Allopurinol has immunomodulating activity following topical and systemic application in experimental autoimmune uveitis

PURPOSE

Allopurinol has beneficial effects in the systemic treatment of lens-induced uveitis and experimental autoimmune uveitis (EAU). This is believed to be due to a reduction of oxidative tissue damage through its dose-dependent free radical scavenging ability, and to an immunomodulating effect. The purpose of this study was to demonstrate the immunological effects on the IgG-antibody repertoire in EAU after topical and systemic allopurinol and steroids.

METHODS

We assigned 43 male Lewis rats to 6 different groups: healthy rats (BASE, n=3)

Suppressive effects of histamine H1 receptor antagonist diphenhydramine on the leukocyte infiltration during endotoxin-induced uveitis

Histamine has been shown to play an important role in the step of leukocyte rolling, the initial step to leukocyte infiltration into an inflamed region. We investigated the roles of histamine in the leukocyte recruitment during endotoxin-induced uveitis (EIU) in vivo using acridine orange digital fluorography. An injection of histamine into the vitreous cavity of a Lewis rat induced leukocyte rolling along the major retinal veins. In other experiments, EIU was induced in Lewis rats by footpad injection of lipopolysaccharide (LPS). Leukocyte rolling was also observed in the retinal veins of EIU rats. To block the histamine H1 receptor, diphenhydramine (DPH) was administered intraperitoneally 15 min before the LPS injection. DPH significantly inhibited leukocyte rolling along the major retinal veins of EIU rats, suppressing leukocyte infiltration into the vitreous cavity. The vasodilation in EIU was also significantly suppressed with DPH. Moreover, leukocyte infiltration into aqueous humor was significantly suppressed in DPH-treated rats. Although the inhibitory effects of DPH was less obvious at later time points, addition of DPH every 12 hr showed prolonged anti-inflammatory effects up to 48 hr after LPS injection. In contrast, protein leakage into the aqueous humor was not suppressed as much as leukocyte infiltration with DPH. These results suggest that histamine would play a pivotal role in leukocyte recruitment during EIU in rats. Blocking the histamine H1 receptor might help to prevent or minimize leukocyte infiltration in uveitis.

Fas expression and apoptosis in rats with experimental autoimmune uveoretinitis

PURPOSE

To evaluate Fas expression on CD4 and CD8 T cells in each organ at each stage of experimental autoimmune uveoretinitis (EAU) and apoptotic cells within EAU eyes.

METHODS

Rats were immunized with the uveitopathogenic peptide derived from interphotoreceptor retinoid-binding protein. Flow cytometry was performed in ocular cells, draining lymph nodes cells and splenic cells of EAU rats to investigate Fas expression by CD4 and CD8 lymphocytes. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining of apoptotic nuclei was performed on sections of EAU eyes.

RESULTS

Fas expression by both ocular and splenic CD4 and CD8 lymphocytes was significantly higher than in lymph nodes at each stage. In EAU eyes, there was a relatively large population of lymphocytes with Fas expression (19.6-25.6% of CD4 and 33.2-53.4% of CD8). Apoptotic cells were more prominent in the EAU eyes with established disease than in those with early or resolving disease.

CONCLUSIONS

These results suggest that the relatively large population of lymphocytes with Fas expression in EAU eyes reflects the activation of lymphocytes in these eyes, and that the increase in apoptotic inflammatory cells at the peak of established disease may participate in the spontaneous disappearance of EAU.

Inhibitory effects of antithrombin III against leukocyte rolling and infiltration during endotoxin-induced uveitis in rats

PURPOSE

This study was designed to investigate the suppressive effects of antithrombin (AT)III on inflammatory reactions during endotoxin-induced uveitis (EIU) in rats by studying leukocyte-endothelium interactions.

METHODS

EIU was induced in Lewis rats by footpad injection of lipopolysaccharide (LPS). ATIII was administered immediately after or at 6 hours after LPS injection. Its suppressive effects on inflammatory leukocyte behavior were evaluated in vivo with acridine orange digital fluorography. Clinical signs of inflammation were also examined, and aqueous humor (AH) was collected to evaluate leukocyte infiltration and protein leakage. In a separate experiment, P-selectin mRNA expression was studied in the iris-ciliary body (ICB) and the retina.

RESULTS

After treatment with ATIII, leukocyte rolling was substantially inhibited along the retinal veins, suppressing subsequent leukocyte infiltration into the vitreous cavity. Similarly, leukocyte infiltration and protein leakage into the AH were significantly reduced with ATIII treatment. The clinical grade of EIU was substantially lower in ATIII-treated rats. In addition, delayed administration of ATIII after EIU induction significantly attenuated these inflammatory reactions. The levels of P-selectin mRNA expression in both ICB and retina, which were upregulated after LPS injection, were substantially lower in the ATIII-treated rats.

CONCLUSIONS

ATIII treatment significantly inhibited inflammatory reactions induced with LPS. Its suppressive effects on P-selectin expression could contribute to the attenuation of leukocyte infiltration, possibly by inhibiting leukocyte rolling. The current findings suggest that ATIII may have a role in the management of patients with uveitis.

Differential activation of microglial cells in local and remote areas of IRBP1169-1191-induced rat uveitis

Using a Lewis rat model of interphotoreceptor retinoid binding protein (IRBP)-induced experimental autoimmune uveitis (EAU) we examined cellular reactions in the optic pathway (retina, choroid, optic nerve, optic tract, colliculus superior, and visual cortex). Two to six animals were studied at days 0, 7, 9, 11, 12, 13, 14, 18 and 22 after immunization by immunohistochemistry with monoclonal antibodies against ED , ED2, OX6, OX22, EMAP II, AIF-1 and W3/13. In the retina, choroid and distal optic nerve increased immunoreactivity to ED1, OX6, OX22, EMAP II, AIF-1 and W3/13 was initially observed at day 9, peaked at days 13-14 and diminished rapidly from day 18 onwards. No changes were seen in the density of ED2-positive resident macrophages. In the optic tract, ED1 and OX6 expression was induced in microglial cells beginning with day 11 and persisted until day 22. AIF-1, EMAP II and ED2 expression was not visibly up-regulated and no lymphocytic infiltrates (OX22-, W3/13-positive cells) were observed. In the central projection fields, no cellular reaction could be found. Thus, cellular response in IRBP-induced rat uveoretinitis is not restricted to the eye. Microglial activation is also seen in the distal optic nerve and optic tract. This remote microglial activation, however, differs in intensity, time course and expression of activation markers, thus indicating different activation cascades. The mild remote microglial activation is probably due to neuronal-microglial interactions resulting from neuronal damage in the retinal ganglion cell layer and nerve fiber layer with consecutive axonal degeneration and not from an inflammatory reaction as seen in the eye.

Ophthalmic manifestations of HIV: an update

A variety of ocular disease processes have been identified in HIV-antibody positive persons, especially in people with AIDS. The most common sight-threatening disease in this population is cytomegalovirus (CMV) retinitis. Effective therapies are available to treat CMV retinitis. However, such therapies carry potentially challenging toxicities. Highly active antiretroviral therapy (HAART) has improved immune system functioning in many of its adherents, decreasing the incidence and improving the clinical course of CMV retinitis. However, a recent phenomenon associated with HAART, immune recovery uveitis (IRU), has been noted with additional, often problematic ocular manifestations in many persons with CMV retinitis. Periodic ophthalmic examination is prudent for all persons with HIV and especially for people with AIDS.

The ganciclovir implant plus oral ganciclovir versus parenteral cidofovir for the treatment of cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome: The Ganciclovir Cidofovir Cytomegalovirus Retinitis Trial

PURPOSE

To compare the regimen of the ganciclovir implant plus oral ganciclovir to one of intravenous cidofovir for the treatment of cytomegalovirus retinitis.

METHODS

Sixty-one patients with acquired immunodeficiency syndrome and cytomegalovirus retinitis were randomized either to the regimen of the ganciclovir implant plus oral ganciclovir, 1 gm three times daily, or intravenous cidofovir, 5 mg/kg once weekly for two doses, followed by 5 mg/kg every other week.

RESULTS

Mortality was similar between the two treatment groups. Mortality rates were 0.41 per person-year in patients assigned to the ganciclovir regimen and 0.49 per person-year in patients assigned to cidofovir (P =.59). Ocular outcomes were similar between the two groups. Retinitis progression occurred at a rate of 0.67 per person-year in the ganciclovir group and 0.71 per person-year in the cidofovir group (P =.72). A loss of visual acuity of 15 letters or more occurred at a rate of 0.78 per person-year in the ganciclovir group and 0.47 per person-year in the cidofovir group (P =.28). The rate of loss of visual field was 7 degrees per month in the ganciclovir group and 2 degrees per month in the cidofovir group (P =.048). Vitreous hemorrhage was more common in the ganciclovir implant group (0.13 per person-year) than in the cidofovir group (no cases, P =.014), whereas uveitis appeared to be more common in the cidofovir group (0.35 per person-year) than in the ganciclovir group (0.09 per person-year, P =.066). Nephrotoxicity (serum creatinine 1.6 mg/dL or greater) occurred at a rate of 0.18 per person-year in the ganciclovir group and 0.48 per person-year in the cidofovir group (P =.10).

CONCLUSIONS

Although the small number of patients in this study limits definitive interpretation, these data suggest that in the era of highly active antiretroviral therapy, the regimens of the ganciclovir implant plus oral ganciclovir and of intravenous cidofovir are similar for controlling cytomegalovirus retinitis and preventing visual loss but have different side effects.

[Effects of topical prostaglandin analogues on the aqueous flare intensity in rabbit eyes at an early phase of endotoxin-induced uveitis]

PURPOSE

We examined the effects of prostaglandin analogues on the blood-aqueous barrier(BAB) permeability in rabbit eyes at an early phase of endotoxin-induced uveitis(EIU).

SUBJECTS AND METHODS

One drop of 0.005% latanoprost or 0.12% unoprostone were applied to rabbit eyes. Escherichia coli lipopolysaccharides were injected to induce uveitis. The changes in flare intensity in normal eyes and EIU eyes after application of eye drops were evaluated. The effect of cyclooxygenase inhibitor on the flare intensity changes caused by the application of unoprostone was also examined.

RESULTS

Flare intensity increased significantly after a single instillation of unoprostone, and the increase was not prevented by pretreatment with cyclooxygenase inhibitor. In eyes with EIU, unoprostone caused an additional increase of flare intensity to uveitis induced flare change. Latanoprost had no effects on BAB in eyes with normal and with uveitic conditions.

CONCLUSION

Latanoprost and unoprostone did not cause an excessive inflammatory reaction in rabbit eyes at an early phase of EIU.

[Irritating effect and dermal toxicity of virkon, a disinfectant widely used in Poland]

The aim of the study was to define the threshold irritating effect of Virkon, a disinfectant widely used in Poland, on the rabbit's skin and eye, and its dermal toxicity in single exposure. The studies were carried out according to the OECD guidelines, modified by Krysiak. A 10% aqueous solution of Virkon in the conditions of multiple open exposure was defined as the threshold concentration evoking small inflammatory reaction. After a single administration of Virkon in aqueous solutions into the rabbit's eye, the value of sensitising effect index was 1.5 for 1% solution of the disinfectant in question which indicates weak inflammatory reaction. The study of dermal toxicity in a single exposure revealed neither animal death nor morphological changes in internal organs which suggests non-cutaneous absorption of Virkon. The present study may provide the basis for assessing dermatological changes in people exposed to disinfectants.

Therapeutic applications of antiflammin peptides in experimental ocular inflammation

Antiflammins are synthetic peptides derived from the region of highest local similarity between uteroglobulin and lipocortin. These peptides have shown anti-inflammatory activity on carrageenan-induced rat footpad edema. They are potent inhibitors for phospholipase A2 activation both in vitro and in vivo. Previously, we have demonstrated the effectiveness of topical antiflammins in suppressing acute ocular inflammation and allergic response in rodent endotoxin-induced uveitis and murine allergic conjunctivitis. The mechanisms by which antiflammins protect against inflammation and allergy in these ocular models may involve inhibition of phospholipase A2 and inducible nitric oxide synthase (iNOS) as well as the production of proinflammatory cytokine, interleukin-6.

Uveitis, an under-recognized adverse effect of pamidronate. Case report and literature review

Ophthalmologic adverse effects of bisphosphonate therapy are infrequent and of unclear pathogenesis. The most common has been anterior uveitis, of which 18 cases have been reported. Onset was within 24 to 48 hours after infusion initiation, and both eyes were affected in most patients. The outcome was favorable within a few days after bisphosphonate discontinuation and topical glucocorticoid therapy, although rechallenge was frequently followed by a recurrence. Bisphosphonates are being used successfully in an increasingly broad range of disorders. We report a case of pamidronate-induced anterior uveitis and present a review of the relevant literature.

IL-18 not required for IRBP peptide-induced EAU: studies in gene-deficient mice

PURPOSE

Interleukin (IL)-18 has been described as a proinflammatory cytokine in rheumatoid arthritis and bacterial infectious diseases. The present study was designed to determine the role of IL-18 in a model of ocular experimental autoimmune uveitis (EAU). The initial studies were conducted to detect the expression of IL-18 in normal mouse eye tissue, and the later studies investigated induction of EAU in mice with an IL-18(-/-) phenotype.

METHODS

IL-18 detection was performed by using 5-bromo-4-chloro-3-indoyl-ss--D-galactopyranoside (X-Gal) staining on frozen sections of eyes from mice (129/CD1, DBA1, and Balb/c), either of normal phenotype (+/+) or of deficiency (+/-, -/-) in the IL-18 gene which had been replaced by introduced genes including LacZ under the control of an IL-18 promotor. Severity of EAU was assessed in DBA1 and 129/CD1 wild-type (WT) or IL-18 knockout (KO) mice after immunization with the uveitogenic antigen: interphotoreceptor retinal binding protein (IRBP) peptide 161-180. Lymphocyte proliferation and cytokine production were also measured in WT and IL-18 KO DBA1 mice 15 days after immunization.

RESULTS

IL-18 is constitutively expressed in the epithelial cells in iris, ciliary body, and retina. EAU-resistant mice (129/CD1) with an IL-18(-/-) phenotype remained resistant after immunization with IRBP peptide (P161-180). However, EAU-susceptible mice (DBA1) exhibited disease with similar histologic characteristics, despite a generalized reduction of interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha on an IL-18(-/-) phenotype. DBA1 IL-18(-/-) also demonstrated reduced IL-10 production.

CONCLUSIONS

The IL-18 gene is not necessary for the initiation or pathogenesis of EAU induced by IRBP peptide 161-180. IL-18 is expressed in the epithelial cells in iris, ciliary body, and retina in the eyes, but its role in the eye remains undetermined.

Distribution of OX2 antigen and OX2 receptor within retina

PURPOSE

OX2 is a member of the immunoglobulin superfamily expressed on a broad range of tissues including neurons of the central and peripheral nervous systems, thymocytes, and endothelium. The recently identified OX2 receptor (OX2R) is restricted to the surfaces of myeloid lineage cells, including microglia. Functional data have implicated the OX2-OX2R interaction as a myeloid downregulatory signal. The purpose of this study was to determine the distribution and extent of expression of OX2 and its receptor within the retina, a tissue developed to restrain immune-mediated inflammatory damage.

METHODS

OX2 and OX2R monoclonal antibodies (mAbs) were used to determine OX2 and OX2R protein expression, respectively, by flow cytometry of isolated myeloid-derived cells from normal and inflamed rat retina and by immunohistochemistry of serial sections of rat retina. For comparison, distribution of OX2 was documented using species-specific monoclonal antibodies in mouse and human retina. No OX2R mAbs are available for mouse or human detection.

RESULTS

OX2 was expressed on retinal vascular endothelium and glial fibrillary acidic protein (GFAP)-negative neurons in retina and optic nerve and on a subpopulation of CD45(+) perivascular and juxtavascular cells. Within normal retina, OX2R was not detected on myeloid-derived cells. During experimental autoimmune uveoretinitis (EAU), expression of both OX2 and OX2R was noted on infiltrating leukocytes.

CONCLUSIONS

Taking these results of the distribution of OX2 in normal and OX2R in inflamed retina with other functional data of OX2-OX2R interaction, it is suggested that the OX2-OX2R interaction has the potential to contribute to a novel pathway that suppresses and limits immunologic inflammatory damage within the retina.

Cytokine gene expression in different strains of mice with endotoxin-induced uveitis (EIU)

PURPOSE

The kinetics of various cytokines in the eye plays a critical role in endotoxin-induced uveitis (EIU). This study examined the cytokine kinetics and susceptibility of EIU in four mice strains.

METHODS

Four strains of TLR-4 or Toll-like receptor-4 (Lps, lipopolysaccharide-susceptible) gene-positive mice (C3H/HeN of H-2(k), C57/B6 of H-2(b), Balb/C of H-2(d), and 129/J of H-2(b)) were injected subcutaneously with either lipopolysaccharide (LPS) in phosphate-buffered saline (PBS) or PBS alone in two repeated experiments. Mice were sacrificed 1, 3, 6, 24 (1 d), 72 (3 d), 120 (5 d), or 168 (7 d) hours after LPS injection. Ocular histology and reverse transcriptase-polymerase chain reaction (RT-PCR) to detect ocular interleukin-1 alpha (IL-1 alpha), IL-6, tumor necrosis factor-alpha (TNF-alpha), and granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA were performed. Serum IL-1 alpha, IL-1 beta, IL-6, and TNF-alpha levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

No ocular inflammation was present in any mice within six hours after LPS injection. Only the C3H/HeN mice developed a biphasic ocular inflammatory response (1 d and 5 d), during which all proinflammatory cytokine messages were expressed. In the other three strains with minimal (129/J and Balb/C) to mild (C57/B6) EIU that peaked at 1 d, IL-6 mRNA was barely detectable in C57/B6 and Balb/C; GM-CSF mRNA was also present in C57/B6. Serum IL-1 alpha, IL-1 beta, IL-6, and TNF-alpha were high in all EIU mice within six hours after LPS injection. Control mice did not develop uveitis or measurable cytokine messages.

CONCLUSION

In the most susceptible strain, C3H/HeN, EIU was biphasic and correlated to multiple proinflammatory cytokines released in the eye. The less susceptible mice strains exhibited a monophasic response to LPS that may result from no cytokine cascade.

Comparison between histopathologic findings and indocyanine green angiographic findings in Lewis rats with experimental autoimmune uveoretinitis

PURPOSE

Recently, indocyanine green angiography (IA) was used to examine chorioretinal circulation in posterior uveitis in humans, and abnormal IA findings were reported. However, choroidal pathologic examination in conjunction with these abnormal IA findings has rarely been done. Experimental autoimmune uveoretinitis (EAU) is a model for posterior uveitis in humans. The purpose of this study was to correlate abnormal IA findings in Lewis rats with EAU with pathologic findings.

METHODS

Eleven male Lewis rats were immunized with bovine S-antigen in complete Freund's adjuvant with Bordetella pertussis. After immunization, IA was performed by using a scanning laser ophthalmoscope. Eyes with abnormal IA findings were enucleated and examined histopathologically.

RESULTS

Demonstrated leakage from retinal vessels at the initial stage of disease; a decrease of background fluorescence and of the number of moderate and large vessels of the choroid, and leakage from choroidal vessels at the progressive stage; and hypofluorescent areas at the late stage. Histopathologic examination at the initial, progressive, and late stages revealed inflammation of the inner layers of the retina, a large number of inflammatory cells in the thickened retina and choroid, and impaired choroidal capillaries, respectively.

CONCLUSION

Since a correlation between pathologic findings and IA findings was demonstrated in Lewis rats with EAU, IA may be useful for evaluating the severity of uveitis in humans.

Uveal mast cells are not required for rodent uveitis

Uveal mast cells have previously been considered to be vital mediators of experimental uveitis. We extended the study of these cells to experimental melanin-induced uveitis (EMIU), a recently described clinically relevant model, and re-examined their role in endotoxin-induced uveitis (EIU) using genetically mast cell-depleted mice on a single background. EMIU was induced in Fischer 344 rats by immunisation with bovine ocular melanin (250 microgram. Animals were killed immediately, and on days 1 and 3 of clinical disease. Numbers of uveal mast cells and the percentage of degranulated cells were counted in whole-mount preparations. There was no significant change in either measure across the selected time points. To induce EIU, normal and mast cell-depleted DBA/2 mice were injected with Escherichia coli lipopolysaccharide (400 microgram). Cells infiltrating the eye 24 h after injection were quantified in 5 micrometer ocular cross-sections. Disease was not significantly reduced in the mast cell-depleted mutants. We conclude that uveal mast cells are not required for the development of EMIU or, in contrast to earlier work, EIU.

Human immunoglobulin preparations for intravenous use prevent endotoxin-induced uveitis in rats

OBJECTIVE

We analyzed the preventive effect of immunoglobulins for intravenous use (IVIgs) in endotoxin-induced uveitis (EIU), a disease related to tumor necrosis factor alpha (TNF-alpha) production.

MATERIALS AND METHODS

EIU was the experimental model in Lewis rats, injecting a systemic dose of 150 microg of lipopolysaccharide (LPS) into the rat's footpad. Half of them were treated with 5 serial intravenous doses of 100 mg of IVIg during the 5 days prior to LPS injection. Eyes were repeatedly examined with a slitlamp, rats were killed and their eyes enucleated for histopathologic study at the 2nd, 16th and 24th hours. TNF-alpha serum levels were measured in aqueous humor at several time intervals by a bioassay using L-929 mouse fibroblasts. Aqueous humor proteins were detected by the Bradford method.

RESULTS

IVIg treatment prevented EIU development, treated animals showing a lower grade of ocular inflammation beyond the 2nd hour (Fisher test, p > 0.05). Inflammatory cell infiltration was significantly reduced in the iris, ciliary body and anterior chamber at a 24-hour interval (Wilcoxon test, p < 0.05). This protection was associated with lower levels of TNF-alpha in serum at all time intervals and in aqueous humor at 16 h (Student's t test, p < 0.05), while differences were not significant between the samples of aqueous humor collected at 2 h. Protein exudate was not reduced in the treated group.

CONCLUSIONS

Repeated IVIg injections could be useful in the preventive treatment of EIU probably mediated by a decrease in TNF-alpha release.

Incidence of ocular side effects of topical beta blockers in the Netherlands

BACKGROUND

Several ocular side effects including uveitis, have been reported following topical beta blocker treatment for glaucoma and ocular hypertension. The incidence of these side effects was investigated in the Netherlands.

METHODS

A prospective observational design was used whereby monthly questionnaires were sent to all practising ophthalmologists in the Netherlands during 3 consecutive months. Questionnaires were returned at the end of each month. Any patient whose topical beta blocker therapy was altered because of an ocular reaction was noted on this questionnaire. Ophthalmologists who did not return their questionnaires were interviewed by telephone at the end of the study period. The number of patients using topical beta blockers was derived from drug sales figures.

RESULTS

70% (328/467) of the ophthalmologists in the Netherlands participated in the study. During the 3 month study period 34 cases were reported: 15 patients had periorbital dermatitis, in eight patients eyelids and conjunctiva were affected, in seven patients the conjunctiva was affected, and four patients had punctate keratitis. The calculated incidence of ocular side effects during topical beta blocker therapy was 1.51 cases/1000 patient years.

CONCLUSION

Topical beta blocker therapy is associated with few clinically important ocular side effects. No cases of uveitis were reported.

Pharmacokinetics and anti-inflammatory activity in rabbits of a novel indomethacin ophthalmic solution

The formulation of aqueous ophthalmic solutions containing indomethacin (IND) presents serious problems due to poor solubility and stability of the drug. The purpose of this study was to evaluate a novel 0.1% IND formulation containing a poly(oxyethylene)-poly(oxypropylene) block copolymer (poloxamer 407) as solubilizer. This formulation was evaluated for stability, bioavailability and anti-inflammatory activity in comparison with an ophthalmic IND solution currently on the market. The experimental solution, tested for IND stability at different temperatures, compared favorably with the commercial solution. In rabbits, it produced significantly higher IND levels in the aqueous humor and, in an immunogenic uveitis model, it induced a comparatively faster resolution of the symptoms, as determined by inflammation scores and by IOP measurements. The data indicate poloxamer 407 as a potentially valuable nonirritating, solubilizing and stabilizing agent for indomethacin.

Digital video-imaging of leukocyte migration in the iris: intravital microscopy in a physiological model during the onset of endotoxin-induced uveitis

The process of inflammation is accompanied by an alteration of leukocyte-endothelial dynamics. Reciprocal changes in the endothelium and the white cell permit the leukocyte to relinquish its normal free-flowing state in order to roll, arrest, and emigrate through the endothelium. Although intravital microscopy is an established method to observe this process, the eye has been under-utilized for this purpose. Iris vasculature can be videophotographed without the artifact of trauma. We used rhodamine 6G in vivo staining of leukocytes from BALB/c mice in a model of inflammation induced by intravitreally injected endotoxin. Digital video technology was used to record observations at baseline, 2 h, and 4 h after the endotoxin injection. Off-line analysis of microhemodynamic parameters established that the percentage of venules exhibiting rolling increased significantly from 4% at baseline to 34% at 2 h and 82% at 4 h after endotoxin injection. We found a marked increase in leukocyte arrest within 4 h (601+/-119 cells per mm(2) vs. 2+/-1 cells per mm(2) in control animals). Although shear stress differs minimally between iris arterioles and venules, both rolling and arrest occurred preferentially in venules indicating that shear stress is not the dominant factor for determining cell adhesion. Compared to previous reports on intravital microscopy, our methodology includes refinements or advantages in visualizing cells that have transmigrated as well as the avoidance of surgical trauma. The resolution and quantifiable nature of this technique are such that the methodology can be applied to repetitive observation of leukocyte-endothelial dynamics during an immune response.

Recurrent intraocular inflammation in endotoxin-induced uveitis

PURPOSE

Endotoxin-induced uveitis (EIU) in rats and mice peaks 24 hours after endotoxin injection and is commonly assumed to be a monophasic disease. This study examined intraocular inflammation at later time points to determine whether endotoxin injection can induce recurrent intraocular inflammation in strains of mice with high or moderate levels of susceptibility to EIU.

METHODS

EIU was elicited in two mouse strains with high (C3H/HeN) and moderate (FVB/N) susceptibility, by means of intraperitoneal injections of Salmonella typhimurium endotoxin. Inflammatory cells in the anterior and posterior segments of the eye were counted by a masked observer on histologic sections of eyes from 1 to 17 days after endotoxin injection.

RESULTS

A bimodal distribution of inflammatory cell infiltration was noted in eyes from C3H/HeN mice. As previously reported, inflammation peaked at 24 hours after endotoxin injection. However, a second, more pronounced peak of intraocular inflammation occurred approximately 5 days after endotoxin injection. FVB/N mice had a single peak of intraocular inflammation 4 days after injection.

CONCLUSIONS

Endotoxin injection in C3H/HeN elicits recurrent intraocular inflammation. The previously unrecognized second peak of inflammation is more severe than the initial inflammatory disease. Studies on this second inflammatory peak may be useful in determining the pathogenesis of recurrent uveitis in humans.

Xenopus IRBP, a phylogenetically remote protein, is uveitogenic in Lewis rats

Mammalian interphotoreceptor retinoid-binding proteins (IRBPs) are highly uveitogenic in Lewis rats. Xenopus laevis IRBP resembles mammalian IRBP in its four-fold structure, and has approximately 70% amino acid sequence identity with the bovine protein. This study investigated the uveitogenicity of recombinant Xenopus IRBP and two of its derived peptides in Lewis rats. Rats immunized with Xenopus IRBP developed uveoretinitis as well as pineal inflammation. The Xenopus molecule was, however, less immunopathogenic than the bovine IRBP. Of the two Xenopus IRBP peptides tested, 1180-1191 was remarkably uveitogenic, whereas sequence 521-540 exhibited low activity. It is assumed, therefore, that as with bovine IRBP, peptide 1180-1191 is the major uveitogenic sequence in Xenopus IRBP. The role individual residues of these peptides play in the immunopathogenic process is discussed. Our data thus demonstrate that despite its being phylogenetically remote, Xenopus IRBP is uveitogenic in Lewis rats

[Systemic sarcoidosis during interferon-alpha therapy for chronic hepatitis C virus infection]

A 62-year-old white woman with chronic hepatitis C virus infection was diagnosed with systemic sarcoidosis during treatment with interferon-alpha. Seventeen cases of sarcoidosis associated with interferon treatment have been reported, with only 8 inpatients with chronic hepatitis C virus infection. Our patient, with no past history of sarcoidosis, developed subcutaneous sarcoid nodules, arthritis, uveitis, pneumonitis and heart involvement two months after she was started on treatment with interferon-alpha. Her symptoms resolved when she began corticosteroid therapy and interferon-alpha was stopped. This case report suggests that exogenous interferon-alpha may trigger or contribute to the development of this multisystem granulomatous disorder in which interferon-gamma and CD4 + T-lymphocyte are mainly involved. Patients should be monitored during and following interferon-alpha therapy, since the autoimmune diseases induced by interferon therapy do not always improve after cessation of treatment.