Tumor necrosis factor alpha and interleukin-6 facilitate corneal lymphangiogenesis in response to herpes simplex virus 1 infection

Chemical (Alkali) Burn-Induced Neurotrophic Keratitis Model in New Zealand Rabbit Investigated Using Medical Clinical Readouts and In Vivo Confocal Microscopy (IVCM)

PURPOSE

Chemical eye injury is an acute emergency that can result in vision loss. Neurotrophic keratitis (NK) is the most common long-term manifestation of chemical injury. NK due to alkali burn affects ocular surface health and is one of its most common causes. Here, we established a rabbit model of corneal alkali burns to evaluate the severity of NK-associated changes.

MATERIAL METHODS

Alkali burns were induced in NZ rabbits by treating the cornea with (i) a 5 mm circular filter paper soaked in 0.75 N NaOH for 10 s (Mild NK) and (ii) trephination using a guarded trephine (5 mm diameter and 150-micron depth), followed by alkali burn, with a 5 mm circular filter paper soaked in 0.75 N NaOH for 10 s (a severe form of NK). Immediately after, the cornea was rinsed with 10 mL of normal saline to remove traces of NaOH. Clinical features were evaluated on Day 0, Day 1, Day 7, Day 15, and Day 21 post-alkali burn using a slit lamp, Pentacam, and anterior segment optical coherence tomography (AS-OCT). NK-like changes in epithelium, sub-basal nerve plexus, and stroma were observed using in vivo confocal microscopy (IVCM), and corneal sensation were measured using an aesthesiometer post alkali injury. After 21 days, pro-inflammatory cytokines were evaluated for inflammation through ELISA.

RESULTS

Trephination followed by alkali burn resulted in the loss of epithelial layers (manifested using fluorescein stain), extensive edema, and increased corneal thickness (550 µm compared to 380 µm thickness of control) evaluated through AS-OCT and increased opacity score in alkali-treated rabbit (80 compared to 16 controls). IVCM images showed complete loss of nerve fibers, which failed to regenerate over 30 days, and loss of corneal sensation-conditions associated with NK. Cytokines evaluation of IL6, VEGF, and MMP9 indicated an increased angiogenic and pro-inflammatory milieu compared to the milder form of NK and the control.

DISCUSSION

Using clinical parameters, we demonstrated that the alkali-treated rabbit model depicts features of NK. Using IVCM in the NaOH burn animal model, we demonstrated a complete loss of nerve fibers with poor self-healing capability associated with sub-basal nerve degeneration and compromised corneal sensation. This pre-clinical rabbit model has implications for future pre-clinical research in neurotrophic keratitis.

Transcriptional profiling specifies the pathogen-specific human host response to infectious keratitis

Purpose

Corneal infections are a leading cause of visual impairment and blindness worldwide. Here we applied high-resolution transcriptomic profiling to assess the general and pathogen-specific molecular and cellular mechanisms during human corneal infection.

Methods

Clinical diagnoses of herpes simplex virus (HSV) (n=5) and bacterial/fungal (n=5) keratitis were confirmed by histology. Healthy corneas (n=7) and keratoconus (n=4) samples served as controls. Formalin-fixed, paraffin-embedded (FFPE) human corneal specimens were analyzed using the 3' RNA sequencing method Massive Analysis of cDNA Ends (MACE RNA-seq). The cellular host response was investigated using comprehensive bioinformatic deconvolution (xCell and CYBERSORTx) analyses and by integration with published single cell RNA-seq data of the human cornea.

Results

Our analysis identified 216 and 561 genes, that were specifically overexpressed in viral or bacterial/fungal keratitis, respectively, and allowed to distinguish the two etiologies. The virus-specific host response was driven by adaptive immunity and associated molecular signaling pathways, whereas the bacterial/fungal-specific host response mainly involved innate immunity signaling pathways and cell types. We identified several genes and pathways involved in the host response to infectious keratitis, including CXCL9, CXCR3, and MMP9 for viral, and S100A8/A9, MMP9, and the IL17 pathway for bacterial/fungal keratitis.

Conclusions

High-resolution molecular profiling provides new insights into the human corneal host response to viral and bacterial/fungal infection. Pathogen-specific molecular profiles may provide the foundation for novel diagnostic biomarker and therapeutic approaches that target inflammation-induced damage to corneal host cells with the goal to improve the outcome of infectious keratitis.

The novel role of lymphatic vessels in the pathogenesis of ocular diseases

Historically, the eye has been considered as an organ free of lymphatic vessels. In recent years, however, it became evident, that lymphatic vessels or lymphatic-like vessels contribute to several ocular pathologies at various peri- and intraocular locations. The aim of this review is to outline the pathogenetic role of ocular lymphatics, the respective molecular mechanisms and to discuss current and future therapeutic options based thereon. We will give an overview on the vascular anatomy of the healthy ocular surface and the molecular mechanisms contributing to corneal (lymph)angiogenic privilege. In addition, we present (i) current insights into the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea triggered e.g. by inflammation or trauma, (ii) the role of lymphatic vessels in different ocular surface pathologies such as dry eye disease, corneal graft rejection, ocular graft versus host disease, allergy, and pterygium, (iii) the involvement of lymphatic vessels in ocular tumors and metastasis, and (iv) the novel role of the lymphatic-like structure of Schlemm's canal in glaucoma. Identification of the underlying molecular mechanisms and of novel modulators of lymphangiogenesis will contribute to the development of new therapeutic targets for the treatment of ocular diseases associated with pathological lymphangiogenesis in the future. The preclinical data presented here outline novel therapeutic concepts for promoting transplant survival, inhibiting metastasis of ocular tumors, reducing inflammation of the ocular surface, and treating glaucoma. Initial data from clinical trials suggest first success of novel treatment strategies to promote transplant survival based on pretransplant corneal lymphangioregression.

A Pilot Study to Evaluate Genipin in Staphylococcus aureus and Pseudomonas aeruginosa Keratitis Models: Modulation of Pro-Inflammatory Cytokines and Matrix Metalloproteinases

Infectious keratitis is a vision-threatening microbial infection. The increasing antimicrobial resistance and the fact that severe cases often evolve into corneal perforation necessitate the development of alternative therapeutics for effective medical management. Genipin, a natural crosslinker, was recently shown to exert antimicrobial effects in an ex vivo model of microbial keratitis, highlighting its potential to serve as a novel treatment for infectious keratitis. This study aimed to evaluate the antimicrobial and anti-inflammatory effects of genipin in an in vivo model of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) keratitis. Clinical scores, confocal microscopy, plate count, and histology were carried out to evaluate the severity of keratitis. To assess the effect of genipin on inflammation, the gene expression of pro- and anti-inflammatory factors, including matrix metalloproteinases (MMPs), were evaluated. Genipin treatment alleviated the severity of bacterial keratitis by reducing bacterial load and repressing neutrophil infiltration. The expression of interleukin 1B (IL1B), interleukin 6 (IL6), interleukin 8 (IL8), interleukin 15 (IL15), tumor necrosis factor-α (TNF-α), and interferon γ (IFNγ), as well as MMP2 and MMP9, were significantly reduced in genipin-treated corneas. Genipin promoted corneal proteolysis and host resistance to S. aureus and P. aeruginosa infection by suppressing inflammatory cell infiltration, regulating inflammatory mediators, and downregulating the expression of MMP2 and MMP9.

Host-microbe interactions in cornea

Corneal infections result through interaction between microbes and host innate immune receptors. Damage to the cornea occurs as a result of microbial virulence factors and is often exacerbated by lack of a controlled host immune response; the latter contributing to bystander damage to corneal structure. Understanding mechanisms involved in host microbial interactions is critical to development of novel therapeutic targets, ultimate control of microbial pathogenesis, and restoration of tissue homeostasis. Studies on these interactions continue to provide exciting findings directly related to this ultimate goal.

Lymphatic vessels in bone support regeneration after injury

Blood and lymphatic vessels form a versatile transport network and provide inductive signals to regulate tissue-specific functions. Blood vessels in bone regulate osteogenesis and hematopoiesis, but current dogma suggests that bone lacks lymphatic vessels. Here, by combining high-resolution light-sheet imaging and cell-specific mouse genetics, we demonstrate presence of lymphatic vessels in mouse and human bones. We find that lymphatic vessels in bone expand during genotoxic stress. VEGF-C/VEGFR-3 signaling and genotoxic stress-induced IL6 drive lymphangiogenesis in bones. During lymphangiogenesis, secretion of CXCL12 from proliferating lymphatic endothelial cells is critical for hematopoietic and bone regeneration. Moreover, lymphangiocrine CXCL12 triggers expansion of mature Myh11+ CXCR4+ pericytes, which differentiate into bone cells and contribute to bone and hematopoietic regeneration. In aged animals, such expansion of lymphatic vessels and Myh11-positive cells in response to genotoxic stress is impaired. These data suggest lymphangiogenesis as a therapeutic avenue to stimulate hematopoietic and bone regeneration.

Osteopontin contributes to virus resistance associated with type I IFN expression, activation of downstream ifn-inducible effector genes, and CCR2+CD115+CD206+ macrophage infiltration following ocular HSV-1 infection of mice

Ocular pathology is often associated with acute herpes simplex virus (HSV)-1 infection of the cornea in mice. The present study was undertaken to determine the role of early T lymphocyte activation 1 protein or osteopontin (OPN) in corneal inflammation and host resistance to ocular HSV-1 infection. C57BL/6 wild type (WT) and osteopontin deficient (OPN KO) mice infected in the cornea with HSV-1 were evaluated for susceptibility to infection and cornea pathology. OPN KO mice were found to possess significantly more infectious virus in the cornea at day 3 and day 7 post infection compared to infected WT mice. Coupled with these findings, HSV-1-infected OPN KO mouse corneas were found to express less interferon (IFN)-α1, double-stranded RNA-dependent protein kinase, and RNase L compared to infected WT animals early post infection that likely contributed to decreased resistance. Notably, OPN KO mice displayed significantly less corneal opacity and neovascularization compared to WT mice that paralleled a decrease in expression of vascular endothelial growth factor (VEGF) A within 12 hr post infection. The change in corneal pathology of the OPN KO mice aligned with a decrease in total leukocyte infiltration into the cornea and specifically, in neutrophils at day 3 post infection and in macrophage subpopulations including CCR2+CD115+CD206+ and CD115+CD183+CD206+ -expressing cells. The infiltration of CD4+ and CD8+ T cells into the cornea was unaltered comparing infected WT to OPN KO mice. Likewise, there was no difference in the total number of HSV-1-specific CD4+ or CD8+ T cells found in the draining lymph node with both sets functionally competent in response to virus antigen comparing WT to OPN KO mice. Collectively, these results demonstrate OPN deficiency directly influences the host innate immune response to ocular HSV-1 infection reducing some aspects of inflammation but at a cost with an increase in local HSV-1 replication.

Pathogenesis and virulence of herpes simplex virus

Two of the most prevalent human viruses worldwide, herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2, respectively), cause a variety of diseases, including cold sores, genital herpes, herpes stromal keratitis, meningitis and encephalitis. The intrinsic, innate and adaptive immune responses are key to control HSV, and the virus has developed mechanisms to evade them. The immune response can also contribute to pathogenesis, as observed in stromal keratitis and encephalitis. The fact that certain individuals are more prone than others to suffer severe disease upon HSV infection can be partially explained by the existence of genetic polymorphisms in humans. Like all herpesviruses, HSV has two replication cycles: lytic and latent. During lytic replication HSV produces infectious viral particles to infect other cells and organisms, while during latency there is limited gene expression and lack of infectious virus particles. HSV establishes latency in neurons and can cause disease both during primary infection and upon reactivation. The mechanisms leading to latency and reactivation and which are the viral and host factors controlling these processes are not completely understood. Here we review the HSV life cycle, the interaction of HSV with the immune system and three of the best-studied pathologies: Herpes stromal keratitis, herpes simplex encephalitis and genital herpes. We also discuss the potential association between HSV-1 infection and Alzheimer's disease.

Polymicrobial Keratitis: Risk Factors, Clinical Characteristics, Bacterial Profile, and Antimicrobial Resistance

OBJECTIVE

To describe clinical characteristics, complications, and the most prevalent microorganisms causing polymicrobial keratitis and their antibiotic sensitivities.

METHODS

A cross-sectional study including a consecutive analysis of patient's records with a diagnosis of bacterial keratitis with a positive culture and antibiogram report were included. Patients were grouped into those having monomicrobial and polymicrobial infection. Features studied included demographic and clinical characteristics, risk factors, Gram stain, cultures, and antibiotic sensitivity.

RESULTS

We included 656 patients; in 31.5% more than one microorganism was found. Seven hundred and twenty-three gram-positive bacteria were isolated, and 336 (46.5%) had polymicrobial keratitis. One hundred sixty-one gram-negative bacteria were isolated, and 99 (61.5%) from polymicrobial keratitis. Fourteen (0.60%) patients presented ring infiltrate, and 10 (71.42%) of those patients had polymicrobial keratitis (X2 10.654, P=0.001). Multivariate analysis showed that patients with history of contact lens use (odds ratio [OR] of 1.78, P=0.042), coexistent autoimmune disease (OR 4.64, P=0.03), irregular edges of the infiltrate (OR 2.06, P=0.005), and ring infiltrate (OR 6.034, P=0.005) have a higher risk for developing polymicrobial infection. In the polymicrobial group, gram-positive and gram-negative organisms showed a high sensitivity to Netilmicin.

CONCLUSIONS

We found a high incidence of polymicrobial keratitis. Our results suggest that it should be suspected in patients with a history of contact lens use, coexistent autoimmune disease, infiltrates with indistinct edges, and ring infiltrates. Sensitivities to moxifloxacin are lower than those reported in previous studies, but sensitivity to Netilmicin is higher.

An intact complement system dampens cornea inflammation during acute primary HSV-1 infection

Corneal transparency is an essential characteristic necessary for normal vision. In response to microbial infection, the integrity of the cornea can become compromised as a result of the inflammatory response and the ensuing tissue pathology including neovascularization (NV) and collagen lamellae destruction. We have previously found complement activation contributes to cornea pathology-specifically, denervation in response to HSV-1 infection. Therefore, we investigated whether the complement system also played a role in HSV-1-mediated neovascularization. Using wild type (WT) and complement component 3 deficient (C3 KO) mice infected with HSV-1, we found corneal NV was accelerated associated with an increase in inflammatory monocytes (CD11b⁺CCR2⁺CD115^+/-Ly6G^-Ly6C^high), macrophages (CD11b⁺CCR2⁺CD115⁺Ly6G^-Ly6C^high) and a subpopulation of granulocytes/neutrophils (CD11b⁺CCR2^-CD115⁺Ly6G⁺Ly6C^low). There were also increases in select pro-inflammatory and pro-angiogenic factors including IL-1α, matrix metalloproteinases (MMP)-2, MMP-3, MMP-8, CXCL1, CCL2, and VEGF-A that coincided with increased inflammation, neovascularization, and corneal opacity in the C3 KO mice. The difference in inflammation between WT and C3 KO mice was not driven by changes in virus titer. However, viral antigen clearance was hindered in C3 KO mouse corneas suggesting the complement system has a dynamic regulatory role within the cornea once an inflammatory cascade is initiated by HSV-1.

Polluted Air Exposure Compromises Corneal Immunity and Exacerbates Inflammation in Acute Herpes Simplex Keratitis

Air pollution is a serious environmental issue worldwide in developing countries’ megacities, affecting the population’s health, including the ocular surface, by predisposing or exacerbating other ocular diseases. Herpes simplex keratitis (HSK) is caused by the herpes simplex virus type 1 (HSV-1). The primary or recurring infection in the ocular site causes progressive corneal scarring that may result in visual impairment. The present study was designed to study the immunopathological changes of acute HSK under urban polluted air, using the acute HSK model combined with an experimental urban polluted air exposure from Buenos Aires City. We evaluated the corneal clinical outcomes, viral DNA and pro-inflammatory cytokines by RT-PCR and ELISA assays, respectively. Then, we determined the innate and adaptive immune responses in both cornea and local lymph nodes after HSV-1 corneal by immunofluorescence staining and flow cytometry. Our results showed that mice exposed to polluted air develop a severe form of HSK with increased corneal opacity, neovascularization, HSV-1 DNA and production of TNF-α, IL-1β, IFN-γ, and CCL2. A high number of corneal resident immune cells, including activated dendritic cells, was observed in mice exposed to polluted air; with a further significant influx of bone marrow-derived cells including GR1+ cells (neutrophils and inflammatory monocytes), CD11c+ cells (dendritic cells), and CD3+ (T cells) during acute corneal HSK. Moreover, mice exposed to polluted air showed a predominant Th1 type T cell response over Tregs in local lymph nodes during acute HSK with decreased corneal Tregs. These findings provide strong evidence that urban polluted air might trigger a local imbalance of innate and adaptive immune responses that exacerbate HSK severity. Taking this study into account, urban air pollution should be considered a key factor in developing ocular inflammatory diseases.

Comparative Analysis of Tear Proteins in Keratoconic Scleral Lens Wearers with Variation in Limbal Clearance

SIGNIFICANCE

Cytokine and protease analysis revealed relative changes in the post-lens tear film of scleral lenses with low and high limbal clearances. Results from this study indicate that midperipheral lens fit is an important fitting feature that can impact the inflammatory response of a keratoconic eye.

PURPOSE

The purpose of this study was to investigate changes in levels of inflammatory mediators in the post-lens tear film of keratoconic scleral lens wearers with varying limbal clearance designs.

METHODS

Twenty-two keratoconic eyes were fitted with two sets of scleral lenses that were consistent in lens diameter and central sagittal depth but varied in limbal clearance by approximately 50 μm. Lenses were worn in a randomly assigned order for a 2-week period each. At each follow-up visit, immediately after lens removal, tear samples were collected with a microcapillary tube (10 μL, 0.5 mm in diameter) from the bowl of the inverted scleral lens. Tear cytokine and protease analysis was performed using a multiplex electrochemiluminescent array (Meso Scale Discovery, Rockville, MD) instrument. Levels of interleukins 1, 6, and 8; tumor necrosis factor α; and matrix metalloproteinases 1 and 9 were compared and analyzed.

RESULTS

Levels of interleukin 1β, tumor necrosis factor α, and matrix metalloproteinase 1 increased with high limbal clearance (P = .01, .006, and .02, respectively). No change in interleukins 6 and 8 levels was found (P > .05). A decrease in matrix metalloproteinase 9 was noted in post-lens tear film of scleral lenses with high limbal clearance (P = .10).

DISCUSSION

Relative changes in the cytokine and protease levels were found when comparing low and high limbal clearance, indicating that the midperipheral lens fit is an important feature that can impact the inflammatory response of the keratoconic eye.

Herpes Simplex Virus 1 (HSV-1) 0ΔNLS Live-Attenuated Vaccine Protects against Ocular HSV-1 Infection in the Absence of Neutralizing Antibody in HSV-1 gB T Cell Receptor-Specific Transgenic Mice

The contribution of T cell and antibody responses following vaccination in resistance to herpes simplex virus 1 (HSV-1) infection continues to be rigorously investigated. In the present article, we explore the contribution of CD8+ T cells specific for the major antigenic epitope for HSV-1 glycoprotein B (gB498-505, gB) in C57BL/6 mice using a transgenic mouse (gBT-I.1) model vaccinated with HSV-1 0ΔNLS. gBT-I.1-vaccinated mice did not generate a robust neutralization antibody titer in comparison to the HSV-1 0ΔNLS-vaccinated wild-type C57BL/6 counterpart. Nevertheless, the vaccinated gBT-I.1 mice were resistant to ocular challenge with HSV-1 compared to vehicle-vaccinated animals based on survival and reduced corneal neovascularization but displayed similar levels of corneal opacity. Whereas there was no difference in the virus titer recovered from the cornea comparing vaccinated mice, HSV-1 0ΔNLS-vaccinated animals possessed significantly less infectious virus during acute infection in the trigeminal ganglia (TG) and brain stem compared to the control-vaccinated group. These results correlated with a significant increase in gB-elicited interferon-γ (IFN-γ), granzyme B, and CD107a and a reduction in lymphocyte activation gene 3 (LAG-3), programmed cell death 1 (PD-1), and T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) expressed by TG infiltrating gB-specific CD8+ T cells from the HSV-1 0ΔNLS-vaccinated group. Antibody depletion of CD8+ T cells in HSV-1 0ΔNLS-vaccinated mice rendered animals highly susceptible to virus-mediated mortality similar to control-vaccinated mice. Collectively, the HSV-1 0ΔNLS vaccine is effective against ocular HSV-1 challenge, reducing ocular neovascularization and suppressing peripheral nerve virus replication in the near absence of neutralizing antibody in this unique mouse model.IMPORTANCE The role of CD8+ T cells in antiviral efficacy using a live-attenuated virus as the vaccine is complicated by the humoral immune response. In the case of the herpes simplex virus 1 (HSV-1) 0ΔNLS vaccine, the correlate of protection has been defined to be primarily antibody driven. The current study shows that in the near absence of anti-HSV-1 antibody, vaccinated mice are protected from subsequent challenge with wild-type HSV-1 as measured by survival. The efficacy is lost following depletion of CD8+ T cells. Whereas increased survival and reduction in virus replication were observed in vaccinated mice challenged with HSV-1, cornea pathology was mixed with a reduction in neovascularization but no change in opacity. Collectively, the study suggests CD8+ T cells significantly contribute to the host adaptive immune response to HSV-1 challenge following vaccination with an attenuated virus, but multiple factors are involved in cornea pathology in response to ocular virus challenge.

Comparative analysis of the tear protein profile in herpes simplex virus type 1 epithelial keratitis

BACKGROUND

Herpes simplex virus type 1 (HSV-1) keratitis is a major cause of corneal blindness in the world, and an in-depth understanding of its pathogenesis may help improve existing diagnosis and treatment. The purpose of this study is to compare and analysis the total tear protein profile of HSV-1 epithelial keratitis patients, and to quantify the potential candidate biomarkers of HSV-1 epithelial keratitis.

METHODS

We investigated the proteome in tear fluid from three HSV-1 epithelial keratitis patients and three healthy control subjects using nano-scale liquid chromatography-tandem mass spectrometry (nLC-MS/MS) analysis. Functional annotation of differentially expressed proteins was done with the Gene Ontology (GO) analysis. ELISA was done to quantify the potential candidate biomarkers in 26 clinical cases.

RESULTS

Tear fluid from three HSV-1 epithelial keratitis patients and three healthy control subjects contained a total of 1275 proteins and 326 proteins were unique to tear fluid of HSV-1 epithelial keratitis patients. Bioinformatics analysis revealed that tear proteins from HSV-1 epithelial keratitis patients may be involved in metabolic processes, antigen presentation, inflammatory response, and in the TNF-mediated and T cell receptor pathways. Furthermore, IL1A, IL12B, DEFB4A, and CAMP, which are associated with the inflammatory response and inhibition of viral infection, were significantly more abundant in the HSV-1 epithelial keratitis patients than in the healthy control subjects.

CONCLUSIONS

This study reports the proteomic profile of tears in HSV-1 epithelial keratitis for the first time and identifies a number of unique differentially expressed proteins.

Loss of Osteopontin Expression Reduces HSV-1-Induced Corneal Opacity

Purpose

Corneal opacity and neovascularization (NV) are often described as outcomes of severe herpes simplex virus type 1 (HSV-1) infection. The current study investigated the role of colony-stimulating factor 1 receptor (CSF1R)+ cells and soluble factors in the progression of HSV-1-induced corneal NV and opacity.

Methods

MaFIA mice were infected with 500 plaque-forming units of HSV-1 in the cornea following scarification. From day 10 to day 13 post-infection (pi), mice were treated with 40 µg/day of AP20187 (macrophage ablation) or vehicle intraperitoneally. For osteopontin (OPN) neutralization experiments, C57BL/6 mice were infected as above and treated with 2 µg of goat anti-mouse OPN or isotypic control IgG subconjunctivally every 2 days from day 4 to day 12 pi. Mice were euthanized on day 14 pi, and tissue was processed for immunohistochemistry to quantify NV and opacity by confocal microscopy and absorbance or detection of pro- and anti-angiogenic and inflammatory factors and cells by suspension array analysis and flow cytometry, respectively.

Results

In the absence of CSF1R+ cells, HSV-1-induced blood and lymphatic vessel growth was muted. These results correlated with a loss in fibroblast growth factor type 2 (FGF-2) and an increase in OPN expression in the infected cornea. However, a reduction in OPN expression in mice did not alter corneal NV but significantly reduced opacity.

Conclusions

Our data suggest that CSF1R+ cell depletion results in a significant reduction in HSV-1-induced corneal NV that correlates with the loss of FGF-2 expression. A reduction in OPN expression was aligned with a significant drop in opacity associated with reduced corneal collagen disruption.

Cathelicidin bovine myeloid antimicrobial peptide (BMAP) 28 is involved in the inflammatory response against alpha-herpesviruses in the bovine nervous system

The role of the local innate immune response in the neuropathogenesis of bovine herpesvirus (BoHV) type 1 and 5 remains largely unknown. This study determined the gene transcriptional expression of relevant bovine cathelicidins, TNFα and IFNβ in the nervous system of experimentally-infected cattle during the different stages of BoHV-1 and BoHV-5 infectious cycle. We studied the modulation of bovine myeloid antimicrobial peptide (BMAP) 27 and 28 by alpha-herpesviruses during acute infection of the central nervous system (CNS). However, BMAP28 was the main cathelicidin modulated. BoHV-5 supressed BMAP28 expression mainly in frontal cortex and cervical medulla whereas BoHV-1 slightly induced the expression of cathelicidins in the olfactory and posterior cortex. The differences in the regulation of the innate response are likely related to distinct replication rates of both alpha-herpesviruses in the CNS. During latency and reactivation, BoHV-1 and -5 decreased BMAP28 and BMAP27 expression, accompanied by high levels of TNFα and IFNβ transcripts in the posterior brain region and medulla during BoHV reactivation. In terms of cytokines, a remarkably overexpression of IFNβ was induced by BoHV-5 (133.8-fold). In trigeminal ganglion (TG) both alpha-herpesviruses induced cathelidicins gene expression at all stages of the infection cycle, while only acute BoHV-5 infection increased TNFα (129-fold) mRNA levels. This study suggests that the pronounced downregulation of BMAP28 in BoHV-5-acutely-infected CNS is due to a decreased immune stimulation during viral infection, favouring its establishment in the CNS with a low replication rate until latency. Thus, cathelicidins, together with IFNβ and TNFα, are differentially regulated by BoHV-5 and BoHV-1 infections and this regulation is dependent on the stage of virus infection in the bovine nervous system.

Pathogenesis of herpes simplex keratitis: The host cell response and ocular surface sequelae to infection and inflammation

Herpes simplex virus type 1 (HSV) keratitis is a leading cause of infectious blindness. Clinical disease occurs variably throughout the cornea from epithelium to endothelium and recurrent HSV stromal keratitis is associated with corneal scarring and neovascularization. HSV keratitis can be associated with ocular pain and subsequent neutrophic keratopathy. Host cell interactions with HSV trigger an inflammatory cascade responsible not only for clearance of virus but also for progressive corneal opacification due to inflammatory cell infiltrate, angiogenesis, and corneal nerve loss. Current antiviral therapies target viral replication to decrease disease duration, severity and recurrence, but there are limitations to these agents. Therapies directed towards viral entry into cells, protein synthesis, inflammatory cytokines and vascular endothelial growth factor pathways in animal models represent promising new approaches to the treatment of recurrent HSV keratitis.

Autophagy Quantification and STAT3 Expression in a Human Skin Organ Culture Model for Innate Immunity to Herpes Zoster

The goal of this project was to document the autophagy response in human neonatal skin organ culture (SOC) after infection with varicella-zoster virus (VZV). The VZV-infected SOC model has attributes of herpes zoster, in that an injection of virus into the skin is analogous to exit of virus from the sensory nerve termini into skin during herpes zoster. Cultures were maintained for 28 days and periodically examined for an autophagy response by quantitation of autophagosomes with Imaris software. Expression of the STAT3 protein was plentiful in the VZV-infected SOC. Abundant autophagy was observed in VZV-infected SOC between 14 and 28 days after infection, while autophagy in mock-infected SOC was minimal (p = 0.0003). The autophagic response after infection of SOC with a recombinant VZV genome containing the herpes simplex virus ICP34.5 neurovirulence gene was similar to wild-type VZV (p = 0.3). These results suggested that the VZV-infected SOC system resembled biopsy data from herpes zoster infection of skin. An enhanced autophagy response has now been reported after infection with two additional alpha herpesviruses besides VZV, namely, pseudorabies virus and duck enteritis herpes virus; both lack the ICP34.5 protein.

Tyrosinase Is a Novel Endogenous Regulator of Developmental and Inflammatory Lymphangiogenesis

Lymphangiogenesis is critically involved in tissue fluid balance, graft rejection, and tumor metastasis. Endogenous regulation of lymphangiogenesis is poorly understood. Herein, we use the lymphatic vessel architecture at the limbal border of the normally avascular cornea, a quantitative trait under strong genetic influence, as a model system to identify new candidate genes regulating lymphangiogenesis. Comparing low-lymphangiogenic BALB/cN with high-lymphangiogenic C57BL/6N mice, we performed quantitative trait loci analysis of five phenotypes in a large BALB/cN × C57BL/6N intercross (n = 795) and identified three to eight genome-wide significant loci, the strongest on chromosome 7 containing tyrosinase (Tyr). Tyrosinase-negative mice showed significantly increased limbal lymph vascularized areas, a higher number of lymphatic vessel end points, and branching points and increased inflammation-induced lymphangiogenesis. These findings confirm that tyrosinase is a novel lymphangiogenesis regulator in developmental and inflammatory lymphangiogenesis. Our findings link melanin synthesis with lymphangiogenesis and open new treatment options in lymphangiogenesis-related diseases.

Insights into the pathogenesis of herpes simplex encephalitis from mouse models

A majority of the world population is infected with herpes simplex viruses (HSV; human herpesvirus types 1 and 2). These viruses, perhaps best known for their manifestation in the genital or oral mucosa, can also cause herpes simplex encephalitis, a severe and often fatal disease of the central nervous system. Antiviral therapies for HSV are only partially effective since the virus can establish latent infections in neurons, and severe pathological sequelae in the brain are common. A better understanding of disease pathogenesis is required to develop new strategies against herpes simplex encephalitis, including the precise viral and host genetic determinants that promote virus invasion into the central nervous system and its associated immunopathology. Here we review the current understanding of herpes simplex encephalitis from the host genome perspective, which has been illuminated by groundbreaking work on rare herpes simplex encephalitis patients together with mechanistic insight from single-gene mouse models of disease. A complex picture has emerged, whereby innate type I interferon-mediated antiviral signaling is a central pathway to control viral replication, and the regulation of immunopathology and the balance between apoptosis and autophagy are critical to disease severity in the central nervous system. The lessons learned from mouse studies inform us on fundamental defense mechanisms at the interface of host–pathogen interactions within the central nervous system, as well as possible rationales for intervention against infections from severe neuropathogenic viruses.

Transcriptional Profile and Integrative Analyses of Long Noncoding RNAs in Primary Human Corneal Epithelial Cells in Response to HSV-1 Infection

PURPOSE

Long noncoding RNAs (lncRNAs) have been demonstrated to have important regulatory functions in diverse cellular processes; however, the role of lncRNAs in the pathogenesis of herpes simplex keratitis (HSK) remains poorly understood.

METHODS

Primary human corneal epithelial cells (HCECs) were infected with herpes simplex virus-1 (HSV-1) and the total RNAs extracted from both the infected group and the mock-infected group subjected to microarray analysis to identify the differential expression of lncRNAs and mRNAs. We also performed bioinformatic analysis including gene ontology (GO) analysis, pathway analysis and co-expression network analysis.

RESULTS

Compared with mock-infected group, the expression of thousands of lncRNAs and mRNAs were significantly changed, and the microarray results were validated by qRT-PCR. The most enriched GOs targeted by up-regulated transcripts were defense response, intrinsic component of plasma membrane and cytokine activity，and the most enriched GOs targeted by the down-regulated transcripts were cellular metabolic process, intracellular part and poly (A) RNA binding. Pathway analysis indicated that the most correlated pathways for up- and down-regulated transcripts were cytokine-cytokine receptor interaction and RNA transport, respectively.

CONCLUSIONS

Our study identified the genome-wide profile of lncRNAs and mRNAs expression in primary corneal epithelial cells with HSV-1 infection. These transcriptomic data together with subsequent bioinformatic analysis will provide us with novel clue to the insight into molecular mechanism and potential therapeutic targets of HSK. Further studies are expected to verify the potentially functional genes and pathways and explore the critical lncRNAs.

ABBREVIATIONS

Long noncoding RNAs: lncRNAs; herpes simplex virus-1: HSV-1; herpes simplex virus keratitis: HSK; human corneal epithelial cells: HCECs.

Cooperative Effects of Vascular Angiogenesis and Lymphangiogenesis

In this study, we modeled lymphangiogenesis and vascular angiogenesis in a microdevice using a tissue engineering approach. Lymphatic vessels (LV) and blood vessels (BV) were fabricated by sacrificial molding with seeding human lymphatic endothelial cells and human umbilical vein endothelial cells into molded microchannels (600 μm diameter). During subsequent perfusion culture, lymphangiogenesis and vascular angiogenesis were induced by addition of phorbol 12-myristate 13-acetate (PMA) and VEGF-C or VEGF-A characterized by podoplanin and Prox-1 expression. The lymphatic capillaries formed button-like junctions treated with dexamethasone. To test the potential for screening anti-angiogenic (vascular and lymphatic) factors, antagonists of VEGF were introduced. We found that an inhibitor of VEGF-R3 did not completely suppress lymphatic angiogenesis with BVs present, although lymphatic angiogenesis was selectively prevented by addition of a VEGF-R3 inhibitor without BVs. To probe the mechanism of action, we focus on matrix metalloproteinase (MMP) secretion by vascular endothelial cells and lymphatic endothelial cells under monoculture or co-culture conditions. We found that vascular angiogenesis facilitated lymphangiogenesis via remodeling of the local microenvironment by the increased secretion of MMP, mainly by endothelial cells. Applications of this model include a drug screening assay for corneal disease and models for tumorigenesis including lymphatic angiogenesis and vascular angiogenesis.

Application of our understanding of pathogenesis of herpetic stromal keratitis for novel therapy

HSV-1 ocular infection can cause herpes stromal keratitis (SK), an immunopathological lesion. Frequent recurrences can lead to progressive corneal scaring which can result in vision impairment if left untreated. Currently, the acute and epithelial forms of SK are usually controlled using anti-viral drugs. However, chronic forms of SK which are inflammatory in nature, require the addition of a topical corticosteroid to the anti-viral treatment regimen. In this review, we highlight the essential events involved in SK pathogenesis which can be targeted for improved therapy. We also examine some approaches which can be combined with the current treatments to effectively control SK.

Fibroblast growth factor-2 drives and maintains progressive corneal neovascularization following HSV-1 infection

Herpes simplex virus type 1 (HSV-1) infection of the cornea induces vascular endothelial growth factor A (VEGF-A)-dependent lymphangiogenesis that continues to develop well beyond the resolution of infection. Inflammatory leukocytes infiltrate the cornea and have been implicated to be essential for corneal neovascularization, an important clinically relevant manifestation of stromal keratitis. Here we report that cornea infiltrating leukocytes including neutrophils and T cells do not have a significant role in corneal neovascularization past virus clearance. Antibody-mediated depletion of these cells did not impact lymphatic or blood vessel genesis. Multiple pro-angiogenic factors including IL-6, angiopoietin-2, hepatocyte growth factor, fibroblast growth factor-2 (FGF-2), VEGF-A, and matrix metalloproteinase-9 were expressed within the cornea following virus clearance. A single bolus of dexamethasone at day 10 post infection (pi) resulted in suppression of blood vessel genesis and regression of lymphatic vessels at day 21 pi compared to control-treated mice. Whereas IL-6 neutralization had a modest impact on hemangiogenesis (days 14-21 pi) and lymphangiogenesis (day 21 pi) in a time-dependent fashion, neutralization of FGF-2 had a more pronounced effect on the suppression of neovascularization (blood and lymphatic vessels) in a time-dependent, leukocyte-independent manner. Furthermore, FGF-2 neutralization suppressed the expression of all pro-angiogenic factors measured and preserved visual acuity.

Downregulation of Interferon-β and Inhibition of TLR3 Expression are associated with Fatal Outcome of Severe Fever with Thrombocytopenia Syndrome

Severe Fever with Thrombocytopenia Syndrome (SFTS) is an emerging infectious disease with high mortality and increasing prevalence in the East Asia. Though the etiological agent has been identified as a novel Bunyavirus, cellular mechanisms of viral pathogenesis and host immune response to SFTS virus infection remain unknown. A comprehensive study was conducted on a cohort of 70 patients on clinical manifestations, viral loads, modulation of cytokines, serum interferon level, immune related gene expression in peripheral blood cells, and dynamic changes of circulating dendritic cells during the acute phase of SFTSV infection. We found that high level viremia, reduced platelets, coagulation dysfunction, multi-organ injuries, elevated IL-6 and TNF-α were closely associated with the aggravation of SFTS. In addition, we demonstrated strong correlations between disease severity and the decline of serum IFN-β and IL-1β level, reduction of myeloid dendritic cells (mDCs) and suppressed Toll like receptor 3 expression in monocytes and mDCs. In general, dysfunction of innate immune response and cytokine storm are both involved in the pathogenesis of SFTS. Reduction of myeloid DCs contributes to the fatal outcome of SFTS virus infection, and the regulation of TLR3 could probably be the mechanism.

Impact of Type I Interferon on the Safety and Immunogenicity of an Experimental Live-Attenuated Herpes Simplex Virus 1 Vaccine in Mice

Viral fitness dictates virulence and capacity to evade host immune defenses. Understanding the biological underpinnings of such features is essential for rational vaccine development. We have previously shown that the live-attenuated herpes simplex virus 1 (HSV-1) mutant lacking the nuclear localization signal (NLS) on the ICP0 gene (0ΔNLS) is sensitive to inhibition by interferon beta (IFN-β) in vitro and functions as a highly efficacious experimental vaccine. Here, we characterize the host immune response and in vivo pathogenesis of HSV-1 0ΔNLS relative to its fully virulent parental strain in C57BL/6 mice. Additionally, we explore the role of type 1 interferon (IFN-α/β) signaling on virulence and immunogenicity of HSV-1 0ΔNLS and uncover a probable sex bias in the induction of IFN-α/β in the cornea during HSV-1 infection. Our data show that HSV-1 0ΔNLS lacks neurovirulence even in highly immunocompromised mice lacking the IFN-α/β receptor. These studies support the translational viability of the HSV-1 0ΔNLS vaccine strain by demonstrating that, while it is comparable to a virulent parental strain in terms of immunogenicity, HSV-1 0ΔNLS does not induce significant tissue pathology.IMPORTANCE HSV-1 is a common human pathogen associated with a variety of clinical presentations ranging in severity from periodic "cold sores" to lethal encephalitis. Despite the consistent failures of HSV subunit vaccines in clinical trials spanning the past 28 years, opposition to live-attenuated HSV vaccines predicated on unfounded safety concerns currently limits their widespread acceptance. Here, we demonstrate that a live-attenuated HSV-1 vaccine has great translational potential.

Zinc oxide tetrapods inhibit herpes simplex virus infection of cultured corneas

PURPOSE

Infection of the human cornea by herpes simplex virus type-1 (HSV-1) can cause significant vision loss. The purpose of this study was to develop an ex vivo model to visualize viral growth and spread in the cornea. The model was also used to analyze cytokine production and study the antiviral effects of zinc oxide tetrapods.

METHODS

A β-galactosidase-expressing recombinant virus, HSV-1(KOS)tk12, was used to demonstrate the ability of the virus to enter and develop blue plaques on human corneal epithelial (HCE) cells and corneal tissues. Freshly obtained porcine corneas were cultured and then scratched before infection with HSV-1(KOS)tk12. The blue plaques on the corneas were imaged using a stereomicroscope. Western blot analysis for HSV-1 proteins was performed to verify HSV-1 infection of the cornea. Using the ex vivo model, zinc oxide tetrapods were tested for their anti-HSV-1 potential, and a cytokine profile was developed to assess the effects of the treatment.

RESULTS

Cultured corneas and the use of β-galactosidase-expressing HSV-1(KOS)tk12 virus can provide an attractive ex vivo model to visualize and study HSV-1 entry and spread of the infection in tissues. We found that unlike cultured HCE cells, which demonstrated nearly 100% infectivity, HSV-1 infection of the cultured cornea was more restrictive and took longer to develop. We also found that the zinc oxide tetrapod-shaped nano- and microstructures inhibited HSV infection of the cultured cells, as well as the cultured corneas. The cytokine profile of the infected samples was consistent with previous studies of HSV-1 corneal infection.

CONCLUSIONS

The ability to visualize HSV-1 growth and spread in corneal tissues can provide new details about HSV-1 infection of the cornea and the efficacy of new cornea-specific antiviral drug candidates. The ex vivo model also demonstrates antiviral effects of zinc oxide tetrapods and adequately portrays the drug delivery issues that cornea-specific treatments face.

Cornea lymphatics drive the CD8+ T-cell response to herpes simplex virus-1

Herpes simplex virus type 1 (HSV-1) infection of the cornea induces vascular endothelial growth factor (VEGF)-A-dependent lymphangiogenesis. However, the extent to which HSV-1-induced corneal lymphangiogenesis impacts the adaptive immune response has not been characterized. Here, we used floxed VEGF-A mice to study the importance of newly created corneal lymphatic vessels in the host adaptive immune response to infection. Whereas the mice infected with the parental virus (strain SC16) exhibited robust corneal lymphangiogenesis, mice that received the recombinant virus (SC16 ICP0-Cre) that expresses Cre recombinase under the control of infected cell protein 0 (ICP0), an HSV-1 immediate early gene, showed a significant reduction in lymphangiogenesis. There was no difference in virus recovered from the cornea of mice infected with SC16 vs SC16 ICP0-Cre. However, viral loads were significantly elevated in the trigeminal ganglia (TG) of mice with reduced corneal lymphangiogenesis. The increase in viral titer correlated with a significant loss of HSV-1-specific CD8⁺ T cells that traffic to the TG of mice infected with the recombinant virus. Intrastromal delivery of size exclusion dye (FITC-dextran) revealed a time-dependent defect in the ability of the lymphatic vessels in SC16 ICP0-Cre infected mice to transport soluble antigen from the cornea to the draining lymph nodes. We interpret these results to suggest that the newly created lymphatic vessels in the cornea driven by HSV-1 infection are critical in the delivery of soluble viral antigen to the draining lymph node and subsequent development of the CD8⁺ T cell response to HSV-1.

IL-6 Contributes to Corneal Nerve Degeneration after Herpes Simplex Virus Type I Infection

Herpes simplex virus type 1 (HSV-1) is a leading cause of neurotrophic keratitis characterized by decreased corneal sensation because of damage to the corneal sensory fibers. We and others have reported regression of corneal nerves during acute HSV-1 infection. To determine whether denervation is caused directly by the virus or indirectly by the elicited immune response, mice were infected with HSV-1 and topically treated with dexamethasone (DEX) or control eye drops. Corneal sensitivity was measured using a Cochet-Bonnet esthesiometer and nerve network structure via immunohistochemistry. Corneas were assessed for viral content by plaque assay, leukocyte influx by flow cytometry, and content of chemokines and inflammatory cytokines by suspension array. DEX significantly preserved corneal nerve structure and sensitivity on infection. DEX reduced myeloid and T-cell populations in the cornea and did not affect viral contents at 4 and 8 days post infection. The elevated protein contents of chemokines and inflammatory cytokines on infection were greatly suppressed by DEX. Subconjunctival delivery of neutralizing antibody against IL-6 to infected mice resulted in partial preservation of corneal nerve structure and sensitivity. Our study supports a role for the immune response, but not local virus replication in the development of HSV-1-induced neurotrophic keratitis. IL-6 is one of the factors produced by the elicited inflammatory response to HSV-1 infection contributing to nerve regression.

Challenges of corneal infections

INTRODUCTION

Ocular infections remain an important cause of blindness worldwide and represent a challenging public health concern. In this regard, microbial keratitis due to fungal, bacterial, or viral infection can result in significant vision loss secondary to corneal scarring or surface irregularity. Left untreated corneal perforation and endophthalmitis can result, leading to loss of the eye. Rigorously studied animal models of disease pathogenesis have provided novel information that suggests new modes of treatment that may be efficacious clinically and emerging clinical data is supportive of some of these discoveries.

AREAS COVERED

This review focuses on advances in our understanding of disease pathogenesis in animal models and clinical studies and how these relate to improved clinical treatment. We also discuss a novel approach to treatment of microbial keratitis due to infection with these bacterial pathogens using PACK-CXL and recommend increased basic and clinical studies to address and refine the efficacy of this procedure.

EXPERT COMMENTARY

Because resistance to antibiotics has developed over time to these bacterial pathogens, caution must be exercised in treatment. Attractive novel modes of treatment that hold new promise for further investigation include lipid based therapy, as well as use of small molecules that bind deleterious specific host responsive molecules and use of microRNA based therapies.

Pathological lymphangiogenesis is modulated by galectin-8-dependent crosstalk between podoplanin and integrin-associated VEGFR-3

Lymphangiogenesis plays a pivotal role in diverse pathological conditions. Here, we demonstrate that a carbohydrate-binding protein, galectin-8, promotes pathological lymphangiogenesis. Galectin-8 is markedly upregulated in inflamed human and mouse corneas, and galectin-8 inhibitors reduce inflammatory lymphangiogenesis. In the mouse model of corneal allogeneic transplantation, galectin-8-induced lymphangiogenesis is associated with an increased rate of corneal graft rejection. Further, in the murine model of herpes simplex virus keratitis, corneal pathology and lymphangiogenesis are ameliorated in Lgals8(-/-) mice. Mechanistically, VEGF-C-induced lymphangiogenesis is significantly reduced in the Lgals8(-/-) and Pdpn(-/-) mice; likewise, galectin-8-induced lymphangiogenesis is reduced in Pdpn(-/-) mice. Interestingly, knockdown of VEGFR-3 does not affect galectin-8-mediated lymphatic endothelial cell (LEC) sprouting. Instead, inhibiting integrins α1β1 and α5β1 curtails both galectin-8- and VEGF-C-mediated LEC sprouting. Together, this study uncovers a unique molecular mechanism of lymphangiogenesis in which galectin-8-dependent crosstalk among VEGF-C, podoplanin and integrin pathways plays a key role.

Therapeutic antibodies that target inflammatory cytokines in autoimmune diseases

Inflammatory cytokines are key regulators of immune responses. Persistent and excessive production of inflammatory cytokines underscores the development of autoimmune diseases. Therefore, neutralizing inflammatory cytokines or antagonizing their receptor function is considered as a useful therapeutic strategy to treat autoimmune diseases. To achieve the success of such a strategy, understanding of the complex actions of these cytokines and cytokine networks is required. In this review we focus on four inflammatory cytokines--tumor necrosis factor α (TNFα), interleukin-6 (IL-6), IL-23 and IL-17--and dissect how the dysregulation of these cytokines regulates autoimmune diseases. On the basis of pre-clinical and clinical data, we specifically discuss the therapeutic rationale for targeting these cytokines and describe the potential adverse effects.

Macrophages: An Inflammatory Link Between Angiogenesis and Lymphangiogenesis

Angiogenesis and lymphangiogenesis often occur in response to tissue injury or in the presence of pathology (e.g., cancer), and it is these types of environments in which macrophages are activated and increased in number. Moreover, the blood vascular microcirculation and the lymphatic circulation serve as the conduits for entry and exit for monocyte-derived macrophages in nearly every tissue and organ. Macrophages both affect and are affected by the vessels through which they travel. Therefore, it is not surprising that examination of macrophage behaviors in both angiogenesis and lymphangiogenesis has yielded interesting observations that suggest macrophages may be key regulators of these complex growth and remodeling processes. In this review, we will take a closer look at macrophages through the lens of angiogenesis and lymphangiogenesis, examining how their dynamic behaviors may regulate vessel sprouting and function. We present macrophages as a cellular link that spatially and temporally connects angiogenesis with lymphangiogenesis, in both physiological growth and in pathological adaptations, such as tumorigenesis. As such, attempts to therapeutically target macrophages in order to affect these processes may be particularly effective, and studying macrophages in both settings will accelerate the field's understanding of this important cell type in health and disease.

IL-10 Indirectly Regulates Corneal Lymphangiogenesis and Resolution of Inflammation via Macrophages

The role of IL-10, a primarily anti-inflammatory cytokine, in the regulation of inflammatory lymphangiogenesis is undetermined. Herein, we show that IL-10 modulates corneal lymphangiogenesis and resolution of inflammation. IL-10 was not expressed in healthy corneas but was up-regulated in inflamed corneas by infiltrating macrophages. Macrophages up-regulated the expression of prolymphangiogenic vascular endothelial growth factor-C upon stimulation with IL-10. Consistently, corneal inflammation resulted in reduced expression of vascular endothelial growth factor-C and decreased corneal lymphangiogenesis in IL-10-deficient mice (IL-10(-/-)). The effect of IL-10 on lymphangiogenesis was indirect via macrophages, because IL-10 did not directly affect lymphatic endothelial cells. The expression of proinflammatory cytokines and the numbers of infiltrating macrophages increased and remained elevated in inflamed corneas of IL-10(-/-) mice, indicating that IL-10 deficiency led to more severe and prolonged inflammation. The corneal phenotype of IL-10 deficient mice was mimicked in mice with conditional deletion of Stat3 in myeloid cells (lysozyme M Cre mice Stat3(fl/fl) mice), corroborating the critical role of macrophages in the regulation of lymphangiogenesis. Furthermore, local treatment with IL-10 promoted lymphangiogenesis and faster egress of macrophages from inflamed corneas. Taken together, we demonstrate that IL-10 indirectly regulates inflammatory corneal lymphangiogenesis via macrophages. Reduced lymphangiogenesis in IL-10(-/-) and lysozyme M Cre Stat3(fl/fl) mice is associated with more severe inflammatory responses, whereas IL-10 treatment results in faster resolution of inflammation. IL-10 might be used therapeutically to terminate pathological inflammation.

Killing effect of TNF-mediated by conditionally replicating adenovirus on esophageal cancer and lung cancer cell lines

OBJECTIVE

The killing effect of TNF mediated by conditionally replicating adenovirus SG502 on human cancer cell lines was assessed by in vivo and in vitro experiments.

METHODS

The recombinant adenovirus SG502-TNF was used to infect human lung cancer cell line A549 and human esophageal cancer cell line TE-1. The expression of the exogenous gene and its inhibitory effect on the tumor cell lines were thus detected. Tumor transplantation experiment was performed in mice with the purpose of assessing the inhibitory effect of the adenovirus on tumor cells and tumor formation. The targeting of the adenovirus and the mechanism of tumor inhibition were discussed by in vivo imaging technology, HE staining and TUNEL assay.

RESULTS

Recombinant adenovirus SG502-TNF targeted the tumor cells specifically with stable expression of TNF, which produced a killing effect on tumor cells by regulating the apoptotic signaling pathway.

CONCLUSION

Recombinant adenovirus SG502-TNF possessed significant killing effect on TE-1 cells either in vivo or in vitro. This finding demonstrated the potential clinical application of adenovirus SG502.

Dendritic Cell Autophagy Contributes to Herpes Simplex Virus-Driven Stromal Keratitis and Immunopathology

Herpetic stromal keratitis (HSK) is a blinding ocular disease that is initiated by HSV-1 and characterized by chronic inflammation in the cornea. Although HSK immunopathology of the cornea is well documented in animal models, events preceding this abnormal inflammatory cascade are poorly understood. In this study, we have examined the activation of pathological CD4⁺ T cells in the development of HSK. Dendritic cell autophagy (DC-autophagy) is an important pathway regulating major histocompatibility complex class II (MHCII)-dependent antigen presentation and proper CD4⁺ T cell activation during infectious diseases. Using DC-autophagy-deficient mice, we found that DC-autophagy significantly and specifically contributes to HSK disease without impacting early innate immune infiltration, viral clearance, or host survival. Instead, the observed phenotype was attributable to the abrogated activation of CD4⁺ T cells and reduced inflammation in HSK lesions. We conclude that DC-autophagy is an important contributor to primary HSK immunopathology upstream of CD4⁺ T cell activation.

Herpetic stromal keratitis (HSK) is the leading cause of infectious blindness in the United States and a rising cause worldwide. HSK is induced by herpes simplex virus 1 but is considered a disease of inappropriately sustained inflammation driven by CD4⁺ T cells. In this study, we investigated whether pathways preceding CD4⁺ T cell activation affect disease outcome. We found that autophagy in dendritic cells significantly contributed to the incidence of HSK. Dendritic cell autophagy did not alter immune control of the virus or neurological disease but specifically augmented CD4⁺ T cell activation and pathological corneal inflammation. This study broadens our understanding of the immunopathology that drives HSK and implicates the autophagy pathway as a new target for therapeutic intervention against this incurable form of infectious blindness.

Herpesvirus entry mediator on radiation-resistant cell lineages promotes ocular herpes simplex virus 1 pathogenesis in an entry-independent manner

Ocular herpes simplex virus 1 (HSV-1) infection leads to a potentially blinding immunoinflammatory syndrome, herpes stromal keratitis (HSK). Herpesvirus entry mediator (HVEM), a widely expressed tumor necrosis factor (TNF) receptor superfamily member with diverse roles in immune signaling, facilitates viral entry through interactions with viral glycoprotein D (gD) and is important for HSV-1 pathogenesis. We subjected mice to corneal infection with an HSV-1 mutant in which HVEM-mediated entry was specifically abolished and found that the HVEM-entry mutant produced clinical disease comparable to that produced by the control virus. HVEM-mediated induction of corneal cytokines, which correlated with an HVEM-dependent increase in levels of corneal immune cell infiltrates, was also gD independent. Given the complexity of HVEM immune signaling, we used hematopoietic chimeric mice to determine which HVEM-expressing cells mediate HSV-1 pathogenesis in the eye. Regardless of whether the donor was a wild-type (WT) or HVEM knockout (KO) strain, HVEM KO recipients were protected from ocular HSV-1, suggesting that HVEM on radiation-resistant cell types, likely resident cells of the cornea, confers wild-type-like susceptibility to disease. Together, these data indicate that HVEM contributes to ocular pathogenesis independently of entry and point to an immunomodulatory role for this protein specifically on radiation-resistant cells.

Immune privilege is maintained in the eye in order to protect specialized ocular tissues, such as the translucent cornea, from vision-reducing damage. Ocular herpes simplex virus 1 (HSV-1) infection can disrupt this immune privilege, provoking a host response that ultimately brings about the majority of the damage seen with the immunoinflammatory syndrome herpes stromal keratitis (HSK). Our previous work has shown that HVEM, a host TNF receptor superfamily member that also serves as a viral entry receptor, is a critical component contributing to ocular HSV-1 pathogenesis, although its precise role in this process remains unclear. We hypothesized that HVEM promotes an inflammatory microenvironment in the eye through immunomodulatory actions, enhancing disease after ocular inoculation of HSV-1. Investigating the mechanisms responsible for orchestrating this aberrant immune response shed light on the initiation and maintenance of HSK, one of the leading causes of infectious blindness in the developed world.

Role of the DNA Sensor STING in Protection from Lethal Infection following Corneal and Intracerebral Challenge with Herpes Simplex Virus 1

STING is a protein in the cytosolic DNA and cyclic dinucleotide sensor pathway that is critical for the initiation of innate responses to infection by various pathogens. Consistent with this, herpes simplex virus 1 (HSV-1) causes invariable and rapid lethality in STING-deficient (STING(-/-)) mice following intravenous (i.v.) infection. In this study, using real-time bioluminescence imaging and virological assays, as expected, we demonstrated that STING(-/-) mice support greater replication and spread in ocular tissues and the nervous system. In contrast, they did not succumb to challenge via the corneal route even with high titers of a virus that was routinely lethal to STING(-/-) mice by the i.v. route. Corneally infected STING(-/-) mice also showed increased periocular disease and increased corneal and trigeminal ganglia titers, although there was no difference in brain titers. They also showed elevated expression of tumor necrosis factor alpha (TNF-α) and CXCL9 relative to control mice but surprisingly modest changes in type I interferon expression. Finally, we also showed that HSV strains lacking the ability to counter autophagy and the PKR-driven antiviral state had near-wild-type virulence following intracerebral infection of STING(-/-) mice. Together, these data show that while STING is an important component of host resistance to HSV in the cornea, its previously shown immutable role in mediating host survival by the i.v. route was not recapitulated following a mucosal infection route. Furthermore, our data are consistent with the idea that HSV counters STING-mediated induction of the antiviral state and autophagy response, both of which are critical factors for survival following direct infection of the nervous system.

IMPORTANCE

HSV infections represent an incurable source of morbidity and mortality in humans and are especially severe in neonatal and immunocompromised populations. A key step in the development of an immune response is the recognition of microbial components within infected cells. The host protein STING is important in this regard for the recognition of HSV DNA and the subsequent triggering of innate responses. STING was previously shown to be essential for protection against lethal challenge from intravenous HSV-1 infection. In this study, we show that the requirement for STING depends on the infection route. In addition, STING is important for appropriate regulation of the inflammatory response in the cornea, and our data are consistent with the idea that HSV modulates STING activity through inhibition of autophagy. Our results elucidate the importance of STING in host protection from HSV-1 and demonstrate the redundancy of host protective mechanisms, especially following mucosal infection.