Francois Willermain

Interplay between innate and adaptive immunity in the development of non infectious uveitis

In vertebrates, the innate and adaptive immune systems have evolved seamlessly to protect the host by rapidly responding to danger signals, eliminating pathogens and creating immunological memory as well as immunological tolerance to self. The innate immune system harnesses receptors that recognize conserved pathogen patterns and alongside the more specific recognition systems and memory of adaptive immunity, their interplay is evidenced by respective roles during generation and regulation of immune responses. The hallmark of adaptive immunity which requires engagement of innate immunity is an ability to discriminate between self and non-self (and eventually between pathogen and symbiont) as well as peripheral control mechanisms maintaining immunological health and appropriate responses. Loss of control mechanisms and/or regulation of either the adaptive or the innate immune system lead to autoimmunity and autoinflammation respectively. Although autoimmune pathways have been largely studied to date in the context of development of non-infectious intraocular inflammation, the recruitment and activation of innate immunity is required for full expression of the varied phenotypes of non-infectious uveitis. Since autoimmunity and autoinflammation implicate different molecular pathways, even though some convergence occurs, increasing our understanding of their respective roles in the development of uveitis will highlight treatment targets and influence our understanding of immune mechanisms operative in other retinal diseases. Herein, we extrapolate from the basic mechanisms of activation and control of innate and adaptive immunity to how autoinflammatory and autoimmune pathways contribute to disease development in non-infectious uveitis patients.

Endogenous endophthalmitis complicating Klebsiella pneumoniae liver abscess in Europe: case report

Purpose: To report the first European case of endogenous endophthalmitis secondary to a liver abscess due to Klebsiella pneumoniae expressing MagA gene. Methods: A 33-year-old diabetic patient was admitted for fever and right upper quadrant abdominal pain. Abdominal computed tomography and laboratory studies were performed. On day 4 after admission, patient complained of a painful and red right eye with decreased vision. A complete ophthalmological examination, including visual acuity assessment, slit lamp examination and fundus ophthalmoscopy was started. Results: Klebsiella pneumoniae liver abscess was diagnosed and antibiotherapy initiated. Polymerase chain reaction revealed that the isolated Klebsiella pneumoniae was serotype K1 and positive for Mag A. Ophthalmological examination disclosed cells in the anterior chamber and an important vitritis. Fundus was barely visible. A diagnosis of Klebsiella pneumoniae endogenous endophthalmitis complicating liver abscess was made. Intravitreal injection of antibiotics resulted in a preservation of visual acuity. Conclusion: This report suggests that rather than being confined to Taiwan, endogenous endophthalmitis secondary to a liver abscess due to Klebsiella pneumoniae expressing MagA gene, is becoming a global problem.

Uveitis-like syndrome and iris transillumination after the use of oral moxifloxacin.

ObjectiveTo report a newly recognized adverse effect of oral moxifloxacin.DesignObservational case reports.ParticipantsFive patients who used oral moxifloxacin therapy.Main outcome measuresIn five patients, a uveitis-like episode followed oral moxifloxacin therapy, afterwards they experienced photophobia. At slitlamp investigation, the patients showed almost complete iris transillumination, not restricted to one sector, and persistent mydriasis of the pupil, with no reaction to light and no near reflex. Follow-up of 3 years in one of the patients showed no change of symptoms. Only in one patient, with a history of anterior uveitis, an anterior chamber tap was positive for herpes simplex genome. Only after the use of moxifloxacin did she experience continuous photophobia.ConclusionsIris transillumination and sphincter paralysis is a newly recognized adverse effect of oral moxifloxacin therapy.

Aquaporin Expression and Function in Human Pluripotent Stem Cell–Derived Retinal Pigmented Epithelial Cells

PURPOSE Aquaporins (AQPs), a family of transmembrane water channel proteins, are essential for allowing passive water transport through retinal pigmented epithelial (RPE) cells. Even though human native RPE cells and immortalized human RPEs have been shown to express AQPs, the expression of AQPs during the differentiation in stem cell-derived RPE remains to be elucidated. METHODS In human embryonic (hESCs) and induced pluripotent stem cells (hiPSCs)-derived RPE cells, the expression of several AQPs was determined by quantitative real-time PCR and the localization of AQP1 was assessed with confocal microscopy. The functionality of AQP water channels was determined by cell volume assay in hESC-derived RPE cells. RESULTS AQP1, AQP3, AQP4, AQP5, AQP6, AQP7, AQP10, AQP11, and AQP12 were expressed in hESC- and hiPSC-derived RPE cells. Furthermore, the expression of AQP1 and AQP11 genes were significantly upregulated during the maturation of both hESC and iPSC into RPE. Confocal microscopy shows the expression of AQP1 at the apical plasma membrane of polarized cobblestone hESC- and hiPSC-derived RPE cells. Lastly, aquaporin inhibitors significantly reduced AQP functionality in hESC-RPE cells. CONCLUSIONS hESC-RPE and hiPSC-RPE cells express several AQP genes, which are functional in mature hESC-derived RPE cells. The localization of AQP1 on the apical plasma membrane in mature RPE cells derived from both hESC and hiPSC suggests its functionality. These data propose that hESC- and hiPSC-derived RPE cells, grown and differentiated under serum-free conditions, resemble their native counterpart in the human eye.

Treatment Strategies in Primary Vitreoretinal Lymphoma: A 17-Center European Collaborative Study

IMPORTANCE The best treatment option for primary vitreoretinal lymphoma (PVRL) without signs of central nervous system lymphoma (CNSL) involvement determined on magnetic resonance imaging or in cerebrospinal fluid is unknown. OBJECTIVE To evaluate the outcomes of treatment regimens used for PVRL in the prevention of subsequent CNSL. DESIGN, SETTING, AND PARTICIPANTS A retrospective cohort study was conducted at 17 referral ophthalmologic centers in Europe. We reviewed clinical, laboratory, and imaging data on 78 patients with PVRL who did not have CNSL on presentation between January 1, 1991, and December 31, 2012, with a focus on the incidence of CNS manifestations during the follow-up period. INTERVENTIONS The term extensive treatment was used for various combinations of systemic and intrathecal chemotherapy, whole-brain radiotherapy, and peripheral blood stem cell transplantation. Therapy to prevent CNSL included ocular radiotherapy and/or ocular chemotherapy (group A, 31 patients), extensive systemic treatment (group B, 21 patients), and a combination of ocular and extensive treatment (group C, 23 patients); 3 patients did not receive treatment. A total of 40 patients received systemic chemotherapy. MAIN OUTCOMES AND MEASURES Development of CNSL following the diagnosis of PVRL relative to the use or nonuse of systemic chemotherapy and other treatment regimens. RESULTS Overall, CNSL developed in 28 of 78 patients (36%) at a median follow-up of 49 months. Specifically, CNSL developed in 10 of 31 (32%) in group A, 9 of 21 (43%) in group B, and 9 of 23 (39%) in group C. The 5-year cumulative survival rate was lower in patients with CNSL (35% [95% CI, 50% to 86%]) than in patients without CNSL (68% [95% CI, 19% to 51%]; P = .003) and was similar among all treatment groups (P = .10). Adverse systemic effects occurred in 9 of 40 (23%) patients receiving systemic chemotherapy; the most common of these effects was acute renal failure. CONCLUSIONS AND RELEVANCE In the present series of patients with isolated PVRL, the use of systemic chemotherapy was not proven to prevent CNSL and was associated with more severe adverse effects compared with local treatment.

Retinal pigment epithelial cells phagocytosis of T lymphocytes: possible implication in the immune privilege of the eye.

Aim: To investigate the capability of retinal pigment epithelium (RPE) cells to phagocytose T lymphocytes and to further analyse the immunobiological consequences of this phagocytosis. Methods: Human RPE cells pretreated or not by cytochalasin, a phagocytosis inhibitor, were co-cultured with T lymphocytes for different time points. Phagocytosis was investigated by optic microscopy, electron microscopy, and flow cytometry. T cell proliferation was measured by 3H thymidine incorporation. RPE interleukin 1β mRNA expression was quantified by real time PCR. Results: RPE cells phagocytose apoptotic and non-apoptotic T lymphocytes, in a time dependent manner. This is an active process mediated through actin polymerisation, blocked by cytochalasin E treatment. Inhibition of RPE cell phagocytosis capabilities within RPE-T cell co-cultures led to an increase of lectin induced T cell proliferation and an upregulation of interleukin 1β mRNA expression in RPE cells. Conclusions: It is postulated that T lymphocyte phagocytosis by RPE cells might, by decreasing the total number of T lymphocytes, removing apoptotic lymphocytes, and downregulating the expression of IL-1β, participate in vivo in the induction and maintenance of the immune privilege of the eye, preventing the development of intraocular inflammation.

Rifabutin-Associated Panuveitis with Retinal Vasculitis in Pulmonary Tuberculosis

Introduction: Rifabutin-associated uveitis has been reported frequently in AIDS patients and more rarely in immunocompetent patients. It is characterized clinically by anterior acute uveitis. Only a few poorly documented cases of rifabutin-induced panuveitis with retinal vasculitis have been reported. Here, we report four cases of rifabutin-associated panuveitis with retinal vasculitis. Case reports: We describe four patients with active tuberculosis, treated with a multidrug regimen including rifabutin for at least 1.5 months before presentation. The first patient was immunocompetent, the three others had AIDS and were undergoing triple anti-HIV therapy. Three patients were women with a low body weight. All four patients presented with panuveitis and retinal vasculitis. Interruption of the drug rapidly reduced the ocular inflammation in all cases. Conclusion: Four cases of rifabutin-associated panuveitis with retinal vasculitis are reported in patients with active pulmonary tuberculosis. Immunogenicity of Mycobacterium tuberculosis as well as the very low weight of the patients might be implicated in the development of this unusual form of rifabutin-associated uveitis.

Hyperosmotic stress induces cell cycle arrest in retinal pigmented epithelial cells

Osmotic changes occur in many tissues and profoundly influence cell function. Herein, we investigated the effect of hyperosmotic stress on retinal pigmented epithelial (RPE) cells using a microarray approach. Upon 4-h exposure to 100 mM NaCl or 200 mM sucrose, 79 genes were downregulated and 72 upregulated. Three gene ontology categories were significantly modulated: cell proliferation, transcription from RNA polymerase II promoter and response to abiotic stimulus. Fluorescent-activated cell sorting analysis further demonstrated that owing to hyperosmotic stimulation for 24 h, cell count and cell proliferation, as well as the percentage of cells in G0/G1 and S phases were significantly decreased, whereas the percentage of cells in G2/M phases increased, and apoptosis and necrosis remained unaffected. Accordingly, hyperosmotic conditions induced a decrease of cyclin B1 and D1 expression, and an activation of the p38 mitogen-activated protein kinase. In conclusion, our results demonstrate that hypertonic conditions profoundly affect RPE cell gene transcription regulating cell proliferation by downregulation cyclin D1 and cyclin B1 protein expression.

Severe bilateral panuveitis during melanoma treatment by Dabrafenib and Trametinib

BackgroundWe report a case of severe bilateral panuveitis during melanoma therapy with a combination of Dabrafenib, a B-raf (BRAF) inhibitor, and Trametinib, a mitogen/extracellular signal-regulated kinase (MEK) inhibitor. Both of these drugs are effectors in the mitogen-activated protein kinase (MAPK) pathway, which plays an important role in the physiopathology of melanoma. Dabrafenib and Trametinib have shown improved survival of patients with metastatic melanoma but they have also been associated with the development of uveitis.FindingsOur patient was a 55-year-old woman with metastatic melanoma who presented with sudden onset of bilateral painless visual loss. She had been treated with Dabrafenib and Trametinib. Trametinib was discontinued at the onset of symptoms but there was no improvement. Ophthalmological examination revealed severe bilateral non-granulomatous panuveitis, with choroidal thickening, chorio-retinal folds, and multiple serous retinal detachments (SRDs). Topical corticosteroid treatment was initiated, and Dabrafenib was discontinued. A good response was obtained with a recovery of visual acuity of 20/25 on both eyes and an almost complete resolution of the SRDs.ConclusionsThis case highly suggests that MAPK pathway inhibition can lead to severe uveitis. Dabrafenib and Trametinib could have both played a role in inducing the disease. Further studies are needed to evaluate the possible role of the combination of these drugs in inducing uveitis and SRD.

ICAM-1 and VCAM-1 are differentially expressed on blood-retinal barrier cells during experimental autoimmune uveitis.

Adhesion molecules play a central role in leukocyte adhesion to the blood-retinal barrier (BRB) during uveitis. VCAM-1 expression on the BRB has been already described but although structurally similar, ICAM-1 has shown in various autoimmunity models to have distinct role and expression. Here, we induced uveitis in C57Bl/6 mice by adoptive transfer of semi-purified T cells from IRBP1-20-immunized mice. Using Flow cytometry analysis on transferred cells and immunofluorescence staining on retina we have studied the comparative ocular expression of both ICAM-1 and VCAM-1 and their ligands LFA-1 and VLA-4 at the surface of uveitogenic cells. Our results showed that LFA-1 and VLA-4 are expressed on both T and non T cells, VLA-4 sparsely and LFA-1 ubiquitously. Considering retinal expression, ICAM-1 is faintly present and VCAM-1 is absent in naive eyes. Only ICAM-1 is present on infiltrating cells in the retina and vitreous, while only VCAM-1 extends to perivascular glial cells and all along the internal limiting membrane. Finally, ICAM-1 is strongly expressed on the RPE, where VCAM-1 expression is much weaker. VCAM-1 seems most strongly expressed on the internal BRB while ICAM-1 predominates on the external BRB. Those major differences in the expression pattern could represent differential entry pathways for inflammatory cells to penetrate the eye.