Acanthamoeba Keratitis

Chynn, Emil; Lopez, Miguel; Pavan-Langston, Deborah; Talamo, Jonathan H.

doi:10.1016/s0161-6420(95)30862-7

Cited by 43 publications

(8 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Acanthamoeba are the causative agents of life-threatening granulomatous amoebic encephalitis (GAE) in immunocompromised patients (Jones et al, 1975;Martinez, 1987;Di Gregorio et al, 1992;Friedland et al, 1992;Gonzalez et al, 1986;Gordon et al, 1992) and a common amoebic keratitis, a sight-threatening disease of the eye, which is mostly associated with contact-lens use (Chynn et al, 1995;Moore & McCulley, 1989;Wright et al, 1985;Mathers et al, 1996;Niederkorn et al, 1999;Marciano-Cabral & Cabral, 2003;Khan, 2003). In addition, Acanthamoeba have been associated with cutaneous lesions and sinusitis in immunocompromised patients (reviewed by Marciano-Cabral & Cabral, 2003).…”

Section: Introductionmentioning

confidence: 99%

Acanthamoeba induces cell-cycle arrest in host cells

Sissons

Alsam

Jayasekera

et al. 2004

Journal of Medical Microbiology

View full text Add to dashboard Cite

Acanthamoeba can cause fatal granulomatous amoebic encephalitis (GAE) and eye keratitis. However, the pathogenesis and pathophysiology of these emerging diseases remain unclear. In this study, the effects of Acanthamoeba on the host cell cycle using human brain microvascular endothelial cells (HBMEC) and human corneal epithelial cells (HCEC) were determined. Two isolates of Acanthamoeba belonging to the T1 genotype (GAE isolate) and T4 genotype (keratitis isolate) were used, which showed severe cytotoxicity on HBMEC and HCEC, respectively. No tissue specificity was observed in their ability to exhibit binding to the host cells. To determine the effects of Acanthamoeba on the host cell cycle, a cell-cycle-specific gene array was used. This screened for 96 genes specific for host cell-cycle regulation. It was observed that Acanthamoeba inhibited expression of genes encoding cyclins F and G1 and cyclin-dependent kinase 6, which are proteins important for cell-cycle progression. Moreover, upregulation was observed of the expression of genes such as GADD45A and p130 Rb, associated with cell-cycle arrest, indicating cell-cycle inhibition. Next, the effect of Acanthamoeba on retinoblastoma protein (pRb) phosphorylation was determined. pRb is a potent inhibitor of G 1 -to-S cell-cycle progression; however, its function is inhibited upon phosphorylation, allowing progression into S phase. Western blotting revealed that Acanthamoeba abolished pRb phosphorylation leading to cell-cycle arrest at the G 1 -to-S transition. Taken together, these studies demonstrated for the first time that Acanthamoeba inhibits the host cell cycle at the transcriptional level, as well as by modulating pRb phosphorylation using host cell-signalling mechanisms. A complete understanding of Acanthamoeba-host cell interactions may help in developing novel strategies to treat Acanthamoeba infections. INTRODUCTIONAcanthamoeba are the causative agents of life-threatening granulomatous amoebic encephalitis (GAE) in immunocompromised patients (Jones et al., 1975;Martinez, 1987;Di Gregorio et al., 1992;Friedland et al., 1992;Gonzalez et al., 1986;Gordon et al., 1992) and a common amoebic keratitis, a sight-threatening disease of the eye, which is mostly associated with contact-lens use (Chynn et al., 1995;Moore & McCulley, 1989;Wright et al., 1985; Mathers et al., 1996;Niederkorn et al., 1999;Marciano-Cabral & Cabral, 2003;Khan, 2003). In addition, Acanthamoeba have been associated with cutaneous lesions and sinusitis in immunocompromised patients (reviewed by Marciano-Cabral & Cabral, 2003). Over the past few decades, Acanthamoeba infections have remained significant and are on the rise. This is due to increasing populations of contact-lens wearers and immunocompromised patients, as well as improved awareness and detection of these emerging diseases. However, the precise mechanisms associated with the pathogenesis and pathophysiology of Acanthamoeba infection remain unclear. The clinical outcome of Acanthamoeba infection is dependent on the virulence of...

show abstract

Section: Introductionmentioning

confidence: 99%

Acanthamoeba induces cell-cycle arrest in host cells

Sissons

Alsam

Jayasekera

et al. 2004

Journal of Medical Microbiology

View full text Add to dashboard Cite

show abstract

“…Accurate diagnosis and interpretation of results requires highly trained personnel together with a strong clinical suspicion of amoebic infection. A few groups have used the polymerase chain reaction as a rapid detection method for Acanthamoeba but its clinical use, specificity and sensitivity has not been tested [4]. With Acanthamoeba spp.…”

Section: Discussionmentioning

confidence: 99%

“…Acanthamoeba keratitis is typically diagnosed after viral and bacterial causes have been eliminated [1,5] and, as a result, there is a significant delay before appropriate treatment is administered. Because of the severity of Acanthamoeba keratitis a significant loss of visual acuity is common and in many cases total loss of sight in the eye occurs [4,6]. Although commonly isolated, only a limited number of Acanthamoeba are pathogenic thus, the development of a rapid, simple detection method for such strains is important [2,17].…”

Section: Introductionmentioning

confidence: 99%

Use of Phage Antibodies to Distinguish Closely Related Species of Protozoan Parasites

et al. 2000

View full text Add to dashboard Cite

Acanthamoeba are typically identified in the laboratory using culture and microscopic observation. In this paper we describe the isolation and specificity of antibody fragments that can be used for the identification of Acanthamoeba. A phage library expressing a large repertoire (approx. 5×109) of antibody fragments was used to generate two libraries one enriched for bacteriophage that exhibit genus specific binding and the other containing bacteriophage that bind specifically to pathogenic Acanthamoeba. Individual clones were isolated on the basis of binding by ELISA, and then flowcytometry and immunofluorescence were used for further characterisation. Four monoclonal antibodies were isolated, specific for Acanthamoeba at the generic level with clone HPPG6 exhibiting the highest level of binding. Furthermore clone HPPG55 was specific for pathogenic species of Acanthamoeba.

show abstract

“…Symptoms for AK are not specific, however terrible eye pain is typically disproportionate to the degree of keratitis. Clinical signs such as epithelial defects or central ulcers, anterior stromal ring infiltrates and radial keratoneuritis are commonly present [2–4]. No significant differences in signs or symptoms were detected between contact and non-contact lens related patients [2].…”

Section: Introductionmentioning

confidence: 99%

The First Acanthamoeba keratitis Case of Non-Contact Lens Wearer with HIV Infection in Thailand

et al. 2019

View full text Add to dashboard Cite

Acanthamoeba keratitis (AK) is a rare sight-threatening corneal infection, often reporting from contact lens wearers. An asymptomatic human immunodeficiency virus (HIV)-infected Thai male without history of contact lens use complained foreign body sensation at his left eye during motorbike riding. He had neither specific keratitis symptoms nor common drugs responding, which contributed to delayed diagnosis. By corneal re-scraping, Acanthamoeba-like cysts were detected by calcofluor white staining and agar culture. The etiological agent obtained from the culture was molecularly confirmed by Acanthamoeba spp.-specific PCR, followed by DNA sequencing. The results from BLAST and phylogenetic analysis based on the DNA sequences, revealed that the pathogen was Acanthamoeba T4, the major genotype most frequently reported from clinical isolates. The infection was successfully treated with polyhexamethylene biguanide resulting in corneal scar. This appears the first reported AK case from a non-contact lens wearer with HIV infection in Thailand. Although AK is sporadic in developing countries, a role of free-living Acanthamoeba as an opportunistic pathogen should not be neglected. The report would increase awareness of AK, especially in the case presenting unspecific keratitis symptoms without clinical response to empirical antimicrobial therapy.

show abstract

Acanthamoeba Keratitis

Cited by 43 publications

References 16 publications

Acanthamoeba induces cell-cycle arrest in host cells

Acanthamoeba induces cell-cycle arrest in host cells

Use of Phage Antibodies to Distinguish Closely Related Species of Protozoan Parasites

The First Acanthamoeba keratitis Case of Non-Contact Lens Wearer with HIV Infection in Thailand

Contact Info

Product

Resources

About