Infectious agents and pathogenesis of Behçet's disease: An extensive review

Behçet's disease (BD) is a multisystemic chronic vasculitis. Sustained and enhanced immune responses were reportedly associated with active BD. Although genetic polymorphisms increase development risk, genetic factors alone cannot account for BD development, suggesting the involvement of exogenous factors. Also, how various infectious agents promote BD in high-risk populations is not fully understood. In this review, we summarized the current findings on the associations of infectious agents with BD pathogenesis. The review also highlights the potential microbial risk factors and their pathogenic role in BD progression. Interactions between genetic and infectious risk factors was also discussed. Furthermore, evidence implied that after the eradication of infectious agents, BD symptoms and recurrence decreased, thus highlighting that combined use of antibiotics may be an effective therapy for BD. Finally, we summarized the main limitation of the current related studies, providing valuable insights and a basis for future studies on BD pathogenic factors.

Microbiome in Immune-Mediated Uveitis

In the last decades, personalized medicine has been increasing its presence in different fields of medicine, including ophthalmology. A new factor that can help us direct medicine towards the challenge of personalized treatments is the microbiome. The gut microbiome plays an important role in controlling immune response, and dysbiosis has been associated with immune-mediated diseases such as non-infectious uveitis (NIU). In this review, we gather the published evidence, both in the pre-clinical and clinical studies, that support the possible role of intestinal dysbiosis in the pathogenesis of NIU, as well as the modulation of the gut microbiota as a new possible therapeutic target. We describe the different mechanisms that have been proposed to involve dysbiosis in the causality of NIU, as well as the potential pharmacological tools that could be used to modify the microbiome (dietary supplementation, antibiotics, fecal microbiota transplantation, immunomodulators, or biologic drugs) and, consequently, in the control of the NIU. Furthermore, there is increasing scientific evidence suggesting that the treatment with anti-TNF not only restores the composition of the gut microbiota but also that the study of the composition of the gut microbiome will help predict the response of each patient to anti-TNF treatment.

The Impact of COVID-19 on Conjunctival Flora

Purpose: This study aims to evaluate the effect of coronavirus disease 2019 (COVID-19) on conjunctival flora in patients hospitalized with COVID-19.Methods: This prospective, controlled study was conducted between June 2020 and December 2020. The study group consisted of 45 confirmed COVID-19 patients and 43 control subjects. The collected samples were inoculated into the Thioglycollate broth media without delay. The samples with growth were then passed on eosin methylene blue agar, sabouraud dextrose agar, chocolate agar, and 5% sheep blood agar solid media.Results: The mean age of the COVID-19 patients was 64.24 ± 15.4 years, and the control subjects were 59.72 ± 11.4 years. The culture positivity of conjunctiva samples in COVID-19 patients (95.6%) was statistically significantly higher than control subjects (76.7%) (p = .024). Coagulase-negative staphylococcus and Staphylococcus aureus' positivity was significantly higher in COVID-19 patients than control subjects (p < .05).Conclusion: Patients with COVID-19 demonstrate significantly higher culture positivity on conjunctival flora than the control subjects.

Ocular Surface Microbiome in Health and Disease

The ocular surface is exposed continuously to the environment and, as a consequence, to a variety of different microbes. After the results of the Human Microbiome Project became publicly available, international research groups started to focus interest on exploring the ocular surface microbiome and its physiopathological relationship to the eye. For example, numerous research studies the existence of the ocular surface's bacterial flora, typically gathering cultures from healthy patients and finding few variations in the bacterial species. More recently, culture-independent methods, including 16S ribosomal ribonucleic acid (rRNA) gene sequencing, are being used to define the ocular microbiome. These newer methods suggest that the microbial communities have a greater diversity than previously reported. These communities seem to serve an immune-modulating function and maintain relationships with other microbes and organs, even distant ones. This review summarizes the literature exploring the ocular microbiome, both in health and in different diseases.

In vitro adherence of conjunctival bacteria to different oculoplastic materials

AIM

To investigate the resistance to bacterial adhesion of materials used in oculoplastic surgery, particularly materials used in the manufacture of orbital implants.

METHODS

Seven organisms of conjunctival flora (two strains of Staphylococcus epidermidis and one strain each of Staphylococcus aureus, Staphylococcus hominis, Corynebacterium amycolatum, Acinetobacter calcoaceticus, and Serratia marcescens) were selected. A lactic acid bacterium (Lactobacillus rhamnosus) was also included as positive control because of its well-known adhesion ability. Eight materials used to make oculoplastic prostheses were selected (glass, steel, polytetrafluoroethylene, polymethylmethacrylate, silicone from orbital implants, commercial silicone, porous polyethylene, and semi-smooth polyethylene). Materials surfaces and biofilms developed by strains were observed by scanning electron microscopy. Kinetics of growth and adhesion of bacterial strains were determined by spectrophotometry. Each strain was incubated in contact with plates of the different materials. After growth, attached bacteria were re-suspended and colony-forming units (CFUs) were counted. The number of CFUs per square millimetre of material was statistically analyzed.

RESULTS

A mature biofilm was observed in studied strains except Staphylococcus hominis, which simply produced a microcolony. Materials showed a smooth surface on the microbial scale, although steel exhibited 1.0-µm-diameter grooves. Most organisms showed significant differences in adhesion according to the material. There were also significant differences in the total number of CFUs per square millimetre from each material (P=0.044). CFU counts were significantly higher in porous polyethylene than in silicone from orbital implants (P=0.038).

CONCLUSION

Silicone orbital implants can resist microbial colonization better than porous polyethylene implants.

Elevated expression of TSLP and IL-33 in Behçet's disease skin lesions: IL-37 alleviate inflammatory effect of TSLP

The release of TSLP and IL-33 affect the skin integrity, which unsettled transcription factor regulators. We investigate TSLP and IL-33 in Behçet disease (BD) and we prove the effect of the anti-inflammatory cytokine IL-37 in BD skin lesions on TSLP production. TSLP, IL-33 and GATA-3/T-bet, were measured using PCR in BD skin lesions. We tested the suppressive effect of IL-37 on skin samples stimulated with a cytokine mixture inducing TSLP expression. TSLP and IL-33 were increased in BD patients particularly in patients having skin manifestations and correlate with indexed skin lesions. TSLP expression in BD with skin lesions correlates significantly with the transcription factors GATA3/Tbet ratio. The anti-inflammatory mediator IL-37 acted as a suppressor of TSLP-skin synthesis. The microenvironment in cutaneous lesions of BD patients' skin lesions is dominated by the expression of IL-33 and TSLP along an inflammatory Th2-type current. IL-37 acts as a booster to restore homeostasis.

Conjunctival Cytological Alterations in Ocular Behçet Disease

PURPOSE

To evaluate the ocular surface alterations and tear film functions in patients with ocular Behçet disease (BD).

METHODS

This study included 48 eyes of 48 patients with inactive BD and a control group of 33 age- and sex-matched subjects. Schirmer I and tear break-up time (TBUT) tests were used to evaluate the tear film of the subjects. Impression cytology was used to evaluate morphological changes of the conjunctival surface epithelial cells.

RESULTS

The mean Schirmer I test result was 11.6 ± 5.9 mm/5 minutes and 16.1 ± 4.6 mm/5 minutes in the Behçet and control groups, respectively. The mean TBUT test result was 9.8 ± 5.6 seconds and 13.2 ± 5.7 seconds in the study and control groups, respectively. The Schirmer and TBUT test results were significantly lower in the study group than in the controls (P = 0.001 and P = 0.011, respectively). The mean impression cytology score was 1.3 ± 0.9 in the study group and significantly higher than the control group value of 0.4 ± 0.6 (P = 0.001).

CONCLUSIONS

Tear film functions and conjunctival surface epithelial morphology were significantly altered in patients with ocular BD.

Microbial flora and resistance in ophthalmology: a review

Antibiotic resistance in systemic infection is well-researched and well-publicized. Much less information is available on the resistance of normal ocular microbiome and that of ophthalmic infections. An understanding of the distribution of ocular microorganisms may help us in tailoring our empiric treatment, as well as in choosing effective pre-, peri- and postoperative management, to achieve the best results for patients. This study aims to summarize and review the available literature on the subject of normal ocular flora and its resistance, as well as the broader topic of antibiotic resistance in ophthalmology.

Behcet’s disease: from heat shock proteins to infections

Background: Behcet’s disease (BD) is a chronic, inflammatory multisystemic condition of unknown etiology. Although the cause of BD is not clear, it is believed to be the result of an autoimmune process triggered by an infectious or environmental agent (possibly local to a geographic region) in a genetically predisposed individual.

Objective: To detail current knowledge of the role of microorganisms in the pathogenesis of BD and review the infectious etiology of this disease.

Methods: The review based on publication in SCOPUS, Science direct, and PubMed.

Results: A microbial infection has been implicated in the development of the disease to explain the strong inflammatory reactions observed, the activation of monocytes and macrophages, and the induction of proinflammatory cytokines and chemokines detected. Common factors linking some of the possible pathogenetic agents are extrinsically induced tissue stress or heat shock proteins, which react with host tissues and elicit significant T-helper type 1 cell responses.

Conclusion: Based on collected data, we conclude that the microorganisms discussed seem to participate and, at least in part, act as triggers during the course of BD. By clarifying the microbial associations of BD and finding its etiology, particularly the causative antigens leading to BD, it would be easier to suggest more effective treatment and preventive strategies for this disease.

The Effect of Chronic Alcoholism on the Conjunctival Flora

AIM

We aimed to investigate the effect of alcohol abuse on the conjunctival flora.

MATERIALS AND METHODS

The cases were evaluated as two groups. The study group consisted of 55 heavy-drinking males diagnosed with alcohol abuse, while the control group consisted of 55 males without a history of alcohol abuse. Samples were taken from the inferior fornix conjunctiva with sterile cotton-tipped swabs (Amies transport medium) for culture. The samples were inoculated into blood agar, chocolate agar, eosine methylene blue agar and Saboraud-Dextrose agar (Oxoid/UK) with the dilution method.

RESULTS

The microorganisms that grew in study group subjects were Coagulase Negative Staphylococcus (CNS) in 30 (54.5%), Staphylococcus aureus in 14 (25.5%), Moraxella spp. in 3 (5.5%), Streptococcus spp. in 3 (5.5), Bacillus spp. in 3 (5.5%), Corynebacterium spp. in 3 (5.5%), Candida spp. in 3 (5.5%), Haemophilus spp. in 2 (3.6%), Acinetobacter spp. in 2 (3.6%), Neisseria spp. in 1 (1.8%) and Micrococcus spp. in 1 (1.8%). The results for control group were CNS in 31 (56.4%), Bacillus spp. in 7 (12.7%), S. aureus in 5 (9.1%), and Corynebacterium spp. in 2 (3.6%). Moraxella spp., Streptococcus spp., Candida spp., Haemophilus spp., Acinetobacter spp., Neisseria spp. and Micrococcus spp. microorganisms grew in the conjunctival flora samples of the study group but not in the control group. S. aureus colonization was significantly higher in the study group than the control group (p < 0.05).

CONCLUSION

The S. aureus colonization rate was statistically significantly higher in the study group. Some microorganisms only grew in the conjunctival flora samples of the study group. These findings indicate that the conjunctival flora in persons with chronic alcoholism is different than the normal population.

The oral mucosal and salivary microbial community of Behçet's syndrome and recurrent aphthous stomatitis

Background

Behçet's syndrome (BS) is a multisystem immune-related disease of unknown etiology. Recurrent aphthous stomatitis (RAS) is characterized by the presence of idiopathic oral ulceration without extraoral manifestation. The interplay between the oral microbial communities and the immune response could play an important role in the etiology and pathogenesis of both BS and RAS.

Objective

To investigate the salivary and oral mucosal microbial communities in BS and RAS.

Methods

Purified microbial DNA isolated from saliva samples (54 BS, 25 healthy controls [HC], and 8 RAS) were examined by the human oral microbe identification microarray. Cultivable salivary and oral mucosal microbial communities from ulcer and non-ulcer sites were identified by matrix-assisted laser desorption/ionization time-of-flight analysis. Mycobacterium spp. were detected in saliva and in ulcer and non-ulcer oral mucosal brush biopsies following culture on Lowenstein-Jensen slopes and Mycobacterial Growth Indicator Tubes.

Results

There was increased colonization with Rothia denticariosa of the non-ulcer sites of BS and RAS patients (p<0.05). Ulcer sites in BS were highly colonized with Streptococcus salivarius compared to those of RAS (p<0.05), and with Streptococcus sanguinis compared to HC (p<0.0001). Oral mucosa of HC were more highly colonized with Neisseria and Veillonella compared to all studied groups (p<0.0001).

Conclusions

Despite the uncertainty whether the reported differences in the oral mucosal microbial community of BS and RAS are of causative or reactive nature, it is envisaged that restoring the balance of the oral microbial community of the ulcer sites may be used in the future as a new treatment modality for oral ulceration.

Comparison of aerobic conjunctival bacterial flora in pregnant, reproductive-aged and postmenopausal women

AIM

To evaluate the effect of hormonal status on aerobic conjunctival flora in women.

METHODS

One hundred fifty-eight women [reproductive-aged (n=55), pregnant (n=51), and postmenopausal (n=52)] who admitted to outpatient clinic of Obstetrics and Gynecology Department of Denizli State Hospital were enrolled. Age, body-mass index (BMI), obstetric history, cigarette smoking, drug usage, presence of systemic disease, and intraocular pressure (IOP) were recorded for each patient. The samples were taken from the lower fornix with two culture swabs and directly incubated in culture containing 5% sheep blood, eosin-methylene blue and chocolate agar. The other swab specimen was Gram stained. All growths and microscopic results were analyzed.

RESULTS

The coagulase-negative Staphylococcus was the predominant organism isolated in the conjunctival samples in both three groups. The aerobic microorganism growth rate for all isolated aerobic organisms revealed no significant change in the three groups (P >0.05). The conjunctival culture positivity rates were similar in the three groups (49% in reproductive-aged, 57% in pregnant and 58% in postmenopausal women) (P >0.05). Age, IOP, BMI, gravidity, parity, cigarette smoking, drug usage, and presence of systemic diseases did not have an effect on culture positivity in three groups.

CONCLUSION

Results of this study showed that conjunctival aerobic flora and bacterial colonization did not differ between reproductive-aged, pregnant and postmenopausal women.

The possible role of HSPs on Behçet's disease: a bioinformatic approach

Current evidence lends increasing support to immunoinflammatory mechanisms as one of the prime pathogenic processes involved in the development and progression of Behçet's disease (BD). It has been observed that most human beings have cellular and humoral reactions against microbial heat shock proteins (HSPs). The observation that eukaryotic and prokaryotic HSPs have high sequence similarity promoted the hypothesis that HSPs might be potential candidates for molecular mimicry and could act as potentially dangerous autoantigens. In this study, using bioinformatics tools, we examined the hypothesis that HSPs (evolutionarily conserved proteins), which are present in pathogenic and commensal organisms and their hosts, provide the stimulus that initiates BD in susceptible individuals. In this regards, the nucleotide and amino acid sequences of the human HSP 60 kDa and bacterial HSP 60 kDa deposited in the NCBI and PDB databases were subjected to analysis using bioinformatics tools, including The CLC Sequence Viewer and MEGA softwares. These data showed that the sequence homology between bacterial and self HSPs (leading to cross-reactivity and molecular mimicry phenomenon) may be associated with the development of the disease; and suggesting that microbial HSPs, which cross-react with host tissues and elicit significant immune responses are possible pathogenetic agents involved in the development and progression of BD.

Conjunctival microbial florae in patients with seriously sulfur mustard induced eye injuries

INTRODUCTION

Ocular surface disorders and infections in sulfur mustard (SM) exposed patients are of particular clinical importance. The aim of the present study is to detect the conjunctival bacterial florae in patients with seriously SM induced eye injuries.

MATERIALS AND METHODS

Conjunctival bacterial florae of 143 seriously eye injured subjects as the study group was detected. The results were compared with 26 normal participants. Both groups were matched in age and sex. The samples were taken by sterile swab from interior fornixes of conjunctiva in both groups and were transported to microbiology laboratory by Stuart's Transport Medium. All samples were inoculated onto Blood agar, Mac Conkey agar and Chocolate agar and isolated microorganisms were identified by biochemical tests. The data were analyzed by SPSS and Man Whitney tests.

RESULTS

Nineteen cases (13.39%) and none of the controls (0%) had positive culture results (p = .043). Isolated microorganisms from patients included coagulase-negative staphylococci 10 cases (52.6%), Staphylococcus aureus 5 cases (26.3%), non enterobacteriaceae gram negative bacilli 2 cases (10.5%), Penicillium spp. 2 cases (10.5%), Citrobacter sp. 1 case (5.2%), non-spore forming Gram positive bacillus 1 case (5.2%) and α hemolytic streptococcus 1 case (5.2%). Two patients had mixed microorganisms and other patients had just one microorganism. Most of the S. aureus isolates were sensitive to usual antibiotics.

CONCLUSIONS

The results of this study showed that the prevalence rate of conjunctival bacterial isolates in patients with seriously SM induced ocular injuries are higher and potentially more dangerous than normal controls.