The retina as an early biomarker of neurodegeneration in a rotenone-induced model of Parkinson's disease: evidence for a neuroprotective effect of rosiglitazone in the eye and brain.

Parkinson's Disease (PD) is the second most common neurodegenerative disease worldwide, affecting 1 % of the population over 65 years of age. Dopaminergic cell death in the substantia nigra and accumulation of Lewy bodies are the defining neuropathological hallmarks of the disease. Neuronal death and dysfunction have been reported in other central nervous system regions, including the retina. Symptoms of PD typically manifest only when more than 70 % of dopaminergic cells are lost, and the definitive diagnosis of PD can only be made histologically at post-mortem, with few biomarkers available.In this study, a rotenone-induced rodent model of PD was employed to investigate retinal manifestations in PD and their usefulness in assessing the efficacy of a novel therapeutic intervention with a liposomal formulation of the PPAR-γ (Peroxisome proliferator-activated receptor gamma) agonist rosiglitazone.Retinal assessment was performed using longitudinal in vivo imaging with DARC (detection of apoptosing retinal cells) and OCT (optical coherence tomography) technologies and revealed increased RGCs (Retinal Ganglion Cells) apoptosis and a transient swelling of the retinal layers at day 20 of the rotenone insult. Follow-up of this model demonstrated characteristic histological neurodegenerative changes in the substantia nigra and striatum by day 60, suggesting that retinal changes precede the "traditional" pathological manifestations of PD. The therapeutic effect of systemic administration of different formulations of rosiglitazone was then evaluated, both in the retina and the brain. Of all treatment regimen tested, sustained release administration of liposome-encapsulated rosiglitazone proved to be the most potent therapeutic strategy, as evidenced by its significant neuroprotective effect on retinal neurons at day 20, and on nigrostriatal neurons at day 60, provided convincing evidence for its potential as a treatment for PD.Our results demonstrate significant retinal changes occurring in this model of PD. We show that rosiglitazone can efficiently protect retinal neurons from the rotenone insult, and that systemic administration of liposome-encapsulated rosiglitazone has an enhanced neuroprotective effect on the retina and CNS (Central Nervous System). To our knowledge, this is the first in vivo evidence of RGCs loss and early retinal thickness alterations in a PD model. Together, these findings suggest that retinal changes may be a good surrogate biomarker for PD, which may be used to assess new treatments both experimentally and clinically.

NGF Modulates trkANGFR/p75NTR in αSMA-Expressing Conjunctival Fibroblasts from Human Ocular Cicatricial Pemphigoid (OCP).

OBJECTIVE: In a previous study, we reported the upregulation of Nerve Growth Factor (NGF) and trkANGFR expression in Ocular Cicatricial Pemphigoid (OCP), an inflammatory and remodeling eye disease. Herein, we hypothesize a potential NGF-driven mechanism on fibroblasts (FBs) during OCP remodeling events. To verify, human derived OCP-FBs were isolated and characterized either at baseline or after NGF exposure. MATERIALS AND METHODS: Conjunctival biopsies were obtained from 7 patients having OCP and 6 control subjects (cataract surgery). Both conjunctivas and primary FB cultures were characterised for αSMA, NGF and trkANGFR/p75NTR expression. Subcultures were exposed to NGF and evaluated for αSMA, NGF, trkANGFR/p75NTR expression as well as TGFß1/IL4 release. For analysis, early and advanced subgroups were defined according to clinical parameters. RESULTS: OCP-conjunctivas showed αSMA-expressing FBs and high NGF levels. Advanced OCP-FBs showed higher αSMA expression associated with higher p75NTR and lower trkANGFR expression, as compared to early counterparts. αSMA expression was in keeping with disease severity and correlated to p75NTR. NGF exposure did not affect trkANGFR levels in early OCP-FBs while decreased both αSMA/p75NTR expression and TGFß1/IL4 release. These effects were not observed in advanced OCP-FBs. CONCLUSIONS: Taken together, these data are suggestive for a NGF/p75NTR task in the potential modulation of OCP fibrosis and encourages further studies to fully understand the underlying mechanism occurring in fibrosis. NGF/p75NTR might be viewed as a potential therapeutic target.

Molecular and biochemical expression of TLRs in human amniotic membrane: a comparative study of fresh and cryopreserved specimens.

BACKGROUND: To assess the expression of toll-like receptors (TLRs) in human amniotic membrane (AM) specimens and compare this expression with those of AMs undergoing the standard preservation procedure (handling) for ocular surgery. METHODS: Human fresh (n = 10; five spontaneous and five cesarean) or handled (n = 5) AMs were analyzed for TLR gene and protein expression. Two pieces were obtained from each specimen, and subjected to molecular or biochemical analysis. Relative real-time PCR and SDS-PAGE were carried out according to standard procedures. The REST-ANOVA coupled analysis was used to compare the molecular and biochemical data. RESULTS: The fresh membranes expressed all the TLRs (TLR1-10), with different gene expression as detected/evidenced by the Ct values, the intra-fresh group analysis showing that there was a variation of TLR expression whichvaried within the fresh membranes. The handled AMs retained the TLR expression after standard processing and preservation, but with a particular pattern which included a high TLR3/TLR4 and low TLR6 expression, when compared to the fresh membranes. The molecular data were confirmed by Western blot analysis. CONCLUSIONS: AM is routinely used in several ophthalmic surgical procedures, and notwithstanding its preservation procedure, AM is reported to favour wound healing and exert anti-angiogenic, anti-inflammatory, anti-scarring as well as anti-bacterial activities. The presence of TLRs in handled AM would imply that TLRs might be preserved in AMs used in ocular surgery. The findings herein described provide additional data concerning the presence of TLRs in cryopreserved AM, and suggest a possible contribution of AM in ocular surgery, via the innate immune response.

Nerve growth factor modulates toll-like receptor (TLR) 4 and 9 expression in cultured primary VKC conjunctival epithelial cells.

PURPOSE: To investigate if nerve growth factor (NGF) might modulate toll-like receptor (TLR) 4 and 9 expression in primary cultures of vernal keratoconjunctivitis (VKC)-derived conjunctival epithelial cells (VKC-ECs). METHODS: Primary cultures of ECs were established from VKC (n=7) and healthy-control (n=5) conjunctival specimens. Primary untouched and short-term NGF-exposed VKC-ECs were analyzed for molecular (relative real-time PCR) and biochemical (confocal and fluorescence-activated cell sorting analysis of TLR4 and TLR9 expression. Data were compared to their untreated as well as stimulated healthy-control counterparts. Conditioned media were analyzed for interferon (IFN)-gamma, interleukin (IL)-4, IL-10, and IL-12 p40 secretion. RESULTS: Primary untouched VKC-ECs showed TLR4 increase and TLR9 decrease compared to their healthy-control counterparts. NGF exposure resulted in a strong upregulation of TLR4 and a moderate upregulation of TLR9 in few passages VKC-ECs. Both TLR4 and TLR9 upregulation occurred in a dose-dependent fashion and were supported by biochemical analysis. NGF triggered a dose-response release of IL-10 in VKC-ECs conditioned media, an effect not detected for IL-4, IL-12 p40, and IFN-gamma. CONCLUSIONS: Our data indicate that NGF is able to induce TLR4/TLR9 overexpression in VKC-ECs. These cells exhibited poor IL-4, IL-12 p40, and IFN-gamma responses to NGF, while a significant IL-10 decreased secretion was detected. The different NGF-induced TLR response between VKC and healthy-control conjunctival ECs as well as the different cytokine response might reflect a different pattern of cell activation according to the state of VKC.

Natural killer cells in vernal keratoconjunctivitis.

PURPOSE: Recent studies suggest that natural killer (NK) cells exert effector/regulatory properties on both innate and adaptive responses via release of different cytokines. While some information indicates NK cells in allergic asthma and atopic dermatitis, no data are available for allergic conjunctivitis. The aim of this study was to evaluate NK in the blood and the conjunctiva of patients with vernal keratoconjunctivitis (VKC). METHODS: Six patients with active VKC and six healthy subjects were included in the study. Blood samples and conjunctival biopsies were taken from each patient. NK cells in blood and conjunctiva were quantified by flow cytometry and immunohistochemistry, respectively. Clinical findings of the patients were recorded, conjunctival immune infiltrates were characterized, and both parameters were correlated to NK cell number. RESULTS: Compared to healthy subjects, NK cells were significantly decreased in the blood and increased in the conjunctiva of patients with VKC. CONCLUSIONS: Together with lymphocytes, eosinophils, and mast cells, NK cells constitute a significant proportion of the immune cells infiltrating VKC conjunctiva. This finding indicates a potential role of NK and innate immunity in the regulation of allergic reactions and in diseases such as VKC. New therapeutic alternatives for modulating allergic inflammation might target NK cells.

Nerve growth factor has a modulatory role on human primary fibroblast cultures derived from vernal keratoconjunctivitis-affected conjunctiva.

PURPOSE: To evaluate the role of nerve growth factor (NGF) in remodeling processes of vernal keratoconjunctivitis (VKC). VKC is a chronic inflammatory disorder of the conjunctiva and is characterized by marked tissue remodeling. NGF, a pleiotrophic factor with documented profibrogenic activities, is produced by inflammatory and structural cells populating the VKC conjunctiva and is increased in the serum and tears of VKC patients. METHODS: Primary cultures of VKC-derived fibroblasts (VKC-FBs) were exposed to increasing NGF concentrations (1-500 ng/ml) to evaluate and compare the expression of alpha-smooth muscle actin (alphaSMA, a defining myofibroblast marker), collagens (types I and IV), and metalloproteinases and tissue inhibitors (MMP9/TIMP1, MMP2/TIMP2) at the biochemical as well as molecular levels. RESULTS: Endogenous NGF was increased in the VKC-FB supernatant, as compared to healthy-FB supernatant. VKC-FBs expressed alphaSMA and increased types I and IV collagens. VKC-FBs, and in particular all alphaSMA positive cells, expressed both trkA(NGFR) and p75(NTR), while healthy-FBs only expressed trkA(NGFR). Exogenous NGF did not change alphaSMA expression, while alphaSMA expression was enhanced by specific neutralization of p75(NTR). NGF (10 ng/ml) exposure significantly decreased type I collagen expression, without affecting type IV collagen, and increased MMP9mRNA and protein. CONCLUSIONS: The autocrine modulation of differentiation and response of VKC-FBs to NGF exposure with downregulation of type I collagen and upregulation of MMP9 expression supports a relevant role for NGF in tissue remodeling of VKC.