Soluble TNF receptors in vitreoretinal proliferative disease.

PURPOSE: To measure vitreous levels of soluble TNF-receptors (sTNF-Rs) types I and II in eyes with rhegmatogenous retinal detachment (RRD), uncomplicated or complicated with proliferative vitreoretinopathy (PVR), and in eyes with proliferative diabetic retinopathy (PDR). To examine whether there is any relationship between vitreous levels of sTNF-Rs and clinical features of these conditions and between vitreous sTNF-Rs and TNFalpha levels and serum levels of sTNF-RS: METHODS: Vitreous levels of sTNF-Rs and TNFalpha were measured by enzyme-linked immunosorbent assay in 30 eyes with PVR, 30 eyes with uncomplicated RRD, and 29 eyes with PDR. Vitreous from eyes of 10 deceased donors and 9 eyes with macular holes served as control specimens. Serum levels of sTNF-Rs were measured in 17 patients with PDR and 21 patients with PVR. RESULTS: Vitreous levels of sTNF-Rs I and II were increased in eyes with PVR, RRD, and PDR when compared with control eyes (P < 0.002). However, vitreous levels of sTNF-Rs I and II were higher in eyes with PVR than in eyes with RRD (P < 0.01) or PDR (P < 0.03). This contrasted with the findings that serum sTNF-Rs were higher in PDR than in PVR (P < 0.016) and that vitreous levels of TNFalpha were higher in eyes with PDR than in eyes with PVR (P < 0.0005). In PVR, vitreous sTNF-Rs levels were associated with the duration of retinal detachment, number of previous external operations, and grade of severity, whereas in PDR these levels were not related to the type or duration of diabetes or its complication with traction retinal detachment. CONCLUSIONS: These observations suggest the existence of TNF inhibitory mechanisms within the eye during retinal processes of inflammation and angiogenesis. That high vitreous levels of sTNF-Rs relate to severity of retinopathy suggests that these molecules may constitute reactive products of inflammation. Effective control of TNFalpha activity by sTNF-Rs within the retinal microenvironment may determine the outcome and severity of retinal proliferative conditions.

Acute posterior vitreous detachment: the predictive value of vitreous pigment and symptomatology.

AIM: To establish whether the presence of a retinal break can be predicted either by the presence of a positive Shafer's sign (pigment granules in the anterior vitreous) or symptomatology in patients presenting with an acute posterior vitreous detachment (PVD). METHODS: 200 eyes of 200 phakic patients with a symptomatic PVD of less than 1 month's duration underwent documentation of symptomatology and examination of the anterior vitreous for the presence of pigment granules. Indentation ophthalmoscopy was then carried out by an experienced vitreoretinal surgeon with no knowledge of the symptomatology or anterior vitreous gel examination findings. A second prospective group of 115 consecutive patients were assessed in a similar manner before primary rhegmatogenous retinal detachment repair. RESULTS: In 200 eyes presenting with an acute PVD, 25 were found to have an associated retinal break, 23 of which were also Shafer positive. In 115 eyes presenting for retinal detachment repair, 111 had an associated PVD and were found to be Shafer positive. Symptomatology was not predictive of an associated retinal break in the PVD group or in those presenting with a retinal detachment. CONCLUSION: The increased use of Shafer's sign is recommended as a valuable aid in determining which patients require urgent referral for an expert retinal examination. It is not possible to predict those patients with a retinal break secondary to PVD on the basis of symptomatology alone.

Matrix metalloproteinases and their natural inhibitors in fibrovascular membranes of proliferative diabetic retinopathy.

AIM: To examine epiretinal membranes of proliferative diabetic retinopathy (PDR) for the presence of selective matrix metalloproteinases (MMPs) and their natural inhibitors (TIMPs), in order to determine whether neovascularisation and fibrosis, characteristic of this complication of diabetes mellitus, are associated with specific anomalies of MMP or TIMP expression. METHODS: The presence of selected MMPs and TIMPs was investigated in 24 fibrovascular epiretinal membranes of PDR, and the findings compared with that observed in 21 avascular epiretinal membranes of proliferative vitreoretinopathy (PVR) and five normal retinas. Specimens were examined for deposition of interstitial collagenase (MMP-1), stromelysin-1 (MMP-3), gelatinase A (MMP-2), gelatinase B (MMP-9), and three tissue inhibitors of metalloproteinases (TIMP-1, TIMP-2, and TIMP-3). RESULTS: The results showed that unlike normal retina, which constitutively expresses MMP-1 and TIMP-2, a large proportion of PDR membranes (> 62%) stained for MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, and TIMP-3. There were no differences in the expression of these molecules when compared with PVR membranes. A characteristic staining for MMP-9 was observed within the perivascular matrix of PDR membranes, and there was a significant increase in TIMP-2 expression by PDR membranes (p= 0.036) when compared with PVR membranes. CONCLUSIONS: The findings that MMPs involved in degradation of fibrovascular tissue matrix, as well as TIMP-1 and TIMP-2, are found in a large proportion of PDR membranes, and that their expression does not differ from that of PVR membranes, suggest the existence of common pathways of extracellular matrix degradation in pathological processes leading to retinal neovascularisation and fibrosis.

Primary vitrectomy for rhegmatogenous retinal detachment: an analysis of failure.

PURPOSE: To find the cause of failure in primary vitrectomy for rhegmatogenous retinal detachment. METHODS: Retrospective review of 171 consecutive cases of RRD treated by primary pars plana vitrectomy (PPV) from a tertiary referral centre to identify the 25 cases in which surgery had failed. Detachments with giant or macula breaks at initial presentation, with proliferative diabetic retinopathy or with PVR greater than grade B were excluded. RESULTS: The failure rate after the first operation was 14.6% and the commonest cause of failure was missed retinal breaks, accounting for 64.3% of failures. CONCLUSION: Missed retinal breaks are the commonest cause of failure of primary PPV for RRD although proliferative vitreoretinopathy may contribute to surgical failure. This re-emphasises the importance of assiduous peroperative retinal examination.

Vascular adhesion molecules in vitreous from eyes with proliferative diabetic retinopathy.

PURPOSE: To investigate whether proliferative vitreoretinopathy (PDR) is associated with a selective increase in vitreous levels of soluble vascular cell adhesion molecules that mediate leukocyte extravasation and interaction with endothelium during processes of inflammation and neovascularization. METHODS: Vitreous from 55 patients undergoing vitrectomy for treatment of PDR complicated by vitreous hemorrhage and/or traction retinal detachment was assayed for the presence of the soluble vascular cell adhesion molecules sICAM-1, sVCAM-1, and sE-selectin using a standard enzyme-linked immunosorbent assays (ELISA). Vitreous from 12 cadaveric eyes matching age and sex of the patients were used as control samples. RESULTS: Vitreous levels of sICAM-1, sVCAM-1, and sE-selectin were significantly higher in eyes with PDR than in control cadaveric vitreous, and levels of all three molecules did not relate to the type or duration of diabetes mellitus. However, eyes with either traction retinal detachment alone or both traction retinal detachment and vitreous hemorrhage exhibited significantly higher levels of sICAM-1 and sE-selectin than eyes with vitreous hemorrhage alone. Vitreous levels of sVCAM-1 were similar in eyes with either vitreous hemorrhage or traction retinal detachment alone. CONCLUSIONS: The present observations suggest that molecular inflammatory mechanisms may contribute to processes of neovascularization and fibrosis observed in PDR, possibly not as the causative event, but as a result of endothelial, Müller, and retinal pigment epithelial cell activation. The results also indicate that retinal detachment amplifies the existing inflammation within the diabetic retina. Identification of any abnormalities in the production and control of specific adhesion molecules could have important implications in the design of new therapeutic regimens to treat and prevent this sight-threatening complication of diabetes mellitus.

Vitreous levels of intercellular adhesion molecule 1 (ICAM-1) as a risk indicator of proliferative vitreoretinopathy.

AIM: To investigate whether high vitreous levels of the soluble intercellular adhesion molecule 1 (sICAM-1) may be related to clinical risk factors of proliferative vitreoretinopathy (PVR) and whether their measurement may serve as an additional risk indicator of this complication in eyes with rhegmatogenous retinal detachment (RRD). METHODS: Levels of sICAM-1 were measured by enzyme linked immunosorbent assays (ELISA) in vitreous from 36 eyes with RRD clinically considered to be at high risk of developing PVR (large retinal breaks, vitreous haemorrhage, long standing RRD, and previous vitreoretinal surgery). Levels of sICAM-1 in this group were compared with those in vitreous from 31 eyes with RRD without clinical risk factors for PVR, 32 eyes with established PVR and 10 eyes with macular holes. RESULTS: Vitreous from eyes with RRD at high risk of developing PVR contained significantly higher levels of sICAM-1 (range 6.1-97.7 ng/ml; Mann-Whitney test, p=0.0002) than those from eyes with RRD at low risk of developing this complication (range 4.8-17.7 ng/ml). Vitreous sICAM-1 levels in eyes with RRD at high risk of developing PVR were significantly lower than in eyes with established PVR (p=0.037), but higher than in eyes with macular holes (p <0.0001). Levels of sICAM-1 >/=15 ng/ml (3 x median of the levels present in control eyes) provide a useful cut off point for a highly specific test (96.7%) with high positive (91.6%) and negative (96.7%) predictive values, despite a relatively low sensitivity (30. 5%). CONCLUSIONS: The present findings suggest that laboratory measurement of sICAM-1 levels in vitreous from eyes with RRD may constitute an additional factor for identifying patients at high risk of PVR. Hence, determination of sICAM-1 levels may aid in the monitoring of patients likely to develop this complication and in the identification of patients who may benefit from adjuvant anti-inflammatory therapy.

Predominance of MMP-1 and MMP-2 in epiretinal and subretinal membranes of proliferative vitreoretinopathy.

Matrix metalloproteinases (MMPs) and their natural inhibitors (TIMPs) play an important role in matrix remodelling and their involvement in the formation of scar-like tissue in proliferative vitreoretinopathy (PVR) is unknown. In this study we investigated epiretinal and subretinal membranes of PVR for the presence of selected MMPs and TIMPs whose substrates are extracellular matrix components of these membranes. We examined 23 epiretinal membranes and 15 subretinal membranes of PVR for deposition of interstitial collagenase (MMP-1), stromelysin-1 (MMP-3), gelatinase A (MMP-2), gelatinase B (MMP-9) and two tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) by immunohistochemical methods. Normal cadaveric retinas served as controls. We observed that a large proportion of epiretinal and subretinal membranes stained for MMP-1 and MMP-2, whilst MMP-3, MMP-9, TIMP-1 and TIMP-2 were only observed in a small proportion of specimens. Normal cadaveric retinas stained for MMP-1 but not for MMP-2, MMP-3, MMP-9 or TIMP-1. TIMP-2 positive cells were observed within the inner and outer nuclear cell layers of normal retina. Presence of MMP-2, MMP-3 and TIMP-1 in epiretinal and subretinal membranes of PVR but not in normal retina indicates that these molecules may play an important role during the healing process that follows rhegmatogenous retinal detachment. An understanding of the mechanisms that control production and activity of these enzymes and their inhibitors may aid in the design of new therapeutic approaches to treat and prevent PVR.

Vitreous intercellular adhesion molecule 1 in uveitis complicated by retinal detachment.

AIMS: The vitreous levels of soluble intercellular adhesion molecule 1 (sICAM-1) were investigated in uveitic eyes undergoing vitrectomy for retinal detachment (RD) or other complications, and the presence of this molecule was related to disease activity and vitreous levels of the cytokine tumour necrosis factor alpha (TNF alpha), known to upregulate ICAM-1 expression on various cells. METHODS: Vitreous and serum samples from 23 patients with either active or quiescent uveitis undergoing retinal surgery were examined for the levels of immunoreactive sICAM-1 and TNF alpha by ELISA methods, and for the presence of biologically active TNF alpha. Vitreous from non-uveitic eyes with rhegmatogenous retinal detachment (RRD), macular holes or cadaveric eyes were used as controls. RESULTS: As a whole, vitreous from uveitic eyes complicated or uncomplicated by RRD contained significantly higher levels of sICAM-1 than vitreous from non-uveitic eyes with RRD alone (p < 0.0005), eyes with macular holes (p < 0.0001), or normal cadaveric vitreous (p < 0.0001). The proportion of vitreous containing > 20 ng/ml sICAM-1 (> four times the normal values) was significantly higher in eyes with uveitis complicated by RRD than in those eyes without RRD (Fisher's test, p = 0.02), and although levels of sICAM-1 were higher in eyes with active uveitis than in those with quiet disease (p < 0.02), this could not be dissociated from the increase caused by RRD. There was a relation between the vitreous levels of sICAM-1 and those of immunoreactive TNF alpha (Spearman's correlation coefficient; r = 0.601, p = 0.006), but not between the vitreous levels of sICAM-1 and those of biologically active TNF alpha. CONCLUSION: Increased vitreous sICAM-1 levels and the association of this molecule with the presence of immunoreactive TNF alpha in uveitic eyes confirm the operation of cytokine mediated vascular reactions at the blood-retinal barrier during the development of this condition. The persistence of high vitreous levels of sICAM-1 in eyes with uveitis complicated by RRD despite previous immunosuppression may indicate a low rate of clearance of inflammatory molecules from the vitreous cavity and an exacerbation of the existing inflammatory process by the retinal detachment itself.

Intercellular adhesion molecule-1 in proliferative vitreoretinopathy.

PURPOSE: To measure vitreous levels of the soluble intercellular adhesion molecule (sICAM-1) in eyes with rhegmatogenous retinal detachment (RRD) complicated or uncomplicated by proliferative vitreoretinopathy (PVR) to investigate whether levels of this molecule related to history of previous retinal surgery or to the duration and severity of PVR. METHODS: The authors measured vitreous sICAM-1 by enzyme-linked immunosorbent assay in 28 eyes with PVR and 35 eyes with uncomplicated RRD. Vitreous from 10 eyes with macular holes and from 12 cadaveric eye donors were used as control specimens. RESULTS: Vitreous sICAM-1 levels were higher in the group with RRD complicated by PVR as a whole than in the group with RRD alone or in the control groups. In patients with no previous retinal surgery, there was no difference in vitreous sICAM-1 levels between the groups with RRD alone and RRD complicated by PVR. However, in patients who had undergone previous external surgery, those with PVR showed higher levels of vitreous sICAM-1 than those with RRD alone. In PVR, raised levels of sICAM-1 were associated preferentially with a history of previous vitrectomy as well as with a longer duration of the condition, although these levels were not related to the grade of PVR. In eyes with RRD alone, the levels of sICAM-1 were not enhanced with the duration of the detachment. Despite showing high vitreous levels of sICAM-1, patients with PVR did not exhibit increased serum levels of this adhesion molecule. CONCLUSIONS: The current observations suggest that those persons in whom PVR develops may have an impairment of the mechanisms that control the inflammatory response to retinal trauma. Persistently raised vitreous levels of sICAM-1 point to the continued operation of cytokine-mediated vascular reactions at the blood-retinal barrier.

Evidence of chronic inflammation in retina excised after relaxing retinotomy for anterior proliferative vitreoretinopathy.

BACKGROUND: Epiretinal membranes from eyes with proliferative vitreoretinopathy (PVR) frequently express molecules associated with chronic inflammation. To investigate the extent to which inflammation may compromise the detached retina, we determined the expression of inflammatory molecules in anterior retina removed after relaxing retinotomy for retinal detachment complicated by anterior PVR. METHODS: Surgical retinal specimens were studied immunohistochemically for the distribution of the vascular cell adhesion molecules VCAM, E-selectin, P-selectin, ICAM and PECAM and for the presence of the cytokine TNF alpha and of T lymphocytes (CD3-positive cells), macrophages (CD68-positive cells) and HLA-DR molecules. The findings were compared with those in control cadaveric retina. RESULTS: Aberrant expression of ICAM-1 was observed in four of nine retinal specimens from eyes with PVR, whereas its expression in control retinas was confined to the external limiting membrane and ganglion cell layers. PECAM was observed in seven of nine surgical retinal specimens and in four of five controls. E-selectin and P-selectin were expressed within the luminal aspects of four of nine retinal specimens from eyes with PVR, and VCAM was present in three of nine surgical specimens investigated. All cadaveric control retinas were negative for E-selectin and VCAM, whilst one was positive for P-selectin. Staining for TNF alpha was observed within luminal aspects and walls of retinal vessels from eight of nine surgical specimens, but was not seen in any of the cadaveric controls. T lymphocytes and cells expressing the macrophage marker CD68 were identified in two and seven of nine diseased retinas respectively, but not in any of the controls. Cells staining for HLA-DR were observed in eight of nine surgical retinal specimens and in three of five controls. CONCLUSION: The present findings indicate that retina from eyes with advanced PVR may itself be subject to inflammatory changes, and indicate that the PVR process is not limited to retinal membranes, but involves a more widespread distribution of inflammation than is generally appreciated.

Distribution of TNF alpha and its reactive vascular adhesion molecules in fibrovascular membranes of proliferative diabetic retinopathy.

AIMS: This study investigated the presence of the cytokine tumour necrosis factor alpha (TNF alpha) and the vascular adhesion glycoproteins ICAM-1, VCAM-1, E-selectin, P-selectin, and PECAM within fibrovascular membranes of eyes with proliferative diabetic retinopathy (PDR). METHODS: The presence of these molecules was determined by immunohistochemical staining using monoclonal antibodies and the APAAP technique. RESULTS: Staining for TNF alpha was observed on the retinal vascular endothelium of five of 12 specimens, on infiltrating cells within all membranes, and on the extracellular matrix of nine specimens. This staining wa abolished by absorption of the monoclonal antibody with human recombinant TNF alpha. Likewise, ICAM-1 staining was given by infiltrating cells and extracellular matrix of nine membranes and by the endothelium of three of the specimens. VCAM-1, E-selectin, and P-selectin staining was observed on the vascular endothelium of 5/12, 4/12, and 3/12 epiretinal membranes respectively. PECAM was expressed by the endothelium of 4/12 specimens, by infiltrating cells of 8/12 membranes, and also by the extracellular matrix of two of the specimens. CONCLUSION: The widespread distribution of TNF alpha and the nature of the adhesion molecules expressed by vascular endothelial cells in PDR membranes suggest that local activation of TNF alpha and enhanced expression of vascular cell adhesion molecules may play an important role in the development of the proliferative phase of diabetic retinopathy.

Comparison of pars plana vitrectomy and scleral buckling for uncomplicated rhegmatogenous retinal detachment.

Retinal detachment surgery can now achieve a final reattachment rate in over 90% of cases. The operation of choice in most cases is that of external scleral buckling with or without drainage of subretinal fluid. However, in a minority of cases these techniques are difficult to apply either when the breaks are unseen due to media opacities or when the breaks are complex, eg, posterior, large, or multiple breaks at different distances from the ora. Improvements in the technique of pars plana vitrectomy for retinal detachment now offers us an alternative method for treating these difficult cases. Pars plana vitrectomy for retinal detachments with unseen or complex breaks has a final attachment rate of over 90%, is technically easier to perform than conventional surgery, and avoids the refractive and ocular motility problems associated with complicated buckles. For these reasons and despite the high risk of nuclear sclerosis in phakic eyes, a pars plana vitrectomy may be the preferred option in selected cases of primary retinal detachment.

Distribution of cytokine proteins within epiretinal membranes in proliferative vitreoretinopathy.

This study reports on the immunohistochemical staining for cytokine proteins of 26 epiretinal membranes obtained from eyes undergoing surgery for the treatment of proliferative vitreoretinopathy. All specimens were investigated for the distribution of staining for interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF alpha), interferon-gamma (IFN gamma) and interleukin-2 (IL-2). The results showed that 22 of the membranes (85%) stained for TNF alpha not only intracellularly but also in the extracellular matrix. This contrasts with the findings that only 2 membranes stained for IL-1 alpha and that another 3 were positive for IL-1 beta. Staining for the cytokines IL-6 and IFN gamma was also observed in 9 and 7 membranes respectively. None of the specimens investigated stained with antibodies to IL-2 or control antibodies, and none of three normal retinas stained with any of the antibodies used. Pre-absorption of anti-cytokine antibodies with the corresponding human recombinant cytokines abolished staining of cells and extracellular matrix. The present findings support growing evidence that cytokine-mediated pathways of inflammation are involved in the pathogenesis of proliferative vitreoretinopathy, and draw attention to the possibility that interaction between extracellular matrix-bound cytokine and inflammatory leucocytes or resident cells of the retina may promote the development and perpetuation of this condition.

Expression of mRNA coding for TNF alpha, IL-1 beta and IL-6 by cells infiltrating retinal membranes.

BACKGROUND: Cellular mechanisms of inflammation are thought to be involved in the pathogenesis of proliferative vitreoretinopathy, and cytokines, which are products of cell activation, are known to play an important role in the development and maintainance of inflammatory reactions. It was the aim of this work to investigate the presence of cells expressing cytokine mRNA within retinal membranes. METHODS: The presence of mRNA coding for the cytokines interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF alpha) was investigated in 19 epiretinal membranes obtained from eyes undergoing vitrectomy for the treatment of retinal detachment complicated by proliferative vitreoretinopathy. RESULTS: Cells expressing mRNA for IL-1 beta were observed in 7 membranes, cells positive for IL-6 mRNA were seen in 12 membranes, and cells exhibiting mRNA for TNF alpha were present in 9 specimens. Only three membranes contained cells expressing mRNA for all the cytokines investigated. Four membranes possessed positive cells for IL-6 and TNF alpha, two contained cells expressing mRNA for IL-6 and IL-1 beta, and two others exhibited cells expressing mRNA for TNF alpha and IL-1 beta. Five membranes contained IL-6 mRNA-positive cells only, whilst two exhibited cells expressing mRNA for IL-1 beta or TNF alpha only. CONCLUSION: The present findings indicate that cellular activation may occur during the development of PVR, and suggest that these cytokines may be locally produced by cells infiltrating epiretinal membranes. The presence of IL-1 beta, IL-6 and TNF alpha mRNA-positive cells within retinal membranes provides further evidence of a pathogenic role of these cytokines in proliferative vitreoretinopathy.

Proliferative vitreoretinopathy: an examination of the involvement of lymphocytes, adhesion molecules and HLA-DR antigens.

This paper addresses the molecular basis of interactions between leucocytes, other cells in the vitreoretinal environment and extracellular matrix that may underlie the pathogenesis of proliferative vitreoretinopathy. In this study we report the expression of adhesion molecules (CD11a, CD11c, CD18 and ICAM-1), lymphocyte surface markers (CD3, CD4, CD8 and CD22) and HLA-DR molecules in 25 epiretinal membranes obtained from eyes undergoing vitrectomy for the treatment of retinal detachment complicated by epiretinal membrane formation. Retinas from normal cadaveric eyes were used as controls. The results showed that cells expressing the adhesion molecules CD11a, CD11c and CD18 were present in 5 of 25, 17 of 25 and 11 of 23 membranes, respectively. Cells stained with antibodies against intracellular adhesion molecule 1 (ICAM-1) were observed in 24 of 25 membranes, whilst HLA-DR positive cells were seen in all membranes investigated. Immunohistochemical staining revealed that the molecules ICAM-1 or HLA-DR were not only expressed on inflammatory cells but also distributed within the extracellular matrix in several specimens. Lymphocytes expressing CD3 markers were present in 12 of 25 membranes, whilst T lymphocytes expressing CD4 and CD8 markers were observed in 5 of 18 and 12 of 24 membranes, respectively. In contrast, B lymphocytes expressing CD22 molecules were not found in any of the membranes. Leucocyte surface molecules were not expressed in control cadaveric retinas, although occasional cells expressing ICAM-1 were identified in the inner plexiform layer.(ABSTRACT TRUNCATED AT 250 WORDS)