Tofacitinib improved peripheral endothelial dysfunction and brain-derived neurotrophic factor levels in the rat adjuvant-induced arthritis model.

This study aimed to explore the effect of Tofacitinib on endothelial dysfunction and cerebral levels of brain-derived neurotrophic factor (BDNF) in the adjuvant-induced arthritis (AIA) rat model. Tofacitinib (10 mg/kg twice a day) or vehicle was administered from the first signs of inflammation. Arthritis scores were daily monitored while other parameters including endothelial function assessed from aortic rings, radiographic scores, blood pressure, heart rate, circulating levels of triglycerides, cholesterol, and interleukin (IL)-1ß, tumor necrosis factor-α (TNF-α), IL-17A, and cerebral BDNF levels were determined after 3 weeks of treatment. A group of non-AIA rats served as controls. In AIA rats, as compared with vehicle, Tofacitinib significantly reduced arthritis and radiographic scores, decreased total cholesterol and low-density lipoprotein cholesterol (LDL-C), but changed neither blood pressure nor heart rate and proinflammatory cytokines levels. It also fully restored acetylcholine (Ach)-induced relaxation (p < 0.05) through increased nitric oxide (NO) synthase activity, reduced BH4 deficiency and O2 -° production, decreased cyclo-oxygenase-2 (COX-2)/arginase activities, and enhanced endothelium-derived hyperpolarizing factor (EDHF) production. These effects translated into a decrease in atherogenic index and an elevation of BDNF levels in the prefrontal cortex (p < 0.05) and hippocampus (p < 0.001). The present study identified Tofacitinib as an efficient therapeutic option to reduce cardiovascular risk and improve BDNF-dependent cognition in arthritis.

A reconciling hypothesis centred on brain-derived neurotrophic factor to explain neuropsychiatric manifestations in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune chronic inflammatory disease characterized by synovitis leading to joint destruction, pain and disability. Despite efficient antirheumatic drugs, neuropsychiatric troubles including depression and cognitive dysfunction are common in RA but the underlying mechanisms are unclear. However, converging evidence strongly suggests that deficit in brain-derived neurotrophic factor (BDNF) signalling contributes to impaired cognition and depression. Therefore, this review summarizes the current knowledge on BDNF in RA, proposes possible mechanisms linking RA and brain BDNF deficiency including neuroinflammation, cerebral endothelial dysfunction and sedentary behaviour, and discusses neuromuscular electrical stimulation as an attractive therapeutic option.

Double Direct Injection of Blood into the Cisterna Magna as a Model of Subarachnoid Hemorrhage.

Among strokes, subarachnoid hemorrhage (SAH) consecutive to the rupture of a cerebral arterial aneurysm represents 5-9% but is responsible for about 30% of the total stroke-related mortality with an important morbidity in terms of neurological outcome. A delayed cerebral vasospasm (CVS) may occur most often in association with a delayed cerebral ischemia. Different animal models of SAH are now being used including endovascular perforation and direct injection of blood into the cisterna magna or even the prechiasmatic cistern, each exhibiting distinct advantages and disadvantages. In this article, a standardized mouse model of SAH by double direct injection of determined volumes of autologous whole blood into the cisterna magna is presented. Briefly, mice were weighed and then anesthetized by isoflurane inhalation. Then, the animal was placed in a reclining position on a heated blanket maintaining a rectal temperature of 37 °C and positioned in a stereotactic frame with a cervical bend of about 30°. Once in place, the tip of an elongated glass micropipette filled with the homologous arterial blood taken from carotid artery of another mouse of the same age and gender (C57Bl/6J) was positioned at a right angle in contact with the atlanto-occipital membrane by means of a micromanipulator. Then 60 µL of blood was injected in the cisterna magna followed by a 30° downward tilt of the animal for 2 minutes. The second infusion of 30 µL of blood into the cisterna magna was performed 24 h after the first one. The individual follow-up of each animal is carried out daily (careful evaluation of weight and well-being). This procedure allows a predictable and highly reproducible distribution of blood, likely accompanied by intracranial pressure elevation that can be mimicked by an equivalent injection of an artificial cerebral spinal fluid (CSF), and represents an acute to mild-model of SAH inducing low mortality.

Development of Novel 111-In-Labelled DOTA Urotensin II Analogues for Targeting the UT Receptor Overexpressed in Solid Tumours.

Overexpression of G protein-coupled receptors (GPCRs) in tumours is widely used to develop GPCR-targeting radioligands for solid tumour imaging in the context of diagnosis and even treatment. The human vasoactive neuropeptide urotensin II (hUII), which shares structural analogies with somatostatin, interacts with a single high affinity GPCR named UT. High expression of UT has been reported in several types of human solid tumours from lung, gut, prostate, or breast, suggesting that UT is a valuable novel target to design radiolabelled hUII analogues for cancer diagnosis. In this study, two original urotensinergic analogues were first conjugated to a DOTA chelator via an aminohexanoic acid (Ahx) hydrocarbon linker and then -hUII and DOTA-urantide, complexed to the radioactive metal indium isotope to successfully lead to radiolabelled DOTA-Ahx-hUII and DOTA-Ahx-urantide. The 111In-DOTA-hUII in human plasma revealed that only 30% of the radioligand was degraded after a 3-h period. DOTA-hUII and DOTA-urantide exhibited similar binding affinities as native peptides and relayed calcium mobilization in HEK293 cells expressing recombinant human UT. DOTA-hUII, not DOTA-urantide, was able to promote UT internalization in UT-expressing HEK293 cells, thus indicating that radiolabelled 111In-DOTA-hUII would allow sufficient retention of radioactivity within tumour cells or radiolabelled DOTA-urantide may lead to a persistent binding on UT at the plasma membrane. The potential of these radioligands as candidates to target UT was investigated in adenocarcinoma. We showed that hUII stimulated the migration and proliferation of both human lung A549 and colorectal DLD-1 adenocarcinoma cell lines endogenously expressing UT. In vivo intravenous injection of 111In-DOTA-hUII in C57BL/6 mice revealed modest organ signals, with important retention in kidney. 111In-DOTA-hUII or 111In-DOTA-urantide were also injected in nude mice bearing heterotopic xenografts of lung A549 cells or colorectal DLD-1 cells both expressing UT. The observed significant renal uptake and low tumour/muscle ratio (around 2.5) suggest fast tracer clearance from the organism. Together, DOTA-hUII and DOTA-urantide were successfully radiolabelled with 111Indium, the first one functioning as a UT agonist and the second one as a UT-biased ligand/antagonist. To allow tumour-specific targeting and prolong body distribution in preclinical models bearing some solid tumours, these radiolabelled urotensinergic analogues should be optimized for being used as potential molecular tools for diagnosis imaging or even treatment tools.

Growth Differentiation Factor-15 (GDF-15) Is Associated With Mortality in Ischemic Stroke Patients Treated With Acute Revascularization Therapy.

Background and Aims: Growth differentiation factor-15 (GDF-15) has been identified as a robust marker of developing cardiovascular disease, however, little is currently known about its prognostic value in stroke patients. In a context of growing interest to discover new biomarkers in stroke, we aimed to assess the association between circulating GDF-15 levels and three-month mortality in ischemic stroke patients treated with acute revascularization therapy. Methods: 173 patients hospitalized for acute ischemic stroke and treated with either intravenous thrombolysis (n = 99, 57.2%), mechanical thrombectomy (n = 41, 23.4%) or combined therapy (n = 33, 19.1%) were prospectively included. Baseline clinical and biological characteristics were recorded. Plasma GDF-15 levels were measured at admission (D0), and at 24 h, 3 and 7 days. Clinical severity was assessed with the National Institutes of Health Stroke Scale (NIHSS) score, and vital status was obtained 3 months after the stroke. Results: At 3 months post-stroke, 32 patients (18.5%) had died. The deceased patients had higher D0 plasma GDF-15 levels (median [IQR]: 2,777 [1,769-5,446] vs. 1,460 [965-2,079] pg/mL, P < 0.001). In multivariable logistic regression analysis, D0 GDF-15 levels in the third tertile of the distribution were independently associated with mortality at 3 months (OR = 3.71; 95% CI: 1.09-12.6, P = 0.036), even after adjustment for confounding variables including clinical severity. Conclusions: Our data show for the first time that GDF-15 plasma concentration at admission is independently associated with 3-month mortality in ischemic stroke patients treated with acute revascularization therapy. The pathophysiological mechanisms that could explain this association warrant further study.

Brain-derived Neurotrophic Factor Pathway after Downhill and Uphill Training in Rats.

INTRODUCTION: The elevation of brain-derived neurotrophic factor (BDNF) levels in the brain and the subsequent phosphorylation of its cognate tropomyosin-related kinase B (TrkB) receptors at tyrosine 816 (pTrkB) are largely involved in the positive effect of aerobic exercise on brain functioning. Although BDNF levels were reported to increase in proportion with exercise intensity, the effect of the type of contraction is unknown. Therefore, the cerebral BDNF/TrkB pathway was investigated after uphill and downhill treadmill activities at equivalent intensity to preferentially induce eccentric and concentric contractions, respectively. METHODS: A treadmill activity (30 min·d for seven consecutive days) either in a horizontal position at two different speeds to modulate intensity (experiment 1) or at three different inclinations (null, -10%, and +5%) but at equivalent intensity to modulate the type of contraction (experiment 2) was induced in rats. Both experiments included sedentary rats. Levels of BDNF, pTrkB, synaptophysin (marker of synaptogenesis), endothelial nitric oxide synthase phosphorylated at serine 1177 (peNOS), and c-fos levels (indicators of elevation in blood flow in the cerebrovasculature and neuronal activity, respectively) were measured in motor- and cognition-related brain regions using Western blotting analysis. RESULTS: Experiment 1 indicated that treadmill activity induces an intensity-dependent increase in peNOS, c-fos, and BDNF levels. Experiment 2 showed that intensity of exercise as well as activation of the cerebral BDNF pathway, and synaptogenesis did not differ among horizontal, uphill, and downhill treadmill activities. CONCLUSION: The cerebral response of the BDNF pathway to a treadmill activity is dependent on exercise intensity, but not on the type of contraction (eccentric vs concentric).

Vascular brain-derived neurotrophic factor pathway in rats with adjuvant-induced arthritis: Effect of anti-rheumatic drugs.

BACKGROUND AND AIMS: In rheumatoid arthritis, the control of both disease activity and standard cardiovascular (CV) risk factors is expected to attenuate the increased CV risk. Evidence that brain-derived neurotrophic factor (BDNF) plays a role in vascular biology led us to investigate the vascular BDNF pathway in arthritis rats as well as the interaction between endothelial nitric oxide (NO) and BDNF production. METHODS: The aortic BDNF pathway was studied in rats with adjuvant-induced arthritis, (AIA) using Western blot and immunohistochemical analysis. Control of arthritis score was achieved by administration (for 3 weeks) of an equipotent dosage of etanercept, prednisolone, methotrexate, celecoxib or diclofenac. Aortas were exposed to an NO donor or an NO synthase inhibitor and vasoreactivity experiments were performed using LM22A-4 as a TrkB agonist. RESULTS: Vascular BDNF and full length tropomyosin-related kinase B receptor (TrkB-FL) were higher in AIA than in control rats. These changes coincided with decreased endothelial immunoreactivity in BDNF and pTrkBtyr816 and were disconnected from arthritis score. Among anti-rheumatic drugs, only prednisolone and methotrexate prevented AIA-induced vascular BDNF loss. The effect of AIA on aortic BDNF levels was reversed by an NO donor and reproduced by an NOS inhibitor. Finally, LM22A-4 induced both NO-dependent vasodilation and phosphorylation of endothelial NO synthase at serine 1177. CONCLUSIONS: Our study identified changes in the BDNF/TrkB pathway as a disease activity-independent component of AIA-associated changes in endothelial phenotype. It provides new perspectives in the understanding and management of the high CV risk reported in rheumatoid arthritis.

Brain-derived neurotrophic factor secreted by the cerebral endothelium: A new actor of brain function?

Low cerebral levels of brain-derived neurotrophic factor (BDNF), which plays a critical role in many brain functions, have been implicated in neurodegenerative, neurological and psychiatric diseases. Thus, increasing BDNF levels in the brain is considered an attractive possibility for the prevention/treatment of various brain diseases. To date, BDNF-based therapies have largely focused on neurons. However, given the cross-talk between endothelial cells and neurons and recent evidence that BDNF expressed by the cerebral endothelium largely accounts for BDNF levels present in the brain, it is likely that BDNF-based therapies would be most effective if they also targeted the cerebral endothelium. In this review, we summarize the available knowledge about the biology and actions of BDNF derived from endothelial cells of the cerebral microvasculature and we emphasize the remaining gaps and shortcomings.

Brain-derived neurotrophic factor in adjuvant-induced arthritis in rats. Relationship with inflammation and endothelial dysfunction.

OBJECTIVES: Both peripheral and central brain-derived neurotrophic factor (BDNF) levels are decreased in depression and normalized by efficient anti-depressive therapies. While depression symptoms are frequent in rheumatoid arthritis, BDNF has been poorly investigated in this pathology. Therefore, the present study explored cerebral and peripheral BDNF in arthritis rats as well as the link between brain BDNF and the two factors recently involved in the pathogenesis of depression and present in rheumatoid arthritis namely inflammation and endothelial dysfunction. METHODS: The brain (hippocampus and frontal cortex) and blood (serum) were collected in rats subjected to adjuvant-induced arthritis (AIA) when inflammatory symptoms and endothelial dysfunction are fully developed. Anhedonia as a core symptom of depression symptom was assessed from preference for a saccharin drinking solution. Inflammation was assessed from the arthritis score and serum levels of TNFα and IL-1ß. Treatment with the arginase inhibitor N(w)-hydroxy-nor-l-arginine (nor-NOHA) was used as a strategy to prevent endothelial dysfunction without improving inflammatory symptoms. RESULTS: As compared to controls, AIA rats displayed decreased brain BDNF levels that coexisted with anhedonia but contrasted with increased BDNF levels in serum. Brain BDNF deficiency correlated neither with arthritis score nor with pro-inflammatory cytokines levels, while it was mitigated by nor-NOHA treatment. A positive correlation was observed between serum BDNF and TNFα levels. CONCLUSIONS: Our study reveals that arthritis decreases BDNF levels in the brain and that endothelial dysfunction rather than inflammation contributes to the decrease. It also identifies a disconnection between serum and brain BDNF levels in arthritis.

The Cerebral Brain-Derived Neurotrophic Factor Pathway, Either Neuronal or Endothelial, Is Impaired in Rats with Adjuvant-Induced Arthritis. Connection with Endothelial Dysfunction.

Cognitive abilities are largely dependent on activation of cerebral tropomyosin-related kinase B receptors (TrkB) by brain-derived neurotrophic factor (BDNF) that is secreted under a bioactive form by both neurons and endothelial cells. In addition, there is mounting evidence for a link between endothelial function and cognition even though the underlying mechanisms are not well known. Therefore, we investigated the cerebral BDNF pathway, either neuronal or endothelial, in rheumatoid arthritis (RA) that combines both endothelial dysfunction (ED) and impaired cognition. Adjuvant-induced arthritis (AIA) in rats was used as a model of RA. Clinical inflammatory symptoms were evaluated from an arthritis score and brains were collected at day 31 ± 2 post-immunization. Neuronal expression of BDNF and TrkB phosphorylated at tyrosine 816 (p-TrkB) was examined in brain slices. Endothelial BDNF and p-TrkB expression was examined on both brain slices (hippocampal arterioles) and isolated cerebral microvessels-enriched fractions (vessels downstream to arterioles). The connection between endothelial nitric oxide (NO) and BDNF production was explored on the cerebrovascular fractions using endothelial NO synthase (eNOS) levels as a marker of NO production, Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) as a NOS inhibitor and glyceryl-trinitrate as a slow releasing NO donor. Brain slices displayed lower BDNF and p-TrkB staining in both neurons and arteriolar endothelial cells in AIA than in control rats. For endothelial cells but not neurons, a strong correlation was observed between BDNF and p-TrkB staining. Of note, a strong correlation was also observed between neuronal p-TrkB and endothelial BDNF staining. In cerebral microvessels-enriched fractions, AIA led to decreased BDNF and eNOS levels with a positive association between the 2 parameters. These effects coincided with decreased BDNF and p-TrkB staining in endothelial cells. The exposure of AIA cerebrovascular fractions to GTN increased BDNF levels while the exposure of control fractions to L-NAME decreased BDNF levels. Changes in the cerebral BDNF pathway were not associated with arthritis score. The present study reveals that AIA impairs the endothelial and neuronal BDNF/TrkB pathway, irrespective of the severity of inflammatory symptoms but dependent on endothelial NO production. These results open new perspectives for the understanding of the link between ED and impaired cognition.