MANF regulates metabolic and immune homeostasis in ageing and protects against liver damage

Cerebrospinal fluid mesencephalic astrocyte-derived neurotrophic factor: A moderating effect on sleep time and cognitive function

BACKGROUND

Sleeping late has been associated with cognitive impairment, and insufficient sleep can affect the secretion of feeding-related cytokines. Feeding-related cytokines may contribute to cognitive deficits resulting from delayed bedtime. Glial cell line-derived neurotrophic factor (GDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF), which are feeding-related neurotrophic factors, have been associated with improved cognitive function and neuroprotective abilities. Enhanced expression of GDNF and MANF is linked to increased energy expenditure and hyperphagia, respectively.

AIMS

This study aimed to investigate the association between cerebrospinal fluid (CSF) GDNF, MANF, cognition, and sleep time and to explore the moderating effects of GDNF and MANF on cognitive impairment in individuals who sleep late.

METHOD

This cross-sectional study included participants (mean age 31.76 ± 10.22 years) who were categorized as ≤23 o'clock sleepers (n = 66) and >23 o'clock sleepers (n = 125) based on sleep time. Cognition was assessed using Montreal Cognitive Assessment (MoCA), and GDNF and MANF levels in CSF were measured.

RESULTS

MANF may play a moderating role in the relationship between sleep time and cognition (R2 = 0.06, β = 0.59, p = 0.031). Age showed a negative correlation with MoCA scores (R2 = 0.08, β = -0.18), while education exhibited a positive correlation (β = 0.17, both p < 0.05). Only ≤23 o'clock sleepers exhibited a negative correlation between MANF levels and BMI (r = -0.35, p = 0.005).

CONCLUSIONS

This study provides hitherto undocumented evidence of the potential protective effect of CSF MANF on cognitive impairment of late sleepers, which suggests that maintaining a regular sleep schedule may contribute to cognition and overall health, with MANF playing a role in this process.

Extracellular Vesicle-Contained Thrombospondin 1 Retards Age-Related Degenerative Tendinopathy by Rejuvenating Tendon Stem/Progenitor Cell Senescence

Advanced age is a major risk factor for age-related degenerative tendinopathy. During aging, tendon stem/progenitor cell (TSPC) function declines owing to the transition from a normal quiescent state to a senescent state. Extracellular vesicles (EVs) from young stem cells are reported to possess anti-aging functions. However, it remains unclear whether EVs from young TSPCs (TSPC-EVs) can rejuvenate senescent TSPCs to delay age-related degeneration. Here, this study finds that TSPC-EVs can mitigate the aging phenotypes of senescent TSPCs and maintain their tenogenic capacity. In vitro studies reveal that TSPC-EVs can reinstall autophagy in senescent TSPCs to alleviate cellular senescence, and that the re-establishment of autophagy is mediated by the PI3K/AKT pathway. Mechanistically, this study finds that thrombospondin 1, a negative regulator of the PI3K/AKT pathway, is enriched in TSPC-EVs and can be transported to senescent TSPCs. Moreover, in vivo studies show that the local delivery of TSPC-EVs can rejuvenate senescent TSPCs and promote their tenogenic differentiation, thereby rescuing tendon regeneration in aged rats. Taken together, TSPC-EVs as a novel cell-free approach have promising therapeutic potential for aging-related degenerative tendinopathy.

Mesencephalic Astrocyte-derived Neurotrophic Factor Supports Hepatitis B Virus-induced Immunotolerance

BACKGROUND & AIMS

The immune tolerance induced by hepatitis B virus (HBV) is a major challenge for achieving effective viral clearance, and the mechanisms involved are not well-understood. One potential factor involved in modulating immune responses is mesencephalic astrocyte-derived neurotrophic factor (MANF), which has been reported to be increased in patients with chronic hepatitis B. In this study, our objective is to examine the role of MANF in regulating immune responses to HBV.

METHODS

We utilized a commonly used HBV-harboring mouse model, where mice were hydrodynamically injected with the pAAV/HBV1.2 plasmid. We assessed the HBV load by measuring the levels of various markers including hepatitis B surface antigen, hepatitis B envelope antigen, hepatitis B core antigen, HBV DNA, and HBV RNA.

RESULTS

Our study revealed that following HBV infection, both myeloid cells and hepatocytes exhibited increased expression of MANF. Moreover, we observed that mice with myeloid-specific MANF knockout (ManfMye-/-) displayed reduced HBV load and improved HBV-specific T cell responses. The decreased HBV-induced tolerance in ManfMye-/- mice was associated with reduced accumulation of myeloid-derived suppressor cells (MDSCs) in the liver. Restoring MDSC levels in ManfMye-/- mice through MDSC adoptive transfer reinstated HBV-induced tolerance. Mechanistically, we found that MANF promoted MDSC expansion by activating the IL-6/STAT3 pathway. Importantly, our study demonstrated the effectiveness of a combination therapy involving an hepatitis B surface antigen vaccine and nanoparticle-encapsulated MANF siRNA in effectively clearing HBV in HBV-carrier mice.

CONCLUSION

The current study reveals that MANF plays a previously unrecognized regulatory role in liver tolerance by expanding MDSCs in the liver through IL-6/STAT3 signaling, leading to MDSC-mediated CD8+ T cell exhaustion.

Mesencephalic astrocyte-derived neurotrophic factor ameliorates inflammatory response in polycystic ovary syndrome via inhibiting TLR4-NF-κB-NLRP3 pathway

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder in women of reproductive age, which often leads to female infertility. Chronic inflammation is a significant factor in the development of PCOS. Our study aimed to explore the impact of mesencephalic astrocyte-derived neurotrophic factor (MANF), a scientifically validated anti-inflammatory factor, on 99 diagnosed PCOS patients. We also investigated its effects on PCOS mice induced with dehydroepiandrosterone (DHEA) and KGN cells induced with dihydrotestosterone (DHT). Our findings revealed a decrease in serum MANF levels in PCOS patients, which were negatively associated with serum tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels. The administration of recombinant human MANF (rhMANF) in PCOS mice demonstrated a decrease in pro-inflammatory cytokines and monocytes/macrophages in both peripheral blood and ovarian tissues. Furthermore, the inclusion of rhMANF notably ameliorated DHEA-induced ovarian dysfunction and fibrosis by negatively regulating the toll-like receptor 4 (TLR4)-nuclear factor kappa B (NF-κB)-NLR family, pyrin domain containing protein 3 (NLRP3) pathway. Additionally, in vitro experiments showed that the up-regulation of MANF offset DHT-induced inhibition of viability and apoptosis in KGN cells. Collectively, this study highlights the anti-inflammatory properties of MANF in PCOS and suggests its potential as a therapeutic approach for the management of PCOS.

In vitro heterochronic parabiosis identifies pigment epithelium-derived factor as a systemic mediator of rejuvenation by young blood

Several decades of heterochronic parabiosis (HCPB) studies have demonstrated the restorative impact of young blood, and deleterious influence of aged blood, on physiological function and homeostasis across tissues, although few of the factors responsible for these observations have been identified. Here we develop an in vitro HCPB system to identify these circulating factors, using replicative lifespan (RLS) of primary human fibroblasts as an endpoint of cellular health. We find that RLS is inversely correlated with serum donor age and sensitive to the presence or absence of specific serum components. Through in vitro HCPB, we identify the secreted protein pigment epithelium-derived factor (PEDF) as a circulating factor that extends RLS of primary human fibroblasts and declines with age in mammals. Systemic administration of PEDF to aged mice reverses age-related functional decline and pathology across several tissues, improving cognitive function and reducing hepatic fibrosis and renal lipid accumulation. Together, our data supports PEDF as a systemic mediator of the effect of young blood on organismal health and homeostasis and establishes our in vitro HCPB system as a valuable screening platform for the identification of candidate circulating factors involved in aging and rejuvenation.

Polysaccharide from Boletus aereus ameliorates DSS-induced colitis in mice by regulating the MANF/MUC2 signaling and gut microbiota

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions characterized by disruptions in the colonic mucus barrier and gut microbiota. In this study, a novel soluble polysaccharide obtained from Boletus aereus (BAP) through water extraction was examined for its structure. The protective effects of BAP on colitis were investigated using a DSS-induced mice model. BAP was found to promote the expression of intestinal mucosal and tight junction proteins, restore the compromised mucus barrier, and suppress the activation of inflammatory signaling. Moreover, BAP reshape the gut microbiota and had a positive impact on the composition of the gut microbiota by reducing inflammation-related microbes. Additionally, BAP decreased cytokine levels through the MANF-BATF2 signaling pathway. Correlation analysis revealed that MANF was negatively correlated with the DAI and the level of cytokines. Furthermore, the depletion of gut microbiota using antibiotic partially inhabited the effect of BAP on the activation of MANF and Muc2, indicating the role of gut microbiota in its protective effect against colitis. In conclusion, BAP had an obvious activation on MANF under gut inflammation. This provides new insights into the prospective use of BAP as a functional food to enhance intestinal health.

Energy metabolism as therapeutic target for aged wound repair by engineered extracellular vesicle

Aging skin, vulnerable to age-related defects, is poor in wound repair. Metabolic regulation in accumulated senescent cells (SnCs) with aging is essential for tissue homeostasis, and adequate ATP is important in cell activation for aged tissue repair. Strategies for ATP metabolism intervention hold prospects for therapeutic advances. Here, we found energy metabolic changes in aging skin from patients and mice. Our data show that metformin engineered EV (Met-EV) can enhance aged mouse skin repair, as well as ameliorate cellular senescence and restore cell dysfunctions. Notably, ATP metabolism was remodeled as reduced glycolysis and enhanced OXPHOS after Met-EV treatment. We show Met-EV rescue senescence-induced mitochondria dysfunctions and mitophagy suppressions, indicating the role of Met-EV in remodeling mitochondrial functions via mitophagy for adequate ATP production in aged tissue repair. Our results reveal the mechanism for SnCs rejuvenation by EV and suggest the disturbed energy metabolism, essential in age-related defects, to be a potential therapeutic target for facilitating aged tissue repair.

Rejuvenation of cerebromicrovascular function in aged mice through heterochronic parabiosis: insights into neurovascular coupling and the impact of young blood factors

Age-related impairment of neurovascular coupling (NVC; "functional hyperemia") is a critical factor in the development of vascular cognitive impairment (VCI). Recent geroscience research indicates that cell-autonomous mechanisms alone cannot explain all aspects of neurovascular aging. Circulating factors derived from other organs, including pro-geronic factors (increased with age and detrimental to vascular homeostasis) and anti-geronic factors (preventing cellular aging phenotypes and declining with age), are thought to orchestrate cellular aging processes. This study aimed to investigate the influence of age-related changes in circulating factors on neurovascular aging. Heterochronic parabiosis was utilized to assess how exposure to young or old systemic environments could modulate neurovascular aging. Results demonstrated a significant decline in NVC responses in aged mice subjected to isochronic parabiosis (20-month-old C57BL/6 mice [A-(A)]; 6 weeks of parabiosis) when compared to young isochronic parabionts (6-month-old, [Y-(Y)]). However, exposure to young blood from parabionts significantly improved NVC in aged heterochronic parabionts [A-(Y)]. Conversely, young mice exposed to old blood from aged parabionts exhibited impaired NVC responses [Y-(A)]. In conclusion, even a brief exposure to a youthful humoral environment can mitigate neurovascular aging phenotypes, rejuvenating NVC responses. Conversely, short-term exposure to an aged humoral milieu in young mice accelerates the acquisition of neurovascular aging traits. These findings highlight the plasticity of neurovascular aging and suggest the presence of circulating anti-geronic factors capable of rejuvenating the aging cerebral microcirculation. Further research is needed to explore whether young blood factors can extend their rejuvenating effects to address other age-related cerebromicrovascular pathologies, such as blood-brain barrier integrity.

CDNF and ER stress: Pharmacology and therapeutic possibilities

Cerebral dopamine neurotrophic factor (CDNF) is an endogenous protein in humans and other vertebrates, and it has been shown to have protective and restorative effects on cells in various disease models. Although it is named as a neurotrophic factor, its actions are drastically different from classical neurotrophic factors such as neurotrophins or the glial cell line-derived neurotrophic family of proteins. Like all secreted proteins, CDNF has a signal sequence at the N-terminus, but unlike common growth factors it has a KDEL-receptor retrieval sequence at the C-terminus. Thus, CDNF is mainly located in the ER. In response to adverse effects, such as ER stress, the expression of CDNF is upregulated and can alleviate ER stress. Also different from other neurotrophic factors, CDNF reduces protein aggregation and inflammation in disease models. Although it is an ER luminal protein, it can surprisingly directly interact with alpha-synuclein, a protein involved in the pathogenesis of synucleinopathies e.g., Parkinson's disease. Pleiotropic CDNF has therapeutic potential and has been tested as a recombinant human protein and gene therapy. The neuroprotective and neurorestorative effects have been described in a number of preclinical studies of Parkinson's disease, stroke and amyotrophic lateral sclerosis. Currently, it was successfully evaluated for safety in a phase 1/2 clinical trial for Parkinson's disease. Collectively, based on recent findings on the mode of action and therapeutic potential of CDNF, its use as a drug could be expanded to other ER stress-related diseases.

MANF protein expression is upregulated in immune cells in the ischemic human brain and systemic recombinant MANF delivery in rat ischemic stroke model demonstrates anti-inflammatory effects

Mesencephalic astrocyte-derived neurotrophic factor (MANF) has cytoprotective effects on various injuries, including cerebral ischemia, and it can promote recovery even when delivered intracranially several days after ischemic stroke. In the uninjured rodent brain, MANF protein is expressed almost exclusively in neurons, but post-ischemic MANF expression has not been characterized. We aimed to investigate how endogenous cerebral MANF protein expression evolves in infarcted human brains and rodent ischemic stroke models. During infarct progression, the cerebral MANF expression pattern both in human and rat brains shifted drastically from neurons to expression in inflammatory cells. Intense MANF immunoreactivity took place in phagocytic microglia/macrophages in the ischemic territory, peaking at two weeks post-stroke in human and one-week post-stroke in rat ischemic cortex. Using double immunofluorescence and mice lacking MANF gene and protein from neuronal stem cells, neurons, astrocytes, and oligodendrocytes, we verified that MANF expression was induced in microglia/macrophage cells in the ischemic hemisphere. Embarking on the drastic expression transition towards inflammatory cells and the impact of blood-borne inflammation in stroke, we hypothesized that exogenously delivered MANF protein can modulate tissue recovery processes. In an attempt to enhance recovery, we designed a set of proof-of-concept studies using systemic delivery of recombinant MANF in a rat model of cortical ischemic stroke. Intranasal recombinant MANF treatment decreased infarct volume and reduced the severity of neurological deficits. Intravenous recombinant MANF treatment decreased the levels of pro-inflammatory cytokines and increased the levels of anti-inflammatory cytokine IL-10 in the infarcted cortex one-day post-stroke. In conclusion, MANF protein expression is induced in activated microglia/macrophage cells in infarcted human and rodent brains, and this could implicate MANF's involvement in the regulation of post-stroke inflammation in patients and experimental animals. Moreover, systemic delivery of recombinant MANF shows promising immunomodulatory effects and therapeutic potential in experimental ischemic stroke.

Neurotrophic factor MANF regulates autophagy and lysosome function to promote proteostasis in C. elegans

The conserved mesencephalic astrocyte-derived neurotrophic factor (MANF) protects dopaminergic neurons but also functions in several other tissues. Previously, we showed that Caenorhabditis elegans manf-1 null mutants have increased ER stress, dopaminergic neurodegeneration, protein aggregation, slower growth, and a reduced lifespan. The multiple requirements of MANF in different systems suggest its essential role in regulating cellular processes. However, how intracellular and extracellular MANF regulates broader cellular function remains unknown. Here, we report a novel mechanism of action for manf-1 that involves the autophagy transcription factor HLH-30/TFEB-mediated signaling to regulate lysosomal function and aging. We generated multiple transgenic strains overexpressing MANF-1 and found that animals had extended lifespan, reduced protein aggregation, and improved neuronal health. Using a fluorescently tagged MANF-1, we observed different tissue localization of MANF-1 depending on the ER retention signal. Further subcellular analysis showed that MANF-1 localizes within cells to the lysosomes. These findings were consistent with our transcriptomic studies and, together with analysis of autophagy regulators, demonstrate that MANF-1 regulates protein homeostasis through increased autophagy and lysosomal activity. Collectively, our findings establish MANF as a critical regulator of the stress response, proteostasis, and aging.

Navigating the Landscape of MANF Research: A Scientometric Journey with CiteSpace Analysis

This study employs bibliometric analysis through CiteSpace to comprehensively evaluate the status and trends of MANF (mesencephalic astrocyte-derived neurotrophic factor) research spanning 25 years (1997-2022). It aims to fill the gap in objective and comprehensive reviews of MANF research. MANF-related studies were extracted from the Web of Science database. MANF publications were quantitatively and qualitatively analyzed for various factors by CiteSpace, including publication volume, journals, countries/regions, institutions, and authors. Keywords and references were visually analyzed to unveil research evolution and hotspot. Analysis of 353 MANF-related articles revealed escalating annual publications, indicating growing recognition of MANF's importance. High-impact journals such as the International Journal of Molecular Sciences and Journal of Biological Chemistry underscored MANF's interdisciplinary significance. Collaborative networks highlighted China and the USA's pivotal roles, while influential figures and partnerships drove understanding of MANF's mechanisms. Co-word analysis of MANF-related keywords exposed key evolutionary hotspots, encompassing neurotrophic effects, cytoprotective roles, MANF-related diseases, and the CDNF/MANF family. This progression from basic understanding to clinical potential showcased MANF's versatility from cellular protection to therapy. Bibliometric analysis reveals MANF's diverse research trends and pathways, from basics to clinical applications, driving medical progress. This comprehensive assessment enriches understanding and empowers researchers for dynamic evolution, advancing innovation, and benefiting patients. Bibliometric analysis of MANF research. The graphical abstract depicts the bibliometric analysis of MANF research, highlighting its aims, methods, and key results.

MANF stimulates autophagy and restores mitochondrial homeostasis to treat autosomal dominant tubulointerstitial kidney disease in mice

Misfolded protein aggregates may cause toxic proteinopathy, including autosomal dominant tubulointerstitial kidney disease due to uromodulin mutations (ADTKD-UMOD), a leading hereditary kidney disease. There are no targeted therapies. In our generated mouse model recapitulating human ADTKD-UMOD carrying a leading UMOD mutation, we show that autophagy/mitophagy and mitochondrial biogenesis are impaired, leading to cGAS-STING activation and tubular injury. Moreover, we demonstrate that inducible tubular overexpression of mesencephalic astrocyte-derived neurotrophic factor (MANF), a secreted endoplasmic reticulum protein, after the onset of disease stimulates autophagy/mitophagy, clears mutant UMOD, and promotes mitochondrial biogenesis through p-AMPK enhancement, thus protecting kidney function in our ADTKD mouse model. Conversely, genetic ablation of MANF in the mutant thick ascending limb tubular cells worsens autophagy suppression and kidney fibrosis. Together, we have discovered MANF as a biotherapeutic protein and elucidated previously unknown mechanisms of MANF in the regulation of organelle homeostasis, which may have broad therapeutic applications to treat various proteinopathies.

S100a16 Deficiency Prevents Alcohol-induced Fatty Liver Injury via Inducing MANF Expression in Mice

Alcoholic liver disease (ALD) encompasses conditions ranging from simple steatosis to cirrhosis and even liver cancer. It has gained significant global attention in recent years. Despite this, effective pharmacological treatments for ALD remain elusive, and the core mechanisms underlying the disease are not yet fully comprehended. S100A16, a newly identified calcium-binding protein, is linked to lipid metabolism. Our research has discovered elevated levels of the S100A16 protein in both serum and liver tissue of ALD patients. A similar surge in hepatic S100A16 expression was noted in a Gao-binge alcohol feeding mouse model. S100a16 knockdown alleviated ethanol-induced liver injury, steatosis and inflammation. Conversely, S100a16 transgenic mice showed aggravating phenomenon. Mechanistically, we identify mesencephalic astrocyte-derived neurotrophic factor (MANF) as a regulated entity downstream of S100a16 deletion. MANF inhibited ER-stress signal transduction induced by alcohol stimulation. Meanwhile, MANF silencing suppressed the inhibition effect of S100a16 knockout on ethanol-induced lipid droplets accumulation in primary hepatocytes. Our data suggested that S100a16 deletion protects mice against alcoholic liver lipid accumulation and inflammation dependent on upregulating MANF and inhibiting ER stress. This offers a potential therapeutic avenue for ALD treatment.

Effect of mesencephalic astrocyte-derived neurotrophic factor on the inflammatory response in human gingival fibroblasts cells

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a unique member of the neurotrophic factor family residing in the endoplasmic reticulum, where it functions as a stress response protein maintaining endoplasmic reticulum homeostasis, in addition to being secreted extracellularly as a neurotrophic factor to bind with receptors to initiate intracellular signal transduction pathways. Interestingly, MANF has shown an important protective role in the inflammatory response of many diseases. In neural stem cells, pancreatic β cells, and retinal cells, MANF can inhibit the inflammatory response, modulate the immune response, and promote tissue repair. However, the role of MANF in the periodontal inflammatory response remains unclear. In the present study, we used lipopolysaccharide (LPS) from Porphyromonas gingivalis (Pg) to establish a Pg-LPS-stimulated periodontal inflammatory model in human gingival fibroblasts cells (HGF-1) to investigate the role of MANF in vitro. We found that MANF could inhibit pro-inflammatory cytokine secretion, alleviate the endoplasmic reticulum stress response, promote cell survival, and inhibit cell apoptosis. Therefore, MANF might be a novel promising target for the treatment of periodontitis.

MANF brakes TLR4 signaling by competitively binding S100A8 with S100A9 to regulate macrophage phenotypes in hepatic fibrosis

The mesencephalic astrocyte-derived neurotrophic factor (MANF) has been recently identified as a neurotrophic factor, but its role in hepatic fibrosis is unknown. Here, we found that MANF was upregulated in the fibrotic liver tissues of the patients with chronic liver diseases and of mice treated with CCl4. MANF deficiency in either hepatocytes or hepatic mono-macrophages, particularly in hepatic mono-macrophages, clearly exacerbated hepatic fibrosis. Myeloid-specific MANF knockout increased the population of hepatic Ly6Chigh macrophages and promoted HSCs activation. Furthermore, MANF-sufficient macrophages (from WT mice) transfusion ameliorated CCl4-induced hepatic fibrosis in myeloid cells-specific MANF knockout (MKO) mice. Mechanistically, MANF interacted with S100A8 to competitively block S100A8/A9 heterodimer formation and inhibited S100A8/A9-mediated TLR4-NF-κB signal activation. Pharmacologically, systemic administration of recombinant human MANF significantly alleviated CCl4-induced hepatic fibrosis in both WT and hepatocytes-specific MANF knockout (HKO) mice. This study reveals a mechanism by which MANF targets S100A8/A9-TLR4 as a "brake" on the upstream of NF-κB pathway, which exerts an impact on macrophage differentiation and shed light on hepatic fibrosis treatment.

Factors Affecting Stem Cell-Based Regenerative Approaches in Retinal Degeneration

Inherited and age-associated vision loss is often associated with degeneration of the cells of the retina, the light-sensitive layer at the back of the eye. The mammalian retina, being a postmitotic neural tissue, does not have the capacity to repair itself through endogenous regeneration. There has been considerable excitement for the development of cell replacement approaches since the isolation and development of culture methods for human pluripotent stem cells, as well as the generation of induced pluripotent stem cells. This has now been combined with novel three-dimensional organoid culture systems that closely mimic human retinal development in vitro. In this review, we cover the current state of the field, with emphasis on the cell delivery challenges, role of the recipient immunological microenvironment, and challenges related to connectivity between transplanted cells and host circuitry both locally and centrally to the different areas of the brain.

Upregulation of mesencephalic astrocyte-derived neurotrophic factor (MANF) expression offers protection against alcohol neurotoxicity

Alcohol exposure has detrimental effects on both the developing and mature brain. Endoplasmic reticulum (ER) stress is one of the mechanisms that contributes to alcohol-induced neuronal damages. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an ER stress-responsive protein and is neuroprotective in multiple neuronal injury and neurodegenerative disease models. MANF deficiency has been shown to exacerbate alcohol-induced ER stress and neurodegeneration. However, it is unknown whether MANF supplement is sufficient to protect against alcohol neurotoxicity. Alcohol alters MANF expression in the brain, but the mechanisms underlying alcohol modulation of MANF expression remain unclear. This study was designed to determine how alcohol alters MANF expression in neuronal cells and whether exogeneous MANF can alleviate alcohol neurotoxicity. We showed that alcohol increased MANF transcription and secretion without affecting MANF mRNA stability and protein degradation. ER stress was necessary for alcohol-induced MANF upregulation, as pharmacological inhibition of ER stress by 4-PBA diminished alcohol-induced MANF expression. In addition, the presence of ER stress response element II (ERSE-II) was required for alcohol-stimulated MANF transcription. Mutations or deletion of this sequence abolished alcohol-regulated transcriptional activity. We generated MANF knockout (KO) neuronal cells using CRISPR/Cas9. MANF KO cells exhibited increased unfolded protein response (UPR) and were more susceptible to alcohol-induced cell death. On the other hand, MANF upregulation by the addition of recombinant MANF protein or adenovirus gene transduction protected neuronal cells against alcohol-induced cell death. Further studies using early postnatal mouse pups demonstrated that enhanced MANF expression in the brain by intracerebroventricular (ICV) injection of MANF adeno-associated viruses ameliorated alcohol-induced cell death. Thus, alcohol increased MANF expression through inducing ER stress, which could be a protective response. Exogenous MANF was able to protect against alcohol-induced neurodegeneration.

Ketogenic diets initiated in late mid-life improved measures of spatial memory in male mice

Studies have shown ketogenic diets (KD) started from early middle-age improved health span and longevity in mice. KDs started later in life or administered intermittently may be more feasible and promote compliance. Therefore, this study sought to test if continuous or intermittent KDs started in late-middle-aged mice would improve cognition and motor function at advanced age. Eighteen-month-old male C57BL/6JN mice were assigned to an isocaloric control (CD), KD, or intermittent ketogenic (IKD, 3-day KD/week) diet. A panel of behavior tests were performed to assess cognitive and motor functions with aging. Y-maze alternation rate was higher for both IKD and KD mice at 23 months of age and for KD mice at 26 months indicating an improved spatial working memory. Twenty-six-month-old KD mice also showed better spatial learning memory in Barnes maze when compared to the CD. Improved grid wire hang performance was observed in aged IKD and KD versus CD mice indicating better muscle endurance under isometric contraction. A reduced level of circulating proinflammatory cytokines in aged KD (IL-6 and TNF-α) and IKD (IL-6) mice may contribute to the phenotypic improvements observed with these interventions. This study demonstrates that when initiated at late-middle age, the KD improved measures of spatial memory and grid wire hang performance in aged male mice, with IKD showing results intermediate to the CD and KD groups.

Deciphering Nucleic Acid Binding Proteome of Mouse Immune Organs Reveals Hub Proteins for Aging

Profiling the nucleic acid-binding proteins (NABPs) during aging process is critical to elucidate its roles in biological systems as well as transcriptional and translational regulation. Here, we developed a comprehensive strategy to survey the NABPs of mouse immune organs by using single cell preparation and selective capture technology-based proteomics. Our approach provided a global view of tissue NABPs from different organs under normal physiological conditions with extraction specificity of 70 to 90%. Through quantitative proteomics analysis of mouse spleen and thymus at 1, 4, 12, 24, 48, and 72 weeks, we investigated the molecular features of aging-related NABPs. A total of 2674 proteins were quantified in all six stages, demonstrating distinct and time-specific expression pattern of NABPs. Thymus and spleen exhibited unique aging signatures, and differential proteins and pathways were enriched across the mouse lifespan. Three core modules and 16 hub proteins associated with aging were revealed through weighted gene correlation network analysis. Significant candidates were screened for immunoassay verification, and six hub proteins were confirmed. The integrated strategy pertains the capability to decipher the dynamic functions of NABPs in aging physiology and benefit further mechanism research.

CDNF and MANF in the brain dopamine system and their potential as treatment for Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by gradual loss of midbrain dopamine neurons, leading to impaired motor function. Preclinical studies have indicated cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) to be potential therapeutic molecules for the treatment of PD. CDNF was proven to be safe and well tolerated when tested in Phase I-II clinical trials in PD patients. Neuroprotective and neurorestorative effects of CDNF and MANF were demonstrated in animal models of PD, where they promoted the survival of dopamine neurons and improved motor function. However, biological roles of endogenous CDNF and MANF proteins in the midbrain dopamine system have been less clear. In addition to extracellular trophic activities, CDNF/MANF proteins function intracellularly in the endoplasmic reticulum (ER), where they modulate protein homeostasis and protect cells against ER stress by regulating the unfolded protein response (UPR). Here, our aim is to give an overview of the biology of endogenous CDNF and MANF in the brain dopamine system. We will discuss recent studies on CDNF and MANF knockout animal models, and effects of CDNF and MANF in preclinical models of PD. To elucidate possible roles of CDNF and MANF in human biology, we will review CDNF and MANF tissue expression patterns and regulation of CDNF/MANF levels in human diseases. Finally, we will discuss novel findings related to the molecular mechanism of CDNF and MANF action in ER stress, UPR, and inflammation, all of which are mechanisms potentially involved in the pathophysiology of PD.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Programmed ageing: decline of stem cell renewal, immunosenescence, and Alzheimer's disease

The characteristic maximum lifespan varies enormously across animal species from a few hours to hundreds of years. This argues that maximum lifespan, and the ageing process that itself dictates lifespan, are to a large extent genetically determined. Although controversial, this is supported by firm evidence that semelparous species display evolutionarily programmed ageing in response to reproductive and environmental cues. Parabiosis experiments reveal that ageing is orchestrated systemically through the circulation, accompanied by programmed changes in hormone levels across a lifetime. This implies that, like the circadian and circannual clocks, there is a master 'clock of age' (circavital clock) located in the limbic brain of mammals that modulates systemic changes in growth factor and hormone secretion over the lifespan, as well as systemic alterations in gene expression as revealed by genomic methylation analysis. Studies on accelerated ageing in mice, as well as human longevity genes, converge on evolutionarily conserved fibroblast growth factors (FGFs) and their receptors, including KLOTHO, as well as insulin-like growth factors (IGFs) and steroid hormones, as key players mediating the systemic effects of ageing. Age-related changes in these and multiple other factors are inferred to cause a progressive decline in tissue maintenance through failure of stem cell replenishment. This most severely affects the immune system, which requires constant renewal from bone marrow stem cells. Age-related immune decline increases risk of infection whereas lifespan can be extended in germfree animals. This and other evidence suggests that infection is the major cause of death in higher organisms. Immune decline is also associated with age-related diseases. Taking the example of Alzheimer's disease (AD), we assess the evidence that AD is caused by immunosenescence and infection. The signature protein of AD brain, Aβ, is now known to be an antimicrobial peptide, and Aβ deposits in AD brain may be a response to infection rather than a cause of disease. Because some cognitively normal elderly individuals show extensive neuropathology, we argue that the location of the pathology is crucial - specifically, lesions to limbic brain are likely to accentuate immunosenescence, and could thus underlie a vicious cycle of accelerated immune decline and microbial proliferation that culminates in AD. This general model may extend to other age-related diseases, and we propose a general paradigm of organismal senescence in which declining stem cell proliferation leads to programmed immunosenescence and mortality.

Mesencephalic Astrocyte-Derived Neurotrophic Factor (MANF): An Emerging Therapeutic Target for Neurodegenerative Disorders

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a member of the new family of neurotrophic factors (NTFs) with a unique structure and functions compared to other conventionally known NTFs. MANF is broadly expressed in developing and mature tissues, including the central nervous system and peripheral nervous system tissues. Growing research demonstrated that MANF protects neurons from endoplasmic reticulum (ER) stress-associated complications by restoring ER homeostasis and regulating unfolded protein response. This review discusses MANF signaling in neurodegenerative conditions with specific emphasis given to its overall effect and mechanisms of action in experimental models of Parkinson’s disease, Alzheimer’s disease, and stroke. Additional perspectives on its potential unexplored roles in other neurodegenerative conditions are also given.

Aging disrupts MANF-mediated immune modulation during skeletal muscle regeneration

Age-related decline in skeletal muscle regenerative capacity is multifactorial, yet the contribution of immune dysfunction to regenerative failure is unknown. Macrophages are essential for effective debris clearance and muscle stem cell activity during muscle regeneration, but the regulatory mechanisms governing macrophage function during muscle repair are largely unexplored. Here, we uncover a new mechanism of immune modulation operating during skeletal muscle regeneration that is disrupted in aged animals and relies on the regulation of macrophage function. The immune modulator mesencephalic astrocyte-derived neurotrophic factor (MANF) is induced following muscle injury in young mice but not in aged animals, and its expression is essential for regenerative success. Regenerative impairments in aged muscle are associated with defects in the repair-associated myeloid response similar to those found in MANF-deficient models and could be improved through MANF delivery. We propose that restoring MANF levels is a viable strategy to improve myeloid response and regenerative capacity in aged muscle.

Turning Back the Clock: A Retrospective Single-Blind Study on Brain Age Change in Response to Nutraceuticals Supplementation vs. Lifestyle Modifications

BACKGROUND

There is a growing consensus that chronological age (CA) is not an accurate indicator of the aging process and that biological age (BA) instead is a better measure of an individual's risk of age-related outcomes and a more accurate predictor of mortality than actual CA. In this context, BA measures the "true" age, which is an integrated result of an individual's level of damage accumulation across all levels of biological organization, along with preserved resources. The BA is plastic and depends upon epigenetics. Brain state is an important factor contributing to health- and lifespan.

METHODS AND OBJECTIVE

Quantitative electroencephalography (qEEG)-derived brain BA (BBA) is a suitable and promising measure of brain aging. In the present study, we aimed to show that BBA can be decelerated or even reversed in humans (N = 89) by using customized programs of nutraceutical compounds or lifestyle changes (mean duration = 13 months).

RESULTS

We observed that BBA was younger than CA in both groups at the end of the intervention. Furthermore, the BBA of the participants in the nutraceuticals group was 2.83 years younger at the endpoint of the intervention compared with their BBA score at the beginning of the intervention, while the BBA of the participants in the lifestyle group was only 0.02 years younger at the end of the intervention. These results were accompanied by improvements in mental-physical health comorbidities in both groups. The pre-intervention BBA score and the sex of the participants were considered confounding factors and analyzed separately.

CONCLUSIONS

Overall, the obtained results support the feasibility of the goal of this study and also provide the first robust evidence that halting and reversal of brain aging are possible in humans within a reasonable (practical) timeframe of approximately one year.

Heterochronic parabiosis reprograms the mouse brain transcriptome by shifting aging signatures in multiple cell types

Aging is a complex process involving transcriptomic changes associated with deterioration across multiple tissues and organs, including the brain. Recent studies using heterochronic parabiosis have shown that various aspects of aging-associated decline are modifiable or even reversible. To better understand how this occurs, we performed single-cell transcriptomic profiling of young and old mouse brains after parabiosis. For each cell type, we cataloged alterations in gene expression, molecular pathways, transcriptional networks, ligand-receptor interactions and senescence status. Our analyses identified gene signatures, demonstrating that heterochronic parabiosis regulates several hallmarks of aging in a cell-type-specific manner. Brain endothelial cells were found to be especially malleable to this intervention, exhibiting dynamic transcriptional changes that affect vascular structure and function. These findings suggest new strategies for slowing deterioration and driving regeneration in the aging brain through approaches that do not rely on disease-specific mechanisms or actions of individual circulating factors.

MANF regulates neuronal survival and UPR through its ER-located receptor IRE1α

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER)-located protein with cytoprotective effects in neurons and pancreatic β cells in vitro and in models of neurodegeneration and diabetes in vivo. However, the exact mode of MANF action has remained elusive. Here, we show that MANF directly interacts with the ER transmembrane unfolded protein response (UPR) sensor IRE1α, and we identify the binding interface between MANF and IRE1α. The expression of wild-type MANF, but not its IRE1α binding-deficient mutant, attenuates UPR signaling by decreasing IRE1α oligomerization; phosphorylation; splicing of Xbp1, Atf6, and Txnip levels; and protecting neurons from ER stress-induced death. MANF-IRE1α interaction and not MANF-BiP interaction is crucial for MANF pro-survival activity in neurons in vitro and is required to protect dopamine neurons in an animal model of Parkinson's disease. Our data show IRE1α as an intracellular receptor for MANF and regulator of neuronal survival.

MANF stimulates autophagy and restores mitochondrial homeostasis to treat toxic proteinopathy

Misfolded protein aggregates may cause toxic proteinopathy, including autosomal dominant tubulointerstitial kidney disease due to uromodulin mutations (ADTKD- UMOD ), one of the leading hereditary kidney diseases, and Alzheimer’s disease etc. There are no targeted therapies. ADTKD is also a genetic form of renal fibrosis and chronic kidney disease, which affects 500 million people worldwide. For the first time, in our newly generated mouse model recapitulating human ADTKD- UMOD carrying a leading UMOD deletion mutation, we show that autophagy/mitophagy and mitochondrial biogenesis are severely impaired, leading to cGAS- STING activation and tubular injury. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a novel endoplasmic reticulum stress-regulated secreted protein. We provide the first study that inducible tubular overexpression of MANF after the onset of disease stimulates autophagy/mitophagy and clearance of the misfolded UMOD, and promotes mitochondrial biogenesis through p-AMPK enhancement, resulting in protection of kidney function. Conversely, genetic ablation of endogenous MANF upregulated in the mutant mouse and human tubular cells worsens autophagy suppression and kidney fibrosis. Together, we discover MANF as a novel biotherapeutic protein and elucidate previously unknown mechanisms of MANF in regulating organelle homeostasis to treat ADTKD, which may have broad therapeutic application to treat various proteinopathies.

MANF ameliorates DSS-induced mouse colitis via restricting Ly6ChiCX3CR1int macrophage transformation and suppressing CHOP-BATF2 signaling pathway

Mesencephalic astrocyte-derived neurotrophic factor (MANF), an endoplasmic reticulum stress-inducible secreting protein, has evolutionarily conserved immune-regulatory function that contributes to the negative regulation of inflammation in macrophages. In this study, we investigated the profiles of MANF in the macrophages of the patients with active inflammatory bowel disease (IBD) and the mice with experimental colitis, which was induced in both myeloid cell-specific MANF knockout mice and wild-type mice by 3% dextran sodium sulfate (DSS) for 7 days. We found that MANF expression was significantly increased in intestinal macrophages from both the mice with experimental colitis and patients with active IBD. DSS-induced colitis was exacerbated in myeloid cell-specific MANF knockout mice. Injection of recombinant human MANF (rhMANF, 10 mg·kg^-1·d^-1, i.v.) from D4 to D6 significantly ameliorated experimental colitis in DSS-treated mice. More importantly, MANF deficiency in myeloid cells resulted in a dramatic increase in the number of Ly6C^hiCX3CR^int proinflammatory macrophages in colon lamina propria of DSS-treated mice, and the proinflammatory cytokines and chemokines were upregulated as well. Meanwhile, we demonstrated that MANF attenuated Th17-mediated immunopathology by inhibiting BATF2-mediated innate immune response and downregulating CXCL9, CXCL10, CXCL11 and IL-12p40; MANF functioned as a negative regulator in inflammatory macrophages via inhibiting CHOP-BATF2 signaling pathway, thereby protecting against DSS-induced mouse colitis. These results suggest that MANF ameliorates colon injury by negatively regulating inflammatory macrophage transformation, which shed light on a potential therapeutic target for IBD.

The Role of the Mesencephalic Astrocyte-Derived Neurotrophic Factor in Patients in Intensive Care Units Receiving Voriconazole Therapy

Recent publications regarding the role of mesencephalic astrocyte-derived neurotrophic factor (MANF) in various metabolic and degenerative disorders suggest that MANF is both a marker of disease and a possible therapeutic agent. We investigate the role of plasma MANF levels in patients in intensive care units (ICUs) receiving voriconazole (VCZ) therapy while also comparing MANF levels in healthy individuals. A single-center prospective study was conducted. The plasma MANF level in patients in ICU was found to have high interindividual variability and was significantly higher than that in healthy controls (P < .01). Compared with patients using VCZ only, patients using both VCZ and amikacin had 3-fold lower MANF concentrations (P < .05). The MANF concentrations also decreased when alkaline phosphatase (ALP) and serum creatinine levels were above the upper limits of the normal range (P < .05) and the estimated glomerular filtration rate (eGFR) was below the lower limit of the normal range (P < .01). Receiver operating characteristic curve analysis indicated that low MANF levels were associated with high ALP levels, high creatinine levels, and low eGFR. The cut-off value of MANF for ALP levels higher than 126 U/L was 0.35 ng/mL (area under curve, AUC = 0.62, 95%CI = 0.50-0.74, P = .044); for serum creatinine levels higher than 104 μmol/L, the cut-off value was 0.41 ng/mL (AUC = 0.74, 95%CI = 0.62-0.87, P = .001); and for eGFR below 80 mL/min, the cut-off value was 0.75 ng/mL (AUC = 0.70, 95%CI = 0.59-0.81, P = .002). Monitoring plasma MANF levels may be of value for clinical decision-making regarding the choice of antibiotics and the prediction of impaired liver function and renal function in patients admitted to an ICU.

Hepatocyte-derived MANF mitigates ethanol-induced liver steatosis in mice via enhancing ASS1 activity and activating AMPK pathway

Hepatic steatosis plays a detrimental role in the onset and progression of alcohol-associated liver disease (ALD). Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an evolutionarily conserved protein related to the unfolded protein response. Recent studies have demonstrated that MANF plays an important role in liver diseases. In this study, we investigated the role of MANF in ethanol-induced steatosis and the underlying mechanisms. We showed that the hepatic MANF expression was markedly upregulated in mouse model of ALD by chronic-plus-single-binge ethanol feeding. Moreover, after chronic-plus-binge ethanol feeding, hepatocyte-specific MANF knockout (HKO) mice displayed more severe hepatic steatosis and liver injury than wild-type (WT) control mice. Immunoprecipitation-coupled MS proteomic analysis revealed that arginosuccinate synthase 1 (ASS1), a rate-limiting enzyme in the urea cycle, resided in the same immunoprecipitated complex with MANF. Hepatocyte-specific MANF knockout led to decreased ASS1 activity, whereas overexpression of MANF contributed to enhanced ASS1 activity in vitro. In addition, HKO mice displayed unique urea cycle metabolite patterns in the liver with elevated ammonia accumulation after ethanol feeding. ASS1 is known to activate AMPK by generating an intracellular pool of AMP from the urea cycle. We also found that MANF supplementation significantly ameliorated ethanol-induced steatosis in vivo and in vitro by activating the AMPK signaling pathway, which was partly ASS1 dependent. This study demonstrates a new mechanism in which MANF acts as a key molecule in maintaining hepatic lipid homeostasis by enhancing ASS1 activity and uncovers an interesting link between lipid metabolism and the hepatic urea cycle under excessive alcohol exposure.

Cell-type-specific aging clocks to quantify aging and rejuvenation in neurogenic regions of the brain

The diversity of cell types is a challenge for quantifying aging and its reversal. Here we develop 'aging clocks' based on single-cell transcriptomics to characterize cell-type-specific aging and rejuvenation. We generated single-cell transcriptomes from the subventricular zone neurogenic region of 28 mice, tiling ages from young to old. We trained single-cell-based regression models to predict chronological age and biological age (neural stem cell proliferation capacity). These aging clocks are generalizable to independent cohorts of mice, other regions of the brains, and other species. To determine if these aging clocks could quantify transcriptomic rejuvenation, we generated single-cell transcriptomic datasets of neurogenic regions for two interventions-heterochronic parabiosis and exercise. Aging clocks revealed that heterochronic parabiosis and exercise reverse transcriptomic aging in neurogenic regions, but in different ways. This study represents the first development of high-resolution aging clocks from single-cell transcriptomic data and demonstrates their application to quantify transcriptomic rejuvenation.

Feeding-induced hepatokines and crosstalk with multi-organ: A novel therapeutic target for Type 2 diabetes

Hyperglycemia, which can be caused by either an insulin deficit and/or insulin resistance, is the main symptom of Type 2 diabetes, a significant endocrine metabolic illness. Conventional medications, including insulin and oral antidiabetic medicines, can alleviate the signs of diabetes but cannot restore insulin release in a physiologically normal amount. The liver detects and reacts to shifts in the nutritional condition that occur under a wide variety of metabolic situations, making it an essential organ for maintaining energy homeostasis. It also performs a crucial function in glucolipid metabolism through the secretion of hepatokines. Emerging research shows that feeding induces hepatokines release, which regulates glucose and lipid metabolism. Notably, these feeding-induced hepatokines act on multiple organs to regulate glucolipotoxicity and thus influence the development of T2DM. In this review, we focus on describing how feeding-induced cross-talk between hepatokines, including Adropin, Manf, Leap2 and Pcsk9, and metabolic organs (e.g.brain, heart, pancreas, and adipose tissue) affects metabolic disorders, thus revealing a novel approach for both controlling and managing of Type 2 diabetes as a promising medication.

Emerging trophic activities of mesencephalic astrocyte-derived neurotrophic factor in tissue repair and regeneration

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a soluble endoplasmic reticulum (ER) luminal protein and its expression and secretion can be induced by ER stress. Despite initially being classified as a neurotrophic factor, MANF has been demonstrated to have restorative and protective effects in many different cell types such as neurons, liver cells, retinal cells, cardiac myocytes, and pancreatic β cells. However, underlying molecular mechanisms are complex and remain incompletely understood. The aims of this review are to highlight the latest advances in the understanding of the trophic activities of MANF in tissue repair and regeneration as well as underlying molecular mechanisms. The structural motifs and immune modulation of MANF are also described. We therefore propose that MANF might be a promising therapeutic target for tissue repair.

Mesencephalic astrocyte-derived neurotrophic factor (MANF): Structure, functions and therapeutic potential

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a novel evolutionarily conserved protein present in both vertebrate and invertebrate species. MANF shows distinct structural and functional properties than the traditional neurotrophic factors (NTF). MANF is composed of an N-terminal saposin-like lipid-binding domain and a C-terminal SAF-A/B, Acinus and PIAS (SAP) domain connected by a short linker. The two well-described activities of MANF include (1) role as a neurotrophic factor that plays direct neuroprotective effects in the nervous system and (2) cell protective effects in the animal models of non-neuronal diseases, including retinal damage, diabetes mellitus, liver injury, myocardial infarction, nephrotic syndrome, etc. The main objective of the current review is to provide up-to-date insights regarding the structure of MANF, mechanisms regulating its expression and secretion, physiological functions in various tissues and organs, protective effects during aging, and potential clinical applications. Together, this review highlights the importance of MANF in reversing age-related dysfunction and geroprotection.

MANF in POMC Neurons Promotes Brown Adipose Tissue Thermogenesis and Protects Against Diet-Induced Obesity

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an emerging regulator in metabolic control. Hypothalamic proopiomelanocortin (POMC) neurons play critical roles in maintaining whole-body energy homeostasis. Whether MANF in POMC neurons is required for the proper regulation of energy balance remains unknown. Here, we showed that mice lacking MANF in POMC neurons were more prone to develop diet-induced obesity. In addition, the ablation of MANF induced endoplasmic reticulum (ER) stress and leptin resistance in the hypothalamus, reduced POMC expression and posttranslational processing, and ultimately decreased sympathetic nerve activity and thermogenesis in brown adipose tissue (BAT). Conversely, MANF overexpression in hypothalamic POMC neurons attenuated ER stress, increased POMC expression and processing, and then stimulated sympathetic innervation and activity in BAT, resulting in increased BAT thermogenesis, thus protecting mice against dietary obesity. Overall, our findings provide evidence that MANF is required for POMC neurons to combat obesity.

Small extracellular vesicles from young adipose-derived stem cells prevent frailty, improve health span, and decrease epigenetic age in old mice

Aging is associated with an increased risk of frailty, disability, and mortality. Strategies to delay the degenerative changes associated with aging and frailty are particularly interesting. We treated old animals with small extracellular vesicles (sEVs) derived from adipose mesenchymal stem cells (ADSCs) of young animals, and we found an improvement in several parameters usually altered with aging, such as motor coordination, grip strength, fatigue resistance, fur regeneration, and renal function, as well as an important decrease in frailty. ADSC-sEVs induced proregenerative effects and a decrease in oxidative stress, inflammation, and senescence markers in muscle and kidney. Moreover, predicted epigenetic age was lower in tissues of old mice treated with ADSC-sEVs and their metabolome changed to a youth-like pattern. Last, we gained some insight into the microRNAs contained in sEVs that might be responsible for the observed effects. We propose that young sEV treatment can promote healthy aging.

Increased serum concentrations of Mesencephalic astrocyte-derived neurotrophic factor in patients and rats with ischemic stroke

OBJECTIVES

Although Mesencephalic astrocyte-derived neurotrophic factor (MANF) shows protection in multiple cells, the role of circulating MANF in patients with acute ischemic stroke (AIS) and transient ischemic attack (TIA) remains unclear. Here, we aimed to explore the value of circulating MANF levels in cerebral ischemic events.

MATERIALS AND METHODS

Using a rat cerebral ischemic model, MANF expression in ischemic brains and serum was detected. 50 AIS patients, 56 TIA patients and 48 controls were enrolled, and MANF mRNA, inflammatory cytokines and MANF concentrations in serum and different blood cell types were detected. The National Institutes of Health Stroke Scale (NIHSS) score and Alberta Stroke Program Early CT Score (ASPECTS) were used to evaluate stroke severity. Cerebrovascular recurrence within 90 d was documented during TIA follow-up.

RESULTS

MANF expression increased at 2h, peaking at 24h and decreased to baseline at 7d in rat ischemic brains and serum. Serum MANF concentrations increased at 24h and 7d in AIS patients compared to controls and were correlated with NIHSS score, ASPECTS and inflammatory cytokines. MANF protein was present in blood cells, while MANF mRNA levels did not differ between AIS patients and controls. MANF levels revealed a good value to diagnose TIA with area under the curve (AUC) of 0.949 (95% CI: 0.9093-0.9892). MANF levels were lower in TIA patients with recurrence compared to non-recurrence patients. The AUC for MANF to predict a re-event was 0.80 (95% CI: 0.6746-0.9282).

CONCLUSIONS

Serum MANF levels correlate with neuroprotection, stroke severity, inflammation, and TIA recurrence.

Systemic induction of senescence in young mice after single heterochronic blood exchange

ABSTACT

Ageing is the largest risk factor for many chronic diseases. Studies of heterochronic parabiosis, substantiated by blood exchange and old plasma dilution, show that old-age-related factors are systemically propagated and have pro-geronic effects in young mice. However, the underlying mechanisms how bloodborne factors promote ageing remain largely unknown. Here, using heterochronic blood exchange in male mice, we show that aged mouse blood induces cell and tissue senescence in young animals after one single exchange. This induction of senescence is abrogated if old animals are treated with senolytic drugs before blood exchange, therefore attenuating the pro-geronic influence of old blood on young mice. Hence, cellular senescence is neither simply a response to stress and damage that increases with age, nor a chronological cell-intrinsic phenomenon. Instead, senescence quickly and robustly spreads to young mice from old blood. Clearing senescence cells that accumulate with age rejuvenates old circulating blood and improves the health of multiple tissues.

UPR Responsive Genes Manf and Xbp1 in Stroke

Stroke is a devastating medical condition with no treatment to hasten recovery. Its abrupt nature results in cataclysmic changes in the affected tissues. Resident cells fail to cope with the cellular stress resulting in massive cell death, which cannot be endogenously repaired. A potential strategy to improve stroke outcomes is to boost endogenous pro-survival pathways. The unfolded protein response (UPR), an evolutionarily conserved stress response, provides a promising opportunity to ameliorate the survival of stressed cells. Recent studies from us and others have pointed toward mesencephalic astrocyte-derived neurotrophic factor (MANF) being a UPR responsive gene with an active role in maintaining proteostasis. Its pro-survival effects have been demonstrated in several disease models such as diabetes, neurodegeneration, and stroke. MANF has an ER-signal peptide and an ER-retention signal; it is secreted by ER calcium depletion and exits cells upon cell death. Although its functions remain elusive, conducted experiments suggest that the endogenous MANF in the ER lumen and exogenously administered MANF protein have different mechanisms of action. Here, we will revisit recent and older bodies of literature aiming to delineate the expression profile of MANF. We will focus on its neuroprotective roles in regulating neurogenesis and inflammation upon post-stroke administration. At the same time, we will investigate commonalities and differences with another UPR responsive gene, X-box binding protein 1 (XBP1), which has recently been associated with MANF’s function. This will be the first systematic comparison of these two UPR responsive genes aiming at revealing previously uncovered associations between them. Overall, understanding the mode of action of these UPR responsive genes could provide novel approaches to promote cell survival.

Identification of ER/SR resident proteins as biomarkers for ER/SR calcium depletion in skeletal muscle cells

BACKGROUND

Aberrations to endoplasmic/sarcoplasmic reticulum (ER/SR) calcium concentration can result in the departure of endogenous proteins in a phenomenon termed exodosis. Redistribution of the ER/SR proteome can have deleterious effects to cell function and cell viability, often contributing to disease pathogenesis. Many proteins prone to exodosis reside in the ER/SR via an ER retention/retrieval sequence (ERS) and are involved in protein folding, protein modification, and protein trafficking. While the consequences of their extracellular presence have yet to be fully delineated, the proteins that have undergone exodosis may be useful for biomarker development. Skeletal muscle cells rely upon tightly coordinated ER/SR calcium release for muscle contractions, and perturbations to calcium homeostasis can result in myopathies. Ryanodine receptor type-1 (RYR1) is a calcium release channel located in the SR. Mutations to the RYR1 gene can compromise calcium homeostasis leading to a vast range of clinical phenotypes encompassing hypotonia, myalgia, respiratory insufficiency, ophthalmoplegia, fatigue and malignant hyperthermia (MH). There are currently no FDA approved treatments for RYR1-related myopathies (RYR1-RM).

RESULTS

Here we examine the exodosis profile of skeletal muscle cells following ER/SR calcium depletion. Proteomic analysis identified 4,465 extracellular proteins following ER/SR calcium depletion with 1,280 proteins significantly different than vehicle. A total of 54 ERS proteins were identified and 33 ERS proteins significantly increased following ER/SR calcium depletion. Specifically, ERS protein, mesencephalic astrocyte-derived neurotrophic factor (MANF), was elevated following calcium depletion, making it a potential biomarker candidate for human samples. Despite no significant elevation of MANF in plasma levels among healthy volunteers and RYR1-RM individuals, MANF plasma levels positively correlated with age in RYR1-RM individuals, presenting a potential biomarker of disease progression. Selenoprotein N (SEPN1) was also detected only in extracellular samples following ER/SR calcium depletion. This protein is integral to calcium handling and SEPN1 variants have a causal role in SEPN1-related myopathies (SEPN1-RM). Extracellular presence of ER/SR membrane proteins may provide new insight into proteomic alterations extending beyond ERS proteins. Pre-treatment of skeletal muscle cells with bromocriptine, an FDA approved drug recently found to have anti-exodosis effects, curbed exodosis of ER/SR resident proteins.

CONCLUSION

Changes to the extracellular content caused by intracellular calcium dysregulation presents an opportunity for biomarker development and drug discovery.

Mesencephalic astrocyte-derived neurotrophic factor alleviates non-alcoholic steatohepatitis induced by Western diet in mice

Excessive lipid accumulation, inflammation, and fibrosis in the liver are the major characteristics of non-alcoholic steatohepatitis (NASH). Mesencephalic astrocyte-derived neurotrophic factor (MANF) plays an important role in metabolic homeostasis, raising the possibility that it is involved in NASH. Here, we reduced and increased MANF levels in mice in order to explore its influence on hepatic triglyceride homeostasis, inflammation, and fibrosis during NASH progression. The MANF expression was decreased in Western diet-induced NASH mice. In vivo, liver-specific MANF knockout exacerbated hepatic lipid accumulation, inflammation, and fibrosis of mice induced by Western diet, while liver-specific MANF overexpression mitigated these NASH pathogenic features. In vitro, knocking down MANF in primary hepatocyte cultures aggravated hepatic steatosis and inflammation, which MANF overexpression markedly attenuated. Studies in vitro and in vivo suggested that MANF regulated hepatic lipid synthesis by modulating SREBP1 expression. Inhibiting SREBP1 in primary hepatocytes blocked lipid accumulation after MANF knockdown. MANF overexpression reversed LXRs agonist GW3965 induced SREBP1 and LIPIN1 expression. MANF decreased the expression of pro-inflammatory cytokines by inhibiting NF-κB phosphorylation. These results suggest that MANF can protect against NASH by regulating SREBP1 expression and NF-κB signaling.

MANF: an emerging therapeutic target for metabolic diseases

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum-resident protein and a secretory factor and has beneficial effects in multiple diseases. Recent evidence shows that its circulating levels in humans are dynamically regulated under various metabolic diseases, including diabetes, obesity, fatty liver, and cardiovascular diseases, suggesting that MANF may play a role in these pathological states. Also, its downregulation in mice impairs glucose homeostasis, promotes lipid accumulation in the liver, reduces energy expenditure, and induces inflammation. Conversely, MANF overexpression prevents or mitigates some of these metabolic disturbances. In particular, systemic MANF administration alleviates dietary obesity and related metabolic disorders in obese mice. We therefore propose that MANF might be a promising target for treating chronic metabolic diseases.

Old blood from heterochronic parabionts accelerates vascular aging in young mice: transcriptomic signature of pathologic smooth muscle remodeling

Vascular aging has a central role in the pathogenesis of cardiovascular diseases contributing to increased mortality of older adults. There is increasing evidence that, in addition to the documented role of cell-autonomous mechanisms of aging, cell-nonautonomous mechanisms also play a critical role in the regulation of vascular aging processes. Our recent transcriptomic studies (Kiss T. et al. Geroscience. 2020;42(2):727-748) demonstrated that circulating anti-geronic factors from young blood promote vascular rejuvenation in aged mice. The present study was designed to expand upon the results of this study by testing the hypothesis that circulating pro-geronic factors also contribute to the genesis of vascular aging phenotypes. To test this hypothesis, through heterochronic parabiosis, we determined the extent to which shifts in the vascular transcriptome (RNA-seq) are modulated by the old systemic environment. We reanalyzed existing RNA-seq data, comparing the transcriptome in the aorta arch samples isolated from isochronic parabiont aged (20-month-old) C57BL/6 mice [A-(A); parabiosis for 8 weeks] and young isochronic parabiont (6-month-old) mice [Y-(Y)] and also assessing transcriptomic changes in the aortic arch in young (6-month-old) parabiont mice [Y-(A); heterochronic parabiosis for 8 weeks] induced by the presence of old blood derived from aged (20-month-old) parabionts. We identified 528 concordant genes whose expression levels differed in the aged phenotype and were shifted towards the aged phenotype by the presence of old blood in young Y-(A) animals. Among them, the expression of 221 concordant genes was unaffected by the presence of young blood in A-(Y) mice. GO enrichment analysis suggests that old blood-regulated genes may contribute to pathologic vascular remodeling. IPA Upstream Regulator analysis (performed to identify upstream transcriptional regulators that may contribute to the observed transcriptomic changes) suggests that the mechanism of action of pro-geronic factors present in old blood may include inhibition of pathways mediated by SRF (serum response factor), insulin-like growth factor-1 (IGF-1) and VEGF-A. In conclusion, relatively short-term exposure to old blood can accelerate vascular aging processes. Our findings provide additional evidence supporting the significant plasticity of vascular aging and the existence of circulating pro-geronic factors mediating pathological remodeling of the vascular smooth muscle cells and the extracellular matrix.

Restoring the oxidative balance in age-related diseases - An approach in glaucoma

As human life expectancy increases, age-related health issues including neurodegenerative diseases continue to rise. Regardless of genetic or environmental factors, many neurodegenerative conditions share common pathological mechanisms, such as oxidative stress, a hallmark of many age-related health burdens. In this review, we describe oxidative damage and mitochondrial dysfunction in glaucoma, an age-related neurodegenerative eye disease affecting 80 million people worldwide. We consider therapeutic approaches used to counteract oxidative stress in glaucoma, including untapped treatment options such as novel plant-derived antioxidant compounds that can reduce oxidative stress and prevent neuronal loss. We summarize the current pre-clinical models and clinical work exploring the therapeutic potential of a range of candidate plant-derived antioxidant compounds. Finally, we explore advances in drug delivery systems, particular those employing nanotechnology-based carriers which hold significant promise as a carrier for antioxidants to treat age-related disease, thus reviewing the key current state of all of the aspects required towards translation.

Shrimp Plasma MANF Works as an Invertebrate Anti-Inflammatory Factor via a Conserved Receptor Tyrosine Phosphatase

For a long time, how anti-inflammatory factors evolved was largely unknown. In this study, we chose a marine invertebrate, Litopenaeus vannamei, as a model and identified that shrimp mesencephalic astrocyte-derived neurotrophic factor (MANF) was an LPS-induced plasma protein, which exerted its anti-inflammatory roles on shrimp hemocytes by suppressing ERK phosphorylation and Dorsal expression. In addition, we demonstrated that shrimp MANF could be associated with a receptor protein tyrosine phosphatase (RPTP) to mediate negative regulation of ERK activation and Dorsal expression. More interestingly, shrimp RPTP-S overexpression in 293T cells could switch shrimp and human MANF-mediated ERK pathway activation to inhibition. In general, our results indicate that this conserved RPTP is the key component for extracellular MANF-mediated ERK pathway inhibition, which gives a possible explanation about why this neurotropic factor could both protect neuron cells from apoptosis and inhibit immune cell M1 activation in various species.

CDNF and MANF regulate ER stress in a tissue-specific manner

Cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) display cytoprotective effects in animal models of neurodegenerative diseases. These endoplasmic reticulum (ER)-resident proteins belong to the same protein family and function as ER stress regulators. The relationship between CDNF and MANF function, as well as their capability for functional compensation, is unknown. We aimed to investigate these questions by generating mice lacking both CDNF and MANF. Results showed that CDNF-deficient Manf^−/− mice presented the same phenotypes of growth defect and diabetes as Manf^−/− mice. In the muscle, CDNF deficiency resulted in increased activation of unfolded protein response (UPR), which was aggravated when MANF was ablated. In the brain, the combined loss of CDNF and MANF did not exacerbate UPR activation caused by the loss of MANF alone. Consequently, CDNF and MANF deficiency in the brain did not cause degeneration of dopamine neurons. In conclusion, CDNF and MANF present functional redundancy in the muscle, but not in the other tissues examined here. Thus, they regulate the UPR in a tissue-specific manner.