: Friends or Foes?

Epstein–Barr virus (EBV) successfully persists in the vast majority of adults but causes lymphoid and epithelial malignancies in a small fraction of latently infected individuals. Innate immunity is the first-line antiviral defense, which EBV has to evade in favor of its own replication and infection. EBV uses multiple strategies to perturb innate immune signaling pathways activated by Toll-like, RIG-I-like, NOD-like, and AIM2-like receptors as well as cyclic GMP-AMP synthase. EBV also counteracts interferon production and signaling, including TBK1-IRF3 and JAK-STAT pathways. However, activation of innate immunity also triggers pro-inflammatory response and proteolytic cleavage of caspases, both of which exhibit proviral activity under some circumstances. Pathogenic inflammation also contributes to EBV oncogenesis. EBV activates NFκB signaling and induces pro-inflammatory cytokines. Through differential modulation of the proviral and antiviral roles of caspases and other host factors at different stages of infection, EBV usurps cellular programs for death and inflammation to its own benefits. The outcome of EBV infection is governed by a delicate interplay between innate immunity and EBV. A better understanding of this interplay will instruct prevention and intervention of EBV-associated cancers.

Pre-treatment serum inflammatory cytokines as survival predictors of patients with nasopharyngeal carcinoma receiving chemoradiotherapy

The present study aimed to examine the predictability of pre-treatment serum levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α for determining the outcome of patients with nasopharyngeal carcinoma (NPC) assigned for chemoradiotherapy. A total of 35 patients with NPC were subjected to clinical examination and evaluation of performance status using Karnofsky scoring. Nasopharyngoscopy was performed for evaluation and to obtain a biopsy. Blood samples were obtained pre- and post-treatment for polymerase chain reaction quantitative estimation of Epstein-Barr virus (EBV) DNA plasma load and enzyme-linked immunosorbent assay for estimation of serum cytokines. All patients received chemoradiotherapy and were followed-up for 2 years. Cervical lymphadenopathy and recurrent attacks of epistaxis are the most common presenting symptoms. Treatment significantly decreased pre-treatment plasma EBV DNA load and serum levels of IL-6 and TNF-α, and increased serum IL-1β levels. Clinical staging and EBV DNA plasma load revealed positively significant correlation with pre-treatment serum levels of both IL-6 and TNF-α, while revealed negative significant correlation with serum IL-1β levels. The 2-year survival rate was negatively significantly correlated with pre-treatment levels of IL-6 and TNF-α, and EBV DNA viral load, while it was positively significantly correlated with pre-treatment performance scores and serum IL-1β levels. Statistical analyses defined high pre-treatment serum IL-6 levels as a significant specific predictor for high mortality rate. It was demonstrated that NPC was associated with high pre-treatment plasma EBV DNA load and serum cytokines, and chemoradiotherapy significantly reduced these high levels. High pre-treatment serum IL-6 level was a significant specific predictor for high mortality rate. Increased post-treatment serum levels of IL-1β indicated good therapeutic response and most probably a high survival rate.

Autocrine CCL3 and CCL4 induced by the oncoprotein LMP1 promote Epstein-Barr virus-triggered B cell proliferation

Epstein-Barr virus (EBV) alters the regulation and expression of a variety of cytokines in its host cells to modulate host immune surveillance and facilitate viral persistence. Using cytokine antibody arrays, we found that, in addition to the cytokines reported previously, two chemotactic cytokines, CCL3 and CCL4, were induced in EBV-infected B cells and were expressed at high levels in all EBV-immortalized lymphoblastoid cell lines (LCLs). Furthermore, EBV latent membrane protein 1 (LMP1)-mediated Jun N-terminal protein kinase activation was responsible for upregulation of CCL3 and CCL4. Inhibition of CCL3 and CCL4 in LCLs using a short hairpin RNA approach or by neutralizing antibodies suppressed cell proliferation and caused apoptosis, indicating that autocrine CCL3 and CCL4 are required for LCL survival and growth. Importantly, significant amounts of CCL3 were detected in EBV-positive plasma from immunocompromised patients, suggesting that EBV modulates this chemokine in vivo. This study reveals the regulatory mechanism and a novel function of CCL3 and CCL4 in EBV-infected B cells. CCL3 might be useful as a therapeutic target in EBV-associated lymphoproliferative diseases and malignancies.

Tumour inflammasome-derived IL-1β recruits neutrophils and improves local recurrence-free survival in EBV-induced nasopharyngeal carcinoma

Inflammasomes sense infection and cellular damage and are critical for triggering inflammation through IL-1β production. In carcinogenesis, inflammasomes may have contradictory roles through facilitating antitumour immunity and inducing oncogenic factors. Their function in cancer remains poorly characterized. Here we show that the NLRP3, AIM2 and RIG-I inflammasomes are overexpressed in Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC), and expression levels correlate with patient survival. In tumour cells, AIM2 and RIG-I are required for IL-1β induction by EBV genomic DNA and EBV-encoded small RNAs, respectively, while NLRP3 responds to extracellular ATP and reactive oxygen species. Irradiation and chemotherapy can further activate AIM2 and NLRP3, respectively. In mice, tumour-derived IL-1β inhibits tumour growth and enhances survival through host responses. Mechanistically, IL-1β-mediated anti-tumour effects depend on infiltrated immunostimulatory neutrophils. We show further that presence of tumour-associated neutrophils is significantly associated with better survival in NPC patients. Thus, tumour inflammasomes play a key role in tumour control by recruiting neutrophils, and their expression levels are favourable prognostic markers and promising therapeutic targets in patients.