A. M. Abu El-Asrar

Immunopathology of trachomatous conjunctivitis.

Upper palpebral conjunctival biopsy specimens obtained from eight patients with active trachoma were examined by routine histological and immunohistochemical methods. The epithelium expressed class I major histocompatibility complex (MHC) products throughout and class II MHC products in the superficial layers. The epithelial inflammatory infiltrate consisted of polymorphonuclear leucocytes, macrophages, T lymphocytes, and dendritic cells. In the underlying stroma the inflammatory infiltrate was organised as B lymphoid follicles, and there was also a diffuse infiltrate consisting of plasma cells and scattered B lymphoid cells, dendritic cells, T cells, macrophages, and polymorphonuclear leucocytes. Each type of cell has its special location in the tissue. Plasma cells were located on a subepithelial band and as a dense infiltrate round the acini of accessory lacrimal glands. IgA+ plasma cells outnumbered IgG+ cells, whereas IgM+ and IgE+ cells were few. Our data provide good evidence for the presence of both humoral and cell mediated immune responses and a possible role for autoimmune mechanisms in the conjunctival tissues of trachoma patients.

Circulating fibrocytes contribute to the myofibroblast population in proliferative vitreoretinopathy epiretinal membranes

Background/aims: Fibrocytes, circulating cells that co-express markers of haematopoietic stem cells, leucocytes and fibroblast products, traffic to sites of tissue injury, differentiate into myofibroblasts and contribute to wound healing and fibrosis. We investigated the presence of fibrocytes and the expression of their chemotactic pathways CCL21/CCR7 and CXCL12/CXCR4 in proliferative vitreoretinopathy (PVR) epiretinal membranes. Methods: Sixteen membranes were studied by immunohistochemical techniques. Results: Cells expressing α-smooth-muscle actin (α-SMA), a marker of differentiation of fibrocytes into myofibroblasts, were present in all membranes. Cells expressing the haematopoietic stem-cell antigen CD34, the leucocyte common antigen CD45, CCR7, CXCR4, CCL21 and CXCL12 were noted in 50%, 75%, 68.8%, 100%, 80% and 93.8% of the membranes, respectively. Double immunohistochemistry indicated that all cells expressing CD34, CD45, CCR7, CXCR4, CCL21 and CXCL12 co-expressed α-SMA. The number of cells expressing CD34 correlated significantly with the numbers of cells expressing CXCL12 (rsu200a=u200a0.567; pu200a=u200a0.022) and CCL21 (rsu200a=u200a0.534; pu200a=u200a0.04). Conclusions: Circulating fibrocytes may function as precursors of myofibroblasts in PVR membranes.

Immunopathogenesis of conjunctival scarring in trachoma

Purpose Trachoma, a chronic follicular conjunctivitis caused by infection with Chlamydia trachomatis, is the leading cause of preventable blindness. The blinding complications are associated with progressive conjunctival scarring that may result from immunologically mediated responses. We studied the processes involved in the regulation of inflammation and fibrosis in trachoma by investigating the expression of fibrogenic cytokines in the conjunctiva.Methods We studied conjunctival biopsy specimens obtained from nine subjects with active trachoma and from four control subjects. We used immunohistochemical techniques and a panel of monoclonal and polyclonal antibodies directed against interleukin-1α (IL-1α), interleukin-lβ (IL-1β), tumour necrosis factor-α (TNF-α) and platelet-derived growth factor (PDGF). In addition, we characterised the composition of the inflammatory infiltrate by the use of a panel of monoclonal antibodies. Sirius red and Van Gieson stains were used to characterise the extent of fibrous tissue in the substantia propria.Results Trachoma specimens showed greater numbers of inflammatory cells than control specimens. The expression of cytokines was absent in the normal conjunctiva. Cytoplasmic IL-1α and IL-1β expression was noted in the conjunctival epithelium in all trachoma specimens. IL-1α, IL-1β, TNF-α and PDGF were detected in macrophages infiltrating the substantia propria. B lymphocytes predominated over T lymphocytes in six trachoma biopsies with fibrosis confined to the deep substantia propria, whereas T lymphocytes predominated over B lymphocytes in three biopsies with more extensive fibrosis. In all trachoma biopsies helper/inducer T lymphocytes outnumbered suppressor/cytotoxic T lymphocytes.Conclusions The upregulated local production of IL-1α, IL-β, TNF-α and PDGF might contribute to conjunctival damage and scarring in trachoma.

Hyperhomocysteinemia and retinal vascular occlusive disease.

Purpose Elevated plasma homocysteine is an independent risk factor for thrombosis and vascular disease. This prospective study compared plasma total homocysteine levels in patients with retinal vascular occlusive disease and in matched healthy controls. Methods We measured plasma total homocysteine in 56 consecutive patients with recently diagnosed retinal vascular occlusive disease: 36 had central retinal vein occlusion, 12 branch retinal vein occlusion, and 8 retinal artery occlusion, and compared them with 59 age- and sex-matched healthy controls. Homocysteine levels were determined by high-performance liquid chromatography with electrochemical detection. Hyperhomocysteinemia was defined as a plasma homocysteine level above the 95th percentile in the control group (13.6 μmol/L). Results Mean plasma total homocysteine levels were significantly higher in patients than controls (16.1 ± 8.3 vs. 8.96 ± 5.6 μmol/L p<0.001). Mean homocysteine levels were significantly higher in the retinal vein occlusion and retinal artery occlusion groups than the control group (15.3 ± 8.2 and 20.95 ± 6.9 vs 8.96 ± 5.6 μmol/L, p<0.001). Estimates of the relative risk indicated that the risk of hyperhomocysteinemia was significantly higher in patients with retinal vascular occlusive disease than controls. Hyperhomocysteinemia was present in 37 (66.1%) of the 56 patients with retinal vascular occlusive disease but only 2 (3.4%) controls (odds ratio [OR] 47.5, 95% confidence interval [CI] 9.8 - 149.9). Hyperhomocysteinemia was present in 29 (60.4%) of the patients with retinal vein occlusion (OR 43.5, 95% CI 8.77 - 141.93) and in 6 (75%) patients with retinal artery occlusion (OR 85.5, 95% CI 7.49 - 1173.1). Conclusions High plasma homocysteine is a risk factor for retinal vascular occlusive disease so it may be useful to measure homocysteine in the management of these patients. A randomized, controlled trial is required to study the effect of lowering with homocysteine folic acid and other B vitamins on the risk of recurrent vascular occlusion in the same eye or its development in the fellow eye.

Visual outcome and prognostic factors after vitrectomy for posterior segment foreign bodies

Purpose To identify the prognostic factors that predict final visual outcome in eyes with posterior segment intraocular foreign body (IOFB) injuries managed by primary pars plana vitrectomy. Methods Ninety-six consecutive patients with posterior segment IOFB injuries were retrospectively reviewed. Factors analyzed included initial visual acuity (VA), time between injury and presentation, site of entrance wound, uveal prolapse, vitreous prolapse, traumatized iris, endophthalmitis, location and size of IOFB, use of scleral buckling and/or an encircling band, gas tamponade, lensectomy, number of surgical procedures, and development of retinal detachment. Data were analyzed using univariate and multivariate logistic regression analysis. Results After a mean follow-up of 8.6 months, 63 eyes (65.6%) achieved VA of 20/200 or better, and 9 eyes (9.4%) had total retinal detachment complicated by inoperable proliferative vitreoretinopathy. On univariate analysis, predictors of poor vision (hand movements or less) were poor initial VA, corneoscleral entrance wound, uveal prolapse, vitreous prolapse, traumatized iris, and development of retinal detachment. In contrast, predictors of good visual outcome (20/200 or better) were absence of uveal prolapse, no endophthalmitis, and no retinal detachment. Multivariate analysis identified corneoscleral entrance wound, uveal prolapse, and development of retinal detachment as the only factors significantly associated with poor visual outcome. Absence of uveal prolapse was the only factor significantly associated with good visual outcome. Conclusions Final visual outcome is greatly determined by the severity of the primary injury. On multivariate analysis, significant predictive factors of final VA were corneoscleral entrance wound, presence or absence of uveal prolapse, and development of retinal detachment.

Full panretinal photocoagulation and early vitrectomy improve prognosis of retinal vasculitis associated with tuberculoprotein hypersensitivity (Eales’ disease)

Background/aims: Eales’ disease is an uncommon vasoproliferative retinal disease affecting otherwise healthy young men that is characterised by obliterative retinal periphlebitis, with sequelae such as recurrent vitreous haemorrhage and traction retinal detachment. This study was undertaken to determine whether visual prognosis of Eales’ disease could be improved by appropriate medical and surgical treatment. Methods: The authors retrospectively studied 30 patients (46 eyes) who were treated from 1992 to 2001. Recorded data included patient age, sex, race, medical history, medications, results of the ophthalmological examination, results of diagnostic laboratory evaluation, and details of systemic and surgical treatments. The mean follow up was 10.6 months. Results: 19 patients (23 eyes) who presented with active periphlebitis received systemic steroids and antituberculous therapy. Extensive full panretinal photocoagulation was performed in 21 eyes that presented with new vessel formation and peripheral capillary closure with or without vitreous haemorrhage. Vitrectomy and endolaser panretinal photocoagulation was necessary in 15 eyes, for severe non-clearing vitreous haemorrhage in 11 eyes and vitreous haemorrhage with traction retinal detachment in four eyes. Complete regression of the disease was achieved in all eyes. Vitrectomy resulted in a significant visual improvement with 14 of the 15 eyes (93.3%) achieving ≥20/200 visual acuity. Overall, the distribution of visual acuities among eyes improved from presentation to final follow up, with 36.4% of eyes having 20/40 or better acuity at presentation compared with 63.6% of eyes by final follow up. Conclusions: These results suggest that aggressive treatment of Eales’ disease with systemic steroids and antituberculous therapy, full panretinal photocoagulation and early vitrectomy, when necessary, may result in improving the anatomic and visual outcome.

Autocrine CCL2, CXCL4, CXCL9 and CXCL10 signal in retinal endothelial cells and are enhanced in diabetic retinopathy

This study aimed at examining the presence and role of chemokines (angiogenic CCL2/MCP-1 and angiostatic CXCL4/PF-4, CXCL9/Mig, CXCL10/IP-10) in proliferative diabetic retinopathy (PDR). Regulated chemokine production in human retinal microvascular cells (HRMEC) and chemokine levels in vitreous samples from 40 PDR and 29 non-diabetic patients were analyzed. MCP-1, PF-4, Mig, IP-10 and VEGF levels in vitreous fluid from PDR patients were significantly higher than in controls. Except for IP-10, cytokine levels were significantly higher in PDR with active neovascularization and PDR without traction retinal detachment (TRD) than those in inactive PDR, PDR with TRD and control subjects. Exploratory regression analysis identified associations between higher levels of IP-10 and inactive PDR and PDR with TRD. VEGF levels correlated positively with MCP-1 and IP-10. Significant positive correlations were observed between MCP-1 and IP-10 levels. In line with these clinical findings Western blot analysis revealed increased PF-4 expression in diabetic rat retinas. HRMEC produced MCP-1, Mig and IP-10 after stimulation with IFN-γ, IL-1β or lipopolysaccharide. IFN-γ synergistically enhanced Mig and IP-10 production in response to IL-1β or lipopolysaccharide. MCP-1 was produced by HRMEC in response to VEGF treatment and activated HRMEC via the ERK and Akt/PKB pathway. On the other hand, phosphorylation of ERK induced by VEGF and MCP-1 was inhibited by PF-4, Mig and IP-10. In accordance with inhibition of angiogenic signal transduction pathways, PF-4 inhibited inxa0vitro migration of HRMEC. Thus, regulatory roles for chemokines in PDR were demonstrated. In particular, IP-10 might be associated with the resolution of active PDR and the development of TRD.

Immunopathogenesis of conjunctival remodelling in vernal keratoconjunctivitis

PurposeTo study the processes involved in mediating conjunctival remodelling in vernal keratoconjunctivitis (VKC) by investigating the expression of integrin receptors, epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), transforming growth factor-β(TGF-β), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF), and Ki67 antigen, which is a marker for cell proliferation.MethodsConjunctival biopsy specimens from 16 patients with active VKC and nine control subjects were studied by immunohistochemical techniques using monoclonal and polyclonal antibodies directed against the integrin α3 and α6 subunits, EGFR, VEGF, TGF-β, bFGF, PDGF, and Ki67 antigen. The phenotype of inflammatory cells expressing growth factors was examined by double immunohistochemistry.ResultsIn the normal conjunctiva, very weak immunoreactivity was observed for EGFR and VEGF in epithelial cells, and for α3 and α6 integrin subunits on basal epithelial cells, and on vascular endothelial cells in the upper substantia propria. There was no immunoreactivity for the other antibodies. In VKC specimens, strong staining for α3 and α6 integrin subunits was observed on the membranes of basal and suprabasal epithelial cells, and all vascular endothelial cells. Immunoreactivity for Ki67 antigen was observed in the nuclei of the basal and suprabasal epithelial cells. Strong immunoreactivity was observed for EGFR in the deeper layers of the epithelium, and for VEGF in all epithelial cells. Inflammatory cells expressing EGFR, VEGF, TGF-β, bFGF, and PDGF were noted in 8, 9, 11, 10, and 10 specimens, respectively. The majority of inflammatory cells expressing growth factors were eosinophils (45±4%) and monocytes/macrophages (35±4%).ConclusionsChronic conjunctival inflammation in VKC is associated with increased staining of α3, and α6 integrin subunits, EGFR, VEGF, TGF-β, bFGF, and PDGF that might mediate conjunctival remodelling.

Expression of T lymphocyte chemoattractants and activation markers in vernal keratoconjunctivitis

Background/aims: T lymphocytes are present in increased numbers in the conjunctiva of patients with vernal keratoconjunctivitis (VKC) and their activation has a central role in the pathogenesis of the chronic allergic inflammatory reactions seen in VKC. The aims of this study were to examine the expression of three recently described potent T lymphocyte chemoattractants, PARC (pulmonary and activation regulated chemokine), macrophage derived chemokine (MDC), and I-309, the MDC receptor CCR4, and T lymphocyte activation markers, CD25, CD26, CD62L, CD71, and CD30, and to correlate them with the counts of CD3+ T lymphocytes in the conjunctiva of patients with VKC. Method: Conjunctival biopsy specimens from 11 patients with active VKC, and eight control subjects were studied by immunohistochemical techniques using a panel of monoclonal and polyclonal antibodies directed against PARC, MDC, I-309, CCR4, CD25, CD26, CD62L, CD71, and CD30. The numbers of positively stained cells were counted. The phenotype of inflammatory cells expressing chemokines was examined by double immunohistochemistry. Results: In the normal conjunctiva, vascular endothelial cells in the upper substantia propria showed weak immunoreactivity for CD26. There was no immunoreactivity for the other antibodies. VKC specimens showed inflammatory cells expressing PARC, MDC, and I-309. The numbers of PARC+ inflammatory cells were higher than the numbers of MDC+ and I-309+ inflammatory cells and the mean values of the three groups differed significantly (17.0 (SD 10.1); 9.5 (9.9), and 4.3 (7.9), respectively, p = 0.0117, ANOVA). The numbers of PARC+ inflammatory cells had the strongest correlation with the numbers of CD3+ T lymphocytes. Few CCR4+ inflammatory cells were observed in only three specimens. Double immunohistochemistry revealed that all inflammatory cells expressing chemokines were CD68+ monocytes/macrophages. The numbers of CD25+ T lymphocytes were higher than the numbers of CD26+, CD62L+, CD71+, and CD30+ T lymphocytes and the mean values of the five groups differed significantly (46.2 (27.9), 30.7 (16.0), 20.1 (8.6), 7.8 (7.7), and 6.5 (4.0), respectively, p <0.001, ANOVA). The numbers of CD25+ T lymphocytes had the strongest correlation with the numbers of CD3+ T lymphocytes. Conclusion: These results suggest a potential role for PARC, MDC, and I-309 in attracting T lymphocytes into conjunctiva in VKC. T lymphocytes in VKC are activated and express several activation markers which might contribute to the pathogenesis of VKC.

Uveitis survey in children

Background/aims: This is a retrospective cohort uveitis survey to determine the clinical features of uveitis in children and assess the rate of complications at two referral centres in Saudi Arabia. Methods: All children under the age of 16 years presenting with uveitis for the first time between 1997 and 2007 to The Eye Center and King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia were included. Clinical features of uveitis entities were described. Last follow-up visual acuity and ocular complications were analysed. Results: A total of 163 cases of uveitis in children were included. The age range was 1–16 years with a mean age of 10 years. The most frequent clinical type of uveitis in children included acute anterior non-granulomatous uveitis 26%, intermediate uveitis 20%, Vogt–Koyanagi–Harada (VKH) disease 16% and juvenile idiopathic arthritis (JIA) 15%. Anterior uveitis accounted for 42%, intermediate for 20%, posterior for 7%, and panuveitis for 31%. Immune-mediated uveitis was present in 144 (88%) patients, while infectious causes manifested in 19 (12%) patients. Conclusions: The most common cause of uveitis in children was anterior non-granulomatous uveitis of undetermined aetiology. There was a high prevalence of intermediate uveitis, VKH and JIA. Infectious causes of uveitis were uncommon.