An Ocular Commensal Protects against Corneal Infection by Driving an Interleukin-17 Response from Mucosal γδ T Cells.

Mucosal sites such as the intestine, oral cavity, nasopharynx, and vagina all have associated commensal flora. The surface of the eye is also a mucosal site, but proof of a living, resident ocular microbiome remains elusive. Here, we used a mouse model of ocular surface disease to reveal that commensals were present in the ocular mucosa and had functional immunological consequences. We isolated one such candidate commensal, Corynebacterium mastitidis, and showed that this organism elicited a commensal-specific interleukin-17 response from γδ T cells in the ocular mucosa that was central to local immunity. The commensal-specific response drove neutrophil recruitment and the release of antimicrobials into the tears and protected the eye from pathogenic Candida albicans or Pseudomonas aeruginosa infection. Our findings provide direct evidence that a resident commensal microbiome exists on the ocular surface and identify the cellular mechanisms underlying its effects on ocular immune homeostasis and host defense.

Small Noncoding RNA (sncRNA1) within the Latency-Associated Transcript Modulates Herpes Simplex Virus 1 Virulence and the Host Immune Response during Acute but Not Latent Infection.

The HSV-1 latency-associated transcript (LAT) locus contains two small noncoding RNA (sncRNA) sequences (sncRNA1 and sncRNA2) that are not microRNAs (miRNAs). We recently reported that sncRNA1 is more important for in vitro activation of the herpesvirus entry mediator than sncRNA2, but its in vivo function is not known. To determine the role, if any, of sncRNA1 during herpes simplex virus 1 (HSV-1) infection in vivo, we deleted the 62-bp sncRNA1 sequence in HSV-1 strain McKrae using dLAT2903 (LAT-minus) virus, creating ΔsncRNA1 recombinant virus. Deletion of the sncRNA1 in ΔsncRNA1 virus was confirmed by complete sequencing of ΔsncRNA1 virus and its parental virus (i.e., McKrae). Replication of ΔsncRNA1 virus in tissue culture or in the eyes of infected mice was similar to that of HSV-1 strain McKrae and dLAT2903 viruses. However, the absence of sncRNA1 significantly reduced the levels of ICP0, ICP4, and gB but not LAT transcripts in infected rabbit skin cells in vitro. In contrast, the absence of sncRNA1 did reduce LAT expression in trigeminal ganglia (TG), but not in corneas, by day 5 postinfection (p.i.) in infected mice. Levels of eye disease in mice infected with ΔsncRNA1 or McKrae virus were similar, and despite reduced LAT levels in TG during acute ΔsncRNA1 infection, McKrae and ΔsncRNA1 viruses did not affect latency or reactivation on day 28 p.i. However, mice infected with ΔsncRNA1 virus were more susceptible to ocular infection than their wild-type (WT) counterparts. Expression of host immune response genes in corneas and TG of infected mice during primary infection showed reduced expression of beta interferon (IFNß) and IFNγ and altered activation of key innate immune pathways, such as the JAK-STAT pathway in ΔsncRNA1 virus compared with parental WT virus. Our results reveal novel functions for sncRNA1 in upregulating the host immune response and suggest that sncRNA1 has a protective role during primary ocular HSV-1 infection. IMPORTANCE HSV-1 latency-associated transcript (LAT) plays a major role in establishing latency and reactivation; however, the mechanism by which LAT controls these processes is largely unknown. In this study, we sought to establish the role of the small noncoding RNA1 (sncRNA1) encoded within LAT during HSV-1 ocular infection. Our results suggest that sncRNA1 has a protective role during acute ocular infection by modulating the innate immune response to infection.

The cornea IV immunology, infection, neovascularization, and surgery chapter 1: Corneal immunology.

PURPOSE: of Review: This review offers an informed and up-to-date insight on the immune profile of the cornea and the factors that govern the regulation of such a unique immune environment. SUMMARY: The cornea is a unique tissue that performs the specialized task of allowing light to penetrate for visual interpretation. To accomplish this, the ocular surface requires a distinct immune environment that is achieved through unique structural, cellular and molecular factors. Not only must the cornea be able to fend off invasive infectious agents but also control the inflammatory response as to avoid collateral, and potentially blinding damage; particularly of post-mitotic cells such as the corneal endothelium. To combat infections, both innate and adaptive arms of the inflammatory immune response are at play in the cornea. Dendritic cells play a critical role in coordinating both these responses in order to fend off infections. On the other side of the spectrum, the ocular surface is also endowed with a variety of anatomic and physiologic components that aid in regulating the immune response to prevent excessive, potentially damaging, inflammation. This attenuation of the immune response is termed immune privilege. The balance between pro and anti-inflammatory reactions is key for preservation of the functional integrity of the cornea. RECENT FINDINGS: The understanding of the molecular and cellular factors governing corneal immunology and its response to antigens is a growing field. Dendritic cells in the normal cornea play a crucial role in combating infections and coordinating the inflammatory arms of the immune response, particularly through coordination with T-helper cells. The role of neuropeptides is recently becoming more highlighted with different factors working on both sides of the inflammatory balance.

Absence of Signal Peptide Peptidase, an Essential Herpes Simplex Virus 1 Glycoprotein K Binding Partner, Reduces Virus Infectivity In Vivo.

We previously reported that herpes simplex virus (HSV) glycoprotein K (gK) binds to signal peptide peptidase (SPP), also known as minor histocompatibility antigen H13. Binding of gK to SPP is required for HSV-1 infectivity in vitro SPP is a member of the γ-secretase family, and mice lacking SPP are embryonic lethal. To determine how SPP affects HSV-1 infectivity in vivo, the SPP gene was deleted using a tamoxifen-inducible Cre recombinase driven by the ubiquitously expressed ROSA26 promoter. SPP mRNA was reduced by more than 93% in the cornea and trigeminal ganglia (TG) and by 99% in the liver of tamoxifen-injected mice, while SPP protein expression was reduced by 90% compared to the level in control mice. Mice lacking SPP had significantly less HSV-1 replication in the eye as well as reduced gK, UL20, ICP0, and gB transcripts in the cornea and TG compared to levels in control mice. In addition, reduced infiltration of CD45+, CD4+, CD8+, F4/80+, CD11c+, and NK1.1+ T cells was observed in the cornea and TG of SPP-inducible knockout mice compared to that in control mice. Finally, in the absence of SPP, latency was significantly reduced in SPP-inducible knockout mice compared to that in control mice. Thus, in this study we have generated SPP-inducible knockout mice and shown that the absence of SPP affects virus replication in the eye of ocularly infected mice and that this reduction is correlated with the interaction of gK and SPP. These results suggest that blocking this interaction may have therapeutic potential in treating HSV-1-associated eye disease.IMPORTANCE Glycoprotein K (gK) is an essential and highly conserved HSV-1 protein. Previously, we reported that gK binds to SPP, an endoplasmic reticulum (ER) protein, and blocking this binding reduces virus infectivity in vitro and also affects gK and UL20 subcellular localization. To evaluate the function of gK binding to SPP in vivo, we generated SPP-inducible knockout mice and observed the following in the absence of SPP: (i) that significantly less HSV-1 replication was seen in ocularly infected mice than in control mice; (ii) that expression of various HSV-1 genes and cellular infiltrates in the eye and trigeminal ganglia of infected mice was less than that in control mice; and (iii) that latency was significantly reduced in infected mice. Thus, blocking of gK binding to SPP may be a useful tool to control HSV-1-induced eye disease in patients with herpes stromal keratitis (HSK).

TIPE2 Suppresses Pseudomonas aeruginosa Keratitis by Inhibiting NF-κB Signaling and the Infiltration of Inflammatory Cells.

BACKGROUND: The role of tumor necrosis factor α (TNF-α) induced protein 8-like-2 (TIPE2) in Pseudomonas aeruginosa (PA) keratitis was explored. METHODS: Eight-week-old TIPE2 knockout (TIPE2-/-) C57BL/6 mice and their wild-type (WT) littermates were used. Corneal disease was graded at 1, 2, and 3 days postinfection, and slit lamp, clinical score, histopathology, and immunostaining were performed in the infected corneas. The corneas were harvested, and messenger ribonucleic acid (mRNA) levels of TNF-α, interleukin-1ß (IL-1ß), and interleukin-6 (IL-6) were tested. Enzyme-linked immunosorbent assay (ELISA) determined the protein levels, and nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB) signaling molecules were tested by Western blot. In vitro human corneal epithelial cells (HCECs) were used to determine the relationship between TIPE2 and TAK1. The HCECs were treated with TIPE2 short hairpin ribonucleic acid (shRNA) and lipopolysaccharide (LPS) to test the NF-κB signaling molecules by Western blot. RESULTS: Pseudomonas aeruginosa infection induced a decreased expression of TIPE2 in mouse corneas 2 days postinfection. Compared with the control group, TIPE2-deficient mice were susceptible to infection with PA and showed increased corneal inflammation. Reduced NF-κB signaling and inflammatory cell infiltration were required in the TIPE2-mediated immune modulation. CONCLUSIONS: TIPE2 promoted host resistance to PA infection by suppressing corneal inflammation via regulating TAK1 signaling negatively and inhibiting the infiltration of inflammatory cells.

An M2 Rather than a TH2 Response Contributes to Better Protection against Latency Reactivation following Ocular Infection of Naive Mice with a Recombinant Herpes Simplex Virus 1 Expressing Murine Interleukin-4.

We found previously that altering macrophage polarization toward M2 responses by injection of colony-stimulating factor 1 (CSF-1) was more effective in reducing both primary and latent infections in mice ocularly infected with herpes simplex virus 1 (HSV-1) than M1 polarization by gamma interferon (IFN-γ) injection. Cytokines can coordinately regulate macrophage and T helper (TH) responses, with interleukin-4 (IL-4) inducing type 2 TH (TH2) as well as M2 responses and IFN-γ inducing TH1 as well as M1 responses. We have now differentiated the contributions of these immune compartments to protection against latency reactivation and corneal scarring by comparing the effects of infection with recombinant HSV-1 in which the latency-associated transcript (LAT) gene was replaced with either the IL-4 (HSV-IL-4) or IFN-γ (HSV-IFN-γ) gene using infection with the parental (LAT-negative) virus as a control. Analysis of peritoneal macrophages in vitro established that the replacement of LAT with the IL-4 or IFN-γ gene did not affect virus infectivity and promoted polarization appropriately. Protection against corneal scarring was significantly higher in mice ocularly infected with HSV-IL-4 than in those infected with HSV-IFN-γ or parental virus. Levels of primary virus replication in the eyes and trigeminal ganglia (TG) were similar in the three groups of mice, but the numbers of gC+ cells were lower on day 5 postinfection in the eyes of HSV-IL-4-infected mice than in those infected with HSV-IFN-γ or parental virus. Latency and explant reactivation were lower in both HSV-IL-4- and HSV-IFN-γ-infected mice than in those infected with parental virus, with the lowest level of latency being associated with HSV-IL-4 infection. Higher latency correlated with higher levels of CD8, PD-1, and IFN-γ mRNA, while reduced latency and T-cell exhaustion correlated with lower gC+ expression in the TG. Depletion of macrophages increased the levels of latency in all ocularly infected mice compared with their undepleted counterparts, with macrophage depletion increasing latency in the HSV-IL-4 group greater than 3,000-fold. Our results suggest that shifting the innate macrophage immune responses toward M2, rather than M1, responses in HSV-1 infection would improve protection against establishment of latency, reactivation, and eye disease.IMPORTANCE Ocular HSV-1 infections are among the most frequent serious viral eye infections in the United States and a major cause of virus-induced blindness. As establishment of a latent infection in the trigeminal ganglia results in recurrent infection and is associated with corneal scarring, prevention of latency reactivation is a major therapeutic goal. It is well established that absence of latency-associated transcripts (LATs) reduces latency reactivation. Here we demonstrate that recombinant HSV-1 expressing IL-4 (an inducer of TH2/M2 responses) or IFN-γ (an inducer of TH1/M1 responses) in place of LAT further reduced latency, with HSV-IL-4 showing the highest overall protective efficacy. In naive mice, this higher protective efficacy was mediated by innate rather than adaptive immune responses. Although both M1 and M2 macrophage responses were protective, shifting macrophages toward an M2 response through expression of IL-4 was more effective in curtailing ocular HSV-1 latency reactivation.

Immune checkpoint inhibitors: what neuro-ophthalmologists need to know.

PURPOSE OF REVIEW: Immune checkpoint inhibitors are currently an exceedingly powerful tool in the management of hitherto incurable malignancies and their use in clinical practice is expected to increase in the near future. The purpose of this review is to discuss the current medical uses of checkpoint inhibitors with a focus on their neuro-ophthalmic side-effects. RECENT FINDINGS: Immune checkpoint inhibitors have emerged as a promising breakthrough in the treatment of several tumor types. However, these targeted therapies can induce a wide range of immune-related ophthalmic and neuro-ophthalmic toxicities. It is important for neuro-ophthamologists to promptly recognize and manage these adverse events that can potentially threaten vision. SUMMARY: There are currently seven FDA-approved immune checkpoint inhibitors and several ones are under investigation. In general, immunotherapy is considered a well tolerated, safe and efficacious treatment option for many cancer patients. Nevertheless, because of their unique mechanism of action, these molecules can alter the immune response and result in immune-related adverse effects in almost every organ with an estimated incidence of ophthalmic side effects in this patient population of less than 1%.

Quantitative Trait Locus Based Virulence Determinant Mapping of the HSV-1 Genome in Murine Ocular Infection: Genes Involved in Viral Regulatory and Innate Immune Networks Contribute to Virulence.

Herpes simplex virus type 1 causes mucocutaneous lesions, and is the leading cause of infectious blindness in the United States. Animal studies have shown that the severity of HSV-1 ocular disease is influenced by three main factors; innate immunity, host immune response and viral strain. We previously showed that mixed infection with two avirulent HSV-1 strains (OD4 and CJ994) resulted in recombinants that exhibit a range of disease phenotypes from severe to avirulent, suggesting epistatic interactions were involved. The goal of this study was to develop a quantitative trait locus (QTL) analysis of HSV-1 ocular virulence determinants and to identify virulence associated SNPs. Blepharitis and stromal keratitis quantitative scores were characterized for 40 OD4:CJ994 recombinants. Viral titers in the eye were also measured. Virulence quantitative trait locus mapping (vQTLmap) was performed using the Lasso, Random Forest, and Ridge regression methods to identify significant phenotypically meaningful regions for each ocular disease parameter. The most predictive Ridge regression model identified several phenotypically meaningful SNPs for blepharitis and stromal keratitis. Notably, phenotypically meaningful nonsynonymous variations were detected in the UL24, UL29 (ICP8), UL41 (VHS), UL53 (gK), UL54 (ICP27), UL56, ICP4, US1 (ICP22), US3 and gG genes. Network analysis revealed that many of these variations were in HSV-1 regulatory networks and viral genes that affect innate immunity. Several genes previously implicated in virulence were identified, validating this approach, while other genes were novel. Several novel polymorphisms were also identified in these genes. This approach provides a framework that will be useful for identifying virulence genes in other pathogenic viruses, as well as epistatic effects that affect HSV-1 ocular virulence.

The pathogenic role of dendritic cells in non-infectious anterior uveitis.

BACKGROUND: Anterior uveitis (AU) is characterised by infiltration of immune cells into the anterior chamber of the eye. Dendritic cells (DC) are professional antigen presenting cells that initiate and promote inflammation. This study aims to characterise DC in AU and to examine the effects of aqueous humor (AqH) on DC maturation and function. METHODS: The frequency and phenotype of AU and healthy control (HC) circulating DC was examined. AU and HC AqH was immunostained and assessed by flow cytometry. The effect of AU and HC AqH on DC activation and maturation was examined and subsequent effects on CD4+ T cell proliferation assessed. RESULTS: AU peripheral blood demonstrated decreased circulating myeloid and plasmacytoid DC. Within AU AqH, three populations of CD45+ cells were significantly enriched compared to HC; DCs (CD11c+ HLA-DR+), neutrophils (CD15+ CD11c+) and T cells (CD4+ and CD8+). A significant increase in IFNγ, IL8 and IL6 was observed in the AU AqH, which was also significantly higher than that of paired serum. AU AqH induced expression of CD40 and CD80 on DC, which resulted in increased T cell proliferation and the production of GM-CSF, IFNγ and TNFα. CONCLUSION: DC are enriched at the site of inflammation in AU. Our data demonstrate an increase in inflammatory mediators in the AU inflamed microenvironment. AU AqH can activate DC, leading to subsequent proliferation and activation of effector T cells. Thus, the AU microenvironment contributes to immune cell responses and intraocular inflammation.

Herpes simplex virus-1 infects the olfactory bulb shortly following ocular infection and exhibits a long-term inflammatory profile in the form of effector and HSV-1-specific T cells.

BACKGROUND: Herpes simplex virus 1 (HSV-1) infection can result in a life-threatening condition known as herpes simplex encephalitis (HSE). Trafficking patterns by which the virus reaches the central nervous system (CNS) following ocular infection are unresolved. We evaluated early viral dissemination pathways following ocular infection that involve trafficking to the olfactory bulb (OB). Additionally, we have characterized the capacity of HSV-1 to establish latency within OB tissue and profiled the local T lymphocyte response over the course of the acute infection into latency. METHODS: Scarified corneas of C57BL/6 or reporter-inducible Rosa mice (RosaTd/Tm) were inoculated with HSV-1 and assessed for viral dissemination into the peripheral nervous system (PNS) and CNS by RT-PCR and confocal microscopy. T cells and the resident microglia activation signatures were analyzed by flow cytometry. T cell effector function in the form of IFN-γ secretion was measured by T cells isolated from OB in comparison to T cells from other nervous system sites known to harbor HSV-1-specific memory T cells. RESULTS: Following ocular infection, HSV-1 viral titers from nasal secretions were detected as early as 48 h through 8 days post infection (8 DPI). HSV-1 gene expression was expressed as early as 2 days following ocular infection in the OB and was consistent with an enhanced expression in the ophthalmic, maxillary, and mandibular branch of the trigeminal nerve ganglia (TG). Rosa fluorescence protein expression (RFP+) representing HSV-1-infected cells from RosaTd/Tm mice was detected in the OB before other areas of the CNS (2 DPI). Additionally, during acute infection, most infected cells appeared to be anatomically distributed within the OB rather than other regions of the CNS. During latency (i.e., 30 DPI and beyond) despite no detectable infectious virus or lytic gene expression and low levels of latency associated transcripts, total effector (CD44+ CD62-) CD4+ T, CD8+ T, HSV-1-specific CD8+ T cells, and MHC class II positive resident microglia numbers continued to increase. CD4+ and CD8+ T cell populations isolated from the OB during latency were capable of responding to PMA/ionomycin in the production of IFN-γ similar to T cells from other tissue that possess latent virus including the TG and brain stem. CONCLUSIONS: It is currently understood that HSV-1 traffics to the TG following ocular infection. We have identified a second conduit by which HSV-1 can directly access the CNS bypassing the brain stem. We have also recognized that the OB is unique in that during HSV-1 latency, latency-associated transcripts levels were marginally above uninfected controls. Despite these findings, the local immune response mimicked the phenotype of an active infection during latency.

[Battle with herpes for 37 years].

Herpes simplex virus type 1(HSV-1) remains latent in the human trigeminal ganglion after primarily infecting the cornea and conjunctiva. Mental stress, heat stimulation, ultraviolet ray and immunosuppression are among the reactivating factors of HSV-1, which can lead to epithelial herpetic keratitis, stromal herpetic keratitis, and other complications. I have been working with HSV-1 for a long time, concentrating especially on its latency and reactivation. I would like to introduce some of the recent research results. 1. Herpetic keratitis cases at the Department of Ophthalmology, Kinki University. There were 129 eyes of 128 patients who visited the Cornea Service in our university hospitals at Osayasayama, Sakai and Nara over 13 years and were diagnosed with herpetic keratitis and followed up for at least one year. They were investigated as to the type of herpetic keratitis at the initial visit and its recurrence. Initial types of herpetic keratitis and number of eyes of each type were: Epithelial type, 65 eyes (50%); Stromal type, 30 eyes (23%); Combined epithelial and stromal types, 18 eyes (14%). Recurrence was seen in 47% of the total 129 eyes. Recurrent cases of the epithelial type were mostly epithelial type. Frequently recurrent cases of the stromal type presented with repeated epithelial, stromal, and combined types. 2. Effects of antiherpetics on mouse epithelial herpetic keratitis. Acyclovir (ACV) eye ointment is usually prescribed for several weeks to treat human epithelial herpetic keratitis. Our question is: Is this long administration really necessary? To find the answer to this question, we investigated time-dependent effects of antiherpetics on mouse epithelial herpetic keratitis. Mouse corneas were infected with HSV-1 and either ACV eye ointment, oral valaciclovir (VACV) or oral famciclovir (FCV) was administered. No virus was detected in the tear fluid examined by viral culture 4 days after start of ACV eye ointment or oral VACV and 6 days after start of oral FCV. Real-time PCR revealed significant decrease of HSV DNA copy number in the eyeball or trigeminal ganglion compared to saline instillation 4 and 6 days after start. These results suggest that antivirals for 5 days could sufficiently decrease the HSV amount in the ocular surface and eyeball. 3. Corneal latency. In order to prove latency of HSV in the human cornea, virological and molecular biological techniques were used to ensure the following 3 prerequisites. 1) Positive HSV DNA in the human cornea. 2) Negative homogenate, positive explant. 3) Only latency-associated transcript (LAT) detected and transcriptional products of other virus genes (α, ß, γ) not detected in the cornea. As a result, all the 3 prerequisites have been satisfied in the 3 corneas that had a past history of herpetic keratitis. This result suggests that HSV could remain latent in the human cornea. 4. Detection of HSV-1, HHV-6, and HHV-7 DNA in the anterior segment and aqueous humor using multiplex real-time PCR. Multiplex real-time PCR was applied for the first time ever in opththalmology to human herpes virus 6 (HHV-6) and 7(HHV-7). Samples taken from tear fluid before and 3 days after phacoemulsification and aspiration (PEA) or penetrating keratoplasty (PKP), and aqueous humor aspirated during PEA were used. The results of multiplex real-time PCR showed HSV-1, HHV-6 and HHV-7 DNA present in tear fluid both before and after PEA or PKP. 5. Gene expression when reactivation is suppressed. Nuclear factor-κB (NF-κB) has recently been reported to be involved in reactivation of HSV-1. IkappaB kinase-ß (IKK2) inhibitors, which inhibit the activity of NF-κB, were used to examine gene expression during HSV reactivation in a mouse model. Significant decrease of HSV DNA copy number was observed at the trigeminal ganglion with real-time PCR in a group which was given IKK2 inhibitors intraperitoneally. Microarray method demonstrated 2-fold or more increased expression of 1812 probe. By Pathway analysis, eased immunosuppressive effects were observed in the group which was given IKK2 inhibitor intraperitoneally. 6. Immunoresponse involved in herpetic keratitis. Chemokine expression profiles in human corneal herpetic cases and mouse herpetic keratitis were analyzed. The results were similar to previously published reports: Cxcl9, Cxcl10, Ccl5, which are Th1 type chemokines, and Ccl20, a Th17 type chemokine, were observed to increase. On the other hand, Th2 type chemokine did not show an increase. Immunoresponse occurred mainly in the trigeminal ganglion. With these results, we suggest herpetic keratitis could be prevented by actively inducing Th17 type immunoresponse.

Microbiota-driven immune cellular maturation is essential for antibody-mediated adaptive immunity to Staphylococcus aureus infection in the eye.

As an immune-privileged site, the eye, and particularly the outer corneal surface, lacks resident mature immune effector cells. Physical barriers and innate mediators are the best-described effectors of immunity in the cornea. When the barriers are breached, infection can result in rapid tissue destruction, leading to loss of visual acuity and frank blindness. To determine the cellular and molecular components needed for effective adaptive immunity on the corneal surface, we investigated which immune system effectors were required for protection against Staphylococcus aureus corneal infections in mice, which are a serious cause of human eye infections. Both systemically injected and topically applied antibodies to the conserved cell surface polysaccharide poly-N-acetylglucosamine (PNAG) were effective at mediating reductions in corneal pathology and bacterial levels. Additional host factors impacting protection included intercellular adhesion molecule 1 (ICAM-1)-dependent polymorphonuclear leukocyte (PMN) recruitment, functional CD4(+) T cells, signaling via the interleukin-17 (IL-17) receptor, and IL-22 production. In germfree mice, there was no protective efficacy of antibody to PNAG due to the lack of LY6G(+) inflammatory cell coeffector recruitment to the cornea. Protection was manifest after 3 weeks of exposure to conventional mice and acquisition of a resident microbiota. We conclude that in the anterior eye, ICAM-1-mediated PMN recruitment to the infected cornea along with endogenous microbiota-matured CD4(+) T cells producing both IL-17 and IL-22 is required for antibody to PNAG to protect against S. aureus infection.

CD11c controls herpes simplex virus 1 responses to limit virus replication during primary infection.

CD11c is expressed on the surface of dendritic cells (DCs) and is one of the main markers for identification of DCs. DCs are the effectors of central innate immune responses, but they also affect acquired immune responses to infection. However, how DCs influence the efficacy of adaptive immunity is poorly understood. Here, we show that CD11c(+) DCs negatively orchestrate both adaptive and innate immunity against herpes simplex virus type 1 (HSV-1) ocular infection. The effectiveness and quantity of virus-specific CD8(+) T cell responses are increased in CD11c-deficient animals. In addition, the levels of CD83, CD11b, alpha interferon (IFN-α), and IFN-ß, but not IFN-γ, were significantly increased in CD11c-deficient animals. Higher levels of IFN-α, IFN-ß, and CD8(+) T cells in the CD11c-deficient mice may have contributed to lower virus replication in the eye and trigeminal ganglia (TG) during the early period of infection than in wild-type mice. However, the absence of CD11c did not influence survival, severity of eye disease, or latency. Our studies provide for the first time evidence that CD11c expression may abrogate the ability to reduce primary virus replication in the eye and TG via higher activities of type 1 interferon and CD8(+) T cell responses.

Role of host-defence peptides in eye diseases.

The eye and its associated tissues including the lacrimal system and lids have evolved several defence mechanisms to prevent microbial invasion. Included among this armory are several host-defence peptides. These multifunctional molecules are being studied not only for their endogenous antimicrobial properties but also for their potential therapeutic effects. Here the current knowledge of host-defence peptide expression in the eye will be summarised. The role of these peptides in eye disease will be discussed with the primary focus being on infectious keratitis, inflammatory conditions including dry eye and wound healing. Finally the potential of using host-defence peptides and their mimetics/derivatives for the treatment and prevention of eye diseases is addressed.

Toll-like receptors in ocular surface diseases: overview and new findings.

The ocular surface is the first line of defence in the eye against environmental microbes. The ocular innate immune system consists of a combination of anatomical, mechanical and immunological defence mechanisms. TLRs (Toll-like receptors), widely expressed by the ocular surface, are able to recognize microbial pathogens and to trigger the earliest immune response leading to inflammation. Increasing evidence highlights the crucial role of TLRs in regulating innate immune responses during ocular surface infective and non-infective inflammatory conditions. In addition, recent observations have shown that TLRs modulate the adaptive immune response, also playing an important role in ocular autoimmune and allergic diseases. One of the main goals of ocular surface treatment is to control the inflammatory reaction in order to preserve corneal integrity and transparency. Recent experimental evidence has shown that specific modulation of TLR pathways induces an improvement in several ocular inflammatory conditions, such as allergic conjunctivitis, suggesting new therapeutic anti-inflammatory strategies. The purpose of the present review is to summarize the current knowledge of TLRs at the ocular surface and to propose them as potential targets of therapy for ocular inflammatory conditions.

The Epithelial Cell Glycocalyx in Ocular Surface Infection.

The glycocalyx is the main component of the transcellular barrier located at the interface between the ocular surface epithelia and the external environment. This barrier extends up to 500 nm from the plasma membrane and projects into the tear fluid bathing the surface of the eye. Under homeostatic conditions, defense molecules in the glycocalyx, such as transmembrane mucins, resist infection. However, many pathogenic microorganisms have evolved to exploit components of the glycocalyx in order to gain access to epithelial cells and consequently exert deleterious effects. This manuscript reviews the implications of the ocular surface epithelial glycocalyx to bacterial, viral, fungal and parasitic infection. Moreover, it presents some ongoing controversies surrounding the functional relevance of the epithelial glycocalyx to ocular infectious disease.

SARS-CoV-2 and the Eye: The Pandora's Box of Ocular Immunology.

The Pandora's box myth addresses the evilness in the world that undisputedly nowadays is identified in severe acute respiratory syndrome (SARS)-Coronavirus 2 (CoV-2), formerly known as Covid-19, which belongs to coronaviridae family, identified in Wuhan, Hubei district of the Republic of China in December 2019. Since then, SARS-CoV-2 has affected ∼180 million people and made almost 4 million victims, with a mortality rate of 6.1%, which is 6 times higher than influenza virus. However, coronaviruses are well known in the ophthalmology field because they were used in the so-called experimental coronavirus retinopathy model. That model certainly brings intriguing concepts for understanding coronavirus pathophysiology, which may have important implications on treatment strategies. Certainly, the recent availability of vaccines gives hope on the control of virus spreading; however, vaccines might create immune reactions involving the eye structure. In this study, we reviewed the literature and elaborated the available data to speculate on possible new interpretation of both pathophysiology and treatment of SARS-CoV-2.

Ocular infection of mice with an avirulent recombinant HSV-1 expressing IL-4 and an attenuated HSV-1 strain generates virulent recombinants in vivo.

PURPOSE: To assess the relative impact of overexpression of interleukin 2 (IL-2), interleukin 4 (IL-4), and interferon gamma (IFN-γ) expressing recombinant herpes simplex virus type 1 (HSV-1) on altering immune responses in ocularly infected mice. METHODS: BALB/c mice were co-infected ocularly with avirulent HSV-1 strain KOS and avirulent recombinant HSV-1 expressing murine IL-4 (HSV-IL-4). Controls mice were co-infected with KOS+HSV-IL-2 or KOS+HSV-IFNγ. Following ocular infection, virus replication in the eye, corneal scarring (CS), and survival were determined. We also isolated recombinant viruses from eye and trigeminal ganglia of KOS+HSV-IL-4 infected mice. RESULTS: In this study we found that ocular infection of BALB/c mice with a mixture of HSV-IL-4 and KOS resulted in increased death and increased eye disease. In contrast, when mice were infected in one eye with KOS and the other eye with HSV-IL-4 no death or eye disease was seen. Intraperitoneal co-infection of mice with KOS and HSV-IL-4 also did not result in HSV-1 induced death. Interestingly, ocular infection of mice with a mixture of HSV-IL-2 and KOS did not have any effect on severity of the disease in infected mice. We isolated recombinant viruses from KOS+HSV-IL-4 infected mice eye and trigeminal ganglia. Some of the isolated viruses were more neurovirulent then either parental virus. Infection of macrophages with IL-4 expressing virus down-regulated IL-12 production by macrophages. CONCLUSIONS: These results suggest a role for IL-4 in suppression of immune response and generation of virulent viruses in vivo.

Experimental oral and ocular Encephalitozoon cuniculi infection in rabbits.

Encephalitozoon cuniculi is an obligate intracellular pathogen that has a wide host distribution, but primarily affects rabbits. The aim of this study was to characterize both the cell-mediated and the antibody response in rabbits after experimental infection using 2 different infection routes: oral and ocular. SPF rabbits were infected with low (10³ spores) and high (107 spores) infection doses. Monitored parameters included clinical signs, detection of spores in urine, antibody response detected with ELISA, and cell-mediated immunity detected by antigen-driven lymphocyte proliferation. At week 13 post-infection, half of the rabbits in each group were suppressed by intramuscular administration of dexamethasone. At week 18 post-infection, animals were euthanized. Clinical signs were mild with exacerbation after immunosuppression. Spores in urine and antigen-specific cell-mediated immunity were detected from weeks 5 and 4 post-infection, respectively. Specific IgM was detected 1 week after infection, and IgG antibodies followed 1 week later in rabbits infected with the high dose. Immunological responses were dose dependent. The authors can conclude that both oral and ocular experimental infection with E. cuniculi resulted in an immune response of the infected animals. Rabbits could be used as an experimental model for the study of ocular microsporidiosis.

Intravitreal infliximab for the treatment of sight-threatening chronic noninfectious uveitis.

PURPOSE: Tumor necrosis factor-alpha is known to play an important role in various immune-mediated ocular diseases. Infliximab, a chimeric monoclonal antibody against tumor necrosis factor-alpha, has been used for the treatment of various chronic systemic and ocular inflammatory diseases. The purpose of this study was to evaluate the effect of intravitreal injection of infliximab on the visual acuity and central macular thickness in patients with chronic noninfectious uveitis. METHODS: Ten eyes of 7 patients with chronic persistent noninfectious uveitis who were nonresponsive to conventional previous medications during the previous 3 months were included in this study. The patients received intravitreal injection of 1.5 mg/0.15 mL infliximab. Mean best-corrected visual acuity and mean central macular thickness 1 day before and 4 weeks after the injection were evaluated and compared. RESULTS: Mean logarithm of the minimum angle of resolution before and after injection was 1.37 ± 0.43 and 0.67 ± 0.56, respectively, with statistically significant improvement after injection (P = 0.005). The mean central macular thickness before and after injection was 673.20 ± 338.39 µm and 456.40 ± 317.46 µm, respectively, with a significant decrease in the central macular thickness after the injection (P = 0.005). CONCLUSION: Intravitreal injection of infliximab may improve the visual acuity and decrease the central macular thickness in patients with chronic noninfectious uveitis and significant visual loss and central macular edema.