Expression of Human β-Defensins in Conjunctival Epithelium: Relevance to Dry Eye Disease

Narayanan, Srihari; Miller, William L.; McDermott, Alison M.

doi:10.1167/iovs.02-1301

Cited by 71 publications

(64 citation statements)

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“…17,18 Human β-defensin-1 (hBD-1) and hBD-3 are constitutively expressed by the corneal and conjunctival epithelia, 18-20 whereas the expression of hBD-2 is inducible by proinflammatory cytokines such as IL-1α, IL-1β, TNF-α, bacterial by-products such as lipopolysaccharide and heat-killed Pseudomonas aeruginosa, and injury. [19][20][21][22] We have also observed that hBD-2 is expressed by conjunctival epithelial cells from patients with moderate dry eye but not in cells from normal subjects. 20 Because it has been reported that proinflammatory cytokines are secreted in greater amounts by HCECs in hyperosmolar media, 10 we reasoned that a differential expression of β-defensins by HCECs may be observed when the cells are in a hyperosmolar environment.…”

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confidence: 59%

“…[19][20][21][22] We have also observed that hBD-2 is expressed by conjunctival epithelial cells from patients with moderate dry eye but not in cells from normal subjects. 20 Because it has been reported that proinflammatory cytokines are secreted in greater amounts by HCECs in hyperosmolar media, 10 we reasoned that a differential expression of β-defensins by HCECs may be observed when the cells are in a hyperosmolar environment. Such a response may underlie our observation of conjunctival hBD-2 expression in dry eye patients but not normal subjects.…”

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confidence: 59%

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Effect of Hyperosmolality on β-Defensin Gene Expression by Human Corneal Epithelial Cells

Narayanan

Manning²,

Proske³

et al. 2006

Cornea

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Purpose-As human β-defensins (hBD) are important antimicrobial peptides at epithelial surfaces, including the ocular surface, we tested the effect of hyperosmolar conditions on the expression of these peptides by human corneal epithelial cells (HCECs).Methods-Simian virus 40-transformed HCECs (n = 5) or primary cultured HCECs (n = 5) were treated with serum-free media or serum-free hyperosmolar (400-500 mOsm/kg) media for 24 hours or serum-free 500 mOsm/kg media for 12 to 48 hours. The effect of hyperosmolality on interleukin-1β (IL-1β)-induced hBD-2 expression was also tested. IL-6 expression was studied as a marker of IL-1β function. Expression of hBD-1, -2, and -3 and IL-6 mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). The levels of active IL-1β (culture supernatants and cell lysates) and pro-IL-1β (cell lysates) were detected by enzyme-linked immunosorbent assay.Results-HCECs constitutively expressed hBD-1 and -3 but not hBD-2. Hyperosmolar media had no effect on the basal expression of hBD-1 or -3 and did not induce the expression of hBD-2. Treatment with 500 mOsm/kg media for 24 hours decreased the ability of IL-1β to upregulate hBD-2 and IL-6 expression. Active or pro-IL-1β was not detected in any cell culture sample.Conclusion-Our results suggest that the hyperosmolar environment observed in diseases such as dry eye does not alter defensin expression. However, a hyperosmolar environment may influence cytokine function in ocular surface cells and thus affect their response to injury and inflammation. Keywords hyperosmolality; human β-defensins; corneal epithelium; cytokines Hyperosmolality at the ocular surface is a characteristic of diseases such as dry eye and diabetes mellitus. The normal osmolality of the tear fluid is approximately 300 mOsm/kg, 1 whereas the suggested "gold standard" diagnostic of dry eye is 312 mOsm/kg or greater. 2 It has been proposed that tear fluid hyperosmolality occurs because of either normal tear evaporation associated with reduced tear flow or excessive tear evaporation with a normal tear flow. 3 The hyperosmolar tear film is thought to affect ocular surface epithelial function and differentiation in dry eye disease, with osmolalities as high as 417 mOsm/kg being reported. 1,4,5 Also, Aragona et al 6 showed that type 1 diabetic patients had a significantly higher mean tear osmolality (332.2 ± 18.3 mOsm/L), poor tear stability, altered tear function, and symptoms of ocular irritation akin to patients with dry eye than normal patients. Hyperosmolality in diabetes mellitus is probably attributable to increased levels of tear glucose seen in patients with both types 1 and 2. 7

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Effect of Hyperosmolality on β-Defensin Gene Expression by Human Corneal Epithelial Cells

Narayanan

Manning²,

Proske³

et al. 2006

Cornea

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“…19,[68][69][70] Furthermore, infiltrating neutrophils and macrophages present in the cornea as a result of microbial challenge also play an important role in limiting bacterial invasion by the production of certain peptides including the cathelicidins. Findings from the present study showed that functional activities of cathelicidin are necessary for bacterial clearance and innate corneal immunity at the ocular surface.…”

Section: Discussionmentioning

confidence: 99%

“…Further, the vessel growth observed in the KO mice could have been initiated by the higher number of infiltrating neutrophils and possibly macrophages, as these cells contain significant amounts of angiogenic mediators that can be released in response to cellular activation. [65][66][67] Notably, the ability of cytokines to induce other cytokines and pro-and/or antiangiogenic factors secondarily and function as chemotactic factors for inflammatory cells makes it difficult to sort out the final and critical mediators of angiogenesis, infiltration, and inflammation conclusively in vivo.In the cornea, epithelial cells are a source of various antimicrobial peptides (including CRAMP, data not shown), particularly after injury or in response to inflammatory 19,[68][69][70] Furthermore, infiltrating neutrophils and macrophages present in the cornea as a result of microbial challenge also play an important role in limiting bacterial invasion by the production of certain peptides including the cathelicidins. Findings from the present study showed that functional activities of cathelicidin are necessary for bacterial clearance and innate corneal immunity at the ocular surface.…”

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Cathelicidin-Deficient (Cnlp⁻^/⁻) Mice Show Increased Susceptibility toPseudomonas aeruginosaKeratitis

Li-min

Reins

Gallo

et al. 2007

Invest. Ophthalmol. Vis. Sci.

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Purpose-To examine the clinical progression and innate immune responses during Pseudomonas aeruginosa (PA) keratitis in cathelicidin-deficient (KO) mice. (ATCC 19660) keratitis was induced in KO mice and wild-type (WT) littermates generated on a 129/SVJ background. Clinical score and histopathology were used to monitor the progression of infection at postinfection (PI) days 1, 3, 7, 14, and 21. Mouse corneas were harvested for viable bacteria quantitation, and myeloperoxidase (MPO) assays were performed to determine the number of infiltrating neutrophils. ELISA was used to quantitate interleukin (IL)-1β, IL-6, macrophage inflammatory peptide (MIP)-2, keratinocyte-derived chemokine (KC), tumor necrosis factor (TNF)-α, and vascular endothelial growth factor (VEGF) levels in the corneas. Methods-PAResults-WT mice were resistant (cornea healed), whereas KO mice showed increased susceptibility (corneas failed to recover by 21 days or perforated) to PA infection. Clinical scores were significantly elevated in the infected corneas of KO mice versus WT mice at 7, 14, and 21 days PI. Absence of cathelicidin resulted in significantly delayed clearance of PA in the cornea and an increased number of infiltrating neutrophils at 1, 3, 7, and 14 days PI. KO mice also exhibited differential expression of protein levels for IL-1β, IL-6, MIP-2, KC, TNF-α, and VEGF up to day 21 PI compared with the WT mice.Conclusions-Cathelicidin-deficient mice showed considerable susceptibility to PA keratitis. The present study demonstrates direct in vivo evidence that endogenous expression of cathelicidin provides defense against corneal PA infection indicating its importance in host innate immunity at the ocular surface.The bacterium Pseudomonas aeruginosa (PA) is one of the leading virulent corneal pathogens associated with contact lens-related keratitis. 1,2 Although an opportunistic organism, PA is notorious for its resistance to antibiotics and is therefore considered a particularly dangerous and dreaded ocular pathogen. PA induced ulcerative keratitis is a rapidly developing and devastating corneal disease that typically presents with severe inflammation, neovascularization, and liquefactive necrosis of the cornea. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript suppurative stromal ulceration and mucopurulent exudate, the clinical picture of advanced PA keratitis may also reveal descemetocele (keratocele) formation resulting from corneal melting. In the absence of timely and appropriate treatments, the infected cornea undergoes progressive degradation leading to perforation and therefore permanent vision loss. [3][4][5] The host immune response to PA corneal infection, which is critical in determining the outcome of the disease, consists primarily of an influx of neutrophils from the tear film and the limbal vasculature into the cornea. Previous studies suggest that both tissue-destructive bacterial proteases and stromal-degrading enzymes liberated by activated neutrophils and other stimulated inflamma...

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“…DES also leads to an increase the risk of secondary infections 1) . Research has demonstrated that inflammatory cytokines including interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-alpha (TNF-) are highly expressed in tears of patients with multi-factorial DES [2][3][4][5][6][7] . Moreover, current research suggests that neurogenic inflammation induced by neuropeptides may be closely associated with both the initial immune response and chronic inflammation in the disease 8) .…”

Section: Introductionmentioning

confidence: 99%

Human Amniotic Membrane Extracts have Anti-Inflammatory Effects on Damaged Human Corneal Epithelial Cells <i>In Vitro</i>

Lee

Raymundo

Han

et al. 2016

J. Hard Tissue Biology.

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The human amniotic membrane has therapeutic potential for several diseases such as cardiac ischemia, liver fibrosis, and ocular surface disorders. In the treatment of ocular surface disorders, human amniotic membrane transplantation promotes epithelial wound healing and suppresses inflammation. The objective of this study was to determine whether human amniotic membrane extracts (HAE) help damaged corneal epithelial cells recover from an inflammatory response. Human corneal epithelial cells (hCEC) which were induced inflammation were treated with human amniotic membrane extracts, and then the levels of inflammatory cytokines were measured. Human amniotic membrane extracts had an anti-inflammatory effect on damaged human corneal epithelial cells. More importantly, homogenized human amniotic membrane extracts of less than 3 kDa had a greater capacity for reducing inflammation and secretion of interleukin-6 (IL-6) and interleukin-8 (IL-8). Thus, these results indicate that the use of human amniotic membrane extracts is a promising treatment for ocular surface disorders accompanied by inflammation.

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Expression of Human β-Defensins in Conjunctival Epithelium: Relevance to Dry Eye Disease

Cited by 71 publications

References 50 publications

Effect of Hyperosmolality on β-Defensin Gene Expression by Human Corneal Epithelial Cells

Effect of Hyperosmolality on β-Defensin Gene Expression by Human Corneal Epithelial Cells

Cathelicidin-Deficient (Cnlp⁻^/⁻) Mice Show Increased Susceptibility toPseudomonas aeruginosaKeratitis

Human Amniotic Membrane Extracts have Anti-Inflammatory Effects on Damaged Human Corneal Epithelial Cells <i>In Vitro</i>

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Expression of Human β-Defensins in Conjunctival Epithelium: Relevance to Dry Eye Disease

Cited by 71 publications

References 50 publications

Effect of Hyperosmolality on β-Defensin Gene Expression by Human Corneal Epithelial Cells

Effect of Hyperosmolality on β-Defensin Gene Expression by Human Corneal Epithelial Cells

Cathelicidin-Deficient (Cnlp−/−) Mice Show Increased Susceptibility toPseudomonas aeruginosaKeratitis

Human Amniotic Membrane Extracts have Anti-Inflammatory Effects on Damaged Human Corneal Epithelial Cells <i>In Vitro</i>

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Cathelicidin-Deficient (Cnlp⁻^/⁻) Mice Show Increased Susceptibility toPseudomonas aeruginosaKeratitis