CCL4 induces inflammatory signalling and barrier disruption in the neurovascular endothelium.

BACKGROUND: During neuroinflammation many chemokines alter the function of the blood-brain barrier (BBB) that regulates the entry of macromolecules and immune cells into the brain. As the milieu of the brain is altered, biochemical and structural changes contribute to the pathogenesis of neuroinflammation and may impact on neurogenesis. The chemokine CCL4, previously known as MIP-1ß, is upregulated in a wide variety of central nervous system disorders, including multiple sclerosis, where it is thought to play a key role in the neuroinflammatory process. However, the effect of CCL4 on BBB endothelial cells (ECs) is unknown. MATERIALS AND METHODS: Expression and distribution of CCR5, phosphorylated p38, F-actin, zonula occludens-1 (ZO-1) and vascular endothelial cadherin (VE-cadherin) were analysed in the human BBB EC line hCMEC/D3 by Western blot and/or immunofluorescence in the presence and absence of CCL4. Barrier modulation in response to CCL4 using hCMEC/D3 monolayers was assessed by measuring molecular flux of 70 â€‹kDa RITC-dextran and transendothelial lymphocyte migration. Permeability changes in response to CCL4 in vivo were measured by an occlusion technique in pial microvessels of Wistar rats and by fluorescein angiography in mouse retinae. RESULTS: CCR5, the receptor for CCL4, was expressed in hCMEC/D3 cells. CCL4 stimulation led to phosphorylation of p38 and the formation of actin stress fibres, both indicative of intracellular chemokine signalling. The distribution of junctional proteins was also altered in response to CCL4: junctional ZO-1 was reduced by circa 60% within 60 â€‹min. In addition, surface VE-cadherin was redistributed through internalisation. Consistent with these changes, CCL4 induced hyperpermeability in vitro and in vivo and increased transmigration of lymphocytes across monolayers of hCMEC/D3 cells. CONCLUSION: These results show that CCL4 can modify BBB function and may contribute to disease pathogenesis.

OCT patterns of macular edema and response to bevacizumab therapy in retinal vein occlusion.

BACKGROUND: Baseline OCT morphology of macular edema (ME) due to branch (BRVO) or central retinal vein occlusion (CRVO) was evaluated with respect to response to bevacizumab treatment. METHODS: Sixty-five patients (33 CRVO, 32 BRVO) were treated with intravitreal injections of 2.5 mg bevacizumab. Reinjections were only performed if ME persisted or recurred. Follow-up ranged from 23 to 128 weeks. OCT (Stratus OCT™, Carl Zeiss Meditec) morphology at baseline was analyzed retrospectively to evaluate its effect on treatment outcome (ETDRS visual acuity and central retinal thickness). Baseline OCT scans were studied with regard to central retinal thickness (CRT), presence and height of subretinal fluid (SRF), intraretinal cystoid spaces (ICS) and maximum horizontal diameter of the largest delimitable ICS. RESULTS: In CRVO patients, baseline CRT is not correlated with CRT at last visit, but there is a significant correlation of baseline CRT with final visual acuity (VA). Presence of SRF and diameter of ICS do not influence functional and morphological response to bevacizumab treatment. Baseline CRT in BRVO patients is not significantly correlated with final VA and final CRT. There is no difference in treatment response between patients with or without baseline SRF. BRVO patients with large ICS >600 µm (13.8%) at baseline had a significantly worse VA at last visit than patients with smaller ICS (p = 0.011), and did not achieve a significant improvement under bevacizumab therapy. The duration of retinal vein occlusion before start of treatment was significantly longer in patients with ICS >600 µm (232 ± 96 weeks versus 17 ± 17 weeks; p < 0.001). There is no correlation of ICS diameter and duration of vein occlusion in patients with ICS <600 µm. CONCLUSIONS: In CRVO patients, baseline CRT and final VA are significantly correlated, whereas the presence of SRF or diameter of ICS was not predictive for treatment outcome. In BRVO patients, ICS with a diameter of >600 µm are associated with a long duration of vein occlusion and poor functional response to treatment with bevacizumab. CRT and SRF were not found to be significant prognostic factors.