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Biomedical subjects

Ali R Djalilian

Publications and source records attributed to Ali R Djalilian.

10 recordsLinked to original sources
PubMed2025

Aging and Corneal Nerve Health: Mechanisms of Degeneration and Emerging Therapies for the Cornea.

Corneal nerves play a crucial role in maintaining ocular surface homeostasis by supporting the functional integrity of corneal epithelial, stromal, and endothelial cells; modulating tear secretion; and facilitating sensory responses essential for overall ocular health. With advancing age, these highly specialized peripheral sensory fibers undergo progressive attrition and morphologic distortion driven by the canonical hallmarks of aging including genomic instability, impaired proteostasis, mitochondrial dysfunction, and chronic low-grade inflammation. The resulting neuro-immune dysregulation reduces trophic support, delays wound healing, and predisposes older adults to dry-eye disease, neurotrophic keratopathy, and postsurgical hypoesthesia. Age-exacerbating cofactors including diabetes, dyslipidemia, neurodegenerative disorders, topical preservatives, chronic contact-lens wear, herpes zoster ophthalmicus, and ocular-surface hypoxia further accelerate sub-basal nerve rarefaction and functional decline. This review provides an overview of age-related physiological alterations in ocular surface nerves, with a particular emphasis on corneal innervation. It also discusses risk factors that speed up these changes. Given the inherently limited regenerative capacity of corneal nerves and their inability to fully restore to baseline conditions following injury or degeneration, it is critical to identify and develop effective strategies aimed at mitigating or delaying physiological nerve degeneration and promoting nerve regeneration. This review also brings up emerging therapeutic strategies, including regenerative medicine, neuroprotective agents, and lifestyle interventions aimed at mitigating age-related corneal nerve degeneration.

Humans↗
PubMed2006

Connexin 26 regulates epidermal barrier and wound remodeling and promotes psoriasiform response.

Inflammatory skin disorders result in significant epidermal changes, including keratinocyte hyperproliferation, incomplete differentiation, and impaired barrier. Here we test whether, conversely, an impaired epidermal barrier can promote an inflammatory response. Mice lacking the transcription factor Kruppel-like factor 4 (Klf4) have a severe defect in epidermal barrier acquisition. Transcription profiling of Klf4(-/-) newborn skin revealed similar changes in gene expression to involved psoriatic plaques, including a significant upregulation of the gap junction protein connexin 26 (Cx26). Ectopic expression of Cx26 from the epidermis-specific involucrin (INV) promoter (INV-Cx26) demonstrated that downregulation of Cx26 is required for barrier acquisition during development. In juvenile and adult mice, persistent Cx26 expression kept wounded epidermis in a hyperproliferative state, blocked the transition to remodeling, and led to an infiltration of immune cells. Mechanistically, ectopic expression of Cx26 in keratinocytes resulted in increased ATP release, which delayed epidermal barrier recovery and promoted an inflammatory response in resident immune cells. These results provide a molecular link between barrier acquisition in utero and epidermal remodeling after wounding. More generally, these studies suggest that the most effective treatments for inflammatory skin disorders might concomitantly suppress the immune response and enhance epidermal differentiation to restore the barrier.

Animals↗
PubMed2006

Inhibition of inflammatory cytokine production in human corneal cells by dexamethasone, but not cyclosporin.

PURPOSE: To evaluate the modulatory effects of anti-inflammatory agents, dexamethasone (Dex) and cyclosporin A (CsA), on the production of cytokines and chemokines by human corneal cells in vitro following stimulation by the pro-inflammatory cytokine after interleukin 1beta (IL-1beta). METHODS: A human corneal epithelial (HCE) cell line and human corneal fibroblasts (HCFs) were stimulated in culture with IL-1beta and treated with Dex or CsA. The gene expression for selected cytokines and chemokines was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The secretion of cytokines and chemokines was measured by enzyme-linked immunosorbent assay. RESULTS: IL-1beta enhanced the mRNA and/or protein levels of granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-8, and monocyte chemotactic protein (MCP)-1 in HCE and IL-6, IL-8, MCP-3, and regulated on T-cell activation expressed secreted (RANTES) in HCFs. Treatment with CsA did not inhibit cytokine production in either HCE or HCFs. In contrast, Dex treatment inhibited the IL-1beta-induced production of GM-CSF, IL-6, IL-8, MCP-3, and RANTES, but not MCP-1. CONCLUSION: These results show that Dex, but not CsA, has direct immunosuppressive effects on the resident corneal cells, HCE and HCFs. This suggests that the clinically observed immunosuppressive effects of topical CsA are mediated primarily through the immune cells.

Anti-Inflammatory Agents↗
PubMed2005

Survival of donor epithelial cells after limbal stem cell transplantation.

PURPOSE: To determine the long-term fate of donor epithelial cells after limbal allograft transplantation. METHODS: Corneal buttons and peripheral blood leukocytes were obtained at the time of penetrating keratoplasty from three patients who had undergone a successful limbal allograft transplantation. Microdissection was used to remove the corneal epithelial cells from the button. The presence of donor and recipient epithelial cells in each sample was determined by using PCR for DNA microsatellites. Phenotypic analysis of the epithelium was performed by immunohistochemistry. RESULTS: Various patterns of DNA microsatellites were observed. Nonrecipient cells (presumed to be donor) were consistently detected in all three corneal buttons. In two of the three cases, recipient cells were also detected, whereas in the third case, exclusively donor epithelial cells were found at 3.5 years after limbal allograft transplantation. Mild T-lymphocytes and macrophages were observed in one of the corneal buttons. CONCLUSIONS: This study provides evidence for the persistence of donor epithelial cells up to 3.5 years after limbal allograft transplantation and supports the use of systemic immunosuppressive therapy.

Aged↗
PubMed2003

Management of aniridic keratopathy with keratolimbal allograft: a limbal stem cell transplantation technique.

OBJECTIVE: Aniridic keratopathy is a major cause of vision loss in patients with aniridia. Penetrating keratoplasty has been proven ineffective for the long-term treatment of this disorder because it does not address the stem cell deficiency that is the primary etiologic factor. We evaluated the role of keratolimbal allograft (KLAL), a stem cell transplantation technique, for the treatment of patients with aniridic keratopathy. DESIGN: Retrospective noncomparative interventional case series. PARTICIPANTS: Thirty-one eyes of 23 patients with aniridic keratopathy. INTERVENTION: KLAL. MAIN OUTCOME MEASURES: Ocular surface stability, visual acuity, and success of subsequent penetrating or lamellar keratoplasty. RESULTS: Thirty-one eyes of 23 patients were treated with KLAL and followed up for 12 to 117 months (mean, 35.7 months). Twenty-three eyes (74.2%) achieved a stable ocular surface. Overall, the mean visual acuity improved from 20/1000 to 20/165. Twenty eyes (64.5%) underwent subsequent penetrating keratoplasty. Fourteen corneal transplant grafts (70.0%) were successful, and six (30.0%) failed. Nineteen (90.5%) of 21 eyes receiving systemic immunosuppression obtained a stable ocular surface, whereas only 4 (40.0%) of 10 eyes not receiving systemic immunosuppression achieved ocular surface stability (P < 0.01). CONCLUSIONS: KLAL is effective in treating aniridic keratopathy. Patients receiving systemic immunosuppression have a greater likelihood of achieving ocular surface stability and improved visual acuity compared with those who receive only topical immunosuppression.

Adolescent↗
PubMed2003

Mycophenolate mofetil for the treatment of scleritis.

PURPOSE: To evaluate the usefulness of mycophenolate mofetil (MMF) (CellCept, Roche, Nutley, NJ), an antimetabolite immunosuppressant with a selective antiproliferative effect on T and B lymphocytes, for the treatment of scleritis. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Eight patients with scleritis treated with MMF in a tertiary referral center. METHODS: Review of the clinical records of patients evaluated at the National Eye Institute and prescribed MMF for the treatment of scleritis. MAIN OUTCOME MEASURES: Control of scleral inflammation, the ability to taper prednisone or other immunosuppressive medications, and adverse events were recorded for each patient. Mycophenolate mofetil was determined to be an effective steroid-sparing agent if the daily prednisone dosage could be reduced by 50% or more and was determined to be an effective adjunctive immunosuppressive agent if the scleral inflammation was controlled in patients with active scleritis. RESULTS: Four patients with diffuse anterior scleritis, two with necrotizing scleritis with inflammation, one with nodular anterior scleritis, and one with nodular anterior and posterior scleritis, were identified. Mycophenolate mofetil administration was initiated as a steroid-sparing agent in 4 patients with controlled scleritis and as an additional immunosuppressive agent in 4 patients with active scleritis receiving concomitant treatment with prednisone and cyclosporine or methotrexate. In 3 of the 4 patients started on MMF as a steroid-sparing agent, the scleritis remained controlled while the prednisone dosage was tapered by more than 50%. One of the patients started on MMF as a steroid-sparing agent had recurrent scleritis, and each of the patients with active scleritis continued to have persistent scleral inflammation requiring additional immunosuppressive therapy. Adverse effects recorded in 4 of the 8 patients included a rash, gastrointestinal symptoms, paresthesias, and laboratory evidence of hepatotoxicity and renal toxicity. CONCLUSIONS: Although MMF maybe be useful as a steroid-sparing agent, it was not effective as an adjunctive immunosuppressive agent in patients with active scleritis in our small, tertiary referral series. The adverse effects encountered with the use of MMF in this study cannot be attributed conclusively to MMF and are more likely complications of the multiagent systemic immunosuppressive therapy required for the treatment of recalcitrant scleritis.

Adult↗
PubMed2003

Ocular surface reconstruction: limbal stem cell transplantation.

In summary, the management of patients with severe ocular surface disease remains difficult. Significant progress has been made toward understanding limbal stem cell disease, and surgical treatments have been refined. Short- and long-term successes have been achieved and have improved the quality of life for patients who otherwise have had no other treatment options. Further research is needed to determine the factors leading to successful long-term stem cell transplantation and those factors associated with transplantation failure. Developments in the management of limbal stem cell disease are progressing rapidly, and the long-term outlook for patients with this challenging disease continues to improve.

Conjunctiva↗
PubMed2002

Feline immunodeficiency virus-mediated gene therapy of middle ear mucosa cells.

HYPOTHESIS: To investigate the feasibility of gene therapy of the middle ear mucosa using a novel vector. BACKGROUND: Given present medications are unable to affect chronic otitis media, cholesteatoma, or tympanic membrane perforation, newer methods of treatment like gene therapy for these diseases must be explored. These genes can then be used to alter cytokines in the middle ear, slow or stop cholesteatoma growth, or improve tympanic membrane perforation healing. Feline immunodeficiency virus (FIV), a new lentiviral vector has been found to have greater than 90% efficiency in transfecting epithelial cells. Therefore, in vivo gene therapy of middle ear mucosa cells was attempted. METHODS: Twenty microliter of 5x10(5) vectors per ml FIV carrying the gene for green fluorescence protein (GFP) was introduced into the middle ears of Sprague-Dawley rats via a bulla approach. RESULTS: Expression of the GFP gene was observed in the middle ear mucosa cells at 1 week post-inoculation indicating transfection. CONCLUSION: Gene therapy of the middle ear is feasible with a FIV-based vector.

Animals↗
PubMed2002

Immunosuppression in uveitis.

The treatment of ocular inflammatory disease continues to be a major challenge as the clinician tries to balance the risks and the benefits of immunosuppressive therapy. Currently, corticosteroids, antimetabolites, and calcineurin inhibitors are the most commonly used agents. Biologically active agents including monoclonal antibodies, however, provide a promising new form of treatment that can target the immune system more specifically and more safely. Long-term studies are needed to determine the role of biologic agents in the treatment of uveitis.

Humans↗