Toll like receptor agonists augment HPV 11 E7-specific T cell responses by modulating monocyte-derived dendritic cells

TLR9 in the Human Papilloma Virus Infections: Friend or Foe?

Immune system plays dual roles during human papilloma virus (HPV) infections, from defense against the virus to induction or stimulation of the HPV-related cancers. It appears that various differences within the immune-related genes and the functions of the immunological parameters of the patients are the main factors responsible for the roles played by immune system during HPV infections. Toll-like receptors (TLRs) play key roles in the recognition of viruses and activation of immune responses. The molecules also can alter the target cell intracellular signaling and may participate in the transformation of the infected cells. TLR9 is the unique intracellular member of TLRs that recognize foreign DNA, including viral DNA. Thus, TLR9 may play significant roles in the defense against HPV and its related cancers. This review article discusses TLR9 antiviral and pathological roles during HPV infection.

Vaccination Strategies for the Control and Treatment of HPV Infection and HPV-Associated Cancer

Human papillomavirus (HPV) is the most common sexually transmitted infection, currently affecting close to 80 million Americans. Importantly, HPV infection is recognized as the etiologic factor for numerous cancers, including cervical, vulval, vaginal, penile, anal, and a subset of oropharyngeal cancers. The prevalence of HPV infection and its associated diseases are a significant problem, affecting millions of individuals worldwide. Likewise, the incidence of HPV infection poses a significant burden on individuals and the broader healthcare system. Between 2011 and 2015, there were an estimated 42,700 new cases of HPV-associated cancers each year in the United States alone. Similarly, the global burden of HPV is high, with around 630,000 new cases of HPV-associated cancer occurring each year. In the last decade, a total of three preventive major capsid protein (L1) virus-like particle-based HPV vaccines have been licensed and brought to market as a means to prevent the spread of HPV infection. These prophylactic vaccines have been demonstrated to be safe and efficacious in preventing HPV infection. The most recent iteration of the preventive HPV vaccine, a nanovalent, L1-VLP vaccine, protects against a total of nine HPV types (seven high-risk and two low-risk HPV types), including the high-risk types HPV16 and HPV18, which are responsible for causing the majority of HPV-associated cancers. Although current prophylactic HPV vaccines have demonstrated huge success in preventing infection, existing barriers to vaccine acquisition have limited their widespread use, especially in low- and middle-income countries, where the burden of HPV-associated diseases is highest. Prophylactic vaccines are unable to provide protection to individuals with existing HPV infections or HPV-associated diseases. Instead, therapeutic HPV vaccines capable of generating T cell-mediated immunity against HPV infection and associated diseases are needed to ameliorate the burden of disease in individuals with existing HPV infection. To generate a cell-mediated immune response against HPV, most therapeutic vaccines target HPV oncoproteins E6 and E7. Several types of therapeutic HPV vaccine candidates have been developed including live-vector, protein, peptide, dendritic cell, and DNA-based vaccines. This chapter will review the commercially available prophylactic HPV vaccines and discuss the recent progress in the development of therapeutic HPV vaccines.

Overexpression of programmed cell death ligand 1 in patients with CIN and its correlation with human papillomavirus infection and CIN persistence

Backround

HPV causes specific cell-mediated immunity in the cervix. Mononuclear cells such as helper T cells (CD4+), cytotoxic T cells (CD8+), and dendritic cells play a critical role in the initiation of the HPV-specific immune response and destruction of virus-infected cervical epithelial cells. The programmed cell death ligand 1 (PD-L1) gene encodes an immune inhibitory receptor ligand and overexpression of PD-L1 inhibits T-cell activation and cytokine production. The aim of this study was to investigate the expression of PD-L1 in cervical tissue and its correlation with clinicopathological findings.

Methods

In this cross-sectional study, a total of 94 women who were referred for colposcopy due to abnormal Papanicolaou (PAP) test results and/or HPV positivity were evaluated. The presence of HR-HPV-DNA was analyzed using type- and gene-specific primers along with commercial real-time polymerase chain reaction. The cervical examination was done with a colposcope. Cervical biopsies were obtained from the areas that were evaluated as abnormal during the colposcopy. Histopathological result of cervical biopsies were defined as no intraepithelial neoplasia (CIN 0), mild CIN (CIN I), and moderate-to-high CIN (CIN II-III). All women were classified into four groups based on their HR-HPV positivity and cervical biopsy results: Group I (controls; n = 29), HR-HPV (-) CIN 0; Group II (n = 21), HR-HPV (+) CIN 0; Group III (n = 20), HR-HPV (+) CIN I; and Group IV (n = 24), HR-HPV (+) CIN II-III. A semi-quantitative scoring system was used to evaluate the degree of Ki-67, p16, and PD-L1 immunoreactivity in the cervical tissue samples.

Results

We found that PD-L1 expression in both mononuclear cells and in cervical epithelial cells gradually increases from the HR-HPV (-), CIN 0 group to the HR-HPV (+), CIN II-III group (p = 0.0003 and p = 0.0394, respectively) and mononuclear PD-L1 expression was correlated with HPV type, initial Pap test results, HPV persistence, and CIN persistence or recurrence (p = 0.0180, p = 0.0109, p = 0.0042, and p = 0.0189, respectively). Moreover, mononuclear PD-L1 expression was also correlated with Ki-67 and p16 immunoreactivity (p = 0.0432 and p = 0.0166, respectively). Epithelial PD-L1 expression was only correlated with HPV type and the presence of HPV persistence (p = 0.0122 and p = 0.0292, respectively).

Conclusion

During the initial evaluation of the cervical histology results, the assessment of PD-L1 expression-especially in mononuclear cells in cervical tissue samples-may provide more information on the progression of HR-HPV infection and its persistence.

TLR4: An Important Molecule Participating in Either Anti-Human Papillomavirus Immune Responses or Development of Its Related Cancers

It has been reported that human papillomavirus (HPV) is a main cause of cervical cancer. Immune system plays key roles in the HPV infection clearance. Additionally, the roles played by immune responses in development of cancers have been documented previously. Toll-like receptors (TLRs) are the main surface or intravesicular receptors driving innate immunity, which either participate in the fight against infectious agents or participate in the progression of cancers. Thus, it has been hypothesized that the molecules may be part of the HPV/cancers puzzle. TLR4 is a unique member of TLRs family that uses both well-known TLRs related intracellular signaling pathways. Furthermore, the roles played by TLR4 against several viruses and also their related complications, such as tumors, have been demonstrated. Thus, it has been hypothesized that TLR4 may play a key role in HPV infection and its related complications. This review article collected the information regarding the mentioned plausible roles by TLR4.

Human papillomavirus (HPV) 16 E6 oncoprotein targets the Toll-like receptor pathway

Cervical cancer is one of the leading causes of death in women worldwide and is etiologically linked to human papillomavirus (HPV) infection. Viral early proteins E6 and E7 manipulate cellular functions to promote the virus life cycle and are essential to the cellular transformation process. The innate immune system plays a pivotal role in the natural history of HPV infection. Among the various proteins that mediate the innate immune response, Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) and initiate the immune response. The objective of this study was to identify HPV E6 protein interaction partners in the TLR signalling pathway that may play a role in the immune response against HPV. Six TLR pathway proteins were shown to interact with HPV16 E6: myeloid differentiation primary response protein (MyD88), TIR domain-containing adapter molecule 1 (TRIF), interleukin-1 receptor-associated kinase-like (IRAK) 2, TNF receptor-associated factor (TRAF) 6, I-κB kinase beta (IKKβ) and I-κB kinase epsilon (IKKε). The interaction site of IKKε with E6 is located in the region containing the enzyme catalytic site, suggesting an influence of E6 on the activation of IKKε target proteins. HPV16 E6 potentiated the activation of NF-κB by various TLR pathway members. These results suggest that HPV16 has the ability to interfere with components of the immune response, contributing to HPV carcinogenesis.

Immunogenicity, safety and tolerability of intradermal influenza vaccines

Intradermal influenza vaccination has been studied for more than 80 y. The revived interest in this strategy of vaccination is a result of the innovative technologies in needle design allowing more precise injection and making the device easier to use. Furthermore, clinical trials on these novel devices have demonstrated significant dose sparing effects, improved immunogenicity and very few adverse effects. This review compares intradermal vaccination with various devices with subcutaneous and intramuscular vaccination. We also discussed the role of topical adjuvant before intradermal vaccination.

Immunomodulatory Effect of Toll-Like Receptor-3 Ligand Poly I:C on Cortical Spreading Depression

The release of inflammatory mediators following cortical spreading depression (CSD) is suggested to play a role in pathophysiology of CSD-related neurological disorders. Toll-like receptors (TLR) are master regulators of innate immune function and involved in the activation of inflammatory responses in the brain. TLR3 agonist poly I:C exerts anti-inflammatory effect and prevents cell injury in the brain. The aim of the present study was to examine the effect of systemic administration of poly I:C on the release of cytokines (TNF-α, IFN-γ, IL-4, TGF-β1, and GM-CSF) in the brain and spleen, splenic lymphocyte proliferation, expression of GAD65, GABAAα, GABAAβ as well as Hsp70, and production of dark neurons after induction of repetitive CSD in juvenile rats. Poly I:C significantly attenuated CSD-induced production of TNF-α and IFN-γ in the brain as well as TNF-α and IL-4 in the spleen. Poly I:C did not affect enhancement of splenic lymphocyte proliferation after CSD. Administration of poly I:C increased expression of GABAAα, GABAAβ as well as Hsp70 and decreased expression of GAD65 in the entorhinal cortex compared to CSD-treated tissues. In addition, poly I:C significantly prevented production of CSD-induced dark neurons. The data indicate neuroprotective and anti-inflammatory effects of TLR3 activation on CSD-induced neuroinflammation. Targeting TLR3 may provide a novel strategy for developing new treatments for CSD-related neurological disorders.

Immunogenicity of intradermal trivalent influenza vaccine with topical imiquimod: a double blind randomized controlled trial

BACKGROUND

Imiquimod, a synthetic Toll-like receptor 7 agonist enhanced immunogenicity of influenza vaccine in a mouse model. We hypothesized that topical imiquimod before intradermal influenza vaccination (TIV) would produce similar effect in human.

METHODS

We performed a prospective 1-year follow-up, double-blind, randomized, controlled trial with adults with comorbidities. Participants were randomized to 1 of the following 3 vaccinations: topical 5% 250 mg imiquimod ointment followed by intradermal TIV, topical aqueous-cream followed by intradermal TIV, or topical aqueous-cream followed by intramuscular TIV. Patients and investigators were blinded to the type of topical treatment applied. Hemagglutination inhibition (HI) and microneutralization antibody titers were measured. The primary outcome was the day 7 seroconversion rate.

RESULTS

Ninety-one recruited participants completed the study. The median age was 73 years. On day 7, 27/30 (90%) patients who received imiquimod and intradermal TIV achieved seroconversion against the H1N1 strain by HI, compared with 4/30 (13.3%) who received aqueous-cream and intramuscular TIV (P < .001), and 12/31 (38.7%) who received aqueous-cream and intradermal TIV (P < .001). The seroconversion, seroprotection, and geometric mean titer-fold increase were met in all 3 strains in the imiquimod and intradermal TIV group 2 weeks earlier, and the better seroconversion rate was sustained from day 7 to year 1 (P ≤ .001). The better immunogenicity was associated with fewer hospitalizations for influenza or pneumonia (P < .05). All adverse reactions were self-limited.

CONCLUSIONS

Pretreatment with topical imiquimod significantly expedited, augmented, and prolonged the immunogenicity of influenza vaccination. This strategy for influenza immunization should be considered for the elderly population.

Control of HPV infection and related cancer through vaccination

Human papillomavirus (HPV), the most common sexually transmitted virus, and its associated diseases continue to cause significant morbidity and mortality in over 600 million infected individuals. Major progress has been made with preventative vaccines, and clinical data have emerged regarding the efficacy and cross-reactivity of the two FDA approved L1 virus like particle (VLP)-based vaccines. However, the cost of the approved vaccines currently limits their widespread use in developing countries which carry the greatest burden of HPV-associated diseases. Furthermore, the licensed preventive HPV vaccines only contain two high-risk types of HPV (HPV-16 and HPV-18) which can protect only up to 75 % of all cervical cancers. Thus, second generation preventative vaccine candidates hope to address the issues of cost and broaden protection through the use of more multivalent L1-VLPs, vaccine formulations, or alternative antigens such as L1 capsomers, L2 capsid proteins, and chimeric VLPs. Preventative vaccines are crucial to controlling the transmission of HPV, but there are already hundreds of millions of infected individuals who have HPV-associated lesions that are silently progressing toward malignancy. This raises the need for therapeutic HPV vaccines that can trigger T cell killing of established HPV lesions, including HPV-transformed tumor cells. In order to stimulate such antitumor immune responses, therapeutic vaccine candidates deliver HPV antigens in vivo by employing various bacterial, viral, protein, peptide, dendritic cell, and DNA-based vectors. This book chapter will review the commercially available preventive vaccines, present second generation candidates, and discuss the progress of developing therapeutic HPV vaccines.

Role of innate immunity against human papillomavirus (HPV) infections and effect of adjuvants in promoting specific immune response

During the early stages of human papillomavirus (HPV) infections, the innate immune system creates a pro-inflammatory microenvironment by recruiting innate immune cells to eliminate the infected cells, initiating an effective acquired immune response. However, HPV exhibits a wide range of strategies for evading immune-surveillance, generating an anti-inflammatory microenvironment. The administration of new adjuvants, such as TLR (Toll-like receptors) agonists and alpha-galactosylceramide, has been demonstrated to reverse the anti-inflammatory microenvironment by down-regulating a number of adhesion molecules and chemo-attractants and activating keratinocytes, dendritic (DC), Langerhans (LC), natural killer (NK) or natural killer T (NKT) cells; thus, promoting a strong specific cytotoxic T cell response. Therefore, these adjuvants show promise for the treatment of HPV generated lesions and may be useful to elucidate the unknown roles of immune cells in the natural history of HPV infection. This review focuses on HPV immune evasion mechanisms and on the proposed response of the innate immune system, suggesting a role for the surrounding pro-inflammatory microenvironment and the NK and NKT cells in the clearance of HPV infections.

Increased expression of programmed death (PD)-1 and its ligand PD-L1 correlates with impaired cell-mediated immunity in high-risk human papillomavirus-related cervical intraepithelial neoplasia

Impaired local cellular immunity contributes to the pathogenesis of persistent high-risk human papillomavirus (HR-HPV) infection and related cervical intraepithelial neoplasia (CIN), but the underlying molecular mechanisms remain unclear. Recently, the programmed death 1/programmed death 1 ligand (PD-1/PD-L1; CD279/CD274) pathway was demonstrated to play a critical role in attenuating T-cell responses and promoting T-cell tolerance during chronic viral infections. In this study, we examined the expression of PD-1 and PD-L1 on cervical T cells and dendritic cells (DCs), respectively, from 40 women who were HR-HPV-negative (-) or HR-HPV-positive (+) with CIN grades 0, I and II-III. We also measured interferon-γ, interleukin-12 (IL-12) and IL-10 in cervical exudates. The most common HPV type was HPV 16, followed by HPV 18, 33, 51 and 58. PD-1 and PD-L1 expression on cervical T cells and DCs, respectively, was associated with HR-HPV positivity and increased in parallel with increasing CIN grade. The opposite pattern was observed for CD80 and CD86 expression on DCs, which decreased in HR-HPV+ patients in parallel with increasing CIN grade. Similarly, reduced levels of the T helper type 1 cytokines interferon-γ and IL-12 and increased levels of the T helper type 2 cytokine IL-10 in cervical exudates correlated with HR-HPV positivity and CIN grade. Our results suggest that up-regulation of the inhibitory PD-1/PD-L1 pathway may negatively regulate cervical cell-mediated immunity to HPV and contribute to the progression of HR-HPV-related CIN. These results may aid in the development of PD-1/PD-L1 pathway-based strategies for immunotherapy of HR-HPV-related CIN.

Toll-like receptors in human papillomavirus infection

Infection with human papillomaviruses (HPVs) often causes cutaneous benign lesions, cervical cancer, and a number of other tumors. The mechanisms of host immune system to prevent and control HPV infection still remain poorly understood. Toll-like receptors (TLRs) are specific pattern recognition molecules that bind to microbial components to trigger innate immunity and direct adaptive immunity in the face of immunological danger. TLRs have been established to play an essential role in sensing and initiating antiviral immune responses. Recent accumulating evidence demonstrated that HPVs modulate TLR expression and interfere with TLR signaling pathways, leading to persistent viral infection and carcinogenesis. This review summarizes current knowledge on the roles of TLR during HPV infection, focusing on TLR recognition, modulation of TLR expression and signaling, regulatory receptors involved in TLR signaling, and cross-talk of TLRs with antimicrobial peptides. Immunotherapeutic strategies based on TLR agonists have emerged to be one of the novel promising avenues in treatment of HPV-associated diseases in the future.

RNA interference for the treatment of papillomavirus disease

Human Papillomavirus (HPV)-induced diseases are a significant burden on our healthcare system and current therapies are not curative. Vaccination provides significant prophylactic protection but effective therapeutic treatments will still be required. RNA interference (RNAi) has great promise in providing highly specific therapies for all HPV diseases yet this promise has not been realised. Here we review the research into RNAi therapy for HPV in vitro and in vivo and examine the various targets and outcomes. We discuss the idea of using RNAi with current treatments and address delivery of RNAi, the major issue holding back clinical adoption. Finally, we present our view of a potential path to the clinic.

Study of the expression of toll-like receptors in different histological types of colorectal polyps and their relationship with colorectal cancer

PURPOSE

Dysregulation of toll-like receptors (TLR) signaling can result in chronic inflammatory and over-exuberant repair responses. The aim of this study was to investigate the expression and clinical relevance of TLR in colorectal polyps.

METHODS

The expression levels of six TLR were analyzed in 70 patients with different histological types of colorectal polyps, 38 of which developed colorectal carcinoma (CC). These analyses were performed by real-time polymerase chain reaction, western blot, and immunohistochemistry.

RESULTS

TLR9 expression was higher in hyperplastic or adenomatous polyps compared to other polyp types. Hyperplastic polyps also showed increased TLR7 levels compared to the other polyp types. TLR7 expression was lower in both hyperplastic and tubulovillous adenoma polyps from patients who developed CC. TLR9 expression was decreased in hyperplastic and villous polyps from patients who developed CC.

CONCLUSIONS

Our findings suggest a possible protective role of TLR expression against malignant transformation in the colorectal mucosa. TLR may represent a pathological marker of CC risk in colorectal polyps. The role of these factors in the pathology of colorectal polyps deserves further investigation.

Imiquimod-induced clearance of HPV is associated with normalization of immune cell counts in usual type vulvar intraepithelial neoplasia

Recently, we reported on the efficacy of imiquimod for treatment of usual type vulvar intraepithelial neoplasia (uVIN). A histologic regression of uVIN to normal tissue was observed in 58% of patients. As success of treatment is related to clearance of high-risk human papilloma virus (HPV), the aim of our study was to assess differences in immune cell counts and in the expression of p16(INK4a) in VIN tissue before and after imiquimod treatment, in relation to HPV clearance and clinical response. Vulvar tissue samples taken prior to imiquimod treatment and 4 weeks after treatment were tested for the presence of HPV. Previously determined immune cell counts (CD1a, CD207, CD208, CD123/CD11c, CD94, CD4, CD8 and CD25/HLA-DR) in epidermis and dermis of 25 VIN patients and 19 healthy controls were completed with the counts for CD14 and CD68. The expression of p16(INK4a) was investigated by immunohistochemistry in 15 patients. Before imiquimod treatment, both HPV cleared and HPV noncleared patients showed mainly in the dermis significantly upregulated immune cell counts compared to healthy controls. However, in patients that cleared HPV and showed histologic regression already 4 weeks after imiquimod treatment, immune cell counts and p16(INK4a) expression were normalized. In conclusion, our data indicate that imiquimod-induced clearance of HPV results in normalization of counts for certain immune cells and is strongly correlated with histologic regression of the disease.

Ubiquitination in host immune response to human papillomavirus infection

Human papillomavirus (HPV) infection with low-risk or high-risk subtypes is very common. Infection with HPVs is often a major causative factor for the development of cutaneous benign lesions, cervical cancer, and a number of other tumors. The mechanisms of host immunity to prevent and control HPV infection still remain unclear. The importance of ubiquitination (or ubiquitylation) as an intracellular proteasomal-mediated protein degradation pathway, and as an important modulator for the regulation of many fundamental cellular processes has been valued over the last decade. Although the molecular and cellular mechanisms are not completely established, the critical role of ubiquitination in host immune response to HPV infection has become increasingly apparent. This review summarizes current knowledge on the possible role that ubiquitination plays in regulating the host immune response during HPV infection. Targeting the components of the ubiquitin system might offer potential therapeutic strategies for HPV-related diseases in the future.