Global Transcriptomic Profiling of Innate and Adaptive Immunity During Aspergillus flavus Endophthalmitis in a Murine Model

Purpose

Fungal endophthalmitis is characterized by chronic inflammation leading to the partial or complete vision loss. Herein, we analyzed the transcriptomic landscape of Aspergillus flavus (A. flavus) endophthalmitis in C57BL/6 mice to understand the host-pathogen interactions.

Methods

Endophthalmitis was induced by intravitreal injection of A. flavus spores in C57BL/6 mice and monitored for disease progression up to 72 hours. The enucleated eyeballs were subjected to histopathological analysis and mRNA sequencing using the Illumina Nextseq 2000. Pathway enrichment analysis was performed to further annotate the functions of differentially expressed genes (DEGs) and validation of cytokines was performed in vitreous of patients with fungal endophthalmitis using multiplex ELISA.

Results

Transcriptomic landscape of A. flavus endophthalmitis revealed upregulated T-cell receptor signaling, PI3K-AKT, MAPK, NF-κB, JAK-STAT, and NOD like receptor signaling pathways. We observed significant increase in the T-cells during infection especially at 72 hours infection along with elevated expression levels of IL-6, IL-10, IL-12, IL-18, IL-19, IL-23, CCR3, and CCR7. Furthermore, host-immune response associated genes, such as T-cell interacting activating receptor, TNF receptor-associated factor 1, TLR1, TLR9, and bradykinin receptor beta 1, were enriched. Histopathological assessment validated the significant increase in inflammatory cells, especially T-cells at 72 hours post-infection along with increased disruption in the retinal architecture. Additionally, IL-6, IL-8, IL-17, TNF-α, and IL-1β were also significantly elevated, whereas IL-10 was downregulated in vitreous of patients with Aspergillus endophthalmitis.

Conclusions

Regulating T-cell influx could be a potential strategy to modulate the excessive inflammation in the retina and potentially aid in better vision recovery in fungal endophthalmitis.

Role of IL-36γ/IL-36R Signaling in Corneal Innate Defense Against Candida albicans Keratitis

Purpose

Interleukin (IL)-36 cytokines have been shown to play either beneficial or detrimental roles in the infection of mucosal tissues in a pathogen-dependent manner, but their involvement in fungal keratitis remains elusive. We herein investigated their expression and function in mediating corneal innate immunity against Candida albicans infection.

Methods

Gene expression in mouse corneas with or without C. albicans infection was determined by regular RT- and real-time (q)-PCR, Western blot analysis, ELISA or proteome profile assay. The severity of C. albicans keratitis was assessed using clinical scoring, bacterial counting, and myeloperoxidase (MPO) activity as an indicator of neutrophil infiltration. IL36R knockout mice and IL-33-specific siRNA were used to assess the involvement IL-33 signaling in C. albicans-infected corneas. B6 CD11c-DTR mice and clodronate liposomes were used to define the involvement of dendritic cells (DCs) and macrophages in IL-36R signaling and C. albicans keratitis, respectively.

Results

IL-36γ were up-regulated in C57BL6 mouse corneas in response to C. albicans infection. IL-36 receptor-deficient mice display increased severity of keratitis, with a higher fungal load, MPO, and IL-1β levels, and lower soluble sIL-1Ra and calprotectin levels. Exogenous IL-36γ prevented fungal keratitis pathogenesis with lower fungal load and MPO activity, higher expression of sIL-1Ra and calprotectin, and lower expression of IL-1β, at mRNA or protein levels. Protein array analysis revealed that the expression of IL-33 and REG3G were related to IL-36/IL36R signaling, and siRNA downregulation of IL-33 increased the severity of C. albicans keratitis. Depletion of dendritic cells or macrophages resulted in severe C. albicans keratitis and yet exhibited minimal effects on exogenous IL-36γ-induced protection against C. albicans infection in B6 mouse corneas.

Conclusions

IL-36/IL36R signaling plays a protective role in fungal keratitis by promoting AMP expression and by suppressing fungal infection-induced expression of proinflammatory cytokines in a dendritic cell- and macrophage-independent manner.

Evaluation of Susceptibility and Innate Immune Response in C57BL/6 and BALB/c Mice During Candida albicans Endophthalmitis

Purpose

Candida remains the leading cause of fungal endophthalmitis. However, the pathobiology and innate immune responses in this disease are not well characterized. Here, we developed two murine models of candida endophthalmitis and evaluated their disease susceptibility and differential immune response.

Methods

Endophthalmitis was induced in C57BL/6 (B6) and BALB/c mice by intravitreal injection of Candida albicans (CA). Disease progression was monitored by slit-lamp examination and clinical scoring, followed by retinal function assessment using electroretinography (ERG). Enucleated eyes were used to estimate fungal burden and retinal tissue damage by hematoxylin and eosin and TUNEL staining. The level of inflammatory mediators were determined by quantitative Polymerase Chain Reaction (qPCR) and enzyme-linked immunosorbent assay, whereas neutrophil infiltration was assessed by flow cytometry and immunostaining.

Results

Intravitreal injection of CA at 6500 colony-forming units resulted in sustained (non-resolving) ocular inflammation in both B6 and BALB/c mice as evidenced by increased levels of inflammatory cytokines (tumor necrosis factor-α, interleukin-1β, and interleukin-6) and chemokine (CXCL2/MIP-2). In both mouse strains, fungal burden peaked at 24 to 48 hours post-infection (hpi) and decreased by 72 to 96 hpi. CA-infected eyes exhibited increased polymorphonuclear neutrophils (PMN) infiltration and retinal tissue damage. Overall retinal function declined rapidly, with a significant reduction in ERG response at 12 hpi and near-total loss by 24 hpi. Differential analyses revealed increased pathology in BALB/c versus B6 mice.

Conclusions

C. albicans was able to cause endophthalmitis in mice. Although BALB/c mice were found to be more susceptible to CA endophthalmitis, both BALB/c and B6 models could be used to study fungal endophthalmitis and test therapeutic modalities.

Regulatory effect of caspase-11 on interleukin-1β in the fungal keratitis

Caused by fungus, fungal keratitis is a kind of infections corneal disease with high rate of blindness, which patients are mainly farmers in developing countries. Interleukin, as important proinflammatory cytokines, involve in immune defense process against fungal infection of cornea. The expression of interleukin in the pathogenesis of fungal keratitis, especially the main source of its cells, is not clear and the cell signaling pathways which regulate the synthesis and modification of interleukin is still unknown. Caspase-11 was obtained and cultured. And the ELISA and Western-blot methods were used to explore the regulatory effect of Caspse-11 on Interleukin-1β in the fungal keratitis. neutrophils were the main cell lineage of IL-1β to take part in the innate anti-fungi immunity in the cornea; IL-1β generation induced by fungal infection might not be through the pre-excitation in the classical signal pathway; TLR4/TRIF pathway was not involved in pro-IL-1β generation; while Dectin-1/syk pathway was involved in IL-1β generation in the fungal keratitis; Caspase-l participated in the modification of IL-1β to change from the precursor into the mature body; but NLRP3 inflammasome and ASC inflammasome were not involved in IL-1β generation; Caspase-11 was involved in IL-1β generation through regulating the modified process of Caspase-l to turning from precursor into mature body. TLR4/TRIF pathway and NLRP3 inflammasome and ASC inflammasome are not involved in the pro-IL-1β generation, while Caspase-l, Caspase-11 and Dectin-1/syk pathway are involved in the IL-1β generation.

[Signal transduction pathways mediated by Toll-like receptors and their relations with fungal keratitis]

Toll-like receptors (TLRs) were identified as transmembrane signal transduction proteins in recent years. As a group of pattern recognition receptors (PRRs), TLRs play important roles in the innate immunity by recognizing pathogen-associated molecular patterns (PAMPs). Activated innate immunity subsequently leads to effective adaptive immunity. It, thereby, activities not only innate but ultimately also adaptive immunity. It has been reported that some kinds of TLRs expressed in corneal epithelial cells, stroma cells and endothelial cells. In addition to their recognition function, TLR activation triggers a complex signal transduction cascade that induces the production of inflammatory cytokines and co-stimulatory molecules, thus initiating innate and adaptive immunity. And TLRs play an important role in innate and adaptive immunity of fungal keratitis. In summary, further studies on the regulation of intracellular signaling transduction will contribute significantly to our understanding of immunoregulation of fungal keratitis, eventually provide some way to cure the fungal infection.

[Mechanism of the immune response to keratomycosis]

Immune system played an important role in recognition and elimination of fungal pathogens. The balance between host factors and fungal pathogens can influence the prognosis of disease. As located on the surface of the eyeball. It was easy for cornea to be attracted by pathogens when traumatic injury occur. Moreover, cornea had characters of transparency and vascularization, which keep it on immune privilege situation relatively. The progress in the study of the mechanism of immunity participating in the keratomycosis and ways of fungus escaped from the attract of immune system was reviewed.

Elevated serum beta-D-glucan level and depressed neutrophil phagocytosis in a heatstroke patient

Endotoxemia has been reported as a mechanism for the fatal sequela after heatstroke. Subsequent disseminated fungal infection in a heatstroke patient has been also described. Beta-D-glucan, a constituent of the fungal cell wall, is an early diagnostic measure for fungal infection. In a heatstroke case, we examined for the first time levels of serum beta-d-glucan and endotoxin. A 34-year-old man with a body temperature of 43.5 degrees C was admitted in a state of shock. Prior to the development of disseminated intravascular coagulopathy (DIC), a remarkable elevation of serum beta-D-glucan level to 116 pg/mL (normal level<6.0 pg/mL) was revealed on the first day of admission. However, serum endotoxin was not detected when using a method that excluded beta-D-glucan contamination from endotoxin measurement (normal level<1.0 pg/mL). This change of beta-D-glucan level was accompanied by a depressed neutrophil function, especially in phagocytosis of 34% (normal range 70-90%) but not in bacterocidal function (81% versus a normal range of 70-100%). After intensive care including continuous hemodiafiltration, the patient regained consciousness but remained ataxic due to cerebellar infarction, which might have resulted from DIC, and subsequent bilateral fungal oculitis were revealed 45 days after admission. This case report demonstrates the elevation of serum beta-D-glucan but normal endotoxin levels after heatstroke, which may prompt further study to re-examine the serum levels of endotoxin in such catastrophic insults.

Photodynamic therapy for inflammatory choroidal neovascularisation unresponsive to immunosuppression

AIM

To report on visual and angiographic outcomes of a consecutive series of patients with inflammatory choroidal neovascular membranes (CNV) unresponsive to systemic immunosuppression treated with photodynamic therapy (PDT).

METHODS

The medical records of six consecutive patients with inflammatory CNVs that failed to respond to systemic immunosuppression and that later underwent PDT were retrospectively reviewed. Patient demographics, visual acuity, and fluorescein angiographic findings were evaluated.

RESULTS

There were five females and one male with a mean age of 40.8 years (range 35-58 years). Four patients had clinical features consistent with punctate inner choroidopathy and two with presumed ocular histoplasmosis. In all cases clinical signs of CNV activity, including subretinal fluid, subretinal blood, hard exudates, and/or recent decrease in visual acuity were present prior to PDT. All patients had been treated with high dose systemic immunosuppressants, which failed to induce regression of the CNV and/or to improve vision. The CNVs were subfoveal in five patients and juxtafoveal in one; all were classified as predominantly classic. Following PDT an improvement in vision occurred in all cases (median improvement of 18 letters, range 3-42 letters). At last follow up, signs of decreased activity in the CNV were detected in all cases. Patients were followed for a median of 10 months (range 9-20 months).

CONCLUSION

PDT appears to be a useful option in the management of patients with inflammatory CNVs unresponsive to immunosuppressive therapies.

Immunosuppression Affects the Severity of ExperimentalFusarium solaniKeratitis

We have established a mouse model of corneal fusariosis that permits the evaluation of fungal infection and pathogenesis. Corneas of immunocompetent and cyclophosphamide-treated adult BALB/c mice were topically inoculated with Fusarium solani after corneal scarification. Eyes were scored for corneal involvement daily for 8 days and at 2 weeks after infection. Eyes were enucleated at various time points for quantitative fungal recovery and histopathological examination. An inoculum-dose response was observed in cyclophosphamide-treated mice, and fungi were recovered from the infected eyes by quantitative microbial culturing. Treatment with cyclophosphamide increased disease severity and delayed fungal clearance. Fungal hyphae, inflammatory cells, and stromal edema were histologically evident within corneal tissue and correlated with disease severity. Although the mouse cornea resists fungal infections, F. solani keratitis could be induced in immunosuppressed mice after surface scarification, which resulted in infection and clinical disease that could be evaluated both in vivo and in vitro.

No apparent association between periocular and ocular microcolonization and the degree of inflammation in patients with atopic keratoconjunctivitis

BACKGROUND

The cause of the chronic inflammation in atopic keratoconjunctivitis (AKC), the ocular manifestation of atopic eczema/dermatitis syndrome, is largely unknown.

OBJECTIVE

To investigate the possibility that microorganisms may be important in the inflammatory activity in AKC.

METHODS

Fifteen patients with AKC participated in the study. The presence of aerobic bacteria and fungi was related to the severity of clinical signs, the numbers of inflammatory cells in tears and conjunctival biopsies, and the concentration of various cytokines in tears. In addition, serological evidence for IgE sensitization to Staphylococcus aureus B antigen and Malassezia sympodialis antigen was investigated. Twelve healthy subjects were included for control purposes.

RESULTS

The patients exhibited moderate clinical signs of AKC. No relation was found between the severity of AKC and the presence of microorganisms, despite the fact that S. aureus was frequently isolated. AKC patients showed significantly higher levels of IFN-gamma, TNF-alpha (tumour necrosis factor-alpha), IL-2, IL-4, IL-5 and IL-10 than controls. An association was found between conjunctival signs and the levels of all cytokines except IL-5.

CONCLUSION

We found no evidence to suggest that periocular and ocular microcolonization are related to inflammatory parameters in AKC. However, confirmation of the present results in a longitudinal study with repeated clinical examinations and samplings in the same individual is required before the contribution of S. aureus to on-going inflammation in AKC can be dismissed.

[A study of total IgE in inflammatory pathologies of the eye anterior segment]

The paper contains data on comparative research of the IgE content in blood serum and lachrymal fluid in patients with ophthalmoherpes and with other inflammatory diseases of the eye. A higher IgE level was found in blood serum and lachrymal fluid in cases of ophthalmoherpes as well as in lachrymal fluid in cases of allergic, Chlamydia and fungus diseases of the eye. The data obtained can be used in the diagnostics of allergic eye diseases as well as in elaborating complex treatment methods for herpetic, Chlamydia and fungus lesions of the anterior eye segment. A detection of the local allergenic effect of acaricide drugs exerted on the conjunctiva and eyelids makes it obligatory to consider the above fact while treating patients with demodectic blepharoconjunctivitis.

Aetiological study of the presumed ocular histoplasmosis syndrome in the Netherlands

AIM

To investigate whether presumed ocular histoplasmosis syndrome in the Netherlands is caused by Histoplasma capsulatum and whether other risk factors might play a role in the pathogenesis of this syndrome.

METHODS

23 patients were clinically diagnosed as having presumed ocular histoplasmosis syndrome based on the following criteria: peripapillary atrophy, punched out lesions, a macular disciform lesion or scar in one eye without vitritis. As controls, 66 sex and age matched healthy volunteers were used. Serum samples from both patients and controls were tested for the presence of antibodies against H capsulatum, Toxoplasma gondii, Toxocara canis et cati, Ascaris sp, and for the presence of antigens of Cryptococcus neoformans. Serum samples were also tested for the presence of autoantibodies against retinal or choroidal proteins. To investigate other risk factors, patients and controls were asked to fill in a health and travel related questionnaire. Ten patients with ocular toxoplasmosis were used as a disease control group.

RESULTS

None of the patients with presumed ocular histoplasmosis syndrome or controls had circulating antibodies directed against H capsulatum. No risk factors could be identified and no indications for autoimmunity and no evidence for the role of the other infectious agents could be demonstrated.

CONCLUSIONS

In a Dutch group of patients fulfilling the criteria of a disease currently named presumed ocular histoplasmosis syndrome, no risk factors or relation with the fungus H capsulatum could be detected.

Histoplasmosis-like choroiditis in a nonendemic area: the northwest United States

PURPOSE

Histoplasmosis is not endemic in the U.S. northwest, but a type of multifocal choroiditis resembling ocular histoplasmosis occurs there. This study was designed to find a group of affected patients and study their clinical characteristics and immunologic responses to Histoplasma antigens.

METHOD

Ten patients were found in the authors' files whose geographic histories made it unlikely that they had ever been exposed to Histoplasma capsulatum and yet they had features of ocular histoplasmosis. They were recalled for examination and testing by lymphocyte-stimulation assay for previous exposure to histoplasmosis.

RESULTS

The clinical features of these patients resembled those of patients with ocular histoplasmosis, but their histories and the results of the assay did not support H. capsulatum as the cause of the ocular disease.

CONCLUSION

This study confirmed that there is a type of choroiditis that resembles ocular histoplasmosis but is due to another agent or agents.

Search for extrapulmonary Pneumocystis carinii in an animal model

Pneumocystis carinii-infected immunosuppressed ferrets and rats were searched for P. carinii cysts and trophozoites in extrapulmonary organs, including the heart, liver, stomach, kidney, and spleen. Foci of P. carinii were found in the liver or kidney of 4 (10%) of 40 ferrets but in no extrapulmonary sites of 30 rats with P. carinii pneumonitis. Attempts to identify P. carinii from immunosuppressed rat or ferret blood or propagate the organism intraorbitally in immunosuppressed rats were unsuccessful. Pneumocystis carinii was identified from aspirated stomach contents of ferrets but in none of the rats infected with P. carinii pneumonitis.

Ocular and disseminated candidiasis in an immunosuppressed cat

Ocular and systemic candidiasis was diagnosed in an immunosuppressed and diabetic 12-year-old cat that initially was examined because of polyuria, polydipsia, and urinary tract disease. Bilateral recurrent corneal erosions and chorioretinitis, urinary tract infections attributable to bacteria or Candida sp, and renal dysfunction developed during the next 2 months. Examination of corneal scrapings revealed spherical to oval, budding, yeast-like cells. The cat's condition progressively deteriorated, and it was euthanatized. Toxoplasmosis was diagnosed by fecal flotation and from serum titers, and pituitary-dependent hyperadrenocorticism was detected at postmortem histologic evaluation. Candida budding yeasts and pseudohyphae with blastospores were detected in the corneas, vitreous bodies, retinas, CNS, pharynx, trachea, esophagus, kidneys, and urinary bladder at postmortem examination.

The syndrome of presumed ocular histoplasmosis in Mexico: a preliminary study

A study to screen for the syndrome of presumed ocular histoplasmosis (SPOH) among native populations from three Mexican states was performed. Two of these states, Guerrero and Querétaro, were selected as histoplasmosis is endemic there, whereas Tlaxcala was considered a control, due to the absence of reported cases. A total of 253 individuals were submitted to ocular fundus examination to obtain evidence of SPOH. A high percentage of positive reactors to histoplasmin skin test (ST) was observed in Guerrero (83%) and Querétaro (53%), whereas in Tlaxcala positive ST were almost absent (2.04%). Only five individuals had retinal lesions, although these lesions were not characteristic of the syndrome. Stimulation of these individual's cells showed different patterns in the histoplasmin-induced lymphocyte transformation response, and two out of five individuals with retinal lesions presented a stimulated response, as well as three controls without lesions. Histocompatibility antigens (HLA) were determined in a sample of each population and no particular allele, including HLA-B7, was found to be related to SPOH as reported in the USA; however, HLA-B22 was found in three individuals who developed pulmonary histoplasmosis. Results do not provide clinical evidence or data on specific HLA risk factors, for the presence of SPOH in the population studied.

Immunopathology of reactivation of experimental ocular histoplasmosis

We have established a non-human primate model of experimental ocular histoplasmosis. This model has been shown to result in chronic lesions that resemble typical 'histo spots' or choroidal scars but that contain infiltrates of lymphocytes for as long as 10 yr following intracarotid injection of live Histoplasma capsulatum. Using this model, we attempted to reactive these late choroidal lesions via intracarotid challenge with specific antigen (heat-killed H. capsulatum). No clinical changes suggestive of reactivation of these lesions were observed following this antigenic challenge. However, immunopathologic analysis of choroidal lesions at 1, 3 and 7 days after antigenic challenge revealed significant increases in both the numbers of inflammatory cells and the relative percentages of the helper/inducer lymphocyte and macrophage populations. Our results demonstrate that, following antigenic challenge, a cellular change, consistent with a type IV delayed hypersensitivity, can be observed in previously active, but clinically quiescent, histoplasmosis lesions. In light of the many parallels between our primate experimental model and human ocular histoplasmosis, our findings suggest that, in the human, significant immunopathologic activity may occur subclinically in the choroid of affected individuals. It is possible that repeated bouts of subclinical reactivation may induce or enhance chronic choroiditis and, over many years, ultimately produce slow progressive damage to the Bruch's membrane/retinal pigment epithelium complex, resulting in clinically 'active' macular disease and, in selected cases, subretinal neovascularization.

Endogenous Aspergillus endophthalmitis in an immunocompetent individual

We present an unusual case of Aspergillus fumigatus endogenous endophthalmitis in a 27 year old Hispanic male with no history of ocular trauma, surgery, hematologic malignancy, compromised immune system, or intravenous drug use. The patient presented with a two-day history of pain, redness, and visual acuity of bare count fingers in his right eye. He was originally suspected of having toxoplasmic retinochoroiditis, but clinically worsened on systemic anti-toxoplasma medication and corticosteroids. He subsequently underwent pars plana vitrectomy and treatment with intravenous and intravitreal amphotericin B. Aspergillus fumigatus was isolated and identified in the vitreous aspirate. With aggressive medical and surgical management, he eventually regained visual acuity of 20/30 in his right eye. This case illustrates the occurrence of endogenous Aspergillus endophthalmitis in a patient with no history of intravenous drug use, ocular trauma, or compromised immune system, and successful outcome with combined medical and surgical management.

Pneumocystis carinii and Mycobacterium avium-intracellulare infection of the choroid

It has been hypothesized that coinfection with mycobacteria occurs in patients with Pneumocystis carinii choroiditis, but cases demonstrating ocular infection by both organisms have not been reported. This study reports the case of a patient with P. carinii choroiditis who was treated with intravenous trimethoprim and sulfamethoxazole, followed by intravenous trimethoprim and dapsone. The choroidal lesions failed to resolve despite 6 weeks of treatment, and the patient died from massive pulmonary infection caused by P. carinii, Mycobacterium avium-intracellulare, and cytomegalovirus infections. Ocular histologic and electron microscopic examinations revealed choroidal infection by both P. carinii and M. avium-intracellulare. Serum levels of sulfamethoxazole were below the recommended therapeutic range for treating P. carinii infection during the first week of therapy, but adequate drug levels were subsequently obtained. Failure of choroidal lesions of P. carinii to resolve in some cases may suggest insufficient antimicrobial levels in the blood or raise the possibility of coexistent M. avium-intracellulare or other opportunistic infection.

Serum and tear immunoglobulins in bacterial, fungal and viral corneal ulcers

Serum and tear IgA, IgG and IgM levels were studied in patients with bacterial, fungal and viral corneal ulcers. In patients with viral corneal ulcers serum IgA and IgG levels were found to be significantly raised, while IgM concentration remained unaltered. In bacterial and mycotic ulcerations, serum IgA, IgG and IgM levels remained unaltered. All three immunoglobulins were found to be raised in tears of patients with viral corneal ulcers, while only IgA levels were found to be increased in bacterial and mycotic ulcerations.