Robust shifts in S100a9 expression with aging: a novel mechanism for chronic inflammation

Effect of calcitriol on myeloid-derived suppressor cells in physiological aging

The active hormonal form of vitamin D, 1,25(OH)2D, regulates many components of the immune system and previous research shows that 1,25(OH)2D reduces the number and suppressive activity of MDSCs in tumors. This study aimed to evaluate the effects of calcitriol treatment on MDSCs in aged mice. We showed that aged BALB/c and CD1 mice exhibited increased levels of CD11b+Gr1+ cells in both the spleen and bone marrow compared to young mice. These cells displayed a less mature phenotype marked by reduced F4/80 expression and demonstrated robust T cell suppressive activity, as evidenced by their ability to inhibit the production of IFNγ and TNFα. Treatment of aged mice with calcitriol, administered twice weekly at a dose equivalent to 1 µg/kg for 4 weeks, significantly increased the population of CD11b+Gr1+ cells in the spleen, but not in the bone marrow of the animals, and promoted their differentiation into a more mature phenotype characterized by elevated F4/80 expression. In addition, calcitriol-treated aged mice exhibited significantly improved T cell responses, as indicated by increased IFNγ production upon specific antigen stimulation compared to the control group of mice. In vitro, calcitriol treatment of bone marrow-derived MDSCs similarly enhanced F4/80 expression without altering other markers such as CD11b, CD11c, or MHCII, and led to reduced expression of reactive oxygen species by these cells. Our study highlights the consistency of MDSC expansion across inbred and outbred mouse strains and supports the immunomodulatory role of calcitriol in promoting MDSC maturation and alleviating immune suppression in aging.

The role of calprotectin in vascular calcification

PURPOSE OF REVIEW

Vascular calcification significantly contributes to cardiovascular morbidity and mortality, particularly in high-risk populations like chronic kidney disease (CKD) patients. Calprotectin, a heterodimeric protein with pro-inflammatory and pro-calcific properties, has emerged as a key molecule in vascular pathology. This review highlights the mechanisms linking calprotectin to vascular calcification, its clinical relevance, and its potential as a therapeutic target.

RECENT FINDINGS

Vascular calcification is an active, cell-mediated process involving vascular smooth muscle cell (VSMC) dysfunction, inflammation, matrix remodeling, and cellular senescence. Calprotectin is strongly associated with cardiovascular disease and vascular calcification, particularly in CKD. Mechanistic studies reveal that calprotectin promotes calcification through the activation of RAGE and TLR4 signaling pathways, driving inflammatory cascades. Preclinical studies demonstrate that pharmacological inhibition of calprotectin attenuates vascular calcification in animal models, supporting its potential as a therapeutic target.

SUMMARY

Calprotectin is emerging as a promising biomarker and therapeutic target in vascular calcification, particularly in CKD and aging-related vascular diseases. However, further studies are required to clarify its mechanisms and assess the long-term efficacy and safety of calprotectin-targeted therapies. A deeper understanding of calprotectin's multifaceted role could pave the way for innovative therapeutic strategies targeting both inflammation and mineralization in calcification-related vascular diseases.

The mechanism of disease progression by aging and age-related gut dysbiosis in multiple sclerosis

Multiple sclerosis (MS) is the most common demyelinating disease caused by a multifaceted interplay of genetic predispositions and environmental factors. Most patients initially experience the relapsing-remitting form of the disease (RRMS), which is characterized by episodes of neurological deficits followed by periods of symptom resolution. However, over time, many individuals with RRMS advance to a progressive form of the disease, known as secondary progressive MS (SPMS), marked by a gradual worsening of symptoms without periods of remission. The mechanisms underlying this transition remain largely unclear, and current disease-modifying therapies (DMTs) are partially effective in treating SPMS. Age is widely acknowledged as a risk factor for the transition from RRMS to SPMS. One factor associated with aging that may influence the progression of MS is gut dysbiosis. This review discusses how aging and age-related gut dysbiosis affect the progression of MS.

The role of the immune system in osteoarthritis: mechanisms, challenges and future directions

Osteoarthritis (OA) is a chronic joint disease that has long been considered a simple wear-and-tear condition. Over the past decade, research has revealed that various inflammatory features of OA, such as low-grade peripheral inflammation and synovitis, contribute substantially to the pathophysiology of the disease. Technological advances in the past 5 years have revealed a large diversity of innate and adaptive immune cells in the joints, particularly in the synovium and infrapatellar fat pad. Notably, the presence of synovial lymphoid structures, circulating autoantibodies and alterations in memory T cell and B cell populations have been documented in OA. These data indicate a potential contribution of self-reactivity to the disease pathogenesis, blurring the often narrow and inaccurate line between chronic inflammatory and autoimmune diseases. The diverse immune changes associated with OA pathogenesis can vary across disease phenotypes, and a better characterization of their underlying molecular endotypes will be key to stratifying patients, designing novel therapeutic approaches and ultimately ameliorating treatment allocation. Furthermore, examining both articular and systemic alterations, including changes in the gut-joint axis and microbial dysbiosis, could open up novel avenues for OA management.

S100A9 protein activates microglia and stimulates phagocytosis, resulting in synaptic and neuronal loss

S100 calcium-binding protein A9 (S100A9, also known as calgranulin B) is expressed and secreted by myeloid cells under inflammatory conditions, and S100A9 can amplify inflammation. There is a large increase in S100A9 expression in the brains of patients with neurodegenerative diseases, such as Alzheimer's disease, and S100A9 has been suggested to contribute to neurodegeneration, but the mechanisms are unclear. Here we investigated the effects of extracellular recombinant S100A9 protein on microglia, neurons and synapses in primary rat brain neuronal-glial cell cultures. Incubation of cell cultures with 250-500 nM S100A9 caused neuronal loss without signs of apoptosis or necrosis, but accompanied by exposure of the "eat-me" signal - phosphatidylserine on neurons. S100A9 caused activation of microglial inflammation as evidenced by an increase in the microglial number, morphological changes, release of pro-inflammatory cytokines, and increased phagocytic activity. At lower concentrations, 10-100 nM S100A9 induced synaptic loss in the cultures. Depletion of microglia from the cultures prevented S100A9-induced neuronal and synaptic loss, indicating that neuronal and synaptic loss was mediated by microglia. These results suggest that extracellular S100A9 may contribute to neurodegeneration by activating microglial inflammation and phagocytosis, resulting in loss of synapses and neurons. This further suggests the possibility that neurodegeneration may be reduced by targeting S100A9 or microglia.

Mechanism of S100A9-mediated astrocyte activation via TLR4/NF-κB in Parkinson's disease

Astrocyte-mediated neuroinflammation plays a key role in Parkinson's disease (PD) progression. The proinflammatory protein S100A9 is linked to various neurodegenerative diseases, but its involvement in astrocyte activation in PD remains unclear. Here, we investigate the role of S100A9 in astrocyte-mediated neuroinflammation in PD. C57BL/6J mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 15 mg/kg four times daily) and subsequently treated with Paquinimod, a S100A9 inhibitor (7 mg/kg, once daily for 7 days, totaling 8 doses). We observed an abnormal increase in S100A9 protein expression and a rise in S100A9-positive cells in the striatum of PD mice. Paquinimod treatment significantly improved behavioral deficits (pole test, rotarod test, traction test, and open field tests), prevented the reduction in striatal tyrosine hydroxylase (TH) protein and the loss of dopaminergic neurons (TH+) in the substantia nigra (SN) in PD mice. Interestingly, S100A9 was predominantly expressed in astrocytes (GFAP+S100A9+ cells) rather than in neurons or microglia, and its inhibition significantly reduced astrocyte activation (GFAP+ cells), reversed A1 astrocyte gene upregulation (H2-D1, C3, Serping1), and increased A2 astrocyte gene expression (Emp1, Ptx3, S100a10). Moreover, S100A9 inhibition also reduced the expression of inflammatory markers (IL-6, IL-1β, TNF-α) and suppressed the TLR4/NF-κB signaling pathway. In vitro, TLR4/NF-κB inhibitors mitigated inflammation and A1/A2 polarization of astrocytic MA cells induced by recombinant S100A9 (rS100A9). These findings suggest that S100A9 mediates astrocyte neuroinflammation and A1/A2 polarization via TLR4/NF-κB signaling, highlighting its potential as a therapeutic target for PD.

Advanced Age Worsens Respiratory Function and Pulmonary Inflammation After Burn Injury and This Correlates With Changes in the Fecal Microbiome in Mice

Cutaneous burn injury in the elderly is associated with poor clinical outcomes and increased pulmonary-related complications. We and others have shown that burn injury triggers a cascade of inflammatory mediators which increase gut permeability and dysbiosis of the fecal microbiota and this is more dramatic in the aged. Since crosstalk between intestinal microbes and the lung, termed the "gut-lung axis," impacts immunity and homeostasis in the airway, we hypothesized that the increased intestinal dysbiosis in age and burn injury may contribute to excessive pulmonary inflammation and poor prognosis after injury. To explore this hypothesis, we used a clinically relevant murine model of burn injury in which young and aged mice are subjected to a 12% TBSA dorsal scald burn or sham injury. About 24 h after injury, lung function was assessed and lungs and feces were collected for analysis of inflammatory mediators and fecal microbial species. The results show that, when compared to younger mice, burn injury in aged mice triggers a decline in respiratory function and exacerbates pulmonary inflammation. In addition to heightened levels of the neutrophil recruiting chemokine CXCL1, aged mice displayed a profound increase in the pro-inflammatory protein, calprotectin, in the lung after burn injury. Comparison of the fecal microbiome and inflammatory markers in the lung revealed unique, age-dependent, correlation patterns between individual taxa and pulmonary inflammation. Taken together, these findings suggest that the postburn dysbiosis of the gut flora in aged mice may contribute to the changes in pulmonary inflammatory profiles.

Menopause mysteries: the exosome-inflammation connection

Extracellular vesicles, or exosomes, are produced by every type of cell and contain metabolites, proteins, lipids, and nucleic acids. Their role in health and disease is to influence different aspects of cell biology and to act as intermediaries between cells. Follicular fluid exosomes or extracellular vesicles (FF-EVs) secreted by ovarian granulosa cells are critical mediators of ovary growth and maturation. The movement and proteins of these exosomes are crucial in the regulation of cellular communication and the aging of cells, a process termed inflammaging. Menopause, a natural progression in the aging of females, is often accompanied by numerous negative symptoms and health issues. It can also act as a precursor to more severe health problems, including neurological, cardiovascular, and metabolic diseases, as well as gynecological cancers. Researchers have discovered pathways that reveal the diverse effects of exosome-driven cellular communication and oocyte development in the follicular fluid. It also explores the complex functions of FF exosomal proteins in the pathologies associated with menopause.

Human monocyte subtype expression of neuroinflammation- and regeneration-related genes is linked to age and sex

Aging profoundly affects the immune system leading to an increased propensity for inflammation. Age-related dysregulation of immune cells is implicated in the development and progression of numerous age-related diseases such as: cardiovascular diseases, neurodegenerative disorders, and metabolic syndromes. Monocytes and monocyte-derived macrophages, being important players in the inflammatory response, significantly influence the aging process and the associated increase in inflammatory disease risk. Ischemic stroke is among age-related diseases where inflammation, particularly monocyte-derived macrophages, plays an important deteriorating role but could also strongly promote post-stroke recovery. Also, biological sex influences the incidence, presentation, and outcomes of ischemic stroke, reflecting both biological differences between men and women. Here, we studied whether human peripheral blood monocyte subtype (classical, intermediate, and non-classical) expression of genes implicated in stroke-related inflammation and post-stroke tissue regeneration depends on age and sex. A flow cytometry analysis of blood samples from 44 healthy volunteers (male and female, aged 28 to 98) showed that in contrast to other immune cells, the proportion of NK-cells increased in females. The proportion of B-cells decreased in both sexes with age. Gene expression analysis by qPCR identified several genes differentially correlating with age and sex within different monocyte subtypes. Interestingly, ANXA1 and CD36 showed a consistent increase with aging in all monocytes, specifically in intermediate (CD36) and intermediate and non-classical (ANXA1) subtypes. Other genes (IL-1β, S100A8, TNFα, CD64, CD33, TGFβ1, TLR8, CD91) were differentially changed in monocyte subtypes with increasing age. Most age-dependent gene changes were differentially expressed in female monocytes. Our data shed light on the nuanced interplay of age and sex in shaping the expression of inflammation- and regeneration-related genes within distinct monocyte subtypes. Understanding these dynamics could pave the way for targeted interventions and personalized approaches in post-stroke care, particularly for the aging population and individuals of different sexes.

Pro-inflammatory protein S100A9 targeted by a natural molecule to prevent neurodegeneration onset

Accumulation of the pro-inflammatory protein S100A9 has been implicated in neuroinflammatory cascades in neurodegenerative diseases (NDs) such as Alzheimer's disease (AD) and Parkinson's disease (PD). S100A9 co-aggregates with other proteins such as α-synuclein in PD and Aβ in AD, contributing to amyloid plaque formation and neurotoxicity. The amyloidogenic nature of this protein and its role in chronic neuroinflammation suggest that it may play a key role in the pathophysiology of these diseases. Research into molecules targeting S100A9 could be a potential therapeutic strategy to prevent its amyloidogenic self-assembly and to attenuate the neuroinflammatory response in affected brain tissue. This work suggests that bioactive natural molecules, such as those found in the Mediterranean diet, may have the potential to alleviate neuroinflammation associated with the accumulation of proteins such as S100A9 in neurodegenerative diseases. A major component of extra virgin olive oil (EVOO), hydroxytyrosol (HT), with its ability to interact with and modulate S100A9 amyloid self-assembly and expression, offers a compelling approach for the development of novel and effective interventions for the prevention and treatment of ND. The findings highlight the importance of exploring natural compounds, such as HT, as potential therapeutic options for these complex and challenging neurological conditions.

Cmtm4 deficiency exacerbates colitis by inducing gut dysbiosis and S100a8/9 expression

The dysfunction of innate immunity components is one of the major drivers for ulcerative colitis (UC), and increasing reports indicate that the gut microbiome serves as an intermediate between genetic mutations and UC development. Here, we find that the IL-17 receptor subunit, CMTM4, is reduced in UC patients and dextran sulfate sodium (DSS)-induced colitis. The deletion of CMTM4 (Cmtm4-/-) in mice leads to a higher susceptibility to DSS-induced colitis than in wild-type, and the gut microbiome significantly changes in composition. The causal role of the gut microbiome is confirmed with a cohousing experiment. We further identify that S100a8/9 is significantly up-regulated in Cmtm4-/- colitis, with the block of its receptor RAGE that reverses the phenotype associated with the CMTM4 deficiency. CMTM4 deficiency rather suppresses S100a8/9 expression in vitro via the IL17 pathway, further supporting that the elevation of S100a8/9 in vivo is most likely a result of microbial dysbiosis. Taken together, the results suggest that CMTM4 is involved in the maintenance of intestinal homeostasis, suppression of S100a8/9, and prevention of colitis development. Our study further shows CMTM4 as a crucial innate immunity component, confirming its important role in UC development and providing insights into potential targets for the development of future therapies.

Influenza virus infection exacerbates gene expression related to neurocognitive dysfunction in brains of old mice

BACKGROUND

Age > 65 years is a key risk factor for poor outcomes after human influenza infection. Specifically, in addition to respiratory disease, non-neurotropic influenza A virus (IAV) causes neuro-cognitive complications, e.g. new onset depression and increases the risk of dementia after hospitalization. This study aimed to identify potential mechanisms of these effects by determining differences between young and old mice in brain gene expression in a mouse model of non-neurotropic IAV infection.

METHODS

Young (12 weeks) and old (70 weeks) C57Bl/6J mice were inoculated intranasally with 200 PFU H1N1 A/PR/34/8 (PR8) or sterile PBS (mock). Gene expression in lung and brain was measured by qRT-PCR and normalized to β-actin. Findings were confirmed using the nCounter Mouse Neuroinflammation Array (NanoString) and analyzed with nSolver 4.0 and Ingenuity Pathway Analysis (IPA, Qiagen).

RESULTS

IAV PR8 did not invade the central nervous system. Young and old mice differed significantly in brain gene expression at baseline and during non-neurotropic IAV infection. Expression of brain Ifnl, Irf7, and Tnf mRNAs was upregulated over baseline control at 3 days post-infection (p.i.) only in young mice, but old mice expressed more Ifnl than young mice 7 days p.i. Gene arrays showed down-regulation of the Epigenetic Regulation, Insulin Signaling, and Neurons and Neurotransmission pathways in old mice 3 days p.i. while young mice demonstrated no change or induction of these pathways at the same time point. IPA revealed marked baseline differences between old and young mice. Gene expression related to Cognitive Impairment, Memory Deficits and Learning worsened in old mice relative to young mice during IAV infection. Aged mice demonstrate more severe changes in gene expression related to memory loss and cognitive dysfunction by IPA.

CONCLUSIONS

These data suggest the genes and pathways related to learning and cognitive performance that were worse at baseline in old mice were further worsened by IAV infection, similar to old patients. Early events in the brain triggered by IAV infection portend downstream neurocognitive pathology in old adults.

S100A8-enriched microglia populate the brain of tau-seeded and accelerated aging mice

Long considered to fluctuate between pro- and anti-inflammatory states, it has now become evident that microglia occupy a variegated phenotypic landscape with relevance to aging and neurodegeneration. However, whether specific microglial subsets converge in or contribute to both processes that eventually affect brain function is less clear. To investigate this, we analyzed microglial heterogeneity in a tauopathy mouse model (K18-seeded P301L) and an accelerated aging model (Senescence-Accelerated Mouse-Prone 8, SAMP8) using cellular indexing of transcriptomes and epitopes by sequencing. We found that widespread tau pathology in K18-seeded P301L mice caused a significant change in the number and morphology of microglia, but only a mild overrepresentation of disease-associated microglia. At the cell population-level, we observed a marked upregulation of the calprotectin-encoding genes S100a8 and S100a9. In 9-month-old SAMP8 mice, we identified a unique microglial subpopulation that showed partial similarity with the disease-associated microglia phenotype and was additionally characterized by a high expression of the same calprotectin gene set. Immunostaining for S100A8 revealed that this population was enriched in the hippocampus, correlating with the cognitive impairment observed in this model. However, incomplete colocalization between their residence and markers of neuronal loss suggests regional specificity. Importantly, S100A8-positive microglia were also retrieved in brain biopsies of human AD and tauopathy patients as well as in a biopsy of an aged individual without reported pathology. Thus, the emergence of S100A8-positive microglia portrays a conspicuous commonality between accelerated aging and tauopathy progression, which may have relevance for ensuing brain dysfunction.

A, Plessis‐Belair J, Kim TW, Martin J, Ni J, Pearson JA, Park EJ, Sher RB, Studer L, Riessland M. The SATB1-MIR22-GBA axis mediates glucocerebroside accumulation inducing a cellular senescence-like phenotype in dopaminergic neurons

Idiopathic Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, which is associated with neuroinflammation and reactive gliosis. The underlying cause of PD and the concurrent neuroinflammation are not well understood. In this study, we utilize human and murine neuronal lines, stem cell-derived dopaminergic neurons, and mice to demonstrate that three previously identified genetic risk factors for PD, namely SATB1, MIR22HG, and GBA, are components of a single gene regulatory pathway. Our findings indicate that dysregulation of this pathway leads to the upregulation of glucocerebrosides (GluCer), which triggers a cellular senescence-like phenotype in dopaminergic neurons. Specifically, we discovered that downregulation of the transcriptional repressor SATB1 results in the derepression of the microRNA miR-22-3p, leading to decreased GBA expression and subsequent accumulation of GluCer. Furthermore, our results demonstrate that an increase in GluCer alone is sufficient to impair lysosomal and mitochondrial function, thereby inducing cellular senescence. Dysregulation of the SATB1-MIR22-GBA pathway, observed in both PD patients and normal aging, leads to lysosomal and mitochondrial dysfunction due to the GluCer accumulation, ultimately resulting in a cellular senescence-like phenotype in dopaminergic neurons. Therefore, our study highlights a novel pathway involving three genetic risk factors for PD and provides a potential mechanism for the senescence-induced neuroinflammation and reactive gliosis observed in both PD and normal aging.

S100A9 aggravates early brain injury after subarachnoid hemorrhage via inducing neuroinflammation and inflammasome activation

Subarachnoid hemorrhage (SAH) is a stroke subtype with high mortality, and its severity is closely related to the short-term prognosis of SAH patients. S100 calcium-binding protein A9 (S100A9) has been shown to be associated with some neurological diseases. In this study, the concentration of S100A9 in clinical cerebrospinal fluid samples was detected by enzyme-linked immunosorbent assay (ELISA), and the relationship between S100A9 and the prognosis of patients was explored. In addition, WT mice and S100A9 knockout mice were used to establish an in vivo SAH model. Neurological scores, brain water content, and histopathological staining were performed after a specified time. A co-culture model of BV2 and HT22 cells was treated with heme chloride to establish an in vitro SAH model. Our study confirmed that the expression of S100A9 protein in the CSF of SAH patients is increased, and it is related to the short-term prognosis of SAH patients. S100A9 protein is highly expressed in microglia in the central nervous system. S100A9 gene knockout significantly improved neurological function scores and reduced neuronal apoptosis. S100A9 protein can activate TLR4 receptor, promote nuclear transcription of NF-κB, increase the activation of inflammatory body, and ultimately aggravate nerve injury.

Human monocyte subtype expression of neuroinflammation and regeneration-related genes is linked to age and sex

Stroke is a leading cause of disability and the third cause of death. The immune system plays an essential role in post-stroke recovery. After an ischemic stroke, monocytes infiltrate the injured brain tissue and can exacerbate or mitigate the damage. Ischemic stroke is more prevalent in the aged population, and the aging brain exhibits an altered immune response. There are also sex disparities in ischemic stroke incidence, outcomes, and recovery, and these differences may be hormone-driven and determined by genetic and epigenetic factors. Here, we studied whether human peripheral blood monocyte subtype (classical, intermediate, and non-classical) expression of neuronal inflammation- and regeneration-related genes depends on age and sex. A FACS analysis of blood samples from 44 volunteers (male and female, aged 28 to 98) showed that in contrast to other immune cells, the proportion of natural killer cells increased in females. The proportion of B-cells decreased in both sexes with age, and subtypes of monocytes were not linked to age or sex. Gene expression analysis by qPCR identified several genes differentially correlating with age and sex within different monocyte subtypes. Interestingly, ANXA1 and CD36 showed a consistent increase with aging in all monocytes, specifically in intermediate (CD36) and intermediate and non-classical (ANXA1) subtypes. Other genes (IL-1β, S100A8, TNFα, CD64, CD33, TGFβ1, TLR8, CD91) were differentially changed in monocyte subtypes with increased aging. Most age-dependent gene changes were differentially expressed in female monocytes. Our data shed light on the nuanced interplay of age and sex in shaping the expression of inflammation- and regeneration-related genes within distinct monocyte subtypes. Understanding these dynamics could pave the way for targeted interventions and personalized approaches in post-stroke care, particularly for the aging population and individuals of different sexes.

Suppression of TCF4 promotes a ZC3H12A-mediated self-sustaining inflammatory feedback cycle involving IL-17RA/IL-17RE epidermal signaling

IL-17C is an epithelial cell-derived proinflammatory cytokine whose transcriptional regulation remains unclear. Analysis of the IL17C promoter region identified TCF4 as putative regulator, and siRNA knockdown of TCF4 in human keratinocytes (KCs) increased IL17C. IL-17C stimulation of KCs (along with IL-17A and TNF-α stimulation) decreased TCF4 and increased NFKBIZ and ZC3H12A expression in an IL-17RA/RE-dependent manner, thus creating a feedback loop. ZC3H12A (MCPIP1/Regnase-1), a transcriptional immune-response regulator, also increased following TCF4 siRNA knockdown, and siRNA knockdown of ZC3H12A decreased NFKBIZ, IL1B, IL36G, CCL20, and CXCL1, revealing a proinflammatory role for ZC3H12A. Examination of lesional skin from the KC-Tie2 inflammatory dermatitis mouse model identified decreases in TCF4 protein concomitant with increases in IL-17C and Zc3h12a that reversed following the genetic elimination of Il17c, Il17ra, and Il17re and improvement in the skin phenotype. Conversely, interference with Tcf4 in KC-Tie2 mouse skin increased Il17c and exacerbated the inflammatory skin phenotype. Together, these findings identify a role for TCF4 in the negative regulation of IL-17C, which, alone and with TNF-α and IL-17A, feed back to decrease TCF4 in an IL-17RA/RE-dependent manner. This loop is further amplified by IL-17C-TCF4 autocrine regulation of ZC3H12A and IL-17C regulation of NFKBIZ to promote self-sustaining skin inflammation.

Secondary Modification of S100B Influences Anti Amyloid-β Aggregation Activity and Alzheimer's Disease Pathology

Proteinaceous aggregates accumulate in neurodegenerative diseases such as Alzheimer's Disease (AD), inducing cellular defense mechanisms and altering the redox status. S100 pro-inflammatory cytokines, particularly S100B, are activated during AD, but recent findings reveal an unconventional molecular chaperone role for S100B in hindering Aβ aggregation and toxicity. This suggests a potential protective role for S100B at the onset of Aβ proteotoxicity, occurring in a complex biochemical environment prone to oxidative damage. Herein, we report an investigation in which extracellular oxidative conditions are mimicked to test if the susceptibility of S100B to oxidation influences its protective activities. Resorting to mild oxidation of S100B, we observed methionine oxidation as inferred from mass spectrometry, but no cysteine-mediated crosslinking. Structural analysis showed that the folding, structure, and stability of oxidized S100B were not affected, and nor was its quaternary structure. However, studies on Aβ aggregation kinetics indicated that oxidized S100B was more effective in preventing aggregation, potentially linked to the oxidation of Met residues within the S100:Aβ binding cleft that favors interactions. Using a cell culture model to analyze the S100B functions in a highly oxidative milieu, as in AD, we observed that Aβ toxicity is rescued by the co-administration of oxidized S100B to a greater extent than by S100B. Additionally, results suggest a disrupted positive feedback loop involving S100B which is caused by its oxidation, leading to the downstream regulation of IL-17 and IFN-α2 expression as mediated by S100B.

Fundamentals of osteoarthritis: Inflammatory mediators in osteoarthritis

OBJECTIVES

As more has become known of the pathophysiology of osteoarthritis (OA), evidence that inflammation plays a critical role in its development and progression has accumulated. Here, we aim to review current knowledge of the complex inflammatory network in the OA joint.

DESIGN

This narrative review is presented in three main sections: local inflammation, systemic inflammation, and therapeutic implications. We focused on inflammatory mediators and their link to OA structural changes in the joint.

RESULTS

OA is characterized by chronic and low-grade inflammation mediated mostly by the innate immune system, which results in cartilage degradation, bone remodeling and synovial changes. Synovitis is regarded as an OA characteristic and associated with increased severity of symptoms and joint dysfunction. However, the articular cartilage and the subchondral bone also produce several pro-inflammatory mediators thus establishing a complex interplay between the different tissues of the joint. In addition, systemic low-grade inflammation induced by aging, obesity and metabolic syndrome can contribute to OA development and progression. The main inflammatory mediators associated with OA include cytokines, chemokines, growth factors, adipokines, and neuropeptides.

CONCLUSIONS

Future research is needed to deeper understand the molecular pathways mediating the inflammation in OA to provide new therapeutics that target these pathways, or to repurpose existing drugs.

The SATB1-MIR22-GBA axis mediates glucocerebroside accumulation inducing a cellular senescence-like phenotype in dopaminergic neurons

Idiopathic Parkinson's Disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, which is associated with neuroinflammation and reactive gliosis. The underlying cause of PD and the concurrent neuroinflammation are not well understood. In this study, we utilized human and murine neuronal lines, stem cell-derived dopaminergic neurons, and mice to demonstrate that three previously identified genetic risk factors for PD, namely SATB1, MIR22HG, and GBA, are components of a single gene regulatory pathway. Our findings indicate that dysregulation of this pathway leads to the upregulation of glucocerebrosides (GluCer), which triggers a cellular senescence-like phenotype in dopaminergic neurons. Specifically, we discovered that downregulation of the transcriptional repressor SATB1 results in the derepression of the microRNA miR-22-3p, leading to decreased GBA expression and subsequent accumulation of GluCer. Furthermore, our results demonstrate that an increase in GluCer alone is sufficient to impair lysosomal and mitochondrial function, thereby inducing cellular senescence dependent on S100A9 and stress factors. Dysregulation of the SATB1-MIR22-GBA pathway, observed in both PD patients and normal aging, leads to lysosomal and mitochondrial dysfunction due to the GluCer accumulation, ultimately resulting in a cellular senescence-like phenotype in dopaminergic neurons. Therefore, our study highlights a novel pathway involving three genetic risk factors for PD and provides a potential mechanism for the senescence-induced neuroinflammation and reactive gliosis observed in both PD and normal aging.

S100A8 gene copy number and protein expression in breast cancer: associations with proliferation, histopathological grade and molecular subtypes

BACKGROUND AND AIMS

Amplification of S100A8 occurs in 10-30% of all breast cancers and has been linked to poorer prognosis. Similarly, the protein S100A8 is overexpressed in a roughly comparable proportion of breast cancers and is also found in infiltrating myeloid-lineage cells, again linked to poorer prognosis. We explore the relationship between these findings.

METHODS

We examined S100A8 copy number (CN) alterations using fluorescence in situ hybridization in 475 primary breast cancers and 117 corresponding lymph nodes. In addition, we studied S100A8 protein expression using immunohistochemistry in 498 primary breast cancers from the same cohort.

RESULTS

We found increased S100A8 CN (≥ 4) in tumor epithelial cells in 20% of the tumors, increased S100A8 protein expression in 15%, and ≥ 10 infiltrating S100A8 + polymorphonuclear cells in 19%. Both increased S100A8 CN and protein expression in cancer cells were associated with high Ki67 status, high mitotic count and high histopathological grade. We observed no association between increased S100A8 CN and S100A8 protein expression, and only a weak association (p = 0.09) between increased CN and number of infiltrating S100A8 + immune cells. Only S100A8 protein expression in cancer cells was associated with significantly worse prognosis.

CONCLUSIONS

Amplification of S100A8 does not appear to be associated with S100A8 protein expression in breast cancer. S100A8 protein expression in tumor epithelial cells identifies a subgroup of predominantly non-luminal tumors with a high mean age at diagnosis and significantly worse prognosis. Finally, S100A8 alone is not a sufficient marker to identify infiltrating immune cells linked to worse prognosis.

Deficiency of S100 calcium binding protein A9 attenuates vascular dysfunction in aged mice

BACKGROUND

S100 calcium-binding protein A9 (S100A9) is a danger-associated molecular pattern molecule that mediates the inflammatory response. Inflammation is essential in aging-related cardiovascular diseases. However, less is known regarding the role of S100A9 in vascular aging.

METHODS

S100A9 null mice were used to investigate the role of S100A9 in aging-related pathologies. Artery rings were used to measure the functional characteristics of vascular with a pressurized myograph. Telomere length, Sirtuin activity, oxidative stress, and endothelial nitric oxide synthetase (eNOS) activity were used to elevate vascular senescence. Intraperitoneal glucose tolerance (IPGTT) and insulin sensitivity test (IST) were employed to investigate the effects of S100A9 on insulin resistance. Inflammation response was reflected by the concentration of inflammatory cytokines. The Toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE) inhibitors were used to identify the downstream molecular mechanisms of S100A9 in aging-induced senescence in endothelial cells.

RESULTS

S100A9 expression in vascular increased with aging in mice and humans. Deficiency of S100A9 alleviated vascular senescence in aged mice, as evidenced by increased telomere length, Sirtuin activity, and eNOS activity. Meanwhile, S100A9 knockout improved endothelium-dependent vasodilatation and endothelial continuity in aged mice. Moreover, the increased insulin resistance, oxidative stress, and inflammation were mitigated by S100A9 deletion in aged mice. In vitro, S100A9 induced senescence in endothelial cells, and that effect was blunted by TLR4 but not RAGE inhibitors.

CONCLUSION

The present study suggested that S100A9 may contribute to aging-related pathologies and endothelial dysfunction via the TLR4 pathway. Therefore, targeting S100A9/TLR4 signaling pathway may represent a crucial therapeutic strategy to prevent age-related cardiovascular diseases.

Inflammaging and Osteoarthritis

Osteoarthritis is a highly prevalent disease particularly in subjects over 65 years of age worldwide. While in the past it was considered a mere consequence of cartilage degradation leading to anatomical and functional joint impairment, in recent decades, there has been a more dynamic view with the synovium, the cartilage, and the subchondral bone producing inflammatory mediators which ultimately lead to cartilage damage. Inflammaging is defined as a chronic, sterile, low-grade inflammation state driven by endogenous signals in the absence of infections, occurring with aging. This chronic status is linked to the production of reactive oxygen species and molecules involved in the development of age-related disease such as cancer, diabetes, and cardiovascular and neurodegenerative diseases. Inflammaging contributes to osteoarthritis development where both the innate and the adaptive immune response are involved. Elevated systemic and local inflammatory cytokines and senescent molecules promote cartilage degradation, and antigens derived from damaged joints further trigger inflammation through inflammasome activation. B and T lymphocyte populations also change with inflammaging and OA, with reduced regulatory functions, thus implicating self-reactivity as an additional mechanism of joint damage. The discovery of the underlying pathogenic pathways may help to identify potential therapeutic targets for the management or the prevention of osteoarthritis. We will provide a comprehensive evaluation of the current literature on the role of inflammaging in osteoarthritis and discuss the emerging therapeutic strategies.

Proinflammatory S100A9 stimulates TLR4/NF-κB signaling pathways causing enhanced phagocytic capacity of microglial cells

Alzheimer's disease (AD) is the main cause of dementia, affecting the increasingly aging population. Growing evidence indicates that neuro-inflammation plays crucial roles, e.g., the association between AD risk genes with innate immune functions. In this study, we demonstrate that moderate concentrations of pro-inflammatory cytokine S100A9 regulate immune response of BV2 microglial cells, i.e., the phagocytic capacity, reflected by elevated number of 1 μm diameter Dsred-stained latex beads in the cytoplasm. In contrast, at high S100A9 concentrations, both the viability and phagocytic capacity of BV2 cells drop substantially. Furthermore, it is uncovered that S100A9 affects phagocytosis of microglia via NF-κB signaling pathways. Application of related target-specific drugs, i.e., IKK and TLR4 inhibitors, effectively suppresses BV2 cells' immune responses. These results suggest that pro-inflammatory S100A9 activates microglial phagocytosis, and possibly contributes to the clearance of amyloidogenic species at the early stage of AD.

Is dexamethasone-induced muscle atrophy an alternative model for naturally aged sarcopenia model?

Background

Primary sarcopenia is usually known as age-related skeletal muscle loss; however, other factors like endocrine, lifestyle and inflammation can also cause muscle loss, known as secondary sarcopenia. Although many studies have used different sarcopenia animal models for exploring the underlying mechanism and therapeutic approaches for sarcopenia, limited study has provided evidence of the relevance of these animal models. This study aims to investigate the similarity and difference in muscle qualities between primary and secondary sarcopenia mice models, using naturally aged mice and dexamethasone-induced mice.

Methods

21-month-old mice were used as naturally aged primary sarcopenia mice and 3-month-old mice received daily intraperitoneal injection of dexamethasone (20 mg/ kg body weight) for 10 days were used as secondary sarcopenia model. This study provided measurements for muscle mass and functions, including Dual-energy X-ray absorptiometry (DXA) scanning, handgrip strength test and treadmill running to exhaustion test. Besides, muscle contraction, muscle fibre type measurements and gene expression were also performed to provide additional information on muscle qualities.

Results

The results suggest two sarcopenia animal models shared a comparable decrease in forelimb lean mass, muscle fibre size, grip strength and muscle contraction ability. Besides, the upregulation of protein degradation genes was also observed in two sarcopenia animal models. However, only primary sarcopenia mice were identified with an early stage of mtDNA deletion.

Conclusion

Collectively, this study evaluated that the dexamethasone-induced mouse model could be served as an alternative model for primary sarcopenia, according to the comparable muscle mass and functional changes. However, whether dexamethasone-induced mice can be used as an animal model when studying the molecular mechanisms of sarcopenia needs to be carefully evaluated.

The translational potential of this article

The purpose of sarcopenia research is to investigate appropriate treatments for reversing the loss of skeletal muscle mass and functions. Using animal models for the preclinical study could predict the safety and efficacy of the treatments. This study compared the typical age-related sarcopenia mice model and dexamethasone-induced secondary sarcopenia mice to provide evidence of the pathological and functional changes in the mice models.

AgeAnno: a knowledgebase of single-cell annotation of aging in human

Aging is a complex process that accompanied by molecular and cellular alterations. The identification of tissue-/cell type-specific biomarkers of aging and elucidation of the detailed biological mechanisms of aging-related genes at the single-cell level can help to understand the heterogeneous aging process and design targeted anti-aging therapeutics. Here, we built AgeAnno (https://relab.xidian.edu.cn/AgeAnno/#/), a knowledgebase of single cell annotation of aging in human, aiming to provide comprehensive characterizations for aging-related genes across diverse tissue-cell types in human by using single-cell RNA and ATAC sequencing data (scRNA and scATAC). The current version of AgeAnno houses 1 678 610 cells from 28 healthy tissue samples with ages ranging from 0 to 110 years. We collected 5580 aging-related genes from previous resources and performed dynamic functional annotations of the cellular context. For the scRNA data, we performed analyses include differential gene expression, gene variation coefficient, cell communication network, transcription factor (TF) regulatory network, and immune cell proportionc. AgeAnno also provides differential chromatin accessibility analysis, motif/TF enrichment and footprint analysis, and co-accessibility peak analysis for scATAC data. AgeAnno will be a unique resource to systematically characterize aging-related genes across diverse tissue-cell types in human, and it could facilitate antiaging and aging-related disease research.

Transcriptome and proteome analysis of dogs with precursor targeted immune-mediated anemia treated with splenectomy

Precursor-targeted immune-mediated anemia (PIMA) in dogs is characterized by persistent non-regenerative anemia and ineffective erythropoiesis, and it is suspected to be an immune-mediated disease. Most affected dogs respond to immunosuppressive therapies; however, some are resistant. In this study, we carried out splenectomy as an alternative therapy for refractory PIMA in dogs, and analyzed gene expression levels in the spleen of dogs with or without PIMA and in serum before and after splenectomy. A total of 1,385 genes were found to express differentially in the spleens from dogs with PIMA compared with healthy dogs by transcriptome analysis, of which 707 genes were up-regulated, including S100A12, S100A8, and S100A9 that are linked directly to the innate immune system and have been characterized as endogenous damage-associated molecular patterns. Furthermore, immunohistochemistry confirmed that S100A8/A9 protein expression levels were significantly higher in dogs with PIMA compared with those in healthy dogs. A total of 22 proteins were found to express differentially between the serum samples collected before and after splenectomy by proteome analysis, of which 12 proteins were up-regulated in the samples before. The lectin pathway of complement activation was identified by pathway analysis in pre-splenectomy samples. We speculated that S100A8/9 expression may be increased in the spleen of dogs with PIMA, resulting in activation of the lectin pathway before splenectomy. These findings further our understanding of the pathology and mechanisms of splenectomy for PIMA.

Salmonella pathogenicity island 1 knockdown confers protection against myocardial fibrosis and inflammation in uremic cardiomyopathy via down-regulation of S100 Calcium Binding Protein A8/A9 transcription

Background/Aim

Uremic cardiomyopathy (UCM) is a characteristic cardiac pathology that is commonly found in patients with chronic kidney disease. This study dissected the mechanism of SPI1 in myocardial fibrosis and inflammation induced by UCM through S100A8/A9.

Methods

An UCM rat model was established, followed by qRT-PCR and western blot analyses of SPI1 and S100A8/A9 expression in myocardial tissues. After alterations of SPI1 and S100A8/A9 expression in UCM rats, the blood specimens were harvested from the cardiac apex of rats. The levels of creatine phosphokinase-MB (CK-MB), blood creatinine, blood urea nitrogen (BUN), and inflammatory cytokines (interleukin [IL]-6, IL-1β, and tumor necrosis factor-α [TNF-α]) were examined in the collected blood. Collagen fibrosis was assessed by Masson staining. The expression of fibrosis markers [transforming growth factor (TGF)-β1, α-smooth muscle actin (SMA), Collagen 4a1, and Fibronectin], IL-6, IL-1β, and TNF-α was measured in myocardial tissues. Chromatin immunoprecipitation and dual-luciferase reporter gene assays were conducted to test the binding relationship between SPI1 and S100A8/A9.

Results

S100A8/A9 and SPI1 were highly expressed in the myocardial tissues of UCM rats. Mechanistically, SPI1 bound to the promoter of S100A8/A9 to facilitate S100A8/A9 transcription. S100A8/A9 or SPI1 knockdown reduced myocardial fibrosis and inflammation and the levels of CK-MB, blood creatinine, and BUN, as well as the expression of TGF-β1, α-SMA, Collagen 4a1, Fibronectin, IL-6, TNF-α, and IL-1β in UCM rats.

Conclusion

SPI1 knockdown diminished S100A8/A9 transcription, thus suppressing myocardial fibrosis and inflammation caused by UCM.

TLR9 Mediates Periodontal Aging by Fostering Senescence and Inflammaging

TLR9 is a critical nucleic acid sensing receptor in mediating periodontitis and periodontitis-associated comorbidities. Emerging evidence implicates TLR9 as a key sensor during aging, although its participation in periodontal aging is unexplored. Here, we investigated whether TLR9-mediated host responses can promote key hallmarks of aging, inflammaging, and senescence, in the course of periodontitis using a multipronged approach comprising clinical and preclinical studies. In a case-control model, we found increased TLR9 gene expression in gingival tissues of older (≥55 y) subjects with periodontitis compared to older healthy subjects as well as those who are younger (<55 y old) with and without the disease. Mechanistically, this finding was supported by an in vivo model in which wild-type (WT) and TLR9-/- mice were followed for 8 to 10 wk (young) and 18 to 22 mo (aged). In this longitudinal model, aged WT mice developed severe alveolar bone resorption when compared to their younger counterpart, whereas aged TLR9-/- animals presented insignificant bone loss when compared to the younger groups. In parallel, a boosted inflammaging milieu exhibiting higher expression of inflammatory/osteoclast mediators (Il-6, Rankl, Cxcl8) and danger signals (S100A8, S100A9) was noted in gingival tissues of aged WT mice compared to the those of aged TLR9-/- mice. Consistently, WT aged mice displayed an increase in prosenescence balance as measured by p16INK4a/p19ARF ratio compared to the younger groups and aged TLR9-/- animals. Ex vivo experiments with bone marrow-derived macrophages primed by TLR9 ligand (ODN 1668) further corroborated in vivo and clinical data and showed enhanced inflammatory-senescence circuit followed by increased osteoclast differentiation. Together, these findings reveal first systematic evidence implicating TLR9 as one of the drivers of periodontitis during aging and functioning by boosting a deleterious inflammaging/senescence environment. This finding calls for further investigations to determine whether targeting TLR9 will improve periodontal health in an aging population.

Bakuchiol and ethyl (linoleate/oleate) synergistically modulate endocannabinoid tone in keratinocytes and repress inflammatory pathway mRNAs

The endocannabinoid (eCB) system plays an active role in epidermal homeostasis. Phytocannabinoids such as cannabidiol modulate this system but also act through eCB-independent mechanisms. This study evaluated the effects of cannabidiol, bakuchiol (BAK), and ethyl (linoleate/oleate) (ELN) in keratinocytes and reconstituted human epidermis. Molecular docking simulations showed that each compound binds the active site of the eCB carrier FABP5. However, BAK and ethyl linoleate bound this site with the highest affinity when combined 1:1 (w/w), and in vitro assays showed that BAK + ELN most effectively inhibited FABP5 and fatty acid amide hydrolase. In TNF-stimulated keratinocytes, BAK + ELN reversed TNF-induced expression shifts and uniquely downregulated type I IFN genes and PTGS2 (COX2). BAK + ELN also repressed expression of genes linked to keratinocyte differentiation but upregulated those associated with proliferation. Finally, BAK + ELN inhibited cortisol secretion in reconstituted human epidermis skin (not observed with cannabidiol). These results support a model in which BAK and ELN synergistically interact to inhibit eCB degradation, favoring eCB mobilization and inhibition of downstream inflammatory mediators (e.g., TNF, COX-2, type I IFN). A topical combination of these ingredients may thus enhance cutaneous eCB tone or potentiate other modulators, suggesting novel ways to modulate the eCB system for innovative skincare product development.

Mitochondrial Fus1/Tusc2 and cellular Ca2+ homeostasis: tumor suppressor, anti-inflammatory and anti-aging implications

FUS1/TUSC2 (FUSion1/TUmor Suppressor Candidate 2) is a tumor suppressor gene (TSG) originally described as a member of the TSG cluster from human 3p21.3 chromosomal region frequently deleted in lung cancer. Its role as a TSG in lung, breast, bone, and other cancers was demonstrated by several groups, but molecular mechanisms of its activities are starting to unveil lately. They suggest that Fus1-dependent mechanisms are relevant in etiologies of diseases beyond cancer, such as chronic inflammation, bacterial and viral infections, premature aging, and geriatric diseases. Here, we revisit the discovery of FUS1 gene in the context of tumor initiation and progression, and review 20 years of research into FUS1 functions and its molecular, structural, and biological aspects that have led to its use in clinical trials and gene therapy. We present a data-driven view on how interactions of Fus1 with the mitochondrial Ca2+ (mitoCa2+) transport machinery maintain cellular Ca2+ homeostasis and control cell apoptosis and senescence. This Fus1-mediated cellular homeostasis is at the crux of tumor suppressor, anti-inflammatory and anti-aging activities.

Single-Cell Gene Expression Analysis Revealed Immune Cell Signatures of Delta COVID-19

The coronavirus disease 2019 (COVID-19) is accompanied by a cytokine storm with the release of many proinflammatory factors and development of respiratory syndrome. Several SARS-CoV-2 lineages have been identified, and the Delta variant (B.1.617), linked with high mortality risk, has become dominant in many countries. Understanding the immune responses associated with COVID-19 lineages may therefore aid the development of therapeutic and diagnostic strategies. Multiple single-cell gene expression studies revealed innate and adaptive immunological factors and pathways correlated with COVID-19 severity. Additional investigations covering host–pathogen response characteristics for infection caused by different lineages are required. Here, we performed single-cell transcriptome profiling of blood mononuclear cells from the individuals with different severity of the COVID-19 and virus lineages to uncover variant specific molecular factors associated with immunity. We identified significant changes in lymphoid and myeloid cells. Our study highlights that an abundant population of monocytes with specific gene expression signatures accompanies Delta lineage of SARS-CoV-2 and contributes to COVID-19 pathogenesis inferring immune components for targeted therapy.

Prostaglandins and calprotectin are genetically and functionally linked to the Inflammatory Bowel Diseases

BACKGROUND

Genome wide association studies (GWAS) have identified and validated more than 200 genomic loci associated with the inflammatory bowel disease (IBD), although for most the causal gene remains unknown. Given the importance of myeloid cells in IBD pathogenesis, the current study aimed to uncover the role of genes within IBD genetic loci that are endogenously expressed in this cell lineage.

METHODS

The open reading frames (ORF) of 42 genes from IBD-associated loci were expressed via lentiviral transfer in the THP-1 model of human monocytes and the impact of each of these on the cell's transcriptome was analyzed using a RNA sequencing-based approach. We used a combination of genetic and pharmacologic approaches to validate our findings in the THP-1 line with further validation in human induced pluripotent stem cell (hiPSC)-derived-monocytes.

RESULTS

This functional genomics screen provided evidence that genes in four IBD GWAS loci (PTGIR, ZBTB40, SLC39A11 and NFKB1) are involved in controlling S100A8 and S100A9 gene expression, which encode the two subunits of calprotectin (CP). We demonstrated that increasing PTGIR expression and/or stimulating PTGIR signaling resulted in increased CP expression in THP-1. This was further validated in hiPSC-derived monocytes. Conversely, knocking-down PTGIR endogenous expression and/or inhibiting PTGIR signaling led to decreased CP expression. These analyses were extended to the known IBD gene PTGER4, whereby its specific agonist also led to increased CP expression. Furthermore, we demonstrated that the PTGIR and PTGER4 mediated control of CP expression was dependent on signaling via adenylate cyclase and STAT3. Finally, we demonstrated that LPS-mediated increases in CP expression could be potentiated by agonists of PTGIR and PTGER4, and diminished by their antagonists.

CONCLUSION

Our results support a causal role for the PTGIR, PTGER4, ZBTB40, SLC39A11 and NFKB1 genes in IBD, with all five genes regulating the expression of CP in myeloid cells, as well as potential roles for the prostacyclin/prostaglandin biogenesis and signaling pathways in IBD susceptibility and pathogenesis.

Gut bacterial isoamylamine promotes age-related cognitive dysfunction by promoting microglial cell death

The intestinal microbiome releases a plethora of small molecules. Here, we show that the Ruminococcaceae metabolite isoamylamine (IAA) is enriched in aged mice and elderly people, whereas Ruminococcaceae phages, belonging to the Myoviridae family, are reduced. Young mice orally administered IAA show cognitive decline, whereas Myoviridae phage administration reduces IAA levels. Mechanistically, IAA promotes apoptosis of microglial cells by recruiting the transcriptional regulator p53 to the S100A8 promoter region. Specifically, IAA recognizes and binds the S100A8 promoter region to facilitate the unwinding of its self-complementary hairpin structure, thereby subsequently enabling p53 to access the S100A8 promoter and enhance S100A8 expression. Thus, our findings provide evidence that small molecules released from the gut microbiome can directly bind genomic DNA and act as transcriptional coregulators by recruiting transcription factors. These findings further unveil a molecular mechanism that connects gut metabolism to gene expression in the brain with implications for disease development.

Systemic Listeria monocytogenes infection in aged mice induces long-term neuroinflammation: the role of miR-155

BACKGROUND

Understanding mechanisms of pathologic neuroinflammation is essential for improving outcomes after central nervous system infections. Brain tissue-resident memory T cells (bT_RM) are recruited during central nervous system infection and promote pathogen control as well as noxious inflammation. Our prior studies in young mice showed optimal recruitment of CD8⁺ bT_RM during neuroinvasive Listeria monocytogenes (Lm) infection required miR-155, and was significantly inhibited by anti-miR-155 oligonucleotides. Since Lm is an important pathogen in the elderly, we hypothesized anti-miR-155 would also inhibit accumulation of CD8⁺ bT_RM in aged mice infected with Lm.

METHODS

Young (2 mo) and aged (> 18 mo) male C57BL/6 mice were infected intra-peritoneally with wild-type Lm, or avirulent Lm mutants lacking the genes required for intracellular motility (ΔactA) or phagosomal escape (Δhly), then were given antibiotics. Brain leukocytes and their intracellular cytokine production were quantified by flow cytometry >28d post-infection (p.i.). The role of miR-155 was tested by injecting mice with anti-miR-155 or control oligonucleotides along with antibiotics.

RESULTS

Aged mice had significantly more homeostatic CD8⁺ bT_RM than did young mice, which did not increase after infection with wild-type Lm despite 50% mortality, whereas young mice suffered no mortality after a larger inoculum. For direct comparison of post-infectious neuroinflammation after the same inoculum, young and aged mice were infected with 10⁷ CFU ΔactA Lm. This mutant caused no mortality and significantly increased CD8⁺ bT_RM 28d p.i. in both groups, whereas bone marrow-derived myeloid cells, particularly neutrophils, increased only in aged mice. Notably, anti-miR-155 reduced accumulation of brain myeloid cells in aged mice after infection, whereas CD8⁺ bT_RM were unaffected.

CONCLUSIONS

Systemic infection with Lm ΔactA is a novel model for studying infection-induced brain inflammation in aged mice without excessive mortality. CD8⁺ bT_RM increase in both young and aged mice after infection, whereas only in aged mice bone marrow-derived myeloid cells increase long-term. In aged mice, anti-miR-155 inhibits brain accumulation of myeloid cells, but not CD8⁺ bT_RM. These results suggest young and aged mice differ in manifestations and mechanisms of infection-induced neuroinflammation and give insight for developing therapies to ameliorate brain inflammation following severe infection in the elderly.

Transcriptomic Analysis of Fumarate Compounds Identifies Unique Effects of Isosorbide Di-(Methyl Fumarate) on NRF2, NF-kappaB and IRF1 Pathway Genes

Dimethyl fumarate (DMF) has emerged as a first-line therapy for relapsing-remitting multiple sclerosis (RRMS). This treatment, however, has been limited by adverse effects, which has prompted development of novel derivatives with improved tolerability. We compared the effects of fumarates on gene expression in astrocytes. Our analysis included diroximel fumarate (DRF) and its metabolite monomethyl fumarate (MMF), along with a novel compound isosorbide di-(methyl fumarate) (IDMF). Treatment with IDMF resulted in the largest number of differentially expressed genes. The effects of DRF and MMF were consistent with NRF2 activation and NF-κB inhibition, respectively. IDMF responses, however, were concordant with both NRF2 activation and NF-κB inhibition, and we confirmed IDMF-mediated NF-κB inhibition using a reporter assay. IDMF also down-regulated IRF1 expression and IDMF-decreased gene promoters were enriched with IRF1 recognition sequences. Genes altered by each fumarate overlapped significantly with those near loci from MS genetic association studies, but IDMF had the strongest overall effect on MS-associated genes. These results show that next-generation fumarates, such as DRF and IDMF, have effects differing from those of the MMF metabolite. Our findings support a model in which IDMF attenuates oxidative stress via NRF2 activation, with suppression of NF-κB and IRF1 contributing to mitigation of inflammation and pyroptosis.

Advanced age exacerbates intestinal epithelial permeability after burn injury in mice

BACKGROUND

Advanced age is an independent risk factor for morbidity and mortality after burn injury. Following burn, the intestines can become permeable leading to the leakage of bacteria and their products from the lumen of the ileum to the portal and systemic circulation. Here, we sought to determine the effects of advanced age on intestinal permeability post burn injury and assess intestinal inflammatory biomarkers.

METHODS

Young (4-5 months) and aged (18-22 months) female BALB/cBy mice were subjected to a 12-15% total body surface area (TBSA) sham or burn injury. 24 h after injury, mice were euthanized, and organs collected. Colony-forming units (CFU) were counted from plated mesenteric lymph nodes (MLN). Gene expression of ileal tight junctional proteins, occludin and zonula occludens 1 (ZO-1), in addition to ileal damage associated molecular pattern (DAMP) proteins, S100A8 and S100A9, as well as ileal inflammatory markers IL-6 and TNF-α were measured by qPCR. Intestinal cell death was measured by ELISA. Intestinal permeability was determined by FITC fluorescence in serum; 4kD FITC-dextran was given by oral gavage 3 h before euthanasia.

RESULTS

Aged mice subjected to burn injury had increased intestinal permeability as evidenced by a 5.8-fold higher level of FITC-dextran in their serum when compared to all other groups (p < 0.05). In addition, aged burn-injured mice exhibited heightened bacterial accumulation in the MLN with a 15.5-fold increase over all other groups (p < 0.05). Histology of ileum failed to show differences in villus length among all groups. Analysis of ileal tight junctional proteins and inflammatory marker gene expression revealed no difference in Ocln, Tjp1, Il6, or Tnf expression among all groups, but 2.3 and 2.9-fold upregulation of S100a8 and S100a9, respectively, in aged burn-injured mice relative to both young groups and aged sham-injured mice (p < 0.05). Lastly, cell death in the ileum was elevated more than two-fold in aged burn-injured mice relative to young animals regardless of injury (p < 0.05).

CONCLUSIONS

These data demonstrate that advanced age exacerbates intestinal epithelial permeability after burn injury. Heightened apoptosis may be responsible for the elevated intestinal leakiness and accumulation of bacteria in mesenteric lymph nodes. In addition, S100a8/9 may serve as a biomarker of elevated inflammation within the intestine.

A Sensitization-Free Dimethyl Fumarate Prodrug, Isosorbide Di-(Methyl Fumarate), Provides a Topical Treatment Candidate for Psoriasis

Dimethyl fumarate (DMF) is an effective oral treatment for psoriasis administered in Europe for nearly 60 years. However, its potential has been limited by contact dermatitis that prohibits topical application. This paper characterizes a DMF derivative, isosorbide DMF (IDMF), which was designed to have antipsoriatic effects without skin-sensitizing properties. We show that IDMF exhibits neither genotoxicity nor radiation sensitivity in skin fibroblasts and is nonirritating and nonsensitizing in animal models (rat, rabbit, guinea pig). Microarray analysis of cytokine-stimulated keratinocytes showed that IDMF represses the expression of genes specifically upregulated in psoriatic skin lesions but not those of other skin diseases. IDMF also downregulated genes induced by IL-17A and TNF in keratinocytes as well as predicted targets of NF-κB and the antidifferentiation noncoding RNA (i.e., ANCR). IDMF further stimulated the transcription of oxidative stress response genes (NQO1, GPX2, GSR) with stronger NRF2/ARE activation compared to DMF. Finally, IDMF reduced erythema and scaling while repressing the expression of immune response genes in psoriasiform lesions elicited by topical application of imiquimod in mice. These data show that IDMF exhibits antipsoriatic activity that is similar or improved compared with that exhibited by DMF, without the harsh skin-sensitizing effects that have prevented topical delivery of the parent molecule.

A microRNA-21-mediated SATB1/S100A9/NF-κB axis promotes chronic obstructive pulmonary disease pathogenesis

[Figure: see text].

Restoration of aged hematopoietic cells by their young counterparts through instructive microvesicles release

This study addresses the potential to reverse age-associated morbidity by establishing methods to restore the aged hematopoietic system. Parabiotic animal models indicated that young secretome could restore aged tissues, leading us to establish a heterochronic transwell system with aged mobilized peripheral blood (MPB), co-cultured with young MPB or umbilical cord blood (UCB) cells. Functional studies and omics approaches indicate that the miRNA cargo of microvesicles (MVs) restores the aged hematopoietic system. The in vitro findings were validated in immune deficient (NSG) mice carrying an aged hematopoietic system, improving aged hallmarks such as increased lymphoid:myeloid ratio, decreased inflammation and cellular senescence. Elevated MYC and E2F pathways, and decreased p53 were key to hematopoietic restoration. These processes require four restorative miRs that target the genes for transcription/differentiation, namely PAX and phosphatase PPMIF. These miRs when introduced in aged cells were sufficient to restore the aged hematopoietic system in NSG mice. The aged MPBs were the drivers of their own restoration, as evidenced by the changes from distinct baseline miR profiles in MPBs and UCB to comparable expressions after exposure to aged MPBs. Restorative natural killer cells eliminated dormant breast cancer cells in vivo, indicating the broad relevance of this cellular paradigm - preventing and reversing age-associated disorders such as clearance of early malignancies and enhanced responses to vaccine and infection.

Calprotectin: from biomarker to biological function

The incidence of inflammatory bowel diseases (IBD) emerged with Westernisation of dietary habits worldwide. Crohn's disease and ulcerative colitis are chronic debilitating conditions that afflict individuals with substantial morbidity and challenge healthcare systems across the globe. Since identification and characterisation of calprotectin (CP) in the 1980s, faecal CP emerged as significantly validated, non-invasive biomarker that allows evaluation of gut inflammation. Faecal CP discriminates between inflammatory and non-inflammatory diseases of the gut and portraits the disease course of human IBD. Recent studies revealed insights into biological functions of the CP subunits S100A8 and S100A9 during orchestration of an inflammatory response at mucosal surfaces across organ systems. In this review, we summarise longitudinal evidence for the evolution of CP from biomarker to rheostat of mucosal inflammation and suggest an algorithm for the interpretation of faecal CP in daily clinical practice. We propose that mechanistic insights into the biological function of CP in the gut and beyond may facilitate interpretation of current assays and guide patient-tailored medical therapy in IBD, a concept warranting controlled clinical trials.

IRAK2 Has a Critical Role in Promoting Feed-Forward Amplification of Epidermal Inflammatory Responses

Many inflammatory skin diseases are characterized by altered epidermal differentiation. Whether this altered differentiation promotes inflammatory responses has been unknown. Here, we show that IRAK2, a member of the signaling complex downstream of IL-1 and IL-36, correlates positively with disease severity in both atopic dermatitis and psoriasis. Inhibition of epidermal IRAK2 normalizes differentiation and inflammation in two mouse models of psoriasis- and atopic dermatitis-like inflammation. Specifically, we demonstrate that IRAK2 ties together proinflammatory and differentiation-dependent responses and show that this function of IRAK2 is specific to keratinocytes and acts through the differentiation-associated transcription factor ZNF750. Taken together, our findings suggest that IRAK2 has a critical role in promoting feed-forward amplification of inflammatory responses in skin through modulation of differentiation pathways and inflammatory responses.

Neutrophil extracellular traps enhance macrophage killing of bacterial pathogens

Neutrophils and macrophages are critical to the innate immune response, but cooperative mechanisms used by these cells to combat extracellular pathogens are not well understood. This study reveals that S100A9-deficient neutrophils produce higher levels of mitochondrial superoxide in response to Staphylococcus aureus and, as a result, form neutrophil extracellular traps (suicidal NETosis). Increased suicidal NETosis does not improve neutrophil killing of S. aureus in isolation but augments macrophage killing. NET formation enhances antibacterial activity by increasing phagocytosis by macrophages and by transferring neutrophil-specific antimicrobial peptides to them. Similar results were observed in response to other phylogenetically distinct bacterial pathogens including Streptococcus pneumoniae and Pseudomonas aeruginosa, implicating this as an immune defense mechanism that broadly enhances antibacterial activity. These results demonstrate that achieving maximal bactericidal activity through NET formation requires macrophages and that accelerated and more robust suicidal NETosis makes neutrophils adept at increasing antibacterial activity, especially when A9 deficient.

The S100 Protein Family as Players and Therapeutic Targets in Pulmonary Diseases

The S100 protein family consists of over 20 members in humans that are involved in many intracellular and extracellular processes, including proliferation, differentiation, apoptosis, Ca₂⁺ homeostasis, energy metabolism, inflammation, tissue repair, and migration/invasion. Although there are structural similarities between each member, they are not functionally interchangeable. The S100 proteins function both as intracellular Ca²⁺ sensors and as extracellular factors. Dysregulated responses of multiple members of the S100 family are observed in several diseases, including the lungs (asthma, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cystic fibrosis, pulmonary hypertension, and lung cancer). To this degree, extensive research was undertaken to identify their roles in pulmonary disease pathogenesis and the identification of inhibitors for several S100 family members that have progressed to clinical trials in patients for nonpulmonary conditions. This review outlines the potential role of each S100 protein in pulmonary diseases, details the possible mechanisms observed in diseases, and outlines potential therapeutic strategies for treatment.

Polyoxometalates as Effective Nano-inhibitors of Amyloid Aggregation of Pro-inflammatory S100A9 Protein Involved in Neurodegenerative Diseases

Pro-inflammatory and amyloidogenic S100A9 protein is central to the amyloid-neuroinflammatory cascade in neurodegenerative diseases. Polyoxometalates (POMs) constitute a diverse group of nanomaterials, which showed potency in amyloid inhibition. Here, we have demonstrated that two selected nanosized niobium POMs, Nb₁₀ and TiNb₉, can act as potent inhibitors of S100A9 amyloid assembly. Kinetics analysis based on ThT fluorescence experiments showed that addition of either Nb₁₀ or TiNb₉ reduces the S100A9 amyloid formation rate and amyloid quantity. Atomic force microscopy imaging demonstrated the complete absence of long S100A9 amyloid fibrils at increasing concentrations of either POM and the presence of only round-shaped and slightly elongated aggregates. Molecular dynamics simulation revealed that both Nb₁₀ and TiNb₉ bind to native S100A9 homo-dimer by forming ionic interactions with the positively charged Lys residue-rich patches on the protein surface. The acrylamide quenching of intrinsic fluorescence showed that POM binding does not perturb the Trp 88 environment. The far and near UV circular dichroism revealed no large-scale perturbation of S100A9 secondary and tertiary structures upon POM binding. These indicate that POM binding involves only local conformational changes in the binding sites. By using intrinsic and 8-anilino-1-naphthalene sulfonate fluorescence titration experiments, we found that POMs bind to S100A9 with a K_d of ca. 2.5 μM. We suggest that the region, including Lys 50 to Lys 54 and characterized by high amyloid propensity, could be the key sequences involved in S1009 amyloid self-assembly. The inhibition and complete hindering of S100A9 amyloid pathways may be used in the therapeutic applications targeting the amyloid-neuroinflammatory cascade in neurodegenerative diseases.

S100A8 and S100A9, both transcriptionally regulated by PU.1, promote epithelial-mesenchymal transformation (EMT) and invasive growth of dermal keratinocytes during scar formation post burn

S100 calcium-binding protein A8 (S100A8) and S100A9 are small molecular weight calcium-binding regulatory proteins that have been involved in multiple chronic inflammatory diseases. However, the role of S100A8 and S100A9 in keratinocytes in wounded skin and how they are regulated during this process are still unclear. Here, we found that S100A8 and S100A9 were both upregulated in burn-wounded skins in vivo and thermal-stimulated epidermal keratinocytes in vitro, accompanied by increased levels of epithelial-mesenchymal transition (EMT). Then, we demonstrated that upregulation of S100A8 and S100A9 alone or together enhanced characteristics of EMT in normal keratinocytes, manifested by excessive proliferation rate, abnormal ability of cell invasion, and high expression levels of EMT marker proteins. The transcription factor PU box-binding protein (PU.1) bound to the promoter regions and transcriptionally promoted the expression of S100A8 and S100A9 both in the human and mice, and it had strong positive correlations with both S100A8 and S100A9 protein levels in burned skin in vivo. Moreover, PU.1 positively regulated expression of S100A8 and S100A9 in a dose-dependent manner, and enhanced EMT of keratinocytes in vitro. Finally, through the burn mouse model, we found that PU.1-/- mice displayed a lower ability of scar formation, manifested by smaller scar volume, thickness, and collagen content, which could be enhanced by S100A8 and S100A9. In conclusion, PU.1 transcriptionally promotes expression of S100A8 and S100A9, thus positively regulating epithelial-mesenchymal transformation (EMT) and invasive growth of dermal keratinocytes during scar formation post burn.

Natural Compound from Olive Oil Inhibits S100A9 Amyloid Formation and Cytotoxicity: Implications for Preventing Alzheimer's Disease

Polyphenolic compounds in the Mediterranean diet have received increasing attention due to their protective properties in amyloid neurodegenerative and many other diseases. Here, we have demonstrated for the first time that polyphenol oleuropein aglycone (OleA), which is the most abundant compound in olive oil, has multiple potencies for the inhibition of amyloid self-assembly of pro-inflammatory protein S100A9 and the mitigation of the damaging effect of its amyloids on neuroblastoma SH-SY5Y cells. OleA directly interacts with both native and fibrillar S100A9 as shown by intrinsic fluorescence and molecular dynamic simulation. OleA prevents S100A9 amyloid oligomerization as shown using amyloid oligomer-specific antibodies and cross-β-sheet formation detected by circular dichroism. It decreases the length of amyloid fibrils measured by atomic force microscopy (AFM) as well as reduces the effective rate of amyloid growth and the overall amyloid load as derived from the kinetic analysis of amyloid formation. OleA disintegrates already preformed fibrils of S100A9, converting them into nonfibrillar and nontoxic aggregates as revealed by amyloid thioflavin-T dye binding, AFM, and cytotoxicity assays. At the cellular level, OleA targets S100A9 amyloids already at the membranes as shown by immunofluorescence and fluorescence resonance energy transfer, significantly reducing the amyloid accumulation in GM1 ganglioside containing membrane rafts. OleA increases overall cell viability when neuroblastoma cells are subjected to the amyloid load and alleviates amyloid-induced intracellular rise of reactive oxidative species and free Ca²⁺. Since S100A9 is both a pro-inflammatory and amyloidogenic protein, OleA may effectively mitigate the pathological consequences of the S100A9-dependent amyloid-neuroinflammatory cascade as well as provide protection from neurodegeneration, if used within the Mediterranean diet as a potential preventive measure.

Differentiating Staphylococcus infection-associated glomerulonephritis and primary IgA nephropathy: a mass spectrometry-based exploratory study

Staphylococcus infection-associated glomerulonephritis (SAGN) and primary IgA nephropathy (IgAN) are separate disease entities requiring different treatment approaches. However, overlapping histologic features may cause a diagnostic dilemma. An exploratory proteomic study to identify potential distinguishing biomarkers was performed on formalin fixed paraffin embedded kidney biopsy tissue, using mass spectrometry (HPLC–MS/MS) (n = 27) and immunohistochemistry (IHC) (n = 64), on four main diagnostic groups—SAGN, primary IgAN, acute tubular necrosis (ATN) and normal kidney (baseline transplant biopsies). Spectral counts modeled as a negative binomial distribution were used for statistical comparisons and in silico pathway analysis. Analysis of variance techniques were used to compare groups and the ROC curve to evaluate classification algorithms. The glomerular proteomes of SAGN and IgAN showed remarkable similarities, except for significantly higher levels of monocyte/macrophage proteins in SAGN—mainly lysozyme and S100A9. This finding was confirmed by IHC. In contrast, the tubulointerstitial proteomes were markedly different in IgAN and SAGN, with a lower abundance of metabolic pathway proteins and a higher abundance of extracellular matrix proteins in SAGN. The stress protein transglutaminase-2 (TGM2) was also significantly higher in SAGN. IHC of differentially-expressed glomerular and tubulointerstitial proteins can be used to help discriminate between SAGN and IgAN in ambiguous cases.

Cigarette smoke induction of S100A9 contributes to chronic obstructive pulmonary disease

S100 calcium-binding protein A9 (S100A9) is elevated in plasma and bronchoalveolar lavage fluid (BALF) of patients with chronic obstructive pulmonary disease (COPD), and aging enhances S100A9 expression in several tissues. Currently, the direct impact of S100A9-mediated signaling on lung function and within the aging lung is unknown. Here, we observed that elevated S100A9 levels in human BALF correlated with age. Elevated lung levels of S100A9 were higher in older mice compared with in young animals and coincided with pulmonary function changes. Both acute and chronic exposure to cigarette smoke enhanced S100A9 levels in age-matched mice. To examine the direct role of S100A9 on the development of COPD, S100a9^-/- mice or mice administered paquinimod were exposed to chronic cigarette smoke. S100A9 depletion and inhibition attenuated the loss of lung function, pressure-volume loops, airway inflammation, lung compliance, and forced expiratory volume in 0.05 s/forced vital capacity, compared with age-matched wild-type or vehicle-administered animals. Loss of S100a9 signaling reduced cigarette smoke-induced airspace enlargement, alveolar remodeling, lung destruction, ERK and c-RAF phosphorylation, matrix metalloproteinase-3 (MMP-3), matrix metalloproteinase-9 (MMP-9), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), and keratinocyte-derived chemokine (KC) release into the airways. Paquinimod administered to nonsmoked, aged animals reduced age-associated loss of lung function. Since fibroblasts play a major role in the production and maintenance of extracellular matrix in emphysema, primary lung fibroblasts were treated with the ERK inhibitor LY3214996 or the c-RAF inhibitor GW5074, resulting in less S100A9-induced MMP-3, MMP-9, MCP-1, IL-6, and IL-8. Silencing Toll-like receptor 4 (TLR4), receptor for advanced glycation endproducts (RAGE), or extracellular matrix metalloproteinase inducer (EMMPRIN) prevented S100A9-induced phosphorylation of ERK and c-RAF. Our data suggest that S100A9 signaling contributes to the progression of smoke-induced and age-related COPD.

A Novel Pathological Scoring System for Hepatic Cirrhosis with Hepatocellular Carcinoma

Purpose

This study aimed to propose an effective quantitative pathological scoring system and to establish nomogram to assess the stage of cirrhosis and predict postoperative survival of hepatocellular carcinoma (HCC) with cirrhosis patients after hepatectomy.

Methods

The scoring system was based on a retrospective study on 163 patients who underwent partial hepatectomy for HCC with cirrhosis. The clinicopathological and follow-up data of 163 HCC with cirrhosis patients who underwent hepatectomy in our hospital from 2010 to 2014 were retrospectively reviewed. A scoring system was established based on the total value of independent predictive factors of cirrhosis. The results were validated using 97 patients operated on from 2011 to 2015 at the same institution. Nomogram was then formulated using a multivariate Cox proportional hazards model to analyze.

Results

The scoring system was ultimately composed of 4 independent predictive factors and was divided into 3 levels. The new cirrhosis system score strongly correlated with Child–Pugh score (r=0.8058, P<0.0001) 3 months after surgery; higher cirrhosis system scores predicted poorer liver function and stronger liver damage 3 months after surgery. Then, a four-factor nomogram for survival prediction was established. The concordance indices were 0.79 for the survival-prediction nomogram. The calibration curves showed good agreement between predictions by the nomogram and actual survival outcomes.

Conclusion

This new scoring system of cirrhosis can help us predict the liver function and liver injury 3 months after surgery, and the nomogram enabled accurate predictions of risk of overall survival in patients of HCC with cirrhosis after hepatectomy.