Publications by authors named "Michelle Callegan"

Purpose: To test the hypothesis that (C-C motif) ligand 2 (CCL2) and CCL3 impact retinal function decline and inflammation during Staphylococcus aureus endophthalmitis.

Methods: Experimental endophthalmitis was initiated by intravitreal injection of 5000 colony-forming units of S. aureus into the eyes of C57BL/6J, CCL2-/-, or CCL3-/- mice.

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Background: can cause self-limiting gastrointestinal infections, but when infecting the eye, can cause rapid and irreversible blindness. This study investigated whether clinical ocular and gastrointestinal isolates differed in terms of virulence-related genotypes and endophthalmitis virulence.

Methods: Twenty-eight ocular, gastrointestinal, and laboratory reference isolates were evaluated.

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Aging is a complex biological process that is characterized by low-grade inflammation, called inflammaging. Aging affects multiple organs including eye and lacrimal gland. Tumor necrosis factor (TNF) is a pleiotropic cytokine that participates in inflammation, activation of proteases such as cathepsin S, and formation of ectopic lymphoid organs.

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Ocular infections can be medical emergencies that result in permanent visual impairment or blindness and loss of quality of life. Bacteria are a major cause of ocular infections. Effective treatment of ocular infections requires knowledge of which bacteria are the likely cause of the infection.

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Bacteriophage lytic enzymes (i.e., phage lysins) are a trending alternative for general antibiotics to combat growing antimicrobial resistance.

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Purpose: To test the hypothesis that the C-X-C chemokines CXCL1, CXCL2, and CXCL10 contribute to inflammation during Staphylococcus aureus endophthalmitis.

Methods: S. aureus endophthalmitis was induced by intravitreal injection of 5000 colony forming units of S.

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Bacillus cereus (B. cereus) endophthalmitis is a vision-threatening bacterial infection. Uncontrolled inflammatory responses are the hallmark of this disease which cause irreversible damage to the retina.

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Pseudomonas aeruginosa is a significant opportunistic pathogen responsible for numerous human infections. Its high pathogenicity resides in a diverse array of virulence factors and an ability to adapt to hostile environments. We report that these factors are tied to the activity of condensins, SMC and MksBEF, which primarily function in structural chromosome maintenance.

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Purpose: The purpose of this study was to explore the C-X-C chemokines CXCL2 and CXCL10 as potential anti-inflammatory targets for Bacillus endophthalmitis.

Methods: Bacillus endophthalmitis was induced in C57BL/6J, CXCL2-/-, and CXCL10-/- mice. At specific times postinfection, eyes were analyzed for Bacillus, retinal function, and inflammation.

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Endophthalmitis is a devastating infection that can cause blindness. Over half of endophthalmitis cases result in significant loss of useful vision. produces many virulence factors that may contribute to retinal damage and robust inflammation.

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is recognized as a causative agent of gastrointestinal syndromes, but can also cause a devastating form of intraocular infection known as endophthalmitis. We have previously reported that the PlcR/PapR master virulence factor regulator system regulates intraocular virulence, and that the S-layer protein (SlpA) contributes to the severity of endophthalmitis. To better understand the role of other virulence genes in endophthalmitis, expression of a subset of factors was measured at the midpoint of disease progression in a murine model of endophthalmitis by RNA-Seq.

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Intraocular bacterial infections are a danger to the vision. Researchers use animal models to investigate the host and bacterial factors and immune response pathways associated with infection to identify viable therapeutic targets and to test drugs to prevent blindness. The intravitreal injection technique is used to inject organisms, drugs, or other substances directly into the vitreous cavity in the posterior segment of the eye.

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Purpose: To explore the consequences of innate interference on intraocular inflammatory responses during Bacillus endophthalmitis.

Methods: Bacillus endophthalmitis was induced in mice. Innate immune pathway activation was interfered by injecting S layer protein-deficient (∆slpA) B.

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Mutations in nucleotide-binding oligomerization domain-containing protein 2 (NOD2) cause Blau syndrome, an inflammatory disorder characterized by uveitis. The antimicrobial functions of Nod2 are well-established, yet the cellular mechanisms by which dysregulated Nod2 causes uveitis remain unknown. Here, we report a non-conventional, T cell-intrinsic function for Nod2 in suppression of Th17 immunity and experimental uveitis.

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Experimental autoimmune uveoretinitis (EAU) is a mouse model of human autoimmune uveitis. EAU spontaneously resolves and is marked by ocular autoantigen-specific regulatory immunity in the spleen. Kallikrein binding protein (KBP) or kallistatin is a serine proteinase inhibitor that inhibits angiogenesis and inflammation, but its role in autoimmune uveitis has not been explored.

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produces many factors linked to pathogenesis and is recognized for causing gastrointestinal toxemia and infections. also causes a fulminant and often blinding intraocular infection called endophthalmitis. We reported that the PlcR/PapR system regulates intraocular virulence, but the specific factors that contribute to virulence in the eye remain elusive.

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endophthalmitis is a severe intraocular infection. Hallmarks of endophthalmitis include robust inflammation and rapid loss of vision. We reported that the absence of surface layer protein (SLP) significantly blunted endophthalmitis severity.

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Bacillus cereus (B. cereus) endophthalmitis is a devastating intraocular infection primarily associated with post-traumatic injuries. The majority of these infections result in substantial vision loss, if not loss of the eye itself, within 12-48 h.

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Some tissues of the eye are susceptible to damage due to their exposure to the outside environment and inability to regenerate. Immune privilege, although beneficial to the eye in terms of homeostasis and protection, can be harmful when breached or when an aberrant response occurs in the face of challenge. In this review, we highlight the role of the PMN (polymorphonuclear leukocyte) in different bacterial ocular infections that invade the immune privileged eye at the anterior and posterior segments: keratitis, conjunctivitis, uveitis, and endophthalmitis.

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Purpose: Bacillus causes a sight-threating infection of the posterior segment of the eye. The robust intraocular inflammatory response in this disease is likely activated via host innate receptor interactions with components of the Bacillus cell envelope. S-layer proteins (SLPs) of some Gram-positive pathogens contribute to the pathogenesis of certain infections.

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is a common pathogen of the eye, capable of infecting external tissues such as the tear duct, conjunctiva, and the cornea, as well the inner and more delicate anterior and posterior chambers. produces numerous toxins and enzymes capable of causing profound damage to tissues and organs, as well as modulating the immune response to these infections. Unfortunately, in the context of ocular infections, this can mean blindness for the patient.

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Ocular glands play a critical role in eye health through the secretion of factors directly onto the ocular surface. The cornea is a normally transparent tissue necessary for visual acuity located in the anterior segment of the eye. Corneal damage can occur during microbial infection of the cornea, resulting in potentially permanent visual deficits.

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Bacterial infection of the posterior segment of the eye (endophthalmitis) leads to a robust host response that often results in irreversible damage to the layers of the retina, significant vision loss, and in some patients, enucleation of the globe. While a great deal of effort has gone into understanding the role of bacterial virulence factors in disease initiation and propagation, it is becoming increasingly clear that the host response to infection plays a major role in causing the damage associated with endophthalmitis. Researchers have identified the host receptors which detect infecting organisms and initiate the cascade of events that result in inflammation.

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Intraocular infections are prevalent after traumatic injuries or after common ocular surgeries. Infections cause inflammation that can damage the retina and architecture of the eye, often resulting in poor visual outcomes. Severe cases may result in blindness or require enucleation of the eye.

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Background: Endophthalmitis is a serious intraocular infection that frequently results in significant inflammation and vision loss. Because current therapeutics are often unsuccessful in mitigating damaging inflammation during endophthalmitis, more rational targets are needed. Toll-like receptors (TLRs) recognize specific motifs on invading pathogens and initiate the innate inflammatory response.

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