scholarly journals Immunoporosis: Role of Innate Immune Cells in Osteoporosis

2021 ◽  
Vol 12 ◽  
Author(s):  
Yogesh Saxena ◽  
Sanjeev Routh ◽  
Arunika Mukhopadhaya
Keyword(s):  
Inflammatory Cytokines ◽  
Immune Cells ◽  
Inflammatory Mediators ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
Myeloid Lineage ◽  
Molecular Patterns ◽  
The Impact ◽  
Pro Inflammatory Cytokines

Osteoporosis or porous bone disorder is the result of an imbalance in an otherwise highly balanced physiological process known as ‘bone remodeling’. The immune system is intricately involved in bone physiology as well as pathologies. Inflammatory diseases are often correlated with osteoporosis. Inflammatory mediators such as reactive oxygen species (ROS), and pro-inflammatory cytokines and chemokines directly or indirectly act on the bone cells and play a role in the pathogenesis of osteoporosis. Recently, Srivastava et al. (Srivastava RK, Dar HY, Mishra PK. Immunoporosis: Immunology of Osteoporosis-Role of T Cells. Frontiers in immunology. 2018;9:657) have coined the term “immunoporosis” to emphasize the role of immune cells in the pathology of osteoporosis. Accumulated pieces of evidence suggest both innate and adaptive immune cells contribute to osteoporosis. However, innate cells are the major effectors of inflammation. They sense various triggers to inflammation such as pathogen-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), cellular stress, etc., thus producing pro-inflammatory mediators that play a critical role in the pathogenesis of osteoporosis. In this review, we have discussed the role of the innate immune cells in great detail and divided these cells into different sections in a systemic manner. In the beginning, we talked about cells of the myeloid lineage, including macrophages, monocytes, and dendritic cells. This group of cells explicitly influences the skeletal system by the action of production of pro-inflammatory cytokines and can transdifferentiate into osteoclast. Other cells of the myeloid lineage, such as neutrophils, eosinophils, and mast cells, largely impact osteoporosis via the production of pro-inflammatory cytokines. Further, we talked about the cells of the lymphoid lineage, including natural killer cells and innate lymphoid cells, which share innate-like properties and play a role in osteoporosis. In addition to various innate immune cells, we also discussed the impact of classical pro-inflammatory cytokines on osteoporosis. We also highlighted the studies regarding the impact of physiological and metabolic changes in the body, which results in chronic inflammatory conditions such as ageing, ultimately triggering osteoporosis.

scholarly journals Macrophages and Dendritic Cells Are Not the Major Source of Pro-Inflammatory Cytokines Upon SARS-CoV-2 Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Marc A. Niles ◽  
Patricia Gogesch ◽  
Stefanie Kronhart ◽  
Samira Ortega Iannazzo ◽  
Georg Kochs ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Inflammatory Cytokines ◽  
Immune Cells ◽  
Influenza A ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
M2 Macrophages ◽  
Myeloid Dendritic Cells ◽  
M1 And M2 Macrophages ◽  
Pro Inflammatory Cytokines

The exact role of innate immune cells upon infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and their contribution to the formation of the corona virus-induced disease (COVID)-19 associated cytokine storm is not yet fully understood. We show that human in vitro differentiated myeloid dendritic cells (mDC) as well as M1 and M2 macrophages are susceptible to infection with SARS-CoV-2 but are not productively infected. Furthermore, infected mDC, M1-, and M2 macrophages show only slight changes in their activation status. Surprisingly, none of the infected innate immune cells produced the pro-inflammatory cytokines interleukin (IL)−6, tumor necrosis factor (TNF)-α, or interferon (IFN)−α. Moreover, even in co-infection experiments using different stimuli, as well as non-influenza (non-flu) or influenza A (flu) viruses, only very minor IL-6 production was induced. In summary, we conclude that mDC and macrophages are unlikely the source of the first wave of cytokines upon infection with SARS-CoV-2.

scholarly journals The Role of Syk/CARD9-Coupled C-Type Lectin Receptors in Immunity toMycobacterium tuberculosisInfections

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Mohlopheni Jackson Marakalala ◽  
Lisa M. Graham ◽  
Gordon D. Brown
Keyword(s):  
Immune Response ◽  
Pattern Recognition ◽  
Mycobacterium Tuberculosis ◽  
Immune Cells ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
Lectin Receptors ◽  
Molecular Patterns

There is increasing interest in understanding the mechanisms underlying the interactions that occur betweenMycobacterium tuberculosisand host innate immune cells. These cells express pattern recognition receptors (PRRs) which recognise mycobacterial pathogen-associated molecular patterns (PAMPs) and which can influence the host immune response to the infection. Although many of the PRRs appear to be redundant in the control ofM. tuberculosisinfectionin vivo, recent discoveries have revealed a key, nonredundant, role of the Syk/CARD9 signalling pathway in antimycobacterial immunity. Here we review these discoveries, as well as recent data investigating the role of the Syk/CARD9-coupled PRRs that have been implicated in mycobacterial recognition, including Dectin-1 and Mincle.

Cytokine networking of innate immunity cells: a potential target of therapy

2014 ◽  
Vol 126 (9) ◽  
pp. 593-612 ◽  
Author(s):  
Ilja Striz ◽  
Eva Brabcova ◽  
Libor Kolesar ◽  
Alena Sekerkova
Keyword(s):  
T Cells ◽  
Epithelial Cells ◽  
Regulatory T Cells ◽  
Inflammatory Cytokines ◽  
Immune Cells ◽  
Innate Immune ◽  
Lymphoid Cells ◽  
Extracellular Matrix Protein ◽  
Innate Immune Cells ◽  
Pro Inflammatory Cytokines

Innate immune cells, particularly macrophages and epithelial cells, play a key role in multiple layers of immune responses. Alarmins and pro-inflammatory cytokines from the IL (interleukin)-1 and TNF (tumour necrosis factor) families initiate the cascade of events by inducing chemokine release from bystander cells and by the up-regulation of adhesion molecules required for transendothelial trafficking of immune cells. Furthermore, innate cytokines produced by dendritic cells, macrophages, epithelial cells and innate lymphoid cells seem to play a critical role in polarization of helper T-cell cytokine profiles into specific subsets of Th1/Th2/Th17 effector cells or regulatory T-cells. Lastly, the innate immune system down-regulates effector mechanisms and restores homoeostasis in injured tissue via cytokines from the IL-10 and TGF (transforming growth factor) families mainly released from macrophages, preferentially the M2 subset, which have a capacity to induce regulatory T-cells, inhibit the production of pro-inflammatory cytokines and induce healing of the tissue by regulating extracellular matrix protein deposition and angiogenesis. Cytokines produced by innate immune cells represent an attractive target for therapeutic intervention, and multiple molecules are currently being tested clinically in patients with inflammatory bowel disease, rheumatoid arthritis, systemic diseases, autoinflammatory syndromes, fibrosing processes or malignancies. In addition to the already widely used blockers of TNFα and the tested inhibitors of IL-1 and IL-6, multiple therapeutic molecules are currently in clinical trials targeting TNF-related molecules [APRIL (a proliferation-inducing ligand) and BAFF (B-cell-activating factor belonging to the TNF family)], chemokine receptors, IL-17, TGFβ and other cytokines.

scholarly journals The Role of the Pathogen Dose and PI3Kγ in Immunometabolic Reprogramming of Microglia for Innate Immune Memory

2021 ◽  
Vol 22 (5) ◽  
pp. 2578
Author(s):  
Trim Lajqi ◽  
Christian Marx ◽  
Hannes Hudalla ◽  
Fabienne Haas ◽  
Silke Große ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Immune Tolerance ◽  
Immune Cells ◽  
Low Dose ◽  
Innate Immune ◽  
Immune Memory ◽  
Innate Immune Cells ◽  
Atp Production ◽  
Dose Dependent

Microglia, the innate immune cells of the CNS, exhibit long-term response changes indicative of innate immune memory (IIM). Our previous studies revealed IIM patterns of microglia with opposing immune phenotypes: trained immunity after a low dose and immune tolerance after a high dose challenge with pathogen-associated molecular patterns (PAMP). Compelling evidence shows that innate immune cells adopt features of IIM via immunometabolic control. However, immunometabolic reprogramming involved in the regulation of IIM in microglia has not been fully addressed. Here, we evaluated the impact of dose-dependent microglial priming with ultra-low (ULP, 1 fg/mL) and high (HP, 100 ng/mL) lipopolysaccharide (LPS) doses on immunometabolic rewiring. Furthermore, we addressed the role of PI3Kγ on immunometabolic control using naïve primary microglia derived from newborn wild-type mice, PI3Kγ-deficient mice and mice carrying a targeted mutation causing loss of lipid kinase activity. We found that ULP-induced IIM triggered an enhancement of oxygen consumption and ATP production. In contrast, HP was followed by suppressed oxygen consumption and glycolytic activity indicative of immune tolerance. PI3Kγ inhibited glycolysis due to modulation of cAMP-dependent pathways. However, no impact of specific PI3Kγ signaling on immunometabolic rewiring due to dose-dependent LPS priming was detected. In conclusion, immunometabolic reprogramming of microglia is involved in IIM in a dose-dependent manner via the glycolytic pathway, oxygen consumption and ATP production: ULP (ultra-low-dose priming) increases it, while HP reduces it.

Role of Inflammasome Activation in Systemic Lupus Erythematosus: Are Innate Immune Cells Activated?

2020 ◽  
Author(s):  
Rodolfo Perez-Alamino ◽  
Raquel Cuchacovich ◽  
Luis R. Espinoza ◽  
Constance P. Porretta ◽  
Arnold H. Zea
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Immune Cells ◽  
Lupus Erythematosus ◽  
Innate Immune ◽  
Inflammasome Activation ◽  
Innate Immune Cells ◽  
Systemic Lupus

scholarly journals Adipocytes, Innate Immunity and Obesity: A Mini-Review

2021 ◽  
Vol 12 ◽  
Author(s):  
Alecia M. Blaszczak ◽  
Anahita Jalilvand ◽  
Willa A. Hsueh
Keyword(s):  
Adipose Tissue ◽  
Immune System ◽  
Immune Cells ◽  
Adaptive Immune System ◽  
Innate Immune ◽  
Lymphoid Cells ◽  
Innate Immune Cells ◽  
Adaptive Immune

The role of adipose tissue (AT) inflammation in obesity and its multiple related-complications is a rapidly expanding area of scientific interest. Within the last 30 years, the role of the adipocyte as an endocrine and immunologic cell has been progressively established. Like the macrophage, the adipocyte is capable of linking the innate and adaptive immune system through the secretion of adipokines and cytokines; exosome release of lipids, hormones, and microRNAs; and contact interaction with other immune cells. Key innate immune cells in AT include adipocytes, macrophages, neutrophils, and innate lymphoid cells type 2 (ILC2s). The role of the innate immune system in promoting adipose tissue inflammation in obesity will be highlighted in this review. T cells and B cells also play important roles in contributing to AT inflammation and are discussed in this series in the chapter on adaptive immunity.

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