BDNF expression of macrophages and angiogenesis after myocardial infarction

New recognition of the heart-brain axis and its implication in the pathogenesis and treatment of PTSD

Post-traumatic stress disorder (PTSD) is a complex psychological disorder provoked by distressing experiences, and it remains without highly effective intervention strategies. The exploration of PTSD's underlying mechanisms is crucial for advancing diagnostic and therapeutic approaches. Current studies primarily explore PTSD through the lens of the central nervous system, investigating concrete molecular alterations in the cerebral area and neural circuit irregularities. However, the body's response to external stressors, particularly the changes in cardiovascular function, is often pronounced, evidenced by notable cardiac dysfunction. Consequently, examining PTSD with a focus on cardiac function is vital for the early prevention and targeted management of the disorder. This review undertakes a comprehensive literature analysis to detail the alterations in brain and heart structures and functions associated with PTSD. It also synthesizes potential mechanisms of heart-brain axis interactions relevant to the development of PTSD. Ultimately, by considering cardiac function, this review proposes novel perspectives for PTSD's prophylaxis and therapy.

Enhancing high-quality fat survival: A novel strategy using cell-free fat extract

High-quality fat (HQF) improves the survival rate of fat and volumetric filling compared to traditional Coleman fat. However, this HQF strategy inevitably leads to a significant amount of unused fat being wasted. "CEFFE" (cell-free fat extract) is an acellular aqueous-phase liquid, rich in bioactive proteins. The remaining fat from preparing HQF can be further processed into CEFFE to promote the survival of HQF. HQF was obtained and the remaining fat was processed into CEFFE, then HQF was transplanted subcutaneously in nude mice. Animal studies showed that CEFFE significantly improved the survival rate of HQF. Histological analysis revealed that CEFFE improved the survival rate of HQF, by enhancing cell proliferation activity, reducing apoptosis, increasing angiogenesis, and improving the inflammatory state. Under simulated anaerobic conditions, CEFFE also improved the viability of HQF. In vitro, studies demonstrated that CEFFE enhanced the survival rate of HQF through multiple mechanisms. Transcriptomic analysis and qPCR showed that CEFFE increased the expression of angiogenesis-related genes in ADSCs while enhancing their proliferation-related gene expression and suppressing the expression of three differentiation-related genes. Moreover, functional experiments demonstrated that CEFFE-induced ADSCs exhibited stronger proliferation and adipogenic differentiation abilities. Tube formation and migration assays revealed that CEFFE promoted tube formation and migration of HUVECs, indicating its inherent pro-angiogenic properties. CEFFE facilitated the development of M0 to M2 macrophages, suggesting its role in improving the inflammatory state. This innovative clinical strategy optimizes HQF transplantation strategy, minimizing fat wastage and enhancing the efficiency of fat utilization.

The Implications of Brain-Derived Neurotrophic Factor in the Biological Activities of Platelet-Rich Plasma

Platelet-rich plasma (PRP) is a biological blood-derived therapeutic obtained from whole blood that contains higher levels of platelets. PRP has been primarily used to mitigate joint degeneration and chronic pain in osteoarthritis (OA). This clinical applicability is based mechanistically on the release of several proteins by platelets that can restore joint homeostasis. Platelets are the primary source of brain-derived neurotrophic factor (BDNF) outside the central nervous system. Interestingly, BDNF and PRP share key biological activities with clinical applicability for OA management, such as anti-inflammatory, anti-apoptotic, and antioxidant. However, the role of BDNF in PRP therapeutic activities is still unknown. Thus, this work aimed to investigate the implications of BDNF in therapeutic outcomes provided by PRP therapy in vitro and in-vivo, using the MIA-OA animal model in male Wistar rats. Initially, the PRP was characterized, obtaining a leukocyte-poor-platelet-rich plasma (LP-PRP). Our assays indicated that platelets activated by Calcium release BDNF, and suppression of M1 macrophage polarization induced by LP-PRP depends on BDNF full-length receptor, Tropomyosin Kinase-B (TrkB). OA animals were given LP-PRP intra-articular and showed functional recovery in gait, joint pain, inflammation, and tissue damage caused by MIA. Immunohistochemistry for activating transcriptional factor-3 (ATF-3) on L4/L5 dorsal root ganglia showed the LP-PRP decreased the nerve injury induced by MIA. All these LP-PRP therapeutic activities were reversed in the presence of TrkB receptor antagonist. Our results suggest that the therapeutic effects of LP-PRP in alleviating OA symptoms in rats depend on BDNF/TrkB activity.

Visualizing temporal dynamics and research trends of macrophage-related diabetes studies between 2000 and 2022: a bibliometric analysis

Background

Macrophages are considered an essential source of inflammatory cytokines, which play a pivotal role in the development of diabetes and its sequent complications. Therefore, a better understanding of the intersection between the development of diabetes and macrophage is of massive importance.

Objectives

In this study, we performed an informative bibliometric analysis to enlighten relevant research directions, provide valuable metrics for financing decisions, and help academics to gain a quick understanding of the current macrophage-related diabetes studies knowledge domain.

Methods

The Web of Science Core Collection database was used for literature retrieval and dataset export. Bibliometrix R-package was performed to conduct raw data screening, calculating, and visualizing.

Results

Between 2000 and 2022, the annual publication and citation trends steadily increased. Wu Yonggui was the scholar with the most published papers in this field. The institute with the highest number of published papers was the University of Michigan. The most robust academic collaboration was observed between China and the United States of America. Diabetologia was the journal that published the most relevant publications. The author's keywords with the highest occurrences were "inflammation", "diabetic nephropathy", and "obesity". In addition, "Macrophage polarization" was the current motor topic with potential research prospects.

Conclusions

These comprehensive and visualized bibliometric results summarized the significant findings in macrophage-related diabetes studies over the past 20 years. It would enlighten subsequent studies from a macro viewpoint and is also expected to strengthen investment policies in future macrophage-related diabetes studies.

Exerkines and redox homeostasis

Exercise physiology has gained increasing interest due to its wide effects to promote health. Recent years have seen a growth in this research field also due to the finding of several circulating factors that mediate the effects of exercise. These factors, termed exerkines, are metabolites, growth factors, and cytokines secreted by main metabolic organs during exercise to regulate exercise systemic and tissue-specific effects. The metabolic effects of exerkines have been broadly explored and entail a promising target to modulate beneficial effects of exercise in health and disease. However, exerkines also have broad effects to modulate redox signaling and homeostasis in several cellular processes to improve stress response. Since redox biology is central to exercise physiology, this review summarizes current evidence for the cross-talk between redox biology and exerkines actions. The role of exerkines in redox biology entails a response to oxidative stress-induced pathological cues to improve health outcomes and to modulate exercise adaptations that integrate redox signaling.

The Mechanism of Action between Pulsed Radiofrequency and Orthobiologics: Is There a Synergistic Effect?

Radiofrequency energy is a common treatment modality for chronic pain. While there are different forms of radiofrequency-based therapeutics, the common concept is the generation of an electromagnetic field in the applied area, that can result in neuromodulation (pulsed radiofrequency—PRF) or ablation. Our specific focus relates to PRF due to the possibility of modulation that is in accordance with the mechanisms of action of orthobiologics. The proposed mechanism of action of PRF pertaining to pain relief relies on a decrease in pro-inflammatory cytokines, an increase in cytosolic calcium concentration, a general effect on the immune system, and a reduction in the formation of free radical molecules. The primary known properties of orthobiologics constitute the release of growth factors, a stimulus for endogenous repair, analgesia, and improvement of the function of the injured area. In this review, we described the mechanism of action of both treatments and pertinent scientific references to the use of the combination of PRF and orthobiologics. Our hypothesis is a synergic effect with the combination of both techniques which could benefit patients and improve the life quality.

Ablation of cardiomyocyte-derived BDNF during development causes myocardial degeneration and heart failure in the adult mouse heart

Objective

Brain-derived neurotrophic factor (BDNF) and its receptor TrkB-T1 were recently found to be expressed in cardiomyocytes. However, the functional role of cardiomyocyte-derived BDNF in heart pathophysiology is not yet fully known. Recent studies revealed that BDNF-TrkB pathway plays a critical role to maintain integrity of cardiac structure and function, cardiac pathology and regeneration of myocardial infarction (MI). Therefore, the BDNF-TrkB pathway may be a novel target for myocardial pathophysiology in the adult heart.

Approach and results

In the present study, we established a cardiomyocyte-derived BDNF conditional knockout mouse in which BDNF expression in developing cardiomyocytes is ablated under the control of the Myosin heavy chain 6 (MYH6) promoter. The results of the present study show that ablation of cardiomyocyte-derived BDNF during development does not impair survival, growth or reproduction; however, in the young adult heart, it causes cardiomyocyte death, degeneration of the myocardium, cardiomyocyte hypertrophy, left atrial appendage thrombosis, decreased cardiac function, increased cardiac inflammation and ROS activity, and metabolic disorders, leading to heart failure (HF) in the adult heart and eventually resulting in a decrease in the one-year survival rate. In addition, ablation of cardiomyocyte-derived BDNF during the developmental stage leads to exacerbation of cardiac dysfunction and poor regeneration after MI in adult hearts.

Conclusion

Cardiomyocyte-derived BDNF is irreplaceable for maintaining the integrity of cardiac structure and function in the adult heart and regeneration after MI. Therefore, the BDNF-TrkB pathway will be a novel target for myocardial pathophysiology in the adult heart.

The Molecular Effects of BDNF Synthesis on Skeletal Muscle: A Mini-Review

The brain-derived neurotrophic factor (BDNF) is a member of the nerve growth factor family which is generated mainly by the brain. Its main role involve synaptic modulation, neurogenesis, neuron survival, immune regulation, myocardial contraction, and angiogenesis in the brain. Together with the encephalon, some peripheral tissues synthesize BDNF like skeletal muscle. On this tissue, this neurotrophin participates on cellular mechanisms related to muscle function maintenance and plasticity as reported on recent scientific works. Moreover, during exercise stimuli the BDNF contributes directly to strengthening neuromuscular junctions, muscle regeneration, insulin-regulated glucose uptake and β-oxidation processes in muscle tissue. Given its vital relevance on many physiological mechanisms, the current mini-review focuses on discussing up-to-date knowledge about BDNF production in skeletal muscle and how this neurotrophin impacts skeletal muscle biology.

MiR-191-5p Disturbed the Angiogenesis in a Mice Model of Cerebral Infarction by Targeting Inhibition of BDNF

BACKGROUND

miRNAs are crucial regulators of angiogenesis, but there have been no detailed studies on the role of miR-191-5p in cerebral infarct angiogenesis. Here, we investigated the role of miR-191-5p in regulating cerebral infarction angiogenesis.

MATERIAL AND METHODS

Mice were injected intracerebroventricularly with antagomir negative control (NC-antagomir), miR-191-5p antagomir, or pcDNA-BDNF 2 h before middle cerebral artery occlusion (MCAO), followed by neurobehavioral score and foot-fault test. The cerebral infarct volume was performed by TTC staining. The microvessel density was detected by FITC-dextran. RT-qPCR was used to detect the levels of miR-191-5p and its target gene BDNF. Western blotting was applied to detect the protein levels of BDNF. The luciferase reporter assay verified that miR-191-5p targeted BDNF.

RESULTS

We found an increased level of miR-191-5p in the brain tissue of mice to MCAO. Down-regulation of miR-191-5p reduced the infarct volume and ameliorated neurological deficits in MCAO mice. Further investigation showed that miR-191-5p directly targeted BDNF and that the protective effect of miR-191-5p inhibition in angiogenesis was achieved by regulating BDNF.

CONCLUSIONS

Our results indicated that miR-191-5p disturbed the angiogenesis in the mouse models of cerebral infarction by inhibiting BDNF.

Neuroinflammation in hemorrhagic transformation after tissue plasminogen activator thrombolysis: Potential mechanisms, targets, therapeutic drugs and biomarkers

Hemorrhagic transformation (HT) is a common and serious complication following ischemic stroke, especially after tissue plasminogen activator (t-PA) thrombolysis, which is associated with increased mortality and disability. Due to the unknown mechanisms and targets of HT, there are no effective therapeutic drugs to decrease the incidence of HT. In recent years, many studies have found that neuroinflammation is closely related to the occurrence and development of HT after t-PA thrombolysis, including glial cell activation in the brain, peripheral inflammatory cell infiltration and the release of inflammatory factors, involving inflammation-related targets such as NF-κB, MAPK, HMGB1, TLR4 and NLRP3. Some drugs with anti-inflammatory activity have been shown to protect the BBB and reduce the risk of HT in preclinical experiments and clinical trials, including minocycline, fingolimod, tacrolimus, statins and some natural products. In addition, the changes in MMP-9, VAP-1, NLR, sICAM-1 and other inflammatory factors are closely related to the occurrence of HT, which may be potential biomarkers for the diagnosis and prognosis of HT. In this review, we summarize the potential inflammation-related mechanisms, targets, therapeutic drugs, and biomarkers associated with HT after t-PA thrombolysis and discuss the relationship between neuroinflammation and HT, which provides a reference for research on the mechanisms, prevention and treatment drugs, diagnosis and prognosis of HT.

M2 Phenotype Macrophages Colocalize with Schwann Cells in Human Dental Pulp

Macrophages are immune cells with high plasticity that perform many functions related to tissue injury and repair. They are generally categorized as 2 functional phenotypes: M1 (proinflammatory) and M2 (anti-inflammatory and prohealing). To investigate the role of macrophages in human dental pulp, we examined the localization and distributional alterations of macrophages in healthy dental pulp as well as during the reparative process of pulp capping with mineral trioxide aggregate (MTA) and in cariously inflamed pulp of adult human teeth. We also quantified the populations of M1/M2 macrophages in healthy dental pulp by flow cytometric analysis. CD68⁺CD86⁺ cells (M1 phenotype) and CD68⁺CD163⁺ cells (M2 phenotype) were 2.11% ± 0.50% and 44.99% ± 2.22%, respectively, of 2.96% ± 0.41% CD68⁺ cells (pan-macrophages) in whole healthy dental pulp. Interestingly, M2 phenotype macrophages were associated with Schwann cells in healthy pulp, during mineralized bridge formation, and in pulp with carious infections in vivo. Furthermore, the M2 macrophages associated with Schwann cells expressed brain-derived neurotrophic factor (BDNF) under all in vivo conditions. Moreover, we found that plasma cells expressed BDNF. Coculture of Schwann cells isolated from human dental pulp and human monocytic cell line THP-1 showed that Schwann cells induced M2 phenotypic polarization of THP-1 cell-derived macrophages. The THP-1 macrophages that maintained contact with Schwann cells were stimulated, leading to elongation of their cell shape and expression of M2 phenotype marker CD163 in cocultures. In summary, we revealed the spatiotemporal localization of macrophages and potent induction of the M2 phenotype by Schwann cells in human dental pulp. M2 macrophages protect neural elements, whereas M1 cells promote neuronal destruction. Therefore, suppressing the neurodestructive M1 phenotype and maintaining the neuroprotective M2 phenotype of macrophages by Schwann cells may be critical for development of effective treatment strategies to maintain the viability of highly innervated dental pulp.

Nerve fiber overgrowth in patients with symptomatic diverticular disease

BACKGROUND

Colonic diverticulosis is a common condition in industrialized countries. Up to 25% of patients with diverticula develop symptoms, a condition termed symptomatic uncomplicated diverticular disease (SUDD). The aim of the present study was to characterize neuroimmune interactions and nerve fiber plasticity in the colonic mucosa of patients with diverticula.

METHODS

Controls, patients with diverticulosis and with SUDD were enrolled in the study. Mucosal biopsies were obtained close to diverticula (diverticular region) and in a normal mucosa (distant site), corresponding to sigmoid and descending colon in the controls. Quantitative immunohistochemistry was used to assess mast cells, T cells, macrophages, nerve fibers, and neuronal outgrowth (growth-associated protein 43, GAP43+fibers).

KEY RESULTS

No difference emerged in mast cells and T cells among the three groups. Macrophages were increased in patients with SUDD and diverticulosis as compared to controls. Nerve fibers were enhanced in patients with SUDD and diverticulosis in comparison with controls in the diverticular region. GAP43+ fibers were increased only in patients with SUDD as compared to controls and to patients with diverticulosis in the diverticular region. In patients with SUDD, GAP43 density was increased in the diverticular region compared to distant site. Macrophages close to GAP43+ fibers were increased in the diverticular region of patients with SUDD. Significant correlations were found between GAP43+ fibers and immune cells.

CONCLUSIONS AND INFERENCES

Patients with diverticula are characterized by increased macrophage counts, while nerve fiber sprouting is increased only in the diverticular region of patients with SUDD suggesting a role in symptom generation.

Exercise training increases cardiac, hepatic and circulating levels of brain-derived neurotrophic factor and irisin in young and aged rats

Background The objective of study was to examine the impacts of exercise training on cardiac, hepatic and plasma brain-derived neurotrophic factor (BDNF) and irisin levels in young and aged rats. Materials and methods Four-month-old (young) and 20-month-old (aged) female rats performed exercise training consisting of voluntary wheel running for 12 weeks. BDNF and irisin levels were analyzed in the heart, liver and plasma samples by using commercially available enzyme-linked immunosorbent assay (ELISA) kits. Results Cardiac, hepatic and plasma BDNF levels were lower in the aged sedentary rats, than in the young exercised and aged exercised rats (p < 0.05). Heart, liver and plasma irisin concentrations were lower in the aged sedentary group than in the young sedentary, young exercised and aged exercised groups (p < 0.05) and regular exercise increased irisin levels in all the analyzed tissues when compared to the sedentary counterparts (p < 0.05). Conclusions The current results show that regular exercise improves aging-induced decrease in the cardiac, hepatic and plasma BNDF and irisin levels.

Effects of exercise training on brain-derived neurotrophic factor in skeletal muscle and heart of rats post myocardial infarction

NEW FINDINGS

What is the central question of this study? Exercise training increases brain-derived neurotrophic factor (BDNF) in the hippocampus, which depends on a myokine, fibronectin type III domain-containing protein 5 (FNDC5). Whether exercise training after myocardial infarction induces parallel increases in FNDC5 and BDNF expression in skeletal muscle and the heart has not yet been studied. What is the main finding and its importance? Exercise training after myocardial infarction increases BDNF protein in skeletal muscle and the non-infarct area of the LV without changes in FNDC5 protein, suggesting that BDNF is not regulated by FNDC5 in skeletal muscle and heart. An increase in cardiac BDNF may contribute to the improvement of cardiac function by exercise training. Exercise training after myocardial infarction (MI) attenuates progressive left ventricular (LV) remodelling and dysfunction, but the peripheral stimuli induced by exercise that trigger these beneficial effects are still unclear. We investigated as possible mediators fibronectin type III domain-containing protein 5 (FNDC5) and brain-derived neurotrophic factor (BDNF) in the skeletal muscle and heart. Male Wistar rats underwent either sham surgery or ligation of the left descending coronary artery, and surviving MI rats were allocated to either a sedentary (Sed-MI) or an exercise group (ExT-MI). Exercise training was done for 4 weeks on a motor-driven treadmill. At the end, LV function was evaluated, and FNDC5 and BDNF mRNA and protein were assessed in soleus muscle, quadriceps and non-, peri- and infarct areas of the LV. At 5 weeks post MI, FNDC5 mRNA was decreased in soleus muscle and all areas of the LV, but FNDC5 protein was increased in the soleus muscle and the infarct area. Mature BDNF (mBDNF) protein was decreased in the infarct area without a change in mRNA. Exercise training attenuated the decrease in ejection fraction and the increase in LV end-diastolic pressure post MI. Exercise training had no effect on FNDC5 mRNA and protein, but increased mBDNF protein in soleus muscle, quadriceps and the non-infarct area of the LV. The mBDNF protein in the non-infarct area correlated positively with ejection fraction and inversely with LV end-diastolic pressure. In conclusion, mBDNF is induced by exercise training in skeletal muscle and the non-infarct area of the LV, which may contribute to improvement of muscle dysfunction and cardiac function post MI.

Upregulation of the BDNF/TrKB pathway promotes epithelial-mesenchymal transition, as well as the migration and invasion of cervical cancer

Brain-derived neurotrophic factor (BDNF) has previously been demonstrated to be associated with several types of cancer. In addition, its receptor, tropomyosin related kinase B (TrkB) is involved in tumor invasion and metastasis. Epithelial-mesenchymal transition (EMT) is associated with metastasis in cancers. Thus, The aim of the present study was to examine whether BDNF/TrKB expression is linked to a poor survival and the acquisition of the EMT phenotype in cervical cancer. We found that a high positive expression of BDNF/TrKB was associated with poor survival in cervical cancer. Our results revealed that high expression levels of BDNF/TrKB were observed in cervical cancer compared to normal cells. Importantly, we demonstrated that the silencing of TrKB suppressed the activation of EMT via the downregulation of N-cadherin, vimentin, matrix metalloproteinase (MMP)2 and MMP9, and the upregulation of E-cadherin and tissue inhibitor of metalloproteinases (TIMP)2, which resulted in suppressed cell proliferation, migration and invasion. Furthermore, high phosphorylation levels of ERK and Akt were observed in the cervical cancer cells, while these levels were decreased in the cells in which TrKB was knocked down. On the whole, these findings suggest that the BDNF/TrKB pathway is a promising target for the prevention of tumor proliferation, invasion, metastasis and EMT in cervical cancer cells.

Brain-derived neurotrophic factor promotes VEGF-C-dependent lymphangiogenesis by suppressing miR-624-3p in human chondrosarcoma cells

Chondrosarcoma is the second most common primary malignancy of bone, and one of the most difficult bone tumors to diagnose and treat. It is well known that increased levels of vascular endothelial growth factor-C (VEGF-C) promote active tumor lymphangiogenesis and lymphatic tumor spread to regional lymph nodes. Brain-derived neurotrophic factor (BDNF) is known to promote metastasis in human chondrosarcoma cells. Knowing more about the mechanism of BDNF in VEGF-C expression and lymphangiogenesis in human chondrosarcoma would improve our understanding as how to prevent chondrosarcoma angiogenesis and metastasis, which currently lacks effective adjuvant treatment. Here, we found that BDNF expression was at least 2.5-fold higher in the highly migratory JJ012(S10) cell line as compared with the primordial cell line (JJ012). In addition, VEGF-C expression and secretion was markedly increased in JJ012(S10) cells. Conditioned medium from JJ012(S10) cells significantly promoted migration and tube formation of human lymphatic endothelial cells (LECs), whereas knockdown of BDNF attenuated LEC migration and tube formation by suppressing VEGF-C production in JJ012(S10) cells. Mechanistic investigations indicated that BDNF facilitated VEGF-C-dependent lymphangiogenesis through the MEK/ERK/mTOR signaling pathway. We also showed that microRNA (miR)-624-3p expression was negatively regulated by BDNF via the MEK/ERK/mTOR cascade. Importantly, BDNF knockdown profoundly inhibited tumor-associated lymphangiogenesis in vivo. Further analyses identified that BDNF promoted tumor lymphangiogenesis by downregulating miR-624-3p in human chondrosarcoma tissues. In conclusion, this study is the first to reveal the mechanism underlying BDNF-induced lymphangiogenesis. We suggest that BDNF may serve as a promising therapeutic target for the restriction of VEGF-C-mediated tumor lymphangiogenesis and lymphatic metastasis.

BDNF - A key player in cardiovascular system

Neurotrophins (NTs) were first identified as target-derived survival factors for neurons of the central and peripheral nervous system (PNS). They are known to control neural cell fate, development and function. Independently of their neuronal properties, NTs exert unique cardiovascular activity. The heart is innervated by sensory, sympathetic and parasympathetic neurons, which require NTs during early development and in the establishment of mature properties, contributing to the maintenance of cardiovascular homeostasis. The identification of molecular mechanisms regulated by NTs and involved in the crosstalk between cardiac sympathetic nerves, cardiomyocytes, cardiac fibroblasts, and vascular cells, has a fundamental importance in both normal heart function and disease. The article aims to review the recent data on the effects of Brain-Derived Neurotrophic Factor (BDNF) on various cardiovascular neuronal and non-neuronal functions such as the modulation of synaptic properties of autonomic neurons, axonal outgrowth and sprouting, formation of the vascular and neural networks, smooth muscle migration, and control of endothelial cell survival and cardiomyocytes. Understanding these mechanisms may be crucial for developing novel therapeutic strategies, including stem cell-based therapies.

Visualizing changes in brain-derived neurotrophic factor (BDNF) expression using bioluminescence imaging in living mice

Brain-derived neurotrophic factor (BDNF) plays a fundamental role in expressing various neural functions including memory consolidation. Alterations of BDNF levels in the brain are associated with neurodegenerative and neuropsychiatric disorders. Therefore, it is important to understand how levels of BDNF are controlled. Recently we generated a novel transgenic mouse strain, termed the Bdnf-Luciferase transgenic (Bdnf-Luc Tg) mouse, to monitor changes in Bdnf expression. In the present study, we detected the bioluminescence signal from living Bdnf-Luc Tg mice after intraperitoneal administration of d-luciferin. Despite high levels of Bdnf expression in the brain, it was difficult to detect a signal from the brain region, probably because of its poorly penetrable (short-wavelength) bioluminescence. However, we could detect the changes in the bioluminescence signal in the brain region using a luciferin analogue generating a near-infrared wavelength of bioluminescence. We also found a strong correlation between increases in body weight and bioluminescence signal in the abdominal region of Tg mice fed a high-fat diet. These results show that changes in Bdnf expression can be visualized using living mice, and that the Tg mouse could be a powerful tool for clarification of the role of Bdnf expression in pathophysiological and physiological conditions.

Protective features of peripheral monocytes/macrophages in stroke

Hematogenous recruitment of monocytes and macrophages has traditionally been viewed as a harmful process causing exacerbation of brain injury after stroke. However, emerging findings suggest equally important protective features. Inflammatory monocytes are rapidly recruited to ischemic brain via a CCR2-dependent pathway and undergo secondary differentiation in the target tissue towards non-inflammatory macrophages, mediating neuroprotection and repair of the ischemic neurovascular unit. In contrast, independent recruitment of non-inflammatory monocytes via CX3CR1 does not occur. Thus, protective features of hematogenous macrophages mainly depend on initial CCR2-dependent cell recruitment. Under therapeutic considerations, specific modulation of monocyte-derived macrophages will therefore be more appropriate than non-selectively blocking their hematogenous recruitment. This article is part of a Special Issue entitled: Neuro Inflammation edited by Helga E. de Vries and Markus Schwaninger.