No abstract

Cytokine- and chemokine-mediated signalling is involved in the neuroinflammatory process that leads to retinal ganglion cell (RGC) damage in glaucoma. Substances with anti-inflammatory properties could decrease these cytokines and chemokines and thus prevent RGC death. The authors of this study analysed the anti-inflammatory effect of a hydrophilic saffron extract standardized to 3% crocin content, focusing on the regulation of cytokine and chemokine production, in a mouse model of unilateral laser-induced ocular hypertension (OHT). We demonstrated that following saffron treatment, most of the concentration of proinflammatory cytokines (IL-1β, IFN-γ, TNF-α, and IL-17), anti-inflammatory cytokines (IL-4 and IL-10), Brain-derived Neurotrophic Factor (BDNF), Vascular Endothelial Growth Factor (VEGF), and fractalkine were unaffected in response to laser-induced OHT in both the OHT eye and its contralateral eye. Only IL-6 levels were significantly increased in the OHT eye one day after laser induction compared with the control group. These results differed from those observed in animals subjected to unilateral OHT and not treated with saffron, where changes in cytokine levels occurred in both eyes. Therefore, saffron extract regulates the production of proinflammatory cytokines, VEGF, and fractalkine induced by increasing intraocular pressure (IOP), protecting the retina from inflammation. These results indicate that saffron could be beneficial in glaucoma by helping to reduce the inflammatory process.

Background and Aims Hyponatremia is the most common electrolyte disturbance in clinical care. Even mild presentations are associated with poor prognosis and increased mortality, in spite of which there is a trend to minimize the importance of small variations in natremia, that have historically been dismissed as not having negative consequences despite growing evidence against it. In this regard, it has not been studied to date whether an intermittent but recurrent hyponatremia is relevant. There are clinical scenarios where this condition could occur and be overlooked, such as cirrhosis or heart failure. Method Different rat models have been used to study the effects of different hypotonic situations on the electrolyte balance and central nervous system: intermittent recurrent hyponatremia (intraperitoneal (i.p.) daily dose of desmopressin acetate (ddAVP) and a water dose equivalent to 2.5% of the animal's body weight in hyposodic diet fed animals), acute on intermittent recurrent hyponatremia (i.p. water overload equivalent to 10% of the animal's body weight in animals subjected to intermittent recurrent hyponatremia) and acute hyponatremia (i.p. administration of a 10% of the animal's body weight water overload in chow fed animals). Apparent diffusion coefficient (ADC) obtained from diffusion weighted images (DWI) acquired through magnetic resonance (7T Bruker Biospec) was used to study content and distribution of brain water, and immunohistochemistry was used to examine glial fibrillary acidic-protein (GFAP), astrocyte marker, and myelin basic protein (MBP), oligodendrocyte and myelin marker. Results In the intermittent recurrent hyponatremia model, mild and transient hyponatremia was induced (baseline Nap 136.50±1.73mEq/L vs 4h post-medication 129.44±1.20mEq/L, p<0.001), which was recovered 24h after treatment (141.25±0.96mEq/L, NS compared to baseline). However, this situation was repeated over a 7 day period. This translated into a lower ADC value in the whole brain (WB) compared to chow fed animals (25.07±1.71 vs 26.71±2.40*10−3mm2/s, p = 0.05) after this 7 day period, suggesting an increase in total brain water in this situation. There was also an increase in GFAP expression in the gray matter (GM) compared to chow fed animals (33.22±5.25 vs 25.07±2.31au, p = 0.031), although no significant changes in MBP’s expression were seen. Acute on intermittent recurrent hyponatremia induced hypotonic hyponatremia (116.00±1.16mEq/L, p<0.001 compared to baseline). In this situation, a progressive decrease in ADC values in the WB was seen, and it was less pronounced compared to chow fed animals (slope -0.11±0.02 vs -0.26±0.006, p = 0.014). When GM and white matter (WM) were analysed separately, they both showed a progressive increase in ADC values, more evident in the WM (slope WM 0.19±0.04, p<0.05; slope GM 0.05±0.02, p = 0.002). The water overload increased GFAP and MBP’s expression in the WM (GFAP 23.17±6.37 vs 16.83±5.17au, p = 0.001; MBP 45.20±8.32 vs 28.76±7.03au, p<0.001), but no changes were seen in the GM, similarly to what had been observed in the acute hyponatremia model. Conclusion Intermittent recurrent hyponatremia is a novel animal model that suggests there can be significant water retention after only a few hours of hyponatremia a day, provided this situation is repeated over time. Such water retention translates into greater brain water accumulation and astroglial activation in the GM. These animals's response to an additional water overload does not show big variations compared to what is observed in acute hyponatremia. This study highlights the importance of slight fluctuations in natremia, which, if maintained over time, can translate underlying water retention with consequences at the central nervous system level.

Purpose: To analyse the anti‐inflammatory effect of saffron extract, by regulating the expression of cytokines and chemokines involved in the neuroinflammatory process leading to retinal ganglion cell (RGC) damage, in a mouse model of unilateral laser‐induced ocular hypertension (OHT). Methods: Three groups of Albino Swiss mice treated with saffron extract were used; saffron naïve group (SNG), saffron laser group 1 day (SLG1d) and saffron laser group 3 days (SLG3d). Both eyes with OHT (treated with laser photocoagulation) and their contralateral were analysed. Retinal samples were processed and multiarray kits (MILLIPLEX MAP Mouse Cytokine/Myokine Magnetic Bead Panel) were used to quantify the expression of: IL‐1β, IL‐4, IL‐6, IL‐10, IL‐17, IFN‐ϒ, TNF‐α, Brain‐derived Neurotrophic Factor (BDNF), Vascular Endothelial Growth Factor (VEGF) and Fractalkine. Immunohistochemical analysis was performed to locate cells expressing the factors and cytokines detected in the multiplex assay. Results: After saffron treatment, no significant differences were found, at 1 and 3 days after laser‐induced OHT, between the concentration of proinflammatory cytokines (IL‐1β, IFN‐γ, TNF‐α and IL‐17), anti‐inflammatory cytokines (IL‐4 and IL‐10), BDNF, VEGF, and fractalkine in both the OHT eye and its contralateral eye, compared to saffron naïve. IL‐6 levels increased significantly in the OHT eye in SLG1d, reaching normal values at SLG3d compared to SNG. These results are contrary to those found in OHT eyes and their contralateral not treated with saffron, in which changes in cytokine levels were observed. Conclusions: Saffron is effective in regulating the production of proinflammatory cytokines, VEGF, and fractalkine induced by increased IOP, thus protecting the retina from its related damage. Saffron could be beneficial as coadjutant therapies in the treatment of glaucoma, thus helping to decrease the inflammatory process that occurs in this pathology.