Immunosenescence in monocytes, macrophages, and dendritic cells: lessons learned from the lung and heart

Characterizing the skeletal muscle immune microenvironment for sarcopenia: insights from transcriptome analysis and histological validation

Background

Sarcopenia is a condition characterized by the age-related loss of skeletal muscle mass and function. The pathogenesis of the disease is influenced by chronic low-grade inflammation. However, the specific changes in the immune landscape changes of sarcopenic muscle are not yet fully understood.

Methods

To gain insights into the immune cell composition and interactions, we combined single-nucleus RNA sequencing data, bulk RNA sequencing dataset, and comprehensive bioinformatic analyses on the skeletal muscle samples from young, aged, and sarcopenic individuals. Histological staining was then performed on skeletal muscles to validate the distribution of immune cells in clinical samples.

Results

We analyzed the transcriptomes of 101,862 single nuclei, revealing a total of 10 major cell types and 6 subclusters of immune cell types within the human skeletal muscle tissues. Notable variations were identified in the immune microenvironment between young and aged skeletal muscle. Among the immune cells from skeletal muscle microenvironment, macrophages constituted the largest fraction. A specific marker gene LYVE1 for skeletal muscle resident macrophages was further identified. Cellular subclasses included four distinct groups of resident macrophages, which play different roles in physiological or non-physiological conditions. Utilizing bulk RNA sequencing data, we observed a significant enrichment of macrophage-rich inflammation in sarcopenia.

Conclusions

Our findings demonstrate age-related changes in the composition and cross-talk of immune cells in human skeletal muscle microenvironment, which contribute to chronic inflammation in aged or sarcopenia muscle. Furthermore, macrophages emerge as a potential therapeutic target, thus advancing our understanding of the pathogenesis of sarcopenia.

Alterations in metabolic pathways: a bridge between aging and weaker innate immune response

Aging is a time-dependent progressive physiological process, which results in impaired immune system function. Age-related changes in immune function increase the susceptibility to many diseases such as infections, autoimmune diseases, and cancer. Different metabolic pathways including glycolysis, tricarboxylic acid cycle, amino acid metabolism, pentose phosphate pathway, fatty acid oxidation and fatty acid synthesis regulate the development, differentiation, and response of adaptive and innate immune cells. During aging all these pathways change in the immune cells. In addition to the changes in metabolic pathways, the function and structure of mitochondria also have changed in the immune cells. Thereby, we will review changes in the metabolism of different innate immune cells during the aging process.

The Impact of Microgravity on Immunological States

As we explore other planetary bodies, astronauts will face unique environmental and physiological challenges. The human immune system has evolved under Earth's gravitational force. Consequently, in the microgravity environment of space, immune function is altered. This can pose problematic consequences for astronauts on deep space missions where medical intervention will be limited. Studying the unique environment of microgravity has its challenges, yet current research has uncovered immunological states that are probable during exploration missions. As microgravity-induced immune states are uncovered, novel countermeasure developments and personalized mitigation programs can be designed to improve astronaut health. This can also benefit immune-related monitoring programs for disorders on Earth. This is a comprehensive review, including gaps in knowledge, of simulated and spaceflight microgravity studies in human and rodent models.

Immunosenescence as a convergence pathway in neurodegeneration

Immunity refers to the body's defense mechanism to protect itself against illness or to produce antibodies against pathogens. Senescence is a cellular phenomenon that integrates a sustainable growth restriction, other phenotypic abnormalities and including a pro-inflammatory secretome. It is highly involved in regulating developmental stages, tissue homeostasis, and tumor proliferation monitoring. Contemporary experimental reports imply that abolition of senescent cells employing evolved genetic and therapeutic approaches augment the chances of survival and boosts the health span of an individual. Immunosenescence is considered as a process in which dysfunction of the immune system occurs with aging and greatly includes remodeling of lymphoid organs. This in turn causes fluctuations in the immune function of the elderly that has strict relation with the expansion of autoimmune diseases, infections, malignant tumors and neurodegenerative disorders. The interaction of the nervous and immune systems during aging is marked by bi-directional influence and mutual correlation of variations. The enhanced systemic inflammatory condition in the elderly, and the neuronal immune cell activity can be modulated by inflamm-aging and peripheral immunosenescence resulting in chronic low-grade inflammatory processes in the central Nervous system known as neuro-inflammaging. For example, glia excitation by cytokines and glia pro-inflammatory productions contribute significantly to memory injury as well as in acute systemic inflammation, which is associated with high levels of Tumor necrosis factor -α and a rise in cognitive decline. In recent years its role in the pathology of Alzheimer's disease has caught research interest to a large extent. This article reviews the connection concerning the immune and nervous systems and highlights how immunosenescence and inflamm-aging can affect neurodegenerative disorders.

Beyond the Complement Cascade: Insights into Systemic Immunosenescence and Inflammaging in Age-Related Macular Degeneration and Current Barriers to Treatment

Landmark genetic studies have revealed the effect of complement biology and its regulation on the pathogenesis of age-related macular degeneration (AMD). Limited phase 3 clinical trial data showing a benefit of complement inhibition in AMD raises the prospect of more complex mediators at play. Substantial evidence supports the role of para-inflammation in maintaining homeostasis in the retina and choroid. With increasing age, a decline in immune system regulation, known as immunosenescence, has been shown to alter the equilibrium maintained by para-inflammation. The altered equilibrium results in chronic, sterile inflammation with aging, termed 'inflammaging', including in the retina and choroid. The chronic inflammatory state in AMD is complex, with contributions from cells of the innate and adaptive branches of the immune system, sometimes with overlapping features, and the interaction of their secretory products with retinal cells such as microglia and retinal pigment epithelium (RPE), extracellular matrix and choroidal vascular endothelial cells. In this review, the chronic inflammatory state in AMD will be explored by immune cell type, with a discussion of factors that will need to be overcome in the development of curative therapies.

Novel nanoadjuvants balance immune activation with modest inflammation: implications for older adult vaccines

BACKGROUND

Age-associated impairments of immune response and inflammaging likely contribute to poor vaccine efficacy. An appropriate balance between activation of immune memory and inflammatory response may be more effective in vaccines for older adults; attempts to overcome reduced efficacy have included the addition of adjuvants or increased antigenic dose. Next generation vaccine formulations may also use biomaterials to both deliver and adjuvant vaccine antigens. In the context of aging, it is important to determine the degree to which new biomaterials may enhance antigen-presenting cell (APC) functions without inducing potent inflammatory responses of APCs or other immune cell types (e.g., T cells). However, the effect of newer biomaterials on these cell types from young and older adults remains unknown.

RESULTS

In this pilot study, cells from young and older adults were used to evaluate the effect of novel biomaterials such as polyanhydride nanoparticles (NP) and pentablock copolymer micelles (Mi) and cyclic dinucleotides (CDN; a STING agonist) on cytokine and chemokine secretion in comparison to standard immune activators such as lipopolysaccharide (LPS) and PMA/ionomycin. The NP treatment showed adjuvant-like activity with induction of inflammatory cytokines, growth factors, and select chemokines in peripheral blood mononuclear cells (PBMCs) of both young (n = 6) and older adults (n = 4), yet the degree of activation was generally less than LPS. Treatment with Mi or CDN resulted in minimal induction of cytokines and chemokine secretion with the exception of increased IFN-α and IL-12p70 by CDN. Age-related decreases were observed across multiple cytokines and chemokines, yet IFN-α, IL-12, and IL-7 production by NP or CDN stimulation was equal to or greater than in cells from younger adults. Consistent with these results in aged humans, a combination nanovaccine composed of NP, Mi, and CDN administered to aged mice resulted in a greater percentage of antigen-specific CD4⁺ T cells and greater effector memory cells in draining lymph nodes compared to an imiquimod-adjuvanted vaccine.

CONCLUSIONS

Overall, our novel biomaterials demonstrated a modest induction of cytokine secretion with a minimal inflammatory profile. These findings suggest a unique role for biomaterial nanoadjuvants in the development of next generation vaccines for older adults.

Macrophages in immunoregulation and therapeutics

Macrophages exist in various tissues, several body cavities, and around mucosal surfaces and are a vital part of the innate immune system for host defense against many pathogens and cancers. Macrophages possess binary M1/M2 macrophage polarization settings, which perform a central role in an array of immune tasks via intrinsic signal cascades and, therefore, must be precisely regulated. Many crucial questions about macrophage signaling and immune modulation are yet to be uncovered. In addition, the clinical importance of tumor-associated macrophages is becoming more widely recognized as significant progress has been made in understanding their biology. Moreover, they are an integral part of the tumor microenvironment, playing a part in the regulation of a wide variety of processes including angiogenesis, extracellular matrix transformation, cancer cell proliferation, metastasis, immunosuppression, and resistance to chemotherapeutic and checkpoint blockade immunotherapies. Herein, we discuss immune regulation in macrophage polarization and signaling, mechanical stresses and modulation, metabolic signaling pathways, mitochondrial and transcriptional, and epigenetic regulation. Furthermore, we have broadly extended the understanding of macrophages in extracellular traps and the essential roles of autophagy and aging in regulating macrophage functions. Moreover, we discussed recent advances in macrophages-mediated immune regulation of autoimmune diseases and tumorigenesis. Lastly, we discussed targeted macrophage therapy to portray prospective targets for therapeutic strategies in health and diseases.

Aging microenvironment and antitumor immunity for geriatric oncology: the landscape and future implications

The tumor microenvironment (TME) has been extensively investigated; however, it is complex and remains unclear, especially in elderly patients. Senescence is a cellular response to a variety of stress signals, which is characterized by stable arrest of the cell cycle and major changes in cell morphology and physiology. To the best of our knowledge, senescence leads to consistent arrest of tumor cells and remodeling of the tumor-immune microenvironment (TIME) by activating a set of pleiotropic cytokines, chemokines, growth factors, and proteinases, which constitute the senescence-associated secretory phenotype (SASP). On the one hand, the SASP promotes antitumor immunity, which enhances treatment efficacy; on the other hand, the SASP increases immunosuppressive cell infiltration, including myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs), M2 macrophages, and N2 neutrophils, contributing to TIME suppression. Therefore, a deeper understanding of the regulation of the SASP and components contributing to robust antitumor immunity in elderly individuals with different cancer types and the available therapies is necessary to control tumor cell senescence and provide greater clinical benefits to patients. In this review, we summarize the key biological functions mediated by cytokines and intercellular interactions and significant components of the TME landscape, which influence the immunotherapy response in geriatric oncology. Furthermore, we summarize recent advances in clinical practices targeting TME components and discuss potential senescent TME targets.

Microbially-Induced Exosomes from Dendritic Cells Promote Paracrine Immune Senescence: Novel Mechanism of Bone Degenerative Disease in Mice

As the aging population grows, chronic age-related bone degenerative diseases become more prevalent and severe. One such disease, periodontitis (PD), rises to 70.1% prevalence in Americans 65 years and older. PD has been linked to increased risk of other age-related diseases with more serious mortality and morbidity profiles such as Alzheimer's disease and cardiovascular disease, but the cellular and biological mechanisms remain unclear. Recent in vitro studies from our group indicate that murine dendritic cells (DCs) and T cells are vulnerable to immune senescence. This occurs through a distinct process involving invasion of DCs by dysbiotic pathogen Porphyromonas gingivalis (Pg) activating the senescence associated secretory phenotype (SASP). Exosomes of the Pg-induced SASP transmit senescence to normal bystander DC and T cells, ablating antigen presentation. The biological significance of these findings in vivo and the mechanisms involved were examined in the present study using young (4-5mo) or old (22-24mo) mice subjected to ligature-induced PD, with or without dysbiotic oral pathogen and injection of Pg-induced DC exosomes. Senescence profiling of gingiva and draining lymph nodes (LN) corroborates role of advanced age and PD in elevation of senescence biomarkers beta galactosidase (SA-β-Gal), p16 INK4A p21Waf1/Clip1, IL6, TNFα, and IL1β, with attendant increase in alveolar bone loss, reversed by senolytic agent rapamycin. Immunophenotyping of gingiva and LN revealed that myeloid CD11c+ DCs and T cells are particularly vulnerable to senescence in vivo under these conditions. Moreover, Pg-induced DC exosomes were the most potent inducers of alveolar bone loss and immune senescence, and capable of overcoming senescence resistance of LN T cells in young mice. We conclude that immune senescence, compounded by advanced age, and accelerated by oral dysbiosis and its induced SASP exosomes, plays a pivotal role in the pathophysiology of experimental periodontitis.

Immunosenescence of brain accelerates Alzheimer's disease progression

Most of Alzheimer's disease (AD) cases are sporadic and occur after age 65. With prolonged life expectancy and general population aging, AD is becoming a significant public health concern. The immune system supports brain development, plasticity, and homeostasis, yet it is particularly vulnerable to aging-related changes. Aging of the immune system, called immunosenescence, is the multifaceted remodeling of the immune system during aging. Immunosenescence is a contributing factor to various age-related diseases, including AD. Age-related changes in brain immune cell phenotype and function, crosstalk between immune cells and neural cells, and neuroinflammation work together to promote neurodegeneration and age-related cognitive impairment. Although numerous studies have confirmed the correlation between systemic immune changes and AD, few studies focus on the immune state of brain microenvironment in aging and AD. This review mainly addresses the changes of brain immune microenvironment in aging and AD. Specifically, we delineate how various aspects of the brain immune microenvironment, including immune gateways, immune cells, and molecules, and the interplay between immune cells and neural cells, accelerate AD pathogenesis during aging. We also propose a theoretical framework of therapeutic strategies selectively targeting the different mechanisms to restore brain immune homeostasis.

Pharmacoinvasive Strategy in Elderly Up to 75 Years or Non-Elderly: Analysis of Biochemical and Cardiac Magnetic Resonance Imaging Parameters

BACKGROUND

Pharmacoinvasive strategy is an alternative when primary percutaneous coronary intervention (PCI) is not feasible.

OBJECTIVES

This study aimed to evaluate the effects of early pharmacoinvasive strategy on the infarct size and left ventricular ejection fraction in elderly and non-elderly patients. The role of inflammatory markers was also examined.

METHODS

Patients (n=223) with ST segment elevation myocardial infarction (STEMI) were prospectively included and submitted to pharmacological thrombolysis in the first six hours, and underwent coronary angiogram and PCI when necessary, in the first 24 hours. Blood samples were collected in the first day (D1) and after 30 days (D30). Cardiac magnetic resonance imaging (cMRI) was performed at D30. Significance was set at p<0.05.

RESULTS

Elderly and non-elderly patients showed similar percentage of infarcted mass (13.7 [6.9-17.0] vs. 14.0 [7.3-26.0], respectively, p=0.13) (median [interquartile range]). However, elderly patients had better left ventricular ejection fraction (53 [45-62] vs. 49 [39-58], p=0.025). Titers of interleukin (IL)1beta, IL-4, IL-6, and IL-10 did not differ between D1 and D30, but elderly patients had higher titers for IL-18 at D1 and D30. Absolute numbers of B and T lymphocytes were similar in both groups at D1 and D30, but elderly patients had higher neutrophil/lymphocyte ratio at D30. Multivariate linear regression analysis of cMRI outcomes in the whole population showed that the independent predictors were not different between elderly and non-elderly patients.

CONCLUSION

Pharmacoinvasive strategy in elderly patients was associated with small differences in inflammatory parameters, similar infarct size and better left ventricular function than non-elderly patients.

Phenotypic and functional alterations of monocyte subsets with aging

BACKGROUND

It has been widely accepted that monocytes are one of the central mediators contributing to inflammaging. However, it remains unclear whether aged monocytes, similar to aged T cells, have characteristics of hyperactivation and increased expression of co-inhibitory molecules.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from young (21-40 years old), middle-aged (41-60 years old), and older human subjects (> 60 years old). Flow cytometry was used to monitor changes in the expression of surface molecules of monocyte subsets and cytokine-producing capacity.

RESULTS

We observed increased tumor necrosis factor-α: TNF-α and decreased interleukin-6 (IL-6) production in monocytes from older adults compared with young and middle-aged adults. Older adults had a greater percentage of intermediate and non-classical monocyte subsets, along with increased levels of the immune activation markers human leukocyte antigen-DR (HLA-DR), and adhesion molecules cluster of differentiation molecule 11b (CD11b) and L-selectin (CD62L). Furthermore, we observed increased C-C motif chemokine receptor 2 (CCR2) expression on classical monocytes and decreased C-X3-C motif chemokine receptor 1 (CX3CR1) expression on non-classical monocytes in older adult subjects. The expression of co-inhibitory receptors was reduced on monocyte subsets in older adults.

CONCLUSIONS

Circulating monocytes in older adults exhibit increased expression of activation, adhesion, and migration markers, but decreased expression of co-inhibitory molecules.

Growth Differentiation Factor-15 in Immunity and Aging

Aging increases susceptibility to and severity of a variety of chronic and infectious diseases. Underlying this is dysfunction of the immune system, including chronic increases in low-grade inflammation (inflammaging) and age-related immunosuppression (immunosenescence). Growth differentiation factor-15 (GDF-15) is a stress-, infection-, and inflammation-induced cytokine which is increased in aging and suppresses immune responses. This mini review briefly covers existing knowledge on the immunoregulatory and anti-inflammatory roles of GDF-15, as well as its potential importance in aging and immune function.

Exogenous and Endogenous Dendritic Cell-Derived Exosomes: Lessons Learned for Immunotherapy and Disease Pathogenesis

Immune therapeutic exosomes, derived exogenously from dendritic cells (DCs), the 'directors' of the immune response, are receiving favorable safety and tolerance profiles in phase I and II clinical trials for a growing number of inflammatory and neoplastic diseases. DC-derived exosomes (EXO), the focus of this review, can be custom tailored with immunoregulatory or immunostimulatory molecules for specific immune cell targeting. Moreover, the relative stability, small size and rapid uptake of EXO by recipient immune cells offer intriguing options for therapeutic purposes. This necessitates an in-depth understanding of mechanisms of EXO biogenesis, uptake and routing by recipient immune cells, as well as their in vivo biodistribution. Against this backdrop is recognition of endogenous exosomes, secreted by all cells, the molecular content of which is reflective of the metabolic state of these cells. In this regard, exosome biogenesis and secretion is regulated by cell stressors of chronic inflammation and tumorigenesis, including dysbiotic microbes, reactive oxygen species and DNA damage. Such cell stressors can promote premature senescence in young cells through the senescence associated secretory phenotype (SASP). Pathological exosomes of the SASP amplify inflammatory signaling in stressed cells in an autocrine fashion or promote inflammatory signaling to normal neighboring cells in paracrine, without the requirement of cell-to-cell contact. In summary, we review relevant lessons learned from the use of exogenous DC exosomes for immune therapy, as well as the pathogenic potential of endogenous DC exosomes.

Cellular Senescence: Pathogenic Mechanisms in Lung Fibrosis

Pulmonary fibrosis is a chronic and fatal lung disease that significantly impacts the aging population globally. To date, anti-fibrotic, immunosuppressive, and other adjunct therapy demonstrate limited efficacies. Advancing our understanding of the pathogenic mechanisms of lung fibrosis will provide a future path for the cure. Cellular senescence has gained substantial interest in recent decades due to the increased incidence of fibroproliferative lung diseases in the older age group. Furthermore, the pathologic state of cellular senescence that includes maladaptive tissue repair, decreased regeneration, and chronic inflammation resembles key features of progressive lung fibrosis. This review describes regulatory pathways of cellular senescence and discusses the current knowledge on the senescence of critical cellular players of lung fibrosis, including epithelial cells (alveolar type 2 cells, basal cells, etc.), fibroblasts, and immune cells, their phenotypic changes, and the cellular and molecular mechanisms by which these cells contribute to the pathogenesis of pulmonary fibrosis. A few challenges in the field include establishing appropriate in vivo experimental models and identifying senescence-targeted signaling molecules and specific therapies to target senescent cells, known collectively as "senolytic" or "senotherapeutic" agents.

Porphyromonas gingivalis Provokes Exosome Secretion and Paracrine Immune Senescence in Bystander Dendritic Cells

Periodontitis is a disease of ageing or inflammaging, and is comorbid with other more severe age-related chronic diseases. With advanced age comes an increase in accumulation of senescent cells that release soluble and insoluble pro-inflammatory factors collectively termed the senescence associated secretory phenotype (SASP). In the present report, we examined whether immune cells typical of those at the oral mucosa-microbe interface, are vulnerable to cellular senescence (CS) and the role of dysbiotic oral pathogen Porphyromonas gingivalis. Bone marrow-derived dendritic cells (DCs) from young (yDCs) and old (oDCs) mice were co-cultured in vitro with CS inducer doxorubicin or P.gingivalis (Pg), plus or minus senolytic agent rapamycin. CS profiling revealed elevated CS mediators SA-β-Gal, p16 ^INK4A, p53, and p21^Waf1/Clip1 in oDCs, or yDCs in response to doxorubicin or P. gingivalis, reversible with rapamycin. Functional studies indicate impaired maturation function of oDCs, and yDC exposed to P. gingivalis; moreover, OVA-driven proliferation of CD4+ T cells from young OTII transgenic mice was impaired by oDCs or yDCs+Pg. The SASP of DCs, consisting of secreted exosomes and inflammasome-related cytokines was further analyzed. Exosomes of DCs cocultured with P. gingivalis (PgDCexo) were purified, quantitated and characterized. Though typical in terms of size, shape and phenotype, PgDCexo were 2-fold greater in number than control DCs, with several important distinctions. Namely, PgDCexo were enriched in age-related miRNAs, and miRNAs reported to disrupt immune homeostasis through negative regulation of apoptosis and autophagy functions. We further show that PgDCexo were enriched in P. gingivalis fimbrial adhesin protein mfa1 and in inflammasome related cytokines IL-1β, TNFα and IL-6. Functionally PgDCexo were readily endocytosed by recipient yDCs, amplifying functional impairment in maturation and ability to promote Ova-driven proliferation of OTII CD4+ T cells from young mice. In conclusion P. gingivalis induces premature (autocrine) senescence in DCs by direct cellular invasion and greatly amplifies senescence, in paracrine, of bystander DCs by secretion of inflammatory exosomes. The implications of this pathological pathway for periodontal disease in vivo is under investigation in mouse models.

Cellular senescence in the aging retina and developments of senotherapies for age-related macular degeneration

Age-related macular degeneration (AMD), a degenerative disease in the central macula area of the neuroretina and the supporting retinal pigment epithelium, is the most common cause of vision loss in the elderly. Although advances have been made, treatment to prevent the progressive degeneration is lacking. Besides the association of innate immune pathway genes with AMD susceptibility, environmental stress- and cellular senescence-induced alterations in pathways such as metabolic functions and inflammatory responses are also implicated in the pathophysiology of AMD. Cellular senescence is an adaptive cell process in response to noxious stimuli in both mitotic and postmitotic cells, activated by tumor suppressor proteins and prosecuted via an inflammatory secretome. In addition to physiological roles in embryogenesis and tissue regeneration, cellular senescence is augmented with age and contributes to a variety of age-related chronic conditions. Accumulation of senescent cells accompanied by an impairment in the immune-mediated elimination mechanisms results in increased frequency of senescent cells, termed “chronic” senescence. Age-associated senescent cells exhibit abnormal metabolism, increased generation of reactive oxygen species, and a heightened senescence-associated secretory phenotype that nurture a proinflammatory milieu detrimental to neighboring cells. Senescent changes in various retinal and choroidal tissue cells including the retinal pigment epithelium, microglia, neurons, and endothelial cells, contemporaneous with systemic immune aging in both innate and adaptive cells, have emerged as important contributors to the onset and development of AMD. The repertoire of senotherapeutic strategies such as senolytics, senomorphics, cell cycle regulation, and restoring cell homeostasis targeted both at tissue and systemic levels is expanding with the potential to treat a spectrum of age-related diseases, including AMD.

A Perspective on Roles Played by Immunosenescence in the Pathobiology of Alzheimer's Disease

Alzheimer's disease (AD) is a chronic progressive neurodegenerative disorder. Aging is the most significant risk factor for late-onset AD. The age-associated changes in the immune system are termed immunosenescence. A close connection between immunosenescence and AD is increasingly recognized. This article provides an overview of immunosenescence and evidence for its role in the pathogenesis of AD and possible mechanisms as well as the outlook for drug development.

Update of Immunosenescence in Cerebral Small Vessel Disease

Aging of the central nervous system (CNS) is closely associated with chronic sterile low-grade inflammation in older organisms and related immune response. As an amplifier for neuro-inflammaging, immunosenescence remodels and deteriorates immune systems gradually with the passage of time, and finally contributes to severe outcomes like stroke, dementia and neurodegeneration in elderly adults. Cerebral small vessel disease (CSVD), one of the major causes of vascular dementia, has an intensive connection with the inflammatory response and immunosenescence plays a crucial role in the pathology of this disorder. In this review, we discuss the impact of immunosenescence on the development of CSVD and its underlying mechanism. Furthermore, the clinical practice significance of immunosenescence management and the diagnosis and treatment of CSVD will be also discussed.

I mmunosenescence and Inflammaging: Risk Factors of Severe COVID-19 in Older People

Old individuals are more susceptible to various infections due to immunological changes that occur during the aging process. These changes named collectively as "immunosenescence" include decreases in both the innate and adaptive immune responses in addition to the exacerbated production of inflammatory cytokines. This scenario of immunological dysfunction and its relationship with disease development in older people has been widely studied, especially in infections that can be fatal, such as influenza and, more recently, COVID-19. In the current scenario of SARS-CoV-2 infection, many mechanisms of disease pathogenesis in old individuals have been proposed. To better understand the dynamics of COVID-19 in this group, aspects related to immunological senescence must be well elucidated. In this article, we discuss the main mechanisms involved in immunosenescence and their possible correlations with the susceptibility of individuals of advanced age to SARS-CoV-2 infection and the more severe conditions of the disease.

Age-associated changes in the circulating human antibody repertoire are upregulated in autoimmunity

Background

The immune system undergoes a myriad of changes with age. While it is known that antibody-secreting plasma and long-lived memory B cells change with age, it remains unclear how the binding profile of the circulating antibody repertoire is impacted.

Results

To understand humoral immunity changes with respect to age, we characterized serum antibody binding to high density peptide microarrays in a diverse cohort of 1675 donors. We discovered thousands of peptides that bind antibodies in age-dependent fashion, many of which contain di-serine motifs. Peptide binding profiles were aggregated into an “immune age” by a machine learning regression model that was highly correlated with chronological age. Applying this regression model to previously-unobserved donors, we found that a donor’s predicted immune age is longitudinally consistent over years, suggesting it could be a robust long-term biomarker of humoral immune ageing. Finally, we assayed serum from donors with autoimmune disease and found a significant association between “accelerated immune ageing” and autoimmune disease activity.

Conclusions

The circulating antibody repertoire has increased binding to thousands of di-serine peptide containing peptides in older donors, which can be represented as an immune age. Increased immune age is associated with autoimmune disease, acute inflammatory disease severity, and may be a broadly relevant biomarker of immune function in health, disease, and therapeutic intervention.

Differential contribution of bone marrow-derived infiltrating monocytes and resident macrophages to persistent lung inflammation in chronic air pollution exposure

Chronic exposure to particulate matter < 2.5µ (PM_2.5) has been linked to cardiopulmonary disease. Tissue-resident (TR) alveolar macrophages (AΦ) are long-lived, self-renew and critical to the health impact of inhalational insults. There is an inadequate understanding of the impact of PM_2.5 exposure on the nature/time course of transcriptional responses, self-renewal of AΦ, and the contribution from bone marrow (BM) to this population. Accordingly, we exposed chimeric (CD45.2/CD45.1) mice to concentrated PM_2.5 or filtered air (FA) to evaluate the impact on these end-points. PM_2.5 exposure for 4-weeks induced an influx of BM-derived monocytes into the lungs with no contribution to the overall TR-AΦ pool. Chronic (32-weeks) PM_2.5 exposure on the other hand while associated with increased recruitment of BM-derived monocytes and their incorporation into the AΦ population, resulted in enhanced apoptosis and decreased proliferation of TR-AΦ. RNA-seq analysis of isolated TR-AΦ and BM-AΦ from 4- and 32-weeks exposed mice revealed a unique time-dependent pattern of differentially expressed genes. PM_2.5 exposure resulted in altered histological changes in the lungs, a reduced alveolar fraction which corresponded to protracted lung inflammation. Our findings suggest a time-dependent entrainment of BM-derived monocytes into the AΦ population of PM_2.5 exposed mice, that together with enhanced apoptosis of TR-AΦ and reorganization of transcriptional responses, could collectively contribute to the perpetuation of chronic inflammation.

Normal Aging and Its Role in Cancer Metastasis

Metastasis is the most common cause of death, with treatments failing to provide a durable response. Aging is a key prognostic factor in many cancers. Emerging data suggest that normal age-related changes in the tumor microenvironment can contribute to metastatic progression. These changes encompass secreted factors, biophysical changes, and changes in both stromal and immune cell populations. These data also highlight the importance of conducting studies in preclinical models of appropriate age. Ultimately, therapies may also need to be tailored to reflect patient age, as markers of metastatic disease differ in young and aged populations. In this review, we will discuss some of the changes that occur during aging that increase the metastatic capacity of tumor cells.

Beneficial effects of IL-4 and IL-6 on rat neonatal target cardiac cells

The nature of the early post-natal immune response in rodents appears to influence cardiac regeneration even though the underlying molecules remain poorly understood. Consistent with this idea, we show now significant changes in the expression of immune and cell movement gene pathways in heart samples from 1- and 7-day-old rats with ventricle resection. We then tested whether conditioned media from adult M2 anti-inflammatory macrophages target neonatal cardiac cells to a pro-regenerative like phenotype compared to the M1 pro-inflammatory macrophages. We found that M2 compared to M1 macrophage-conditioned media upregulates neonatal cardiomyocyte proliferation, suppresses myofibroblast-induced differentiation and stimulates endothelial cell tube formation. Using a cytokine array, we selected four candidate cytokine molecules uniquely expressed in M2 macrophage-conditioned media and showed that two of them (IL-4 and IL-6) induce endothelial cell proliferation whilst IL-4 promotes proliferation in neonatal cardiomyocytes and prevents myofibroblast-induced collagen type I secretion. Altogether, we provided evidence that adult M2 macrophage-conditioned media displays a paracrine beneficial pro-regenerative response in target cardiac cells and that IL-4 and IL-6 recapitulate, at least in part, these pleiotropic effects. Further characterization of macrophage immune phenotypes and their secreted molecules may give rise to novel therapeutic approaches for post-natal cardiac repair.

The Link between Chronic Stress and Accelerated Aging

People exposed to chronic stress age rapidly. The telomeres in their cells of all types shorten faster. Inflammation is another important feature of stress that, along with aging, accounts for the phenomenon of inflammaging. In addition to aging itself, inflammaging can contribute to the development of several pathologies, including atherosclerosis, diabetes, hypertension, and others. Oxidative stress is one of the main mechanisms related to stress. Oxidative stress is caused by the over-production of reactive oxygen species (ROS) that can damage various tissues. The main source of ROS is mitochondria. Being suppressed by mitochondrial mutations, mitophagy can aggravate the situation. In this case, the aging-specific pro-inflammatory changes are amplified. It happens because of the inability of cells to maintain the normal state of mitochondria. Macrophages are the crucial element of the innate immunity associated with the chronic inflammation and, subsequently, with the inflammaging. In this review, we focus on the therapy approaches potentially reducing the deleterious effects of oxidative stress. These include stimulation of mitophagy, activation of mitochondrial uncoupling, induction of the expression of the telomerase catalytic component gene, and use of antioxidants. Any method reducing oxidative stress should improve post-traumatic stress disorder.

How the ageing microenvironment influences tumour progression

Most cancers arise in individuals over the age of 60. As the world population is living longer and reaching older ages, cancer is becoming a substantial public health problem. It is estimated that, by 2050, more than 20% of the world's population will be over the age of 60 - the economic, healthcare and financial burdens this may place on society are far from trivial. In this Review, we address the role of the ageing microenvironment in the promotion of tumour progression. Specifically, we discuss the cellular and molecular changes in non-cancerous cells during ageing, and how these may contribute towards a tumour permissive microenvironment; these changes encompass biophysical alterations in the extracellular matrix, changes in secreted factors and changes in the immune system. We also discuss the contribution of these changes to responses to cancer therapy as ageing predicts outcomes of therapy, including survival. Yet, in preclinical studies, the contribution of the aged microenvironment to therapy response is largely ignored, with most studies designed in 8-week-old mice rather than older mice that reflect an age appropriate to the disease being modelled. This may explain, in part, the failure of many successful preclinical therapies upon their translation to the clinic. Overall, the intention of this Review is to provide an overview of the interplay that occurs between ageing cell types in the microenvironment and cancer cells and how this is likely to impact tumour metastasis and therapy response.

Attenuated Macrophage Infiltration in Glomeruli of Aged Mice Resulting in Ameliorated Kidney Injury in Nephrotoxic Serum Nephritis

Senescent cells have deleterious effects on the tissue microenvironment through proinflammatory senescence-associated secretory phenotypes; meanwhile, the onset of glomerulonephritis is predominant in younger adults. To clarify the influence of aging on the onset and development of glomerulonephritis, we used a murine model of antibody-mediated nephritis. Sheep nephrotoxic serum was administered in C57BL/6J mice at 12 weeks (adult) or 18 months old (aged) after pre-immunization with sheep IgG. Depositions of sheep IgG and autologous mouse IgG along the glomerular basement membrane and the serum titer of anti-sheep IgG-specific mouse IgG were similar between adult and aged mice. However, kidney injury was depressed in aged mice, accompanied by reduced macrophage infiltration in the glomeruli. The mRNA expression of most chemokines involved in monocyte/macrophage chemotaxis was not different between adult and aged mice, but the cell surface expression of C-C chemokine receptor (CCR) 1 and CCR2 was down-regulated in the monocyte/macrophage lineage cells infiltrating the kidneys of aged nephritic mice. Furthermore, expression of all four isotypes of the Fcγ receptor (FcγR) was reduced in these cells. Both CCR and FcγR expression were down-regulated in monocyte/macrophage lineage cells, resulting in attenuated glomerular infiltration of these cells and impaired glomerular injury in aged mice.

Attenuated inflammatory response of monocyte-derived macrophage from patients with BD: a preliminary report

BACKGROUND

Innate immune system dysfunction has been recognized as an important element in the pathophysiology of bipolar disorder (BD). We aimed to investigate whether there are differences in the response of macrophages derived from patients in the early stages and late stages of BD and healthy subjects.

METHODS

Human monocytes purified from peripheral blood mononuclear cells (PBMCs) of patients with BD type I (n = 18)-further classified into early- and late stage BD patients according to their functioning- and from healthy individuals (n = 10) were differentiated into macrophages in vitro. Monocyte-derived macrophages (M) were exposed to IFNγ plus LPS-M(IFNγ + LPS)- or IL-4-M(IL-4)-to induce their polarization into the classical (also called M1) or alternative (also called M2) activation phenotypes, respectively; or either Mψ were not exposed to any stimuli characterizing the resting state (denominated M0). In vitro secretion of cytokines, such as IL-1β, IL-6, IL-10, and TNF-α, was used as an index of macrophage activity.

RESULTS

M(IFNγ + LPS) from late-stage BD patients produced less amount of IL-1β, IL-6, and IL-10 when compared to early-stage BD patients and healthy controls. Following alternative activation, M(IL-4) derived from late-stage patients secreted less IL-6 compared to the other groups. TNFα was less secreted by all macrophage phenotypes derived from late-stage patients when compared to healthy controls only (p < 0.005). Mψ from late-stage patients exhibited lower production of IL-1β and IL-10 compared to macrophages from healthy subjects and early-stage patients respectively. Interestingly, cytokines secretion from M(IFNγ + LPS), M(IL-4) and Mψ were similar between early-stage patients and healthy controls.

CONCLUSION

Our results suggest a progressive dysfunction in the response of peripheral innate immune cells of BD patients in the late stages of the illness. This failure in the regulation of the immune system function may be implicated in the multisystemic progression of BD.

White blood cell counts, CRP, GGT and LDH in the elderly German population

Background

Hematological abnormalities are frequently found in geriatric patients. However, little data is available on reference values for total blood cell counts in older patients. This study is focused on the analysis of reference values for white blood cell counts in aged persons ≥60 years.

Methods

This was a cross-sectional study of outpatient laboratory data of 2015 from a German countrywide working laboratory company; inclusion criteria: age ≥60 years, parameters evaluated by the laboratory company between 1.1.2015 and 31.12.2015; exclusion criteria: glomerular filtration rate (GFR) <60 mL/min, lack of inclusion criteria; primary objective: mean leukocyte count; secondary objective: mean counts of lymphocytes, eosinophil, neutrophil and basophil leukocytes as well as platelets, C-reactive protein (CRP), γ-glutamyl transferase (GGT) and lactate dehydrogenase (LDH) in hematologically healthy persons aged ≥60 years.

Results

Data of 30,611 persons aged ≥60 years were evaluated by age groups. Results for leukocytes, basophils, eosinophils, neutrophils and lymphocytes remained within the reference ranges recommended by the German Society of Hematology and Oncology (DGHO) and the German Association of Specialists in Internal Medicine (BDI); the lower reference limit for normal platelet values in males was below the DGHO reference value with 136,000/μL (confidence interval [CI] 129,000;142,000); similarly, our results for normal monocyte values were above the DGHO reference values with 6.0% (5.7;6.2) to 14.3% (13.9;14.8) in males and 5.4% (5.2;5.6) to 12.9% (12.6;13.4) in females; CRP, GGT and LDH values were above the BDI reference values, comparable with the previous data of a senior patient cohort analysis.

Conclusions

Adaptation of reference values for selected laboratory parameters in older German patients should be well considered.

Immunosenescence and lymphomagenesis

One of the most important determinants of aging-related changes is a complex biological process emerged recently and called “immunosenescence”. Immunosenescence refers to the inability of an aging immune system to produce an appropriate and effective response to challenge. This immune dysregulation may manifest as increased susceptibility to infection, cancer, autoimmune disease, and vaccine failure. At present, the relationship between immunosenescence and lymphoma in elderly patients is not defined in a satisfactory way.

This review presents a brief overview of the interplay between aging, cancer and lymphoma, and the key topic of immunosenescence is addressed in the context of two main lymphoma groups, namely Non Hodgkin Lymphoma (NHL) and Hodgkin Lymphoma (HL). Epstein Barr Virus (EBV) plays a central role in the onset of neoplastic lymphoproliferation associated with immunological changes in aging, although the pathophysiology varies vastly among different disease entities. The interaction between immune dysfunction, immunosenescence and Epstein Barr Virus (EBV) infection appears to differ between NHL and HL, as well as between NHL subtypes.

Mitochondrial Dysfunction in Pulmonary Fibrosis

The aging of the human population has resulted in an unprecedented increase in the incidence and prevalence of age-related diseases, including those of the lung. Idiopathic pulmonary fibrosis is a disease of aging, and is characterized by a progressive decline in lung function and high mortality. Recent studies suggest that mitochondrial dysfunction, which can accompany aging phenotypes, may contribute to the pathogenesis of idiopathic pulmonary fibrosis. In this review, we explore current evidence for mitochondrial dysfunction in alveolar epithelial cells, fibroblasts, and immune cells that participate in the fibrotic process. Further, the fates of these cell populations and the potential to target mitochondrial dysfunction as a therapeutic strategy are discussed.

Aged Mice are More Resistant to Influenza Virus Infection due to Reduced Inflammation and Lung Pathology

Immune responses are a double-edged sword. Effective and appropriate immune responses capable of controlling viral infection while also largely preserving tissue integrity, are critical for host survival. Too strong immune responses might result in immune pathology, while too weak immune responses might cause viral persistence. Physiologic ageing is accompanied with a decline in the normal functioning of the immune system, which is termed as "immunosenescence". We show that aged mice (16-19 months old) are more resistant to influenza A virus (IAV) infection than the young mice. Strong immune responses in the young mice after IAV infection result in faster clearance of virus, but also cause severe lung injury and higher mortality rate. While in the aged mice, the delayed and milder immune responses contribute to reduced pulmonary damage, and are still capable to clear the infection even with a slower kinetics, displaying a more resistant phenotype during IAV infection. Hence, our work demonstrates that moderate immune responses as a decline with ageing in the aged mice balance the immune pathology and viral clearance, might be beneficial for the host during certain circumstances. Our results provide important insight to our basic knowledge of immunosenescence and immune defenses to invading pathogens. Further, our results indicate that age factors should be considered when investigating the vaccination and therapeutic strategies for severe IAV infection.

Expression of CD206 and CD163 on intermediate CD14++CD16+ monocytes are increased in hemorrhagic fever with renal syndrome and are correlated with disease severity

BACKGROUND

Hantaan virus infection causes lethal hemorrhagic fever with renal syndrome (HFRS) in humans. Little is known about how monocytes contribute to HFRS pathogenesis. In this study, we aimed to investigate changes in various monocyte subsets in HFRS patients.

METHODS

A total of 41 HFRS patients and 17 age-, sex-, and ethnicity-matched healthy control subjects were included in this study. Numbers/percentages of various monocyte subsets were quantitatively determined using flow cytometry. Serum levels of interleukin (IL)-10, IL-12, and tumor necrosis factor alpha (TNF-α) were detected using a cytometric bead array (CBA).

RESULTS

CD14⁺⁺CD16⁺ intermediate monocytes were significantly higher in HFRS patients compared to healthy controls (P < 0.01), especially during the acute phase. The expression of both CD163 and CD206 on CD14⁺⁺CD16⁺ intermediate monocytes were increased during the acute phase of HFRS (P < 0.01 and P < 0.05, respectively) when comparing the convalescent phase and healthy controls. Furthermore, the numbers of CD14⁺⁺CD16⁺ monocytes during the acute phase, and the percentages of CD14⁺⁺CD16⁺CD163⁺ monocytes in patients with severe/critical HFRS were much higher compared to patients with mild/moderate HFRS. This also positively correlated with increased levels of white blood cells (WBC), blood urea nitrogen (BUN), and creatinine (Cr). However, the percentages of CD14⁺⁺CD16⁺CD206⁺monocytes were higher in mild/moderate HFRS than in severe/critical HFRS, and they negatively correlated with platelets (PLT) and Cr.

CONCLUSIONS

Higher frequency of the CD14⁺⁺CD16⁺ intermediate monocytes and increased expression of CD163⁺ and CD206⁺ markers on CD14⁺⁺CD16⁺ monocytes were detected in patients with HFRS. The changes in the frequency of CD14⁺⁺CD16⁺ monocytes and expression of CD163 and CD206 markers on CD14⁺⁺CD16⁺ monocytes positively correlated with the severity of HFRS.

Cardioprotective effect of Amaranthus tricolor extract in isoprenaline induced myocardial damage in ovariectomized rats

Red spinach (Amaranthus tricolor) has been reported to possess many benefits and medicinal properties and used as a part of traditional medicine in Ayurveda and Siddha. The aim of the study was to investigate the effects of Amaranthus tricolor on isoproterenol-induced oxidative stress, fibrosis, and myocardial damage in ovariectomized rats. Ovariectomy surgery was conducted to remove both ovaries from the rats. After recovery, rats were administered with ISO subcutaneously (50 mg/kg) twice a week and were treated with ethanolic extracts of A. tricolor. This investigation showed that the level of oxidative stress markers was significantly increased while the superoxide dismutase (SOD) activity decreased in ISO administered ovariectomized rats. A. tricolor extract and atenolol treatment prevented the rise of malondialdehyde, nitric oxide and advanced protein oxidation product. Moreover, elevated activities of AST, ALT, and CK-MB enzymes were also lowered by both atenolol and A. tricolor treatment. Increased uric acid and creatinine levels were also normalized by atenolol, and A. Tricolor treatment in ISO administered ovariectomized rats. ISO-induced ovariectomized rats also showed massive inflammatory cell infiltration, fibrosis and iron deposition in heart compared to sham rats. Atenolol and A. tricolor treatment prevented the inflammatory cells infiltration, fibrosis, and iron deposition. These results suggest that A. tricolor treatment may protect against ISO administered myocardial infarction in ovariectomized rats probably by preventing inflammation, oxidative stress, and fibrosis. Further research is warranted to examine molecular mechanism of cardioprotective effect of A. tricolor.

The Role of Immunosenescence in Neurodegenerative Diseases

Aging is characterized by the progressive decline of physiological function and tissue homeostasis leading to increased vulnerability, degeneration, and death. Aging-related changes of the innate and adaptive immune system include decline in the preservation and enhancement of many immune functions, such as changes in the number of circulating monocytic and dendritic cells, thymic involution, T cell polyfunctionality, or production of proinflammatory cytokines, and are defined as immunosenescence. Inflammatory functions are increased with age, causing the chronic low-grade inflammation, referred to as inflamm-aging, that contribute, together with immunosenescence, to neurodegenerative diseases. In this review, we discuss the link between the immune and nervous systems and how the immunosenescence and inflamm-aging can contribute to neurodegenerative diseases.

Cardiac macrophage biology in the steady-state heart, the aging heart, and following myocardial infarction

Macrophages play critical roles in homeostatic maintenance of the myocardium under normal conditions and in tissue repair after injury. In the steady-state heart, resident cardiac macrophages remove senescent and dying cells and facilitate electrical conduction. In the aging heart, the shift in macrophage phenotype to a proinflammatory subtype leads to inflammaging. Following myocardial infarction (MI), macrophages recruited to the infarct produce both proinflammatory and anti-inflammatory mediators (cytokines, chemokines, matrix metalloproteinases, and growth factors), phagocytize dead cells, and promote angiogenesis and scar formation. These diverse properties are attributed to distinct macrophage subtypes and polarization status. Infarct macrophages exhibit a proinflammatory M1 phenotype early and become polarized toward an anti-inflammatory M2 phenotype later post-MI. Although this classification system is oversimplified and needs to be refined to accommodate the multiple different macrophage subtypes that have been recently identified, general concepts on macrophage roles are independent of subtype classification. This review summarizes current knowledge about cardiac macrophage origins, roles, and phenotypes in the steady state, with aging, and after MI, as well as highlights outstanding areas of investigation.

Age has a role in driving host immunopathological response to alphavirus infection

Alphaviruses are a group of arthropod-borne pathogens capable of causing a wide spectrum of clinical symptoms, ranging from milder symptoms like rashes, fever and polyarthralgia, to life-threatening encephalitis. This genus of viruses is prevalent globally, and can infect patients across a wide age range. Interestingly, disease severity of virus-infected patients is wide-ranging. Definitions of the pathogenesis of alphaviruses, as well as the host factors influencing disease severity, remain limited. The innate and adaptive immune systems are important host defences against alphavirus infections. Several reports have highlighted the roles of specific immune subsets in contributing to the immune pathogenesis of these viruses. However, immunosenescence, a gradual deterioration of the immune system brought about by the natural advancement of age, affects the functional roles of these immune subsets. This phenomenon compromises the host's ability to defend against alphavirus infection and pathogenesis. In addition, the lack of maturity in the immune system in newborns and infants also results in more severe disease outcomes. In this review, we will summarize the subtle yet diverse physiological changes in the immune system during aging, and how these changes underlie the differences in disease severity for common alphaviruses.

Circulating markers of ageing and allostatic load: A slow train coming

Dealing with the growing burden of age-related morbidities is one of the greatest challenges facing modern society. How we age across the lifecourse and how psychosocial and lifestyle factors interplay with the biology of ageing remains to be fully elucidated. Sensitive and specific biomarkers with which to interrogate the biology of the ageing process are sparse. Recent evidence suggests that non-coding RNAs are key determinants of such processes and that these can be used as potential circulatory bio-markers of ageing. They may also provide a mechanism which mediates the spread of allostatic load across the body over time, ultimately reflecting the immunological health and physiological status of tissues and organs. The interplay between exosomal microRNAs and ageing processes is still relatively unexplored, although circulating microRNAs have been linked to the regulation of a range of physiological and pathological processes and offer insight into mechanistic determinants of healthspan.

Methotrexate combined with methylprednisolone for the recovery of motor function and differential gene expression in rats with spinal cord injury

Methylprednisolone is a commonly used drug for the treatment of spinal cord injury, but high doses of methylprednisolone can increase the incidence of infectious diseases. Methotrexate has anti-inflammatory activity and immunosuppressive effects, and can reduce inflammation after spinal cord injury. To analyze gene expression changes and the molecular mechanism of methotrexate combined with methylprednisolone in the treatment of spinal cord injury, a rat model of spinal cord contusion was prepared using the PinPoint™ precision cortical impactor technique. Rats were injected with methylprednisolone 30 mg/kg 30 minutes after injury, and then subcutaneously injected with 0.3 mg/kg methotrexate 1 day after injury, once a day, for 2 weeks. TreadScan gait analysis found that at 4 and 8 weeks after injury, methotrexate combined with methylprednisolone significantly improved hind limb swing time, stride time, minimum longitudinal deviation, instant speed, footprint area and regularity index. Solexa high-throughput sequencing was used to analyze differential gene expression. Compared with methylprednisolone alone, differential expression of 316 genes was detected in injured spinal cord treated with methotrexate and methylprednisolone. The 275 up-regulated genes were mainly related to nerve recovery, anti-oxidative, anti-inflammatory and anti-apoptotic functions, while 41 down-regulated genes were mainly related to proinflammatory and pro-apoptotic functions. These results indicate that methotrexate combined with methylprednisolone exhibited better effects on inhibiting the activity of inflammatory cytokines and enhancing antioxidant and anti-apoptotic effects and thereby produced stronger neuroprotective effects than methotrexate alone. The 316 differentially expressed genes play an important role in the above processes.

Immunosenescence-Related Transcriptomic and Immunologic Changes in Older Individuals Following Influenza Vaccination

The goal of annual influenza vaccination is to reduce mortality and morbidity associated with this disease through the generation of protective immune responses. The objective of the current study was to examine markers of immunosenescence and identify immunosenescence-related differences in gene expression, gene regulation, cytokine secretion, and immunologic changes in an older study population receiving seasonal influenza A/H1N1 vaccination. Surprisingly, prior studies in this cohort revealed weak correlations between immunosenescence markers and humoral immune response to vaccination. In this report, we further examined the relationship of each immunosenescence marker (age, T cell receptor excision circle frequency, telomerase expression, percentage of CD28⁻ CD4⁺ T cells, percentage of CD28⁻ CD8⁺ T cells, and the CD4/CD8 T cell ratio) with additional markers of immune response (serum cytokine and chemokine expression) and measures of gene expression and/or regulation. Many of the immunosenescence markers indeed correlated with distinct sets of individual DNA methylation sites, miRNA expression levels, mRNA expression levels, serum cytokines, and leukocyte subsets. However, when the individual immunosenescence markers were grouped by pathways or functional terms, several shared biological functions were identified: antigen processing and presentation pathways, MAPK, mTOR, TCR, BCR, and calcium signaling pathways, as well as key cellular metabolic, proliferation and survival activities. Furthermore, the percent of CD4⁺ and/or CD8⁺ T cells lacking CD28 expression also correlated with miRNAs regulating clusters of genes known to be involved in viral infection. Integrated (DNA methylation, mRNA, miRNA, and protein levels) network biology analysis of immunosenescence-related pathways and genesets identified both known pathways (e.g., chemokine signaling, CTL, and NK cell activity), as well as a gene expression module not previously annotated with a known function. These results may improve our ability to predict immune responses to influenza and aid in new vaccine development, and highlight the need for additional studies to better define and characterize immunosenescence.

The Progress of Therapeutic Vaccination with Regard to Tuberculosis

A major problem with tuberculosis (TB) control is the long duration of drug therapy-both for latent and for active TB. Therapeutic vaccination has been postulated to improve this situation, and to this end there are several candidates already in clinical phases of development. These candidates follow two main designs, namely bacilli-directed therapy based on inactivated -whole or -fragmented bacillus (Mycobacterium w and RUTI) or fusion proteins that integrate non-replicating bacilli -related antigens (H56 vaccine), and host-directed therapy to reduce the tissue destruction. The administration of inactivated Mycobacterium vaccae prevents the "Koch phenomenon" response, and oral administration of heat-killed Mycobacterium manresensis prevents excessive neutrophilic infiltration of the lesions. This review also tries to explain the success of Mycobacterium tuberculosis by reviewing its evolution from infection to disease, and highlights the lack of a definitive understanding of the natural history of TB pathology and the need to improve our knowledge on TB immunology and pathogenesis.

Intracellular signalling pathways: targets to reverse immunosenescence

Ageing is a very complex process, the result of the dysregulation of multiple systems interacting in many ways. A prominent change occurring with ageing is related to the architecture and functioning of the immune system, viewed commonly as detrimental and termed 'immunosenescence'. However, age-associated changes may also lead to increased function in certain respects, which can be viewed as adaptive. None the less, on balance it is well-recognized that immunosenescence is accompanied by the low-grade inflammation observed commonly in elderly people, which has been dubbed 'inflamm-ageing'. The exact cause and significance of all these changes is not clear, but there is a consensus that they are related to the occurrence of chronic non-infectious age-associated disease, as well as increased susceptibility to infections. Alterations to immune cell signalling may be a prominent cause of malfunctioning immunity. Emerging attempts to reverse immunosenescence have recently targeted the signalling pathways in various different cell types of the immune system. Here, we review and discuss alterations in the signalling pathways of immune cells with ageing and consider current targets and means to modulate altered functions. We discuss the potential dangers as well as the benefits of these interventions, and consider future approaches to this problem.

Senescent endothelial cells: Potential modulators of immunosenescence and ageing

Recent studies have demonstrated that the accumulation of senescent endothelial cells may be the primary cause of cardiovascular diseases. Because of their multifunctional properties, endothelial cells actively take part in stimulating the immune system and inflammation. In addition, ageing is characterized by the progressive deterioration of immune cells and a decline in the activation of the immune response. This results in a loss of the primary function of the immune system, which is eliminating damaged/senescent cells and neutralizing potential sources of harmful inflammatory reactions. In this review, we discuss cellular senescence and the senescence-associated secretory phenotype (SASP) of endothelial cells and summarize the link between endothelial cells and immunosenescence. We describe the possibility that age-related changes in Toll-like receptors (TLRs) and microRNAs can affect the phenotypes of senescent endothelial cells and immune cells via a negative feedback loop aimed at restraining the excessive pro-inflammatory response. This review also addresses the following questions: how do senescent endothelial cells influence ageing or age-related changes in the inflammatory burden; what is the connection between ECs and immunosenescence, and what are the crucial hypothetical pathways linking endothelial cells and the immune system during ageing.