Sympathetic nervous system controls resolution of inflammation via regulation of repulsive guidance molecule A

Growth differentiation factor 15 alleviates diastolic dysfunction in mice with experimental diabetic cardiomyopathy

Growth differentiation factor 15 (GDF15) is a peptide with utility in obesity, as it decreases appetite and promotes weight loss. Because obesity increases the risk for type 2 diabetes (T2D) and cardiovascular disease, it is imperative to understand the cardiovascular actions of GDF15, especially since elevated GDF15 levels are an established biomarker for heart failure. As weight loss should be encouraged in the early stages of obesity-related prediabetes/T2D, where diabetic cardiomyopathy is often present, we assessed whether treatment with GDF15 influences its pathology. We observed that GDF15 treatment alleviates diastolic dysfunction in mice with T2D independent of weight loss. This cardioprotection was associated with a reduction in cardiac inflammation, which was likely mediated via indirect actions, as direct treatment of adult mouse cardiomyocytes and differentiated THP-1 human macrophages with GDF15 failed to alleviate lipopolysaccharide-induced inflammation. Therapeutic manipulation of GDF15 action may thus have utility for both obesity and diabetic cardiomyopathy.

Neuroimmune modulating and energy supporting nanozyme-mimic scaffold synergistically promotes axon regeneration after spinal cord injury

Spinal cord injury (SCI) represents a profound central nervous system affliction, resulting in irreversibly compromised daily activities and disabilities. SCI involves excessive inflammatory responses, which are characterized by the existence of high levels of proinflammatory M1 macrophages, and neuronal mitochondrial energy deficit, exacerbating secondary damage and impeding axon regeneration. This study delves into the mechanistic intricacies of SCI, offering insights from the perspectives of neuroimmune regulation and mitochondrial function, leading to a pro-fibrotic macrophage phenotype and energy-supplying deficit. To address these challenges, we developed a smart scaffold incorporating enzyme mimicry nanoparticle-ceriumoxide (COPs) into nanofibers (NS@COP), which aims to pioneer a targeted neuroimmune repair strategy, rescuing CGRP receptor on macrophage and concurrently remodeling mitochondrial function. Our findings indicate that the integrated COPs restore the responsiveness of pro-inflammatory macrophages to calcitonin gene-related peptide (CGRP) signal by up-regulating receptor activity modifying protein 1 (RAMP1), a vital component of the CGRP receptor. This promotes macrophage fate commitment to an anti-inflammatory pro-resolution M2 phenotype, then alleviating glial scar formation. In addition, NS@COP implantation also protected neuronal mitochondrial function. Collectively, our results suggest that the strategy of integrating nanozyme COP nanoparticles into a nanofiber scaffold provides a promising therapeutic candidate for spinal cord trauma via rational regulation of neuroimmune communication and mitochondrial function.

Therapeutically Fine-Tuning Autonomic Nervous System to Treat Sepsis: A New Perspective on the Immunomodulatory Effects of Acupuncture

Recent studies have highlighted the immunomodulatory effects of acupuncture on sepsis and proposed novel non-pharmacological or bioelectronic approaches to managing inflammatory illnesses. Establishing rules for selectively activating sympathetic or vagal nerve-mediated anti-inflammatory pathways using acupuncture has valuable clinical applications. Over the years, studies have revealed the segmental modulatory role of acupuncture in regulating visceral function by targeting the autonomic nervous system (ANS). In this review, we aim to summarize recent findings on acupuncture in treating sepsis, focusing on the underlying ANS mechanism, as well as the rules of acupoint specificity, intensity, frequency, and other parameters utilized in these studies. Mechanistically, the immunomodulatory properties of the sympathetic nervous system have been highlighted. Furthermore, we explore the immunotherapeutic benefits of acupuncture in treating sepsis. A better understanding of the immunoregulatory mechanism of sympathetic nervous system may offer novel approaches for the development of therapeutics to treat or prevent a variety of inflammatory diseases.

Association between immune-inflammation-based prognostic index and depression: An exploratory cross-sectional analysis of NHANES data

BACKGROUND

Immune-inflammatory mediators influence numerous immune and inflammatory pathways, elevating the likelihood of depression. The systemic immune-inflammation index (SII) emerges as an innovative prognostic indicator, integrating various peripheral blood immune cell subpopulations, specifically neutrophils, platelets, and lymphocytes. This exploratory study aims to examine the correlation between SII and depression.

METHODS

Data from the 2005-2020 National Health and Nutrition Examination Survey (NHANES) were utilized. Depression was diagnosed with a Patient Health Questionnaire score of 10 or higher. The relationship between log2-SII and depression incidence was analyzed using a restricted cubic spline (RCS). Logistic regression was employed to calculate the odds ratio of depression concerning log2-SII. In cases of non-linearity, piecewise linear models with change points were applied to assess the associations in both the overall population and specific subgroups. Additionally, subgroup analyses were conducted to determine the applicability of the findings to particular populations.

RESULTS

A total of 42,133 participants were included in the study, comprising 49.32 % men and 50.68 % women, with an average age of 47.02 ± 17.45 years. RCS analysis demonstrated a J-shaped non-linear relationship between log2-SII and depression incidence. When log2-SII was ≥8.50, SII showed a positive association with depression incidence, even after adjusting for covariates. Additionally, each unit increase in log2-SII corresponded to an 18 % rise in depression incidence (OR = 1.18, 95 % CI: 1.10-1.27). Subgroup analysis further revealed that the association between SII and depression incidence varied across different populations.

LIMITATIONS

Due to the cross-sectional nature of NHANES, causality or long-term implications cannot be inferred. Further research is needed to ascertain if a longitudinal relationship exists between SII and depression.

CONCLUSION

Our findings suggest a significant and complex non-linear association between SII and depression. However, further basic and prospective studies are necessary to explore SII's impact on depression and clarify its underlying mechanisms. Additionally, these studies will provide a foundation for personalized interventions targeting the immune-inflammatory processes in patients with depression and elevated SII.

Knockdown of RGMA improves ischemic stroke via Reprogramming of Neuronal Metabolism

Neuronal energy metabolism dysregulation is involved in various pathologies of Ischemia-reperfusion (I/R), yet the role of RGMA in neuronal metabolic reprogramming has not been reported. In this study, we found that RGMA expression significantly increased after I/R, and compared to control mice, mice with MCAO/R showed an increase in glycolytic metabolic products and the expression of glycolytic pathway proteins. Furthermore, RGMA levels are closely related to neuronal energy metabolism. We discovered that knockdown of RGMA can shift neuronal energy metabolism towards oxidative phosphorylation and the pentose phosphate pathway, thereby protecting mice from ischemic reperfusion injury. Mechanistically, knockdown of RGMA can downregulate PGK1 expression, reducing the increase in glycolytic flux following ischemia reperfusion. Moreover, we found that knockdown of RGMA can reduce the interaction between USP10 and PGK1, thus affecting the ubiquitination degradation of PGK1. In summary, our data suggest that RGMA may regulate neuronal energy metabolism by inhibiting the USP10-mediated deubiquitination of PGK1, thus protecting it from I/R injury. This study provides new ideas for clarifying the intrinsic mechanism of neuronal damage after I/R.

Oregano Essential Oil in Livestock and Veterinary Medicine

With a growing global concern over food safety and animal welfare issues, the livestock and veterinary industries are undergoing unprecedented changes. These changes have not only brought challenges within each industry, but also brought unprecedented opportunities for development. In this context, the search for natural and safe products that can effectively replace traditional veterinary drugs has become an important research direction in the fields of animal husbandry and veterinary medicine. Oregano essential oil (OEO), as a natural extract, is gradually emerging in the fields of animal husbandry and veterinary medicine with its unique antibacterial, antioxidant, and multiple other biological activities. OEO not only has a wide antibacterial spectrum, effectively fighting against a variety of pathogenic microorganisms, but also, because of its natural properties, helps us to avoid traditional veterinary drugs that may bring drug residues or cause drug resistance problems. This indicates OEO has great application potential in animal disease treatment, animal growth promotion, and animal welfare improvement. At present, the application of OEO in the fields of animal husbandry and veterinary medicine has achieved preliminary results. Studies have shown that adding OEO to animal feed can significantly improve the growth performance and health status of animals and reduce the occurrence of disease. At the same time, pharmacokinetic studies in animals show that the absorption, distribution, metabolism, and excretion processes of OEO in animals shows good bioavailability. In summary, oregano essential oil (OEO), as a substitute for natural veterinary drugs with broad application prospects, is gradually becoming a research hotspot in the field of animal husbandry and veterinary medicine. In the future, we look forward to further tapping the potential of OEO through more research and practice and making greater contributions to the sustainable development of the livestock and veterinary industries.

Expression of CGRP in the Trigeminal Ganglion and Its Effect on the Polarization of Macrophages in Rats with Temporomandibular Arthritis

Calcitonin gene-related peptide (CGRP) is synthesized and secreted by trigeminal ganglion neurons, and is a key neuropeptide involved in pain and immune regulation. This study investigates the expression of CGRP in the trigeminal ganglion (TG) and its regulatory role in the polarization of macrophages in rats with temporomandibular arthritis. A rat model of temporomandibular arthritis was established using CFA. Pain behavior was then observed. Temporomandibular joint (TMJ) and the TG were collected, and immunohistochemistry, immunofluorescence (IF) staining, and RT-qPCR were used to examine the expression of CGRP and macrophage-related factors. To investigate the impact of CGRP on macrophage polarization, both CGRP and its antagonist, CGRP 8-37, were separately administered directly within the TG. Statistical analysis revealed that within 24 h of inducing temporomandibular arthritis using CFA, there was a significant surge in CD86 positive macrophages within the ganglion. These macrophages peaked on the 7th day before beginning their decline. In this context, it's noteworthy that administering CGRP to the trigeminal ganglion can prompt these macrophages to adopt the M2 phenotype. Intriguingly, this study demonstrates that injecting the CGRP receptor antagonist (CGRP 8-37) to the ganglion counteracts this shift towards the M2 phenotype. Supporting these in vivo observations, we found that in vitro, CGRP indeed fosters the M2-type polarization of macrophages. CGRP can facilitate the conversion of macrophages into the M2 phenotype. The phenotypic alterations of macrophages within the TG could be instrumental in initiating and further driving the progression of TMJ disorders.

Heat shock response during the resolution of inflammation and its progressive suppression in chronic-degenerative inflammatory diseases

The heat shock response (HSR) is a crucial biochemical pathway that orchestrates the resolution of inflammation, primarily under proteotoxic stress conditions. This process hinges on the upregulation of heat shock proteins (HSPs) and other chaperones, notably the 70 kDa family of heat shock proteins, under the command of the heat shock transcription factor-1. However, in the context of chronic degenerative disorders characterized by persistent low-grade inflammation (such as insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular diseases) a gradual suppression of the HSR does occur. This work delves into the mechanisms behind this phenomenon. It explores how the Western diet and sedentary lifestyle, culminating in the endoplasmic reticulum stress within adipose tissue cells, trigger a cascade of events. This cascade includes the unfolded protein response and activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome, leading to the emergence of the senescence-associated secretory phenotype and the propagation of inflammation throughout the body. Notably, the activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome not only fuels inflammation but also sabotages the HSR by degrading human antigen R, a crucial mRNA-binding protein responsible for maintaining heat shock transcription factor-1 mRNA expression and stability on heat shock gene promoters. This paper underscores the imperative need to comprehend how chronic inflammation stifles the HSR and the clinical significance of evaluating the HSR using cost-effective and accessible tools. Such understanding is pivotal in the development of innovative strategies aimed at the prevention and treatment of these chronic inflammatory ailments, which continue to take a heavy toll on global health and well-being.

Central glucagon-like peptide 1 receptor activation inhibits Toll-like receptor agonist-induced inflammation

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) exert anti-inflammatory effects relevant to the chronic complications of type 2 diabetes. Although GLP-1RAs attenuate T cell-mediated gut and systemic inflammation directly through the gut intraepithelial lymphocyte GLP-1R, how GLP-1RAs inhibit systemic inflammation in the absence of widespread immune expression of the GLP-1R remains uncertain. Here, we show that GLP-1R activation attenuates the induction of plasma tumor necrosis factor alpha (TNF-α) by multiple Toll-like receptor agonists. These actions are not mediated by hematopoietic or endothelial GLP-1Rs but require central neuronal GLP-1Rs. In a cecal slurry model of polymicrobial sepsis, GLP-1RAs similarly require neuronal GLP-1Rs to attenuate detrimental responses associated with sepsis, including sickness, hypothermia, systemic inflammation, and lung injury. Mechanistically, GLP-1R activation leads to reduced TNF-α via α1-adrenergic, δ-opioid, and κ-opioid receptor signaling. These data extend emerging concepts of brain-immune networks and posit a new gut-brain GLP-1R axis for suppression of peripheral inflammation.

Adrenal sympathetic nerve mediated the anti-inflammatory effect of electroacupuncture at ST25 acupoint in a rat model of sepsis

Acupuncture plays a vital anti-inflammatory action in sepsis by activating autonomic nerve anti-inflammatory pathways, such as sympathoadrenal medullary pathway, but the mechanism remains unclear. This study aims to explore the optimum parameter of electroacupuncture (EA) stimulation in regulating the sympathoadrenal medullary pathway and evaluate EA's anti-inflammatory effect on sepsis. To determine the optimum parameter of EA at homotopic acupoint on adrenal sympathetic activity, the left adrenal sympathetic nerve firing rate evoked by different intensities of single shock electrical stimulation (ES) at ST25 in healthy male Sprague-Dawley rats were evaluated by in vivo electrophysiological recording, and the levels of norepinephrine (NE) and its metabolites normetanephrine (NMN) were also examined using mass spectrometry. To verify the role of EA at ST25 in sepsis, the rats were given an intraperitoneal injection of lipopolysaccharide (LPS) to induce sepsis model, and survival rate, clinical score, and the level of interleukin (IL)-6, IL-1β, and IL-10 were evaluated after EA application. We observed that 3 mA is the optimal intensity for activating adrenal sympathetic nerve, which significantly elevated the level of NE in the peripheral blood. For LPS-treated rats, EA at the ST25 apparently increased the survival rate and improved the clinical score compared to the control group. Furthermore, 3 mA EA at ST25 significantly decreased pro-inflammatory cytokines IL-6 and IL-1β and upregulated anti-inflammatory cytokine IL-10 compared to the LPS-treated group. Overall, our data suggested that 3 mA is the optimal EA intensity at ST25 to activate the sympathoadrenal medullary pathway and exert an anti-inflammatory effect in sepsis.

Valvulogenesis of a living, innervated pulmonary root induced by an acellular scaffold

Heart valve disease is a major cause of mortality and morbidity worldwide with no effective medical therapy and no ideal valve substitute emulating the extremely sophisticated functions of a living heart valve. These functions influence survival and quality of life. This has stimulated extensive attempts at tissue engineering "living" heart valves. These attempts utilised combinations of allogeneic/ autologous cells and biological scaffolds with practical, regulatory, and ethical issues. In situ regeneration depends on scaffolds that attract, house and instruct cells and promote connective tissue formation. We describe a surgical, tissue-engineered, anatomically precise, novel off-the-shelf, acellular, synthetic scaffold inducing a rapid process of morphogenesis involving relevant cell types, extracellular matrix, regulatory elements including nerves and humoral components. This process relies on specific material characteristics, design and "morphodynamism".

Traumatic brain injury stimulates sympathetic tone-mediated bone marrow myelopoiesis to favor fracture healing

Traumatic brain injury (TBI) accelerates fracture healing, but the underlying mechanism remains largely unknown. Accumulating evidence indicates that the central nervous system (CNS) plays a pivotal role in regulating immune system and skeletal homeostasis. However, the impact of CNS injury on hematopoiesis commitment was overlooked. Here, we found that the dramatically elevated sympathetic tone accompanied with TBI-accelerated fracture healing; chemical sympathectomy blocks TBI-induced fracture healing. TBI-induced hypersensitivity of adrenergic signaling promotes the proliferation of bone marrow hematopoietic stem cells (HSCs) and swiftly skews HSCs toward anti-inflammation myeloid cells within 14 days, which favor fracture healing. Knockout of β3- or β2-adrenergic receptor (AR) eliminate TBI-mediated anti-inflammation macrophage expansion and TBI-accelerated fracture healing. RNA sequencing of bone marrow cells revealed that Adrb2 and Adrb3 maintain proliferation and commitment of immune cells. Importantly, flow cytometry confirmed that deletion of β2-AR inhibits M2 polarization of macrophages at 7th day and 14th day; and TBI-induced HSCs proliferation was impaired in β3-AR knockout mice. Moreover, β3- and β2-AR agonists synergistically promote infiltration of M2 macrophages in callus and accelerate bone healing process. Thus, we conclude that TBI accelerates bone formation during early stage of fracture healing process by shaping the anti-inflammation environment in the bone marrow. These results implicate that the adrenergic signals could serve as potential targets for fracture management.

The effect of local sympatholysis on bone-tendon interface healing in a murine rotator cuff repair model

Background

Although neuroregulation plays an important role in tissue healing, the key neuroregulatory pathways and related neurotransmitters involved in bone-tendon interface (BTI) healing are still unknown. It is reported that sympathetic nerves can regulate cartilage and bone metabolism, which are the basic aspects of BTI repair after injury, through the release of norepinephrine (NE). Thus, the purpose of this study was to explore the effect of local sympatholysis (LS) on BTI healing in a murine rotator cuff repair model.

Methods

Specifically, C57BL/6 mice underwent unilateral supraspinatus tendon (SST) detachment and repair was established on a total of 174 mature C57BL/6 mice (12 weeks old): 54 mice were used to examine the sympathetic fibers and its neurotransmitter NE for the representation of sympathetic innervation of BTI, while the rest of them were randomly allocated into (LS) group and control group to verify the effect of sympathetic denervation during BTI healing. The LS group were intervened with fibrin sealant containing 10 ​ng/ml guanethidine, while the control group received fibrin sealant only. Mice were euthanized at postoperative 2, 4 and 8 weeks for immunofluorescent, qRT-PCR, ELISA, Micro-computed tomography (CT), histology and biomechanical evaluations.

Results

Immunofluorescence, qRT-PCR and ELISA evaluations indicated that there were the expression of tyrosine hydroxylase (TH), NE and β2-adrenergic receptor (β2-AR) at the BTI site. All the above showed a trend of increasing at the early postoperative stage and they started to decrease with the healing time after a significant peak. Meanwhile, local sympathetic denervation of BTI was achieved after the use of guanethidine as shown in the NE ELISA outcomes in two groups. QRT-PCR analysis revealed that the healing interface in the LS group expressed more transcription factors, such as Runx2, Bmp2, Sox9, and Aggrecan, than the control group. Further, radiographic data showed that the LS group significantly possessed higher bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), and lower trabecular spacing (Tb.Sp) than the control group. Also, histological test results showed that there was more fibrocartilage regenerated at the healing interface in the LS group compared with the control group. Mechanical testing results demonstrated that the failure load, ultimate strength and stiffness in the LS group were significantly higher at postoperative week 4 (P ​< ​0.05), but not at postoperative week 8 (P ​> ​0.05), compared to the control group.

Conclusion

The regulation of sympathetic innervation was involved in the healing process of injured BTI, and local sympathetic denervation by using guanethidine was beneficial for BTI healing outcomes.The translational potential of this article: This is the first study to evaluate the expression and specific role of sympathetic innervation during BTI healing. The findings of this study also imply that the antagonists of β2-AR could serve as a potential therapeutic strategy for BTI healing. Also, we firstly successfully constructed a local sympathetic denervation mouse model by using guanethidine loaded fibrin sealant, which provided a new effective methodology for future neuroskeletal biology study.

Possibility of averting cytokine storm in SARS-COV 2 patients using specialized pro-resolving lipid mediators

Fatal "cytokine storms (CS)" observed in critically ill COVID-19 patients are consequences of dysregulated host immune system and over-exuberant inflammatory response. Acute respiratory distress syndrome (ARDS), multi-system organ failure, and eventual death are distinctive symptoms, attributed to higher morbidity and mortality rates among these patients. Consequent efforts to save critical COVID-19 patients via the usage of several novel therapeutic options are put in force. Strategically, drugs being used in such patients are dexamethasone, remdesivir, hydroxychloroquine, etc. along with the approved vaccines. Moreover, it is certain that activation of the resolution process is important for the prevention of chronic diseases. Until recently Inflammation resolution was considered a passive process, rather it's an active biochemical process that can be achieved by the use of specialized pro-resolving mediators (SPMs). These endogenous mediators are an array of atypical lipid metabolites that include Resolvins, lipoxins, maresins, protectins, considered as immunoresolvents, but their role in COVID-19 is ambiguous. Recent evidence from studies such as the randomized clinical trial, in which omega 3 fatty acid was used as supplement to resolve inflammation in COVID-19, suggests that direct supplementation of SPMs or the use of synthetic SPM mimetics (which are still being explored) could enhance the process of resolution by regulating the aberrant inflammatory process and can be useful in pain relief and tissue remodeling. Here we discussed the biosynthesis of SPMs, & their mechanistic pathways contributing to inflammation resolution along with sequence of events leading to CS in COVID-19, with a focus on therapeutic potential of SPMs.

The role of nerve fibers and their neurotransmitters in regulating intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) has been the major contributor to chronic lower back pain (LBP). Abnormal apoptosis, senescence, and pyroptosis of IVD cells, extracellular matrix (ECM) degradation, and infiltration of immune cells are the major molecular alternations during IVDD. Changes at tissue level frequently occur at advanced IVD tissue. Ectopic ingrowth of nerves within inner annulus fibrosus (AF) and nucleus pulposus (NP) tissue has been considered as the primary cause for LBP. Innervation at IVD tissue mainly included sensory and sympathetic nerves, and many markers for these two types of nerves have been detected since 1940. In fact, in osteoarthritis (OA), beyond pain transmission, the direct regulation of neuropeptides on functions of chondrocytes have attracted researchers' great attention recently. Many physical and pathological similarities between joint and IVD have shed us the light on the neurogenic mechanism involved in IVDD. Here, an overview of the advances in the nervous system within IVD tissue will be performed, with a discussion on in the role of nerve fibers and their neurotransmitters in regulating IVDD. We hope this review can attract more research interest to address neuromodulation and IVDD itself, which will enhance our understanding of the contribution of neuromodulation to the structural changes within IVD tissue and inflammatory responses and will help identify novel therapeutic targets and enable the effective treatment of IVDD disease.

Neural control of the spleen as an effector of immune responses to inflammation: mechanisms and treatments

Immune system responses are a vital defense mechanism against pathogens. Inflammatory mediators finely regulate complex inflammatory responses from initiation to resolution. However, in certain conditions, the inflammation is initiated and amplified, but not resolved. Understanding the biological mechanisms underlying the regulation of the immune response is critical for developing therapeutic alternatives, including pharmaceuticals and bioelectronic tools. The spleen is an important immune effector organ since it orchestrates innate and adaptive immune responses such as pathogen clearance, cytokine production, and differentiation of cells, therefore playing a modulatory role that balances pro- and anti-inflammatory responses. However, modulation of splenic immune activity is a largely unexplored potential therapeutic tool that could be used for the treatment of inflammatory and life-threatening conditions. This review discusses some of the mechanisms controlling neuroimmune communication and the brain-spleen axis.

Reduced plasma levels of RGM-A predict stroke-associated pneumonia in patients with acute ischemic stroke: A prospective clinical study

Background

Stroke-induced immunodepression syndrome is considered the major etiology of stroke-associated pneumonia (SAP). Repulsive guidance molecule A (RGM-A) is an immunomodulatory protein that is closely related to inflammation and immune responses. To explore the relationship between RGM-A and SAP and facilitate the early identification of patients at high risk of developing SAP, we investigated the predictive value of RGM-A in SAP.

Methods

We enrolled 178 patients with acute ischemic stroke (AIS) and finally analyzed 150 patients, among whom 69 had SAP and 81 had non-SAP. During the same period, 40 patients with community-acquired pneumonia and 40 healthy participants were included as controls. SAP was defined according to the modified US Centers for Disease Control and Prevention criteria. Blood samples were collected at 24 h, 48 h, 3 days, 4 to 7 days, and 8 to 14 days after stroke onset. An enzyme-linked immunosorbent assay was used to detect the plasma levels of RGM-A and interleukin-6.

Results

The plasma RGM-A levels were significantly decreased in both patients with community-acquired pneumonia and those with AIS, and the decline was most pronounced in patients with SAP (P < 0.001). RGM-A started to decline within 24 h after stroke in the SAP group, and the lowest levels were detected on day 3 and days 4 to 7 (P < 0.001). The RGM-A levels in the SAP group were lower than those in the non-SAP group at all blood collection time points (P < 0.05). In the logistic regression analyses, RGM-A was a protective factor for SAP after adjusting for confounders (adjusted odds ratio = 0.22, 95% confidence interval = 0.091–0.538, P = 0.001). Receiver operating characteristic curve analysis showed that the area under the curve for RGM-A was 0.766 (0.091–0.538; P = 0.001), the cutoff value was 4.881 ng/mL, and the sensitivity and specificity were 80.00 and 76.36%, respectively.

Conclusions

We demonstrated that reduced plasma levels of RGM-A might help in the early identification of high-risk patients with SAP and predict the occurrence of SAP in patients with AIS. RGM-A might provide new clues to a potential alternative therapy for SAP.

Therapeutics That Promote Sympathetic Reinnervation Modulate the Inflammatory Response After Myocardial Infarction

Myocardial infarction (MI) triggers an inflammatory response that transitions from pro-inflammatory to reparative over time. Restoring sympathetic nerves in the heart after MI prevents arrhythmias. This study investigated if reinnervation altered the immune response after MI. This study used quantitative multiplex immunohistochemistry to identify the immune cells present in the heart 2 weeks after ischemia-reperfusion. Two therapeutics stimulated reinnervation, preventing arrhythmias and shifting the immune response from inflammatory to reparative, with fewer pro-inflammatory macrophages and more regulatory T cells and reparative macrophages. Treatments did not alter macrophage phenotype in vitro, which suggested reinnervation contributed to the altered immune response.

Inhibition of Sympathetic Activation by Delivering Calcium Channel Blockers from a 3D Printed Scaffold to Promote Bone Defect Repair

Enhancing osteogenesis by promoting neural network reconstruction and neuropeptide release is considered to be an attractive strategy for repairing of critical size bone defects. However, traumatic bone defects often activate the damaged sympathetic nervous system (SNS) in the defect area and release excessive catecholamine to hinder bone defect repair. Herein, a 3D printed scaffold loaded with the calcium channel blocker-nifedipine is proposed to reduce the concentration of catecholamine present in the bone defect region and to accelerate bone healing. To this end, nifedipine-loaded ethosome and laponite are added into a mixed solution containing sodium alginate, methacrylated gelatin, and bone mesenchymal stem cells (BMSCs) to prepare a cell-laden scaffold using 3D bioprinting. The released nifedipine is able to close the calcium channels of nerve cells, thereby blocking sympathetic activation and ultimately inhibiting the release of catecholamine by sympathetic nerve cells, which further promotes the osteogenic differentiation and migration of BMSCs, inhibits osteoclastogenesis in vitro, and effectively improves bone regeneration in a rat critical-size calvarial defect model. Therefore, the results suggest that sustained release of nifedipine from the scaffold can effectively block SNS activation, providing promising strategies for future treatment of bone defects.

Modulation of Microglia M2 Polarization and Alleviation of Hippocampal Neuron Injury By MiR-106b-5p/RGMa in a Mouse Model of Status Epilepticus

MicroRNAs (miRNAs) regulate gene expression at the post-transcriptional level. The miRNA miR-106b-5p has been linked to epilepsy, but its specific role and mechanism of action remain unclear. This was investigated in the present study using a mouse model of pilocarpine-induced status epilepticus and an in vitro system of HT22 hippocampal cells treated with Mg²⁺-free solution and cocultured with BV2 microglia cells. We found that inhibiting miR-106b-5p expression promoted microglia M2 polarization, reduced the inflammatory response, and alleviated neuronal injury. These effects involved modulation of the repulsive guidance molecule A (RGMa)-Rac1-c-Jun N-terminal kinase (JNK)/p38-mitogen-activated protein kinase (MAPK) signaling axis. Our results suggest that therapeutic strategies targeting miR-106b-5p or downstream factors can be effective in preventing epileptogenesis or treating epilepsy.

Interactions between the Autonomic Nervous System and the Immune System after Stroke

Acute stroke is one of the leading causes of morbidity and mortality worldwide. Stroke-induced immune-inflammatory response occurs in the perilesion areas and the periphery. Although stroke-induced immunosuppression may alleviate brain injury, it hinders brain repair as the immune-inflammatory response plays a bidirectional role after acute stroke. Furthermore, suppression of the systemic immune-inflammatory response increases the risk of life-threatening systemic bacterial infections after acute stroke. Therefore, it is essential to explore the mechanisms that underlie the stroke-induced immune-inflammatory response. Autonomic nervous system (ANS) activation is critical for regulating the local and systemic immune-inflammatory responses and may influence the prognosis of acute stroke. We review the changes in the sympathetic and parasympathetic nervous systems and their influence on the immune-inflammatory response after stroke. Importantly, this article summarizes the mechanisms on how ANS regulates the immune-inflammatory response through neurotransmitters and their receptors in immunocytes and immune organs after stroke. To facilitate translational research, we also discuss the promising therapeutic approaches modulating the activation of the ANS or the immune-inflammatory response to promote neurologic recovery after stroke. © 2022 American Physiological Society. Compr Physiol 12:3665-3704, 2022.

Perspective: cell death mechanisms and early diagnosis as precondition for disease modification in Parkinson's disease: are we on the right track?

INTRODUCTION

Current research paradigms on biomarkers for chronic neurodegenerative diseases, such as Parkinson's disease, focus on identification of reliable, easy-to-apply tools for diagnostic screening and progression assessment.

AREAS COVERED

This perspective discusses possible misconceptions of biomarker research in chronic neurodegeneration from a clinician's view based on a not systematic literature search. Multifactorial disease triggers, heterogeneity of symptom and their progression are main reasons for the still missing availability of biomarkers.

EXPERT OPINION

Onset of chronic neurodegenerative disease entities may probably result from a decompensated endogenous repair machinery in the central nervous system, for example the neogenin receptor associated repulsive guidance molecule pathway. Future clinical research is warranted on these repair structures and aim to identify markers for the imbalance between damage and repair, which hypothetically contributes to generation of disease. An assignment to a specific chronic neurodegenerative disease entity probably appears to be secondary. Decryption of probable molecular signals of an impaired repair potential will enable an earlier diagnosis, better monitoring of disease progress and of treatment response. This concept will hopefully provide better preconditions for prevention, cure or therapeutic beneficial disease modification. These unmet therapeutic needs may be achieved for example via antagonism of repulsive guidance molecule A.

The Neuroimmune Interplay in Joint Pain: The Role of Macrophages

Chronic pain associated with joint disorders, such as rheumatoid arthritis (RA), osteoarthritis (OA) and implant aseptic loosening (AL), is a highly debilitating symptom that impacts mobility and quality of life in affected patients. The neuroimmune crosstalk has been demonstrated to play a critical role in the onset and establishment of chronic pain conditions. Immune cells release cytokines and immune mediators that can activate and sensitize nociceptors evoking pain, through interaction with receptors in the sensory nerve terminals. On the other hand, sensory and sympathetic nerve fibers release neurotransmitters that bind to their specific receptor expressed on surface of immune cells, initiating an immunomodulatory role. Macrophages have been shown to be key players in the neuroimmune crosstalk. Moreover, macrophages constitute the dominant immune cell population in RA, OA and AL. Importantly, the targeting of macrophages can result in anti-nociceptive effects in chronic pain conditions. Therefore, the aim of this review is to discuss the nature and impact of the interaction between the inflammatory response and nerve fibers in these joint disorders regarding the genesis and maintenance of pain. The role of macrophages is highlighted. The alteration in the joint innervation pattern and the inflammatory response are also described. Additionally, the immunomodulatory role of sensory and sympathetic neurotransmitters is revised.

Phosphoinositide 3 Kinase γ Plays a Critical Role in Acute Kidney Injury

Inflammatory cells contribute to the pathogenesis of renal ischemia-reperfusion injury (IRI). However, the signaling mechanisms underlying the infiltration of inflammatory cells into the kidney are not well understood. In this study, we examined the effects of phosphoinositide 3 kinase γ (PI3Kγ) on inflammatory cells infiltration into the kidney in response to ischemia-reperfusion injury. Compared with wild-type mice, PI3Kγ knockout mice displayed less IRI in the kidney with fewer tubular apoptotic cell. Furthermore, PI3Kγ deficiency decreased the number of infiltrated neutrophils, macrophages, and T cells in the kidney, which was accompanied by a decrease in the expression of pro-inflammatory cytokines in the kidney. Moreover, wild-type mice treated with AS-605240, a selective PI3Kγ inhibitor, displayed less tubular damage, accumulated fewer inflammatory cells, and expressed less proinflammatory molecules in the kidney following IRI. These results demonstrate that PI3Kγ has a critical role in the pathogenesis of kidney damage in IRI, indicating that PI3Kγ inhibition may serve as a potential therapeutic strategy for the prevention of ischemia-reperfusion-induced kidney injury.

The Omnipresence of Autonomic Modulation in Health and Disease

The Autonomic Nervous System (ANS) is a critical part of the homeostatic machinery with both central and peripheral components. However, little is known about the integration of these components and their joint role in the maintenance of health and in allostatic derailments leading to somatic and/or neuropsychiatric (co)morbidity. Based on a comprehensive literature search on the ANS neuroanatomy we dissect the complex integration of the ANS: (1) First we summarize Stress and Homeostatic Equilibrium - elucidating the responsivity of the ANS to stressors; (2) Second we describe the overall process of how the ANS is involved in Adaptation and Maladaptation to Stress; (3) In the third section the ANS is hierarchically partitioned into the peripheral/spinal, brainstem, subcortical and cortical components of the nervous system. We utilize this anatomical basis to define a model of autonomic integration. (4) Finally, we deploy the model to describe human ANS involvement in (a) Hypofunctional and (b) Hyperfunctional states providing examples in the healthy state and in clinical conditions.

Somatosensory and autonomic neuronal regulation of the immune response

Bidirectional communication between the peripheral nervous system (PNS) and the immune system is a crucial part of an effective but balanced mammalian response to invading pathogens, tissue damage and inflammatory stimuli. Here, we review how somatosensory and autonomic neurons regulate immune cellular responses at barrier tissues and in peripheral organs. Immune cells express receptors for neuronal mediators, including neuropeptides and neurotransmitters, allowing neurons to influence their function in acute and chronic inflammatory diseases. Distinct subsets of peripheral sensory, sympathetic, parasympathetic and enteric neurons are able to signal to innate and adaptive immune cells to modulate their cellular functions. In this Review, we highlight recent studies defining the molecular mechanisms by which neuroimmune signalling mediates tissue homeostasis and pathology. Understanding the neural circuitry that regulates immune responses can offer novel targets for the treatment of a wide array of diseases.

Sensory nerves promote corneal inflammation resolution via CGRP mediated transformation of macrophages to the M2 phenotype through the PI3K/AKT signaling pathway

OBJECTIVES

To explore the role of the corneal sensory nerves in Pseudomonas aeruginosa (P. aeruginosa) keratitis, the synergistic effect between the sensory neurons and macrophages in calcitonin gene-related peptide (CGRP) release, and the functional mechanisms of CGRP-mediated transformation of macrophages to the M2 phenotype.

METHODS

Corneal nerve loss, macrophage recruitment, and CGRP expression were evaluated. To explore the synergistic effect between the sensory neurons and macrophages, RAW 264.7 cells were challenged with lipopolysaccharide (LPS), then trigeminal ganglion (TG) sensory neurons were isolated and co-incubated with macrophages, and CGRP expression was tested. To investigate the biological function of cornea neuron-initiated immune responses mediated by CGRP, BIBN 4096BS was used to inhibit CGRP in vivo and α-CGRP was used to simulate CGRP in vitro. The expressions of inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-10), M1 (CD80/CD86), M2 (CD163/CD206) macrophage markers, and signal transducers (PI3K/AKT) were detected.

RESULTS

P. aeruginosa infection induced corneal nerve loss, macrophage recruitment, and CGRP up-expression. CGRP was co-localized with macrophages. Co-culture showed that sensory neurons and macrophages can mediate CGRP release. More CGRP was released when the two types of cells were combined to respond to LPS. BIBN 4096BS promoted pro-inflammatory cytokines and inhibited the anti-inflammatory cytokines and signal transducers, while, α-CGRP inhibited the pro-inflammatory cytokines and M1 markers and promoted the anti-inflammatory cytokine, M2 markers, and signal transducers.

CONCLUSIONS

P. aeruginosa infection induces corneal sensory neuron activation, macrophage recruitment, and CGRP up-expression. The synergistic effect between the sensory neurons and macrophages promotes CGRP release. CGRP inhibits corneal inflammation and promotes the transformation of macrophages to the M2 phenotype through the PI3K/AKT signaling pathway.

Common Polymorphisms in the RGMa Promoter Are Associated With Cerebrovascular Atherosclerosis Burden in Chinese Han Patients With Acute Ischemic Cerebrovascular Accident

Repulsive guidance molecule a (RGMa) plays a vital role in the progression of numerous inflammatory diseases. However, whether it participates in atherosclerosis development is not known. Here, we explored the influence of RGMa in atherogenesis by investigating whether an association exists between functional polymorphisms in the RGMa promoter and cerebrovascular atherosclerosis burden (CAB) in Chinese Han patients diagnosed with acute ischemic cerebrovascular accident. To this end, we conducted a genetic association study on 201 patients with prior diagnoses of acute ischemic stroke or transient ischemic attack recruited from our hospital. After admission, we conducted three targeted single-nucleotide polymorphisms (SNPs) genotyping and evaluated CAB by computed tomography angiography. We used logistic regression modeling to analyze genetic associations. Functional polymorphism analysis indicated an independent association between the rs725458 T allele and increased CAB in patients with acute ischemic cerebrovascular accident [adjusted odds ratio (OR) = 1.66, 95% confidence interval (CI) = 1.01–2.74, P = 0.046]. In contrast, an association between the rs4778099 AA genotype and decreased CAB (adjusted OR = 0.10, 95% CI = 0.01–0.77, P = 0.027) was found. Our Gene Expression Omnibus analysis revealed lower RGMa levels in the atherosclerotic aortas and in the macrophages isolated from plaques than that in the normal aortas and macrophages from normal tissue, respectively. In conclusion, the relationship between RGMa and cerebrovascular atherosclerosis suggests that RGMa has a potential vasoprotective effect. The two identified functional SNPs (rs725458 and rs4778099) we identified in the RGMa promoter are associated with CAB in patients diagnosed with acute ischemic cerebrovascular accident. These findings offer a promising research direction for RGMa-related translational studies on atherosclerosis.

Sema7A is crucial for resolution of severe inflammation

Nonresolving inflammation, a hallmark of sepsis and/or multi-organ failure, still poses a challenge in medicine. The mortality rate is enormous, and so far no adequate curative therapy is available. Here we identify a previously unrecognized role of the neuronal guidance protein semaphorin 7A in the transition to resolution processes in severe systematic inflammation such as sepsis.

Endogenous mediators regulating acute inflammatory responses in both the induction and resolution phases of inflammatory processes are pivotal in host defense and tissue homeostasis. Recent studies have identified neuronal guidance proteins characterized in axonal development that display immunomodulatory functions. Here, we identify the neuroimmune guidance cue Semaphorin 7A (Sema7A), which appears to link macrophage (MΦ) metabolic remodeling to inflammation resolution. Sema7A orchestrated MΦ chemotaxis and chemokinesis, activated MΦ differentiation and polarization toward the proresolving M2 phenotype, and promoted leukocyte clearance. Peritoneal MΦ^{Sema7A−/−} displayed metabolic reprogramming, characterized by reductions in fatty acid oxidation and oxidative phosphorylation, increases in glycolysis and the pentose phosphate pathway, and truncation of the tricarboxylic acid cycle, which resulted in increased levels of the intermediates succinate and fumarate. The low accumulation of citrate in MΦ^{Sema7A−/−} correlated with the decreased synthesis of prostaglandins, leading to a reduced impact on lipid-mediator class switching and the generation of specialized pro resolving lipid mediators. Signaling network analysis indicated that Sema7A induced the metabolic reprogramming of MΦ by activating the mTOR- and AKT2-signaling pathways. Administration of Sema7A^SL4cd orchestrated the resolution response to tissue homeostasis by shortening the resolution interval, promoting tissue protection in murine peritonitis, and enhancing survival in polymicrobial sepsis.

Sympathetic Denervation Alters the Inflammatory Response of Resident Muscularis Macrophages upon Surgical Trauma and Ameliorates Postoperative Ileus in Mice

Interactions between the peripheral nervous system and resident macrophages (MMs) modulate intestinal homeostatic functions. Activation of β2-adrenergic receptors on MMs has been shown to reduce bacterial challenges. These MMs are also crucial for the development of bowel inflammation in postoperative ileus (POI), an iatrogenic, noninfectious inflammation-based motility disorder. However, the role of the sympathetic nervous system (SNS) in the immune modulation of these MMs during POI or other noninfectious diseases is largely unknown. By employing 6-OHDA-induced denervation, we investigated the changes in the muscularis externa by RNA-seq, quantitative PCR, and flow cytometry. Further, we performed transcriptional phenotyping of sorted CX3CR1⁺ MMs and ex vivo LPS/M-CSF stimulation on these MMs. By combining denervation with a mouse POI model, we explored distinct changes on CX3CR1⁺ MMs as well as in the muscularis externa and their functional outcome during POI. Our results identify SNS as an important mediator in noninfectious postoperative inflammation. Upon denervation, MMs anti-inflammatory genes were reduced, and the muscularis externa profile is shaped toward a proinflammatory status. Further, denervation reduced MMs anti-inflammatory genes also in the early phase of POI. Finally, reduced leukocyte infiltration into the muscularis led to a quicker recovery of bowel motility in the late phase of POI.

Sensing the world and its dangers: An evolutionary perspective in neuroimmunology

Detecting danger is key to the survival and success of all species. Animal nervous and immune systems cooperate to optimize danger detection. Preceding studies have highlighted the benefits of bringing neurons into the defense game, including regulation of immune responses, wound healing, pathogen control, and survival. Here, we summarize the body of knowledge in neuroimmune communication and assert that neuronal participation in the immune response is deeply beneficial in each step of combating infection, from inception to resolution. Despite the documented tight association between the immune and nervous systems in mammals or invertebrate model organisms, interdependence of these two systems is largely unexplored across metazoans. This review brings a phylogenetic perspective of the nervous and immune systems in the context of danger detection and advocates for the use of non-model organisms to diversify the field of neuroimmunology. We identify key taxa that are ripe for investigation due to the emergence of key evolutionary innovations in their immune and nervous systems. This novel perspective will help define the primordial principles that govern neuroimmune communication across taxa.

PMN-derived netrin-1 attenuates cardiac ischemia-reperfusion injury via myeloid ADORA2B signaling

Previous studies implicated the neuronal guidance molecule netrin-1 in attenuating myocardial ischemia-reperfusion injury. However, the tissue-specific sources and receptor signaling events remain elusive. Neutrophils are among the first cells responding to an ischemic insult and can be associated with tissue injury or rescue. We found netrin-1 levels were elevated in the blood of patients with myocardial infarction, as well as in mice exposed to myocardial ischemia-reperfusion. Selectively increased infarct sizes and troponin levels were found in Ntn1loxP/loxP Lyz2 Cre+ mice, but not in mice with conditional netrin-1 deletion in other tissue compartments. In vivo studies using neutrophil depletion identified neutrophils as the main source for elevated blood netrin-1 during myocardial injury. Finally, pharmacologic studies using treatment with recombinant netrin-1 revealed a functional role for purinergic signaling events through the myeloid adenosine A2b receptor in mediating netrin-1-elicited cardioprotection. These findings suggest an autocrine signaling loop with a functional role for neutrophil-derived netrin-1 in attenuating myocardial ischemia-reperfusion injury through myeloid adenosine A2b signaling.

Identification of epigenetic memory candidates associated with gestational age at birth through analysis of methylome and transcriptional data

Preterm birth is known to be associated with chronic disease risk in adulthood whereby epigenetic memory may play a mechanistic role in disease susceptibility. Gestational age (GA) is the most important prognostic factor for preterm infants, and numerous DNA methylation alterations associated with GA have been revealed by epigenome-wide association studies. However, in human preterm infants, whether the methylation changes relate to transcription in the fetal state and persist after birth remains to be elucidated. Here, we identified 461 transcripts associated with GA (range 23-41 weeks) and 2093 candidate CpG sites for GA-involved epigenetic memory through analysis of methylome (110 cord blood and 47 postnatal blood) and transcriptional data (55 cord blood). Moreover, we discovered the trends of chromatin state, such as polycomb-binding, among these candidate sites. Fifty-four memory candidate sites showed correlation between methylation and transcription, and the representative corresponding gene was UCN, which encodes urocortin.

Bidirectional Brain-Systemic Interactions and Outcomes After TBI

Traumatic brain injury (TBI) is a debilitating disorder associated with chronic progressive neurodegeneration and long-term neurological decline. Importantly, there is now substantial and increasing evidence that TBI can negatively impact systemic organs, including the pulmonary, gastrointestinal (GI), cardiovascular, renal, and immune system. Less well appreciated, until recently, is that such functional changes can affect both the response to subsequent insults or diseases, as well as contribute to chronic neurodegenerative processes and long-term neurological outcomes. In this review, we summarize evidence showing bidirectional interactions between the brain and systemic organs following TBI and critically assess potential underlying mechanisms.

Placenta accreta spectrum: biomarker discovery using plasma proteomics

BACKGROUND

Many cases of placenta accreta spectrum are not diagnosed antenatally, despite identified risk factors and improved imaging methods. Identification of plasma protein biomarkers could further improve the antenatal diagnosis of placenta accreta spectrum .

OBJECTIVE

The purpose of this study was to determine if women with placenta accreta spectrum have a distinct plasma protein profile compared with control subjects.

STUDY DESIGN

We obtained plasma samples before delivery from 16 participants with placenta accreta spectrum and 10 control subjects with similar gestational ages (35.1 vs 35.5 weeks gestation, respectively). We analyzed plasma samples with an aptamer-based proteomics platform for alterations in 1305 unique proteins. Heat maps of the most differentially expressed proteins (T test, P<.01) were generated with matrix visualization and analysis software. Principal component analysis was performed with the use of all 1305 proteins and the top 21 dysregulated proteins. We then confirmed dysregulated proteins using enzyme-linked immunosorbent assay and report significant differences between placenta accreta spectrum and control cases (Wilcoxon-rank sum test, P<.05).

RESULTS

Many of the top 50 proteins that significantly dysregulated in participants with placenta accreta spectrum were inflammatory cytokines, factors that regulate vascular remodeling, and extracellular matrix proteins that regulate invasion. Placenta accreta spectrum, with the use of the top 21 proteins, distinctly separated the placenta accreta spectrum cases from control cases (P<.01). Using enzyme-linked immunosorbent assay, we confirmed 4 proteins that were dysregulated in placenta accreta spectrum compared with control cases: median antithrombin III concentrations (240.4 vs 150.3 mg/mL; P=.002), median plasminogen activator inhibitor 1 concentrations (4.1 vs 7.1 ng/mL; P<.001), soluble Tie2 (13.5 vs 10.4 ng/mL; P=.02), soluble vascular endothelial growth factor receptor 2 (9.0 vs 5.9 ng/mL; P=.003).

CONCLUSION

Participants with placenta accreta spectrum had a unique and distinct plasma protein signature.

Colocalization of dopamine receptors in BDNF-expressing peptidergic neurons in the paraventricular nucleus of rats

Brain-derived neurotrophic factor (BDNF) in the paraventricular nucleus of the hypothalamus (PVN) can regulate food intake and energy expenditure. However, the regulatory mediator of BDNF-positive neurons in the PVN remains unclear. Recently, widespread expression of the dopamine D1 receptor (DRD1) and D2 receptor (DRD2) has been observed in PVN neurons. We hypothesized that dopamine receptors (DRs) are also expressed in BDNF-positive neurons and mediate the function of BDNF in the PVN. Using multiple immunofluorescence assays combined with confocal microscopy, we found that BDNF-immunoreactive (IR) neurons were widely distributed throughout the PVN in both the magnocellular and parvocellular regions. The BDNF protein was mainly expressed in the somas of neurons. The distribution of DR-IR neurons exhibited a pattern similar to that of BDNF. Nearly all DRD1 and DRD2 expression occurred within BDNF-IR neurons. A large number of tyrosine hydroxylase (TH)-IR fibers innervated the entire PVN. The BDNF-IR neurons were surrounded by TH-IR nerve fibers that were punctiform or shaped like short bars. Additionally, BDNF colocalized with vasopressin-, oxytocin- and corticotrophin releasing hormone-positive neurons in the PVN. The present study suggests that DRs have a potential role in mediating the function of the PVN BDNF neurons. This finding is important for elucidating the central circuitry involved in energy balance.

Novel Resolution Mediators of Severe Systemic Inflammation

Nonresolving inflammation, a hallmark of underlying severe inflammatory processes such as sepsis, acute respiratory distress syndrome and multiple organ failure is a major cause of admission to the intensive care unit and high mortality rates. Many survivors develop new functional limitations and health problems, and in cases of sepsis, approximately 40% of patients are rehospitalized within three months. Over the last few decades, better treatment approaches have been adopted. Nevertheless, the lack of knowledge underlying the complex pathophysiology of the inflammatory response organized by numerous mediators and the induction of complex networks impede curative therapy. Thus, increasing evidence indicates that resolution of an acute inflammatory response, considered an active process, is the ideal outcome that leads to tissue restoration and organ function. Many mediators have been identified as immunoresolvents, but only a few have been shown to contribute to both the initial and resolution phases of severe systemic inflammation, and these agents might finally substantially impact the therapeutic approach to severe inflammatory processes. In this review, we depict different resolution mediators/immunoresolvents contributing to resolution programmes specifically related to life-threatening severe inflammatory processes.

Blockade of adrenergic β-receptor activation through local delivery of propranolol from a 3D collagen/polyvinyl alcohol/hydroxyapatite scaffold promotes bone repair in vivo

Objectives

Activation of the sympathetic system and adrenergic β‐receptors following traumatic bone defects negatively impairs bone regeneration. Whether preventing β‐receptor activation could potentially improve bone defect repair is unknown. In this study, we investigated the effect of systematic administration and local delivery of propranolol through composite scaffolds on bone healing.

Materials and methods

Collagen/PVA/propranolol/hydroxyapatite（CPPH）composite scaffolds were fabricated with 3D printing technique and characterized by scanning electron microscope (SEM). Micro‐CT analysis and bone formation histology were performed to detect new bone formation. Osteogenic differentiation of bone marrow stromal cells (BMSCs) and osteoclastogenesis of bone marrow monocytes cultured with scaffolds extract were performed for further verification.

Results

Intraperitoneal injection of propranolol did not significantly improve bone repair, as indicated by micro‐CT analysis and bone formation histology. However, CPPH scaffolds exhibited sustained release of propranolol in vitro and significantly enhanced bone regeneration compared with vehicle collagen/PVA/hydroxyapatite (CPH) scaffolds in vivo. Moreover, in vitro experiments indicated the scaffolds containing propranolol promoted the osteogenic differentiation and migration of rat BMSCs and inhibited osteoclastogenesis by preventing β‐receptor activation.

Conclusions

This study demonstrates that local adrenergic β‐receptor blockade can effectively enhance the treatment of bone defects by stimulating osteogenic differentiation, inhibiting osteoclastogenesis and enhancing BMSCs migration.

Inhibition of Δ24-dehydrocholesterol reductase activates pro-resolving lipid mediator biosynthesis and inflammation resolution

Targeting metabolism through bioactive key metabolites is an upcoming future therapeutic strategy. We questioned how modifying intracellular lipid metabolism could be a possible means for alleviating inflammation. Using a recently developed chemical probe (SH42), we inhibited distal cholesterol biosynthesis through selective inhibition of Δ²⁴-dehydrocholesterol reductase (DHCR24). Inhibition of DHCR24 led to an antiinflammatory/proresolving phenotype in a murine peritonitis model. Subsequently, we investigated several omics layers in order to link our phenotypic observations with key metabolic alterations. Lipidomic analysis revealed a significant increase in endogenous polyunsaturated fatty acid (PUFA) biosynthesis. These data integrated with gene expression analysis, revealing increased expression of the desaturase Fads6 and the key proresolving enzyme Alox-12/15 Protein array analysis, as well as immune cell phenotype and functional analysis, substantiated these results confirming the antiinflammatory/proresolving phenotype. Ultimately, lipid mediator (LM) analysis revealed the increased production of bioactive lipids, channeling the observed metabolic alterations into a key class of metabolites known for their capacity to change the inflammatory phenotype.