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Current Osteoporosis Reports Aug 2020Skeletal muscle and bone are connected anatomically and physiologically, and play a crucial role in human locomotion and metabolism. Historically, the coupling between... (Review)
Review
PURPOSE OF REVIEW
Skeletal muscle and bone are connected anatomically and physiologically, and play a crucial role in human locomotion and metabolism. Historically, the coupling between muscle and bone has been viewed in light of mechanotransduction, which dictates that the mechanical forces applied to muscle are transmitted to the skeleton to initiate bone formation. However, these organs also communicate through the endocrine system, orchestrated by a family of cytokines namely myokines (derived from myocytes) and osteokines (derived from bone cells). A third player in this biochemical crosstalk is adipose tissue and the secretion of adipokines (derived from adipocytes). In this review, we discuss the bidirectional effects of myokines and osteokines on muscle and bone metabolism, and the impact of adipokines on both of these secretory organs.
RECENT FINDINGS
Several myokines, notably, IL6, irisin, IGF-1, BDNF, myostatin, and FGF2 exert anabolic/catabolic effects on bone, while the osteokines osteocalcin and sclerostin have shown to induce muscle anabolism and catabolism, respectively. Adipokines, such as leptin, resistin, adiponectin, and TNFα (released from adipose tissue), can also modulate muscle and bone metabolism. Contrarily, exercise-mediated release of lipolytic myokines (IL6, irisin, and LIF) stimulates thermogenesis by promoting the browning of adipocytes. Myokines, osteokines, and adipokines exert autocrine/paracrine effects locally as well as through the endocrine system, to regulate muscle, bone, and fat metabolism. Reductions in physical activity and increases in energy intake, both linked with aging, leads to adipocyte hypertrophy and the recruitment of immunological cells (macrophages). In turn, this releases pro-inflammatory adipokines which induces chronic low-grade inflammation (LGI), a key player in the pathology of several diseases. However, exercise-induced stimulation of bioactive cytokines, through muscle-bone-fat crosstalk, increases muscle anabolism, bone formation, mitochondrial biogenesis, glucose utilization, and fatty acid oxidation, and attenuates chronic LGI.
Topics: Adaptor Proteins, Signal Transducing; Adipokines; Adipose Tissue; Autocrine Communication; Bone and Bones; Brain-Derived Neurotrophic Factor; Energy Intake; Exercise; Fatty Acids; Fibroblast Growth Factor 2; Fibronectins; Glucose; Humans; Inflammation; Insulin-Like Growth Factor I; Interleukin-6; Leukemia Inhibitory Factor; Muscle, Skeletal; Myostatin; Organelle Biogenesis; Osteocalcin; Osteogenesis; Oxidation-Reduction; Paracrine Communication; Tumor Necrosis Factor-alpha
PubMed: 32529456
DOI: 10.1007/s11914-020-00599-y -
Osteoarthritis and Cartilage May 2020OA is now well accepted as a low-grade inflammatory disease affecting the whole joint. In addition to mechanical loading, inflammation (particularly synovitis),... (Review)
Review
OA is now well accepted as a low-grade inflammatory disease affecting the whole joint. In addition to mechanical loading, inflammation (particularly synovitis), contributes significantly to OA. Synovial macrophages act as immune cells and are of critical importance in the symptomology and structural progression of OA. Activated macrophages are regulated by mTOR, NF-κB, JNK, PI3K/Akt and other signaling pathways, and are polarized into either M1 or M2 subtypes in OA synovial tissues, synovial fluid, and peripheral blood. The activation state and the M1/M2 ratio is highly associated with OA severity. Aside from autocrine interactions, paracrine interactions between macrophages and chondrocytes play a vital role in the initiation and development of OA by secreting inflammatory cytokines, growth factors, matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs), which lead to subsequent cartilage degradation and destruction. Treatments targeting synovial macrophages relieve pain, and protect from synovitis, cartilage damage, and osteophyte formation during OA development. Macrophage reprogramming of transformation from the M1 to M2 subtype, more than a decrease in the quantity of activated macrophages, appears to be an effective treatment option for OA. This review provides a broad understanding of the contributions of polarized macrophages to joint health and disease. Multifunctional agents with immunomodulatory effects on macrophage reprogramming can skew the inflammatory microenvironment towards a pro-chondrogenic atmosphere, and are thus, potential therapeutic options for the treatment of OA and other immune diseases.
Topics: Chondrocytes; Disease Progression; Humans; Inflammation; Intercellular Signaling Peptides and Proteins; Macrophage Activation; Macrophages; Matrix Metalloproteinases; Osteoarthritis; Paracrine Communication; Phenotype; Synovial Membrane; Synovitis; Tissue Inhibitor of Metalloproteinases
PubMed: 31982565
DOI: 10.1016/j.joca.2020.01.007 -
Nature Apr 2024The immune system has a critical role in orchestrating tissue healing. As a result, regenerative strategies that control immune components have proved effective. This is...
The immune system has a critical role in orchestrating tissue healing. As a result, regenerative strategies that control immune components have proved effective. This is particularly relevant when immune dysregulation that results from conditions such as diabetes or advanced age impairs tissue healing following injury. Nociceptive sensory neurons have a crucial role as immunoregulators and exert both protective and harmful effects depending on the context. However, how neuro-immune interactions affect tissue repair and regeneration following acute injury is unclear. Here we show that ablation of the Na1.8 nociceptor impairs skin wound repair and muscle regeneration after acute tissue injury. Nociceptor endings grow into injured skin and muscle tissues and signal to immune cells through the neuropeptide calcitonin gene-related peptide (CGRP) during the healing process. CGRP acts via receptor activity-modifying protein 1 (RAMP1) on neutrophils, monocytes and macrophages to inhibit recruitment, accelerate death, enhance efferocytosis and polarize macrophages towards a pro-repair phenotype. The effects of CGRP on neutrophils and macrophages are mediated via thrombospondin-1 release and its subsequent autocrine and/or paracrine effects. In mice without nociceptors and diabetic mice with peripheral neuropathies, delivery of an engineered version of CGRP accelerated wound healing and promoted muscle regeneration. Harnessing neuro-immune interactions has potential to treat non-healing tissues in which dysregulated neuro-immune interactions impair tissue healing.
Topics: Animals; Mice; Autocrine Communication; Calcitonin Gene-Related Peptide; Diabetes Mellitus, Experimental; Efferocytosis; Macrophages; Monocytes; Muscle, Skeletal; NAV1.8 Voltage-Gated Sodium Channel; Neutrophils; Nociceptors; Paracrine Communication; Peripheral Nervous System Diseases; Receptor Activity-Modifying Protein 1; Regeneration; Skin; Thrombospondin 1; Wound Healing; Humans; Male; Female
PubMed: 38538784
DOI: 10.1038/s41586-024-07237-y -
Nature Jul 2021Obesity is a worldwide epidemic that predisposes individuals to many age-associated diseases, but its exact effects on organ dysfunction are largely unknown. Hair...
Obesity is a worldwide epidemic that predisposes individuals to many age-associated diseases, but its exact effects on organ dysfunction are largely unknown. Hair follicles-mini-epithelial organs that grow hair-are miniaturized by ageing to cause hair loss through the depletion of hair follicle stem cells (HFSCs). Here we report that obesity-induced stress, such as that induced by a high-fat diet (HFD), targets HFSCs to accelerate hair thinning. Chronological gene expression analysis revealed that HFD feeding for four consecutive days in young mice directed activated HFSCs towards epidermal keratinization by generating excess reactive oxygen species, but did not reduce the pool of HFSCs. Integrative analysis using stem cell fate tracing, epigenetics and reverse genetics showed that further feeding with an HFD subsequently induced lipid droplets and NF-κB activation within HFSCs via autocrine and/or paracrine IL-1R signalling. These integrated factors converge on the marked inhibition of Sonic hedgehog (SHH) signal transduction in HFSCs, thereby further depleting lipid-laden HFSCs through their aberrant differentiation and inducing hair follicle miniaturization and eventual hair loss. Conversely, transgenic or pharmacological activation of SHH rescued HFD-induced hair loss. These data collectively demonstrate that stem cell inflammatory signals induced by obesity robustly represses organ regeneration signals to accelerate the miniaturization of mini-organs, and suggests the importance of daily prevention of organ dysfunction.
Topics: Alopecia; Animals; Autocrine Communication; Cell Count; Cell Differentiation; Cell Lineage; Cellular Senescence; Diet, High-Fat; Disease Models, Animal; Hair Follicle; Hedgehog Proteins; Inflammation; Male; Mice; Mice, Inbred C57BL; Obesity; Oxidative Stress; Paracrine Communication; Receptors, Interleukin-1; Stem Cells
PubMed: 34163066
DOI: 10.1038/s41586-021-03624-x -
Cancer Letters Feb 2021The endocrine FGF21 was discovered as a novel metabolic regulator in 2005 with new functions bifurcating from the canonic heparin-binding FGFs that directly promote cell... (Review)
Review
The endocrine FGF21 was discovered as a novel metabolic regulator in 2005 with new functions bifurcating from the canonic heparin-binding FGFs that directly promote cell proliferation and growth independent of a co-receptor. Early studies have demonstrated that FGF21 is a stress sensor in the liver and possibly, several other endocrine and metabolic tissues. Hepatic FGF21 signals via endocrine routes to quench episodes of metabolic derangements, promoting metabolic homeostasis. The convergence of mouse and human studies shows that FGF21 promotes lipid catabolism, including lipolysis, fatty acid oxidation, mitochondrial oxidative activity, and thermogenic energy dissipation, rather than directly regulating insulin and appetite. The white and brown adipose tissues and, to some extent, the hypothalamus, all of which host a transmembrane receptor binary complex of FGFR1 and co-receptor KLB, are considered the essential tissue and molecular targets of hepatic or pharmacological FGF21. On the other hand, a growing body of work has revealed that pancreatic acinar cells form a constitutive high-production site for FGF21, which then acts in an autocrine or paracrine mode. Beyond regulation of macronutrient metabolism and physiological energy expenditure, FGF21 appears to function in forestalling the development of fatty pancreas, steato-pancreatitis, fatty liver, and steato-hepatitis, thereby preventing the development of advanced pathologies such as pancreatic ductal adenocarcinoma or hepatocellular carcinoma. This review is intended to provide updates on these new discoveries that illuminate the protective roles of FGF21-FGFR1-KLB signal pathway in metabolic anomalies-associated severe tissue damage and malignancy, and to inform potential new preventive or therapeutic strategies for obesity-inflicted cancer patients via reducing metabolic risks and inflammation.
Topics: Adipose Tissue; Animals; Autocrine Communication; Carcinoma, Hepatocellular; Carcinoma, Pancreatic Ductal; Cell Proliferation; Disease Models, Animal; Energy Metabolism; Fatty Liver; Fibroblast Growth Factors; Humans; Hypothalamus; Klotho Proteins; Lipid Metabolism; Liver; Liver Neoplasms; Membrane Proteins; Mice; Mice, Transgenic; Obesity; Pancreas; Pancreatic Neoplasms; Paracrine Communication; Protective Factors; Receptor, Fibroblast Growth Factor, Type 1; Signal Transduction
PubMed: 33264641
DOI: 10.1016/j.canlet.2020.11.026 -
Nature Reviews. Cancer Mar 2022Resistance to therapeutic treatment and metastatic progression jointly determine a fatal outcome of cancer. Cancer metastasis and therapeutic resistance are... (Review)
Review
Resistance to therapeutic treatment and metastatic progression jointly determine a fatal outcome of cancer. Cancer metastasis and therapeutic resistance are traditionally studied as separate fields using non-overlapping strategies. However, emerging evidence, including from in vivo imaging and in vitro organotypic culture, now suggests that both programmes cooperate and reinforce each other in the invasion niche and persist upon metastatic evasion. As a consequence, cancer cell subpopulations exhibiting metastatic invasion undergo multistep reprogramming that - beyond migration signalling - supports repair programmes, anti-apoptosis processes, metabolic adaptation, stemness and survival. Shared metastasis and therapy resistance signalling are mediated by multiple mechanisms, such as engagement of integrins and other context receptors, cell-cell communication, stress responses and metabolic reprogramming, which cooperate with effects elicited by autocrine and paracrine chemokine and growth factor cues present in the activated tumour microenvironment. These signals empower metastatic cells to cope with therapeutic assault and survive. Identifying nodes shared in metastasis and therapy resistance signalling networks should offer new opportunities to improve anticancer therapy beyond current strategies, to eliminate both nodular lesions and cells in metastatic transit.
Topics: Cell Communication; Humans; Integrins; Neoplasm Metastasis; Neoplasms; Signal Transduction; Tumor Microenvironment
PubMed: 35013601
DOI: 10.1038/s41568-021-00427-0 -
International Journal of Molecular... Jun 2020Interventions to prevent pregnancy complications have been largely unsuccessful. We suggest this is because the foundation for a healthy pregnancy is laid prior to the... (Review)
Review
Interventions to prevent pregnancy complications have been largely unsuccessful. We suggest this is because the foundation for a healthy pregnancy is laid prior to the establishment of the pregnancy at the time of endometrial decidualization. Humans are one of only a few mammalian viviparous species in which decidualization begins during the latter half of each menstrual cycle and is therefore independent of the conceptus. Failure to adequately prepare (decidualize) the endometrium hormonally, biochemically, and immunologically in anticipation of the approaching blastocyst-including the downregulation of genes involved in the pro- inflammatory response and resisting tissue invasion along with the increased expression of genes that promote angiogenesis, foster immune tolerance, and facilitate tissue invasion-leads to abnormal implantation/placentation and ultimately to adverse pregnancy outcome. We hypothesize, therefore, that the primary driver of pregnancy health is the quality of the soil, not the seed.
Topics: Animals; Autocrine Communication; Biomarkers; Decidua; Embryo Implantation; Endometrium; Female; Gene Expression Regulation; Humans; Paracrine Communication; Placentation; Pregnancy; Pregnancy Complications; Pregnancy Outcome
PubMed: 32521725
DOI: 10.3390/ijms21114092 -
The Journal of Clinical Investigation Apr 2022Dysfunction of protein trafficking has been intensively associated with neurological diseases, including neurodegeneration, but whether and how protein transport...
Dysfunction of protein trafficking has been intensively associated with neurological diseases, including neurodegeneration, but whether and how protein transport contributes to oligodendrocyte (OL) maturation and myelin repair in white matter injury remains unclear. ER-to-Golgi trafficking of newly synthesized proteins is mediated by coat protein complex II (COPII). Here, we demonstrate that the COPII component Sec13 was essential for OL differentiation and postnatal myelination. Ablation of Sec13 in the OL lineage prevented OPC differentiation and inhibited myelination and remyelination after demyelinating injury in the central nervous system (CNS), while improving protein trafficking by tauroursodeoxycholic acid (TUDCA) or ectopic expression of COPII components accelerated myelination. COPII components were upregulated in OL lineage cells after demyelinating injury. Loss of Sec13 altered the secretome of OLs and inhibited the secretion of pleiotrophin (PTN), which was found to function as an autocrine factor to promote OL differentiation and myelin repair. These data suggest that Sec13-dependent protein transport is essential for OL differentiation and that Sec13-mediated PTN autocrine signaling is required for proper myelination and remyelination.
Topics: Autocrine Communication; Carrier Proteins; Cell Differentiation; Cytokines; Demyelinating Diseases; Humans; Myelin Sheath; Oligodendroglia
PubMed: 35143418
DOI: 10.1172/JCI155096 -
Science Signaling Oct 2022The tumor microbiome is increasingly implicated in cancer progression and resistance to chemotherapy. In pancreatic ductal adenocarcinoma (PDAC), high intratumoral loads...
The tumor microbiome is increasingly implicated in cancer progression and resistance to chemotherapy. In pancreatic ductal adenocarcinoma (PDAC), high intratumoral loads of correlate with shorter survival in patients. Here, we investigated the potential mechanisms underlying this association. We found that infection induced both normal pancreatic epithelial cells and PDAC cells to secrete increased amounts of the cytokines GM-CSF, CXCL1, IL-8, and MIP-3α. These cytokines increased proliferation, migration, and invasive cell motility in both infected and noninfected PDAC cells but not in noncancerous pancreatic epithelial cells, suggesting autocrine and paracrine signaling to PDAC cells. This phenomenon occurred in response to infection regardless of the strain and in the absence of immune and other stromal cells. Blocking GM-CSF signaling markedly limited proliferative gains after infection. Thus, infection in the pancreas elicits cytokine secretion from both normal and cancerous cells that promotes phenotypes in PDAC cells associated with tumor progression. The findings support the importance of exploring host-microbe interactions in pancreatic cancer to guide future therapeutic interventions.
Topics: Humans; Fusobacterium nucleatum; Granulocyte-Macrophage Colony-Stimulating Factor; Paracrine Communication; Interleukin-8; Pancreatic Neoplasms; Carcinoma, Pancreatic Ductal; Cell Proliferation; Pancreas
PubMed: 36256708
DOI: 10.1126/scisignal.abn4948 -
Nature Communications Jan 2021IL11 is important for fibrosis in non-alcoholic steatohepatitis (NASH) but its role beyond the stroma in liver disease is unclear. Here, we investigate the role of IL11...
IL11 is important for fibrosis in non-alcoholic steatohepatitis (NASH) but its role beyond the stroma in liver disease is unclear. Here, we investigate the role of IL11 in hepatocyte lipotoxicity. Hepatocytes highly express IL11RA and secrete IL11 in response to lipid loading. Autocrine IL11 activity causes hepatocyte death through NOX4-derived ROS, activation of ERK, JNK and caspase-3, impaired mitochondrial function and reduced fatty acid oxidation. Paracrine IL11 activity stimulates hepatic stellate cells and causes fibrosis. In mouse models of NASH, hepatocyte-specific deletion of Il11ra1 protects against liver steatosis, fibrosis and inflammation while reducing serum glucose, cholesterol and triglyceride levels and limiting obesity. In mice deleted for Il11ra1, restoration of IL11 cis-signaling in hepatocytes reconstitutes steatosis and inflammation but not fibrosis. We found no evidence for the existence of IL6 or IL11 trans-signaling in hepatocytes or NASH. These data show that IL11 modulates hepatocyte metabolism and suggests a mechanism for NAFLD to NASH transition.
Topics: Adult; Animals; Autocrine Communication; Cells, Cultured; Disease Models, Animal; Feeding Behavior; Hepatic Stellate Cells; Hepatocytes; Humans; Interleukin-11; Interleukin-11 Receptor alpha Subunit; Interleukin-6; Lipids; Mice, Knockout; Models, Biological; Non-alcoholic Fatty Liver Disease; Paracrine Communication; Phenotype; Signal Transduction; Mice
PubMed: 33397952
DOI: 10.1038/s41467-020-20303-z