Chronic Activation Research Articles

Neuroretinal degeneration in a mouse model of systemic chronic immune activation observed by proteomics.

Blindness or vision loss due to neuroretinal and photoreceptor degeneration affects millions of individuals worldwide. In numerous neurodegenerative diseases, including age-related macular degeneration, dysregulated immune response-mediated retinal degeneration has been found to play a critical role in the disease pathogenesis. To better understand the pathogenic mechanisms underlying the retinal degeneration, we used a mouse model of systemic immune activation where we infected mice with lymphocytic choriomeningitis virus (LCMV) clone 13. Here, we evaluated the effects of LCMV infection and present a comprehensive discovery-based proteomic investigation using tandem mass tag (TMT) labeling and high-resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS). Changes in protein regulation in the posterior part of the eye, neuroretina, and RPE/choroid were compared to those in the spleen as a secondary lymphoid organ and to the kidney as a non-lymphoid but encapsulated organ at 1, 8, and 28 weeks of infection. Using bioinformatic tools, we found several proteins responsible for maintaining normal tissue homeostasis to be differentially regulated in the neuroretina and the RPE/choroid during the degenerative process. Additionally, in the organs we observed, several important protein pathways contributing to cellular homeostasis and tissue development were perturbed and associated with LCMV-mediated inflammation, promoting disease progression. Our findings suggest that the response to a systemic chronic infection differs between the neuroretina and the RPE/choroid, and the processes induced by chronic systemic infection in the RPE/choroid are not unlike those induced in non-immune-privileged organs such as the kidney and spleen. Overall, our data provide detailed insight into several molecular mechanisms of neuroretinal degeneration and highlight various novel protein pathways that further suggest that the posterior part of the eye is not an isolated immunological entity despite the existence of neuroretinal immune privilege.

Dietary Peppermint Extract Inhibits Chronic Heat Stress-Induced Activation of Innate Immunity and Inflammatory Response in the Spleen of Broiler Chickens.

The aim of this study was to investigate the effect of dietary peppermint extract (PE) on innate immunity and inflammatory responses in the spleen of broiler chickens under chronic heat stress. In order to further study the mechanism of the activation of innate immunity and inflammation induced by chronic heat stress and the regulatory effect of peppermint extract, we examined the spleen's histological change, the mRNA expression of major pattern recognition receptors (PRRs) (TLR2, TLR4, NOD1, MDA5 and DAI) and transcription factors (NF-κB, AP-1 and IRF3) and downstream inflammatory cytokines (IFN-α, IFN-β, IL-1β, IL-6 and TNF-α) of innate immune signaling pathways associated with heat stress in the spleen of broiler chickens. The results indicated that chronic heat stress damaged the spleen tissue. In addition, chronic heat stress induced the activation of innate immunity and inflammatory responses by increasing the mRNA expression of TLR2, TLR4 and DAI, mRNA expression of transcriptional factors (NF-κB, AP-1 and IRF3) and the concentration of downstream inflammatory cytokines in the spleen of broiler chickens. Dietary peppermint extract alleviated the damage of spleen tissue caused by chronic heat stress. In addition, peppermint extract reduced the mRNA expression of DAI, mRNA expression of transcriptional factors NF-κB, AP-1 and IRF3, and the concentration of inflammatory cytokines in the spleen of broiler chickens under chronic heat stress. In conclusion, dietary peppermint extract could have a beneficial effect on regulating inflammatory response and innate immunity via inhibiting the activation of NF-κB, AP-1 and IRF3 signaling pathways mediated by DAI in the spleen of broiler chickens induced by chronic heat stress.

Optogenetic induction of chronic glucocorticoid exposure in early-life leads to blunted stress-response in larval zebrafish.

Early life stress (ELS) exposure alters stress susceptibility in later life and affects vulnerability to stress-related disorders, but how ELS changes the long-lasting responsiveness of the stress system is not well understood. Zebrafish provides an opportunity to study conserved mechanisms underlying the development and function of the stress response that is regulated largely by the neuroendocrine hypothalamus-pituitary-adrenal/interrenal (HPA/I) axis, with glucocorticoids (GC) as the final effector. In this study, we established a method to chronically elevate endogenous GC levels during early life in larval zebrafish. To this end, we employed an optogenetic actuator, beggiatoa photoactivated adenylyl cyclase, specifically expressed in the interrenal cells of zebrafish and demonstrate that its chronic activation leads to hypercortisolaemia and dampens the acute-stress evoked cortisol levels, across a variety of stressor modalities during early life. This blunting of stress-response was conserved in ontogeny at a later developmental stage. Furthermore, we observe a strong reduction of proopiomelanocortin (pomc)-expression in the pituitary as well as upregulation of fkbp5 gene expression. Going forward, we propose that this model can be leveraged to tease apart the mechanisms underlying developmental programming of the HPA/I axis by early-life GC exposure and its implications for vulnerability and resilience to stress in adulthood.

Canonical and non-canonical roles of complement in atherosclerosis.

Cardiovascular diseases are the leading cause of death globally, and atherosclerosis is the major contributor to the development and progression of cardiovascular diseases. Immune responses have a central role in the pathogenesis of atherosclerosis, with the complement system being an acknowledged contributor. Chronic activation of liver-derived and serum-circulating canonical complement sustains endothelial inflammation and innate immune cell activation, and deposition of complement activation fragments on inflamed endothelial cells is a hallmark of atherosclerotic plaques. However, increasing evidence indicates that liver-independent, cell-autonomous and non-canonical complement activities are underappreciated contributors to atherosclerosis. Furthermore, complement activation can also have atheroprotective properties. These specific detrimental or beneficial contributions of the complement systemto the pathogenesis of atherosclerosis are dictated by the location of complement activation and engagement of its canonical versus non-canonical functions in a temporal fashion during atherosclerosis progression. In this Review, we summarize the classical and the emerging non-classical roles of the complement system in the pathogenesis of atherosclerosis and discuss potential strategies for therapeutic modulation of complement for the prevention and treatment of atherosclerotic cardiovascular disease.

Effects of statins beyond lipid-lowering agents in ART-treated HIV infection.

Antiretroviral therapies (ART) have reduced human immunodeficiency virus (HIV) infection-associated morbidity and mortality improving the life of people with HIV (PWH). However, ART lead to residual HIV production, which in conjunction with microbial translocation and immune dysfunction contributes to chronic inflammation and immune activation. PWH on ART remain at an increased risk for cardiovascular diseases (CVDs) including myocardial infarction and stroke; which in part is explained by chronic inflammation and immune activation. Lifestyle factors and certain ART are associated with dyslipidemia characterized by an increase of low-density lipoprotein (LDL), which further contributes in the increased risk for CVDs. Lipid-lowering agents like statins are emerging as immune modulators in decreasing inflammation in a variety of conditions including HIV. The international randomized clinical trial REPRIEVE has shed light on the reduction of CVDs with statin therapy among PWH. Such reports indicate a more than expected benefit of statins beyond their lipid-lowering effects. Bempedoic acid, a first-in-class non-statin LDL-lowering drug with immune modulatory effects, may further aid PWH in combination with statins. Herein, we critically reviewed studies aimed at lipid-lowering and immune-modulating roles of statins that may benefit aging PWH.

Comprehensive Ocular and Systemic Safety Evaluation of Polysialic Acid-Decorated Immune Modulating Therapeutic Nanoparticles (PolySia-NPs) to Support Entry into First-in-Human Clinical Trials.

An inflammation-resolving polysialic acid-decorated PLGA nanoparticle (PolySia-NP) has been developed to treat geographic atrophy/age-related macular degeneration and other conditions caused by macrophage and complement over-activation. While PolySia-NPs have demonstrated pre-clinical efficacy, this study evaluated its systemic and intraocular safety. PolySia-NPs were evaluated in vitro for mutagenic activity using Salmonella strains and E. coli, with and without metabolic activation; cytotoxicity was evaluated based on its interference with normal mitosis. PolySia-NPs were administered intravenously in CD-1 mice and Sprague Dawley rats and assessed for survival and toxicity. Intravitreal (IVT) administration in Dutch Belted rabbits and non-human primates was assessed for ocular or systemic toxicity. In vitro results indicate that PolySia-NPs did not induce mutagenicity or cytotoxicity. Intravenous administration did not show clastogenic activity, effects on survival, or toxicity. A single intravitreal (IVT) injection and two elevated repeat IVT doses of PolySia-NPs separated by 7 days in rabbits showed no signs of systemic or ocular toxicity. A single IVT inoculation of PolySia-NPs in non-human primates demonstrated no adverse clinical or ophthalmological effects. The demonstration of systemic and ocular safety of PolySia-NPs supports its advancement into human clinical trials as a promising therapeutic approach for systemic and retinal degenerative diseases caused by chronic immune activation.

Association between proinflammatory cytokines and arterial stiffness in type 1 diabetic adolescents.

Type 1 diabetes mellitus is considered a state of chronic low-grade inflammation and activation of the innate immune system, which is regulated by several proinflammatory cytokines and other acute-phase reactants. Arterial stiffness, a dynamic property of the vessels evaluated by the determination of pulse wave velocity (PWV), is increased in diabetic patients and is associated with microvascular and macrovascular complications of diabetes and higher cardiovascular risk. In the present study, we aimed to compare the proinflammatory state and arterial stiffness in diabetic and non-diabetic adolescents, and to characterize the association between these two parameters. Twenty-three type 1 diabetic patients, aged 12-16 years, followed at a tertiary center, and 23 adolescents nonoverweighted healthy controls, from a Portuguese birth-cohort, were included in the present analysis. Anthropometry, blood pressure, glycemic control data, and lipid parameters were collected. Arterial stiffness was evaluated by carotid-femoral pulse wave velocity. Proinflammatory cytokines' concentrations (TNF-α, IL-1β, IL-6, IL-10, IFN-γ, and GM-CSF) were quantified by multiplex immunoassays using a Luminex 200 analyzer. There were no statistically significant differences between the proinflammatory cytokines' concentrations in the two groups. PWV [6.63 (6.23-7.07) vs. 6.07 (5.15-6.65) m/s, p=0.015] was significantly higher in the diabetic group. PWV was negatively correlated with GM-CSF (ρ=-0.437, p=0.037) in the diabetic group. A linear association was found between diabetes duration and PWV (with PWV increasing by 0.094 m/s (95 % confidence interval, 0.019 to 0.169) per month of disease duration). In the diabetic group, HbA1c was negatively correlated with IL-10 (ρ=-0.473, p=0.026). Negative correlations were also found between IL-10 and total, HDL, and LDL cholesterol only in the diabetic group. Diabetic adolescent patients present higher PWV, when compared to their healthy counterparts, even though we could not find differences in the levels of several proinflammatory cytokines between the two groups. The negative correlation found between IL-10 and HbA1c might translate a protective counterbalance effect of this anti-inflammatory cytokine, which might also explain the negative correlations found with blood lipids. Further studies are needed to better clarify the association between arterial stiffness and the proinflammatory milieu of diabetes.

Ageing, osteoporosis and intellectual disability; risks differ, and diagnosis can be missed

AbstractBackgroundPeople with intellectual disability often present atypically for various health conditions, making it challenging to identify concerns, particularly when communication challenges are also considered. Additionally, they may face barriers to healthcare access, resulting in many conditions going unnoticed. Health screening inequities are also evident in this population, and osteoporosis, a silent condition often only diagnosed postfracture, requires screening; however, if this does not happen, it may result in unnecessary fracture. Therefore the aim of this study is to identify predictors of osteoporosis in older adults with intellectual disability and examine potential inequity in the diagnosis of the condition.MethodsThe study used data from the Intellectual Disability Supplement to The Irish Longitudinal Study on Ageing (IDS‐TILDA). Bone quality was measured using quantitative ultrasound (QUS). Logistic regression was performed to identify significant predictors of poor bone quality, including chronic health conditions, dietary intake, medication use and activity levels.ResultsOut of 575 participants who completed QUS, osteoporosis prevalence was objectively measured at 41%, with a further 33.2% measured within the osteopenic range, but less than 2 in 10 had a doctor's diagnosis of osteoporosis. Reported Dual‐Energy X‐ray Absorptiometry screening uptake was low at 18.2%. Three major predictor variables of osteoporosis and osteopenia were found significant: difficulty walking 100 yards, taking antiepileptic drugs medicines and taking proton pump inhibitors. The model achieved an overall classification accuracy of 70.8% for osteopenia and 72.5% for identifying osteoporosis.ConclusionThe study highlights the different risk factors in people with intellectual disability, the potential for missed diagnoses and the likelihood there is inadequate screening. There is an urgent need for robust risk assessment and reasonable adjustments to ensure equitable screening and targeted preventive strategies. Clinicians must consider specific concerns for this population to avoid missed diagnoses and reduce the adverse effects of osteoporosis/osteopenia, such as an increased risk of fragility fractures.

TCF1-LEF1 co-expression identifies a multipotent progenitor cell (TH2-MPP) across human allergic diseases.

Repetitive exposure to antigen in chronic infection and cancer drives T cell exhaustion, limiting adaptive immunity. In contrast, aberrant, sustained T cell responses can persist over decades in human allergic disease. To understand these divergent outcomes, we employed bioinformatic, immunophenotyping and functional approaches with human diseased tissues, identifying an abundant population of type 2 helper T (TH2) cells with co-expression of TCF7 and LEF1, and features of chronic activation. These cells, which we termed TH2-multipotent progenitors (TH2-MPP) could self-renew and differentiate into cytokine-producing effector cells, regulatory T (Treg) cells and follicular helper T (TFH) cells. Single-cell T-cell-receptor lineage tracing confirmed lineage relationships between TH2-MPP, TH2 effectors, Treg cells and TFH cells. TH2-MPP persisted despite in vivo IL-4 receptor blockade, while thymic stromal lymphopoietin (TSLP) drove selective expansion of progenitor cells and rendered them insensitive to glucocorticoid-induced apoptosis in vitro. Together, our data identify TH2-MPP as an aberrant T cell population with the potential to sustain type 2 inflammation and support the paradigm that chronic T cell responses can be coordinated over time by progenitor cells.

Bi-directional neuro-immune dysfunction after chronic experimental brain injury

BackgroundIt is well established that traumatic brain injury (TBI) causes acute and chronic alterations in systemic immune function and that systemic immune changes contribute to posttraumatic neuroinflammation and neurodegeneration. However, how TBI affects bone marrow (BM) hematopoietic stem/progenitor cells chronically and to what extent such changes may negatively impact innate immunity and neurological function has not been examined.MethodsTo further understand the role of BM cell derivatives on TBI outcome, we generated BM chimeric mice by transplanting BM from chronically injured or sham (i.e., 90 days post-surgery) congenic donor mice into otherwise healthy, age-matched, irradiated CD45.2 C57BL/6 (WT) hosts. Immune changes were evaluated by flow cytometry, multiplex ELISA, and NanoString technology. Moderate-to-severe TBI was induced by controlled cortical impact injury and neurological function was measured using a battery of behavioral tests.ResultsTBI induced chronic alterations in the transcriptome of BM lineage−c-Kit+Sca1+ (LSK+) cells in C57BL/6 mice, including modified epigenetic and senescence pathways. After 8 weeks of reconstitution, peripheral myeloid cells from TBI→WT mice showed significantly higher oxidative stress levels and reduced phagocytic activity. At eight months after reconstitution, TBI→WT chimeric mice were leukopenic, with continued alterations in phagocytosis and oxidative stress responses, as well as persistent neurological deficits. Gene expression analysis revealed BM-driven changes in neuroinflammation and neuropathology after 8 weeks and 8 months of reconstitution, respectively. Chimeric mice subjected to TBI at 8 weeks and 8 months post-reconstitution showed that longer reconstitution periods (i.e., time post-injury) were associated with increased microgliosis and leukocyte infiltration. Pre-treatment with a senolytic agent, ABT-263, significantly improved behavioral performance of aged C57BL/6 mice at baseline, although it did not attenuate neuroinflammation in the acutely injured brain.ConclusionsTBI causes chronic activation and progressive dysfunction of the BM stem/progenitor cell pool, which drives long-term deficits in hematopoiesis, innate immunity, and neurological function, as well as altered sensitivity to subsequent brain injury.

The Micro-Immunotherapy Medicine 2LPAPI® Displays Immune-Modulatory Effects in a Model of Human Papillomavirus Type-16 L1-Protein Capsid-Treated Human Peripheral Blood Mononuclear Cells and Antiproliferative Effects in a Model of Cervical Cancer Cells.

Human papillomavirus (HPV) is the second most common infectious agent causing cancer. Persistent infection with high-risk (HR)-HPV can lead to cervical intra-epithelial neoplasia and cervical carcinomas (CC). While host immune response is necessary for viral clearance, chronic immune activation contributes to a low-grade inflammation that can ultimately lead to carcinogenesis. The micro-immunotherapy medicine (MIM) 2LPAPI® could be a valuable tool to manage the clearance of the virus and reduce the risk of developing CC. In this in vitro study, we aimed to investigate its mode of action. We showed that actives from the MIM increased the IL-6, IFN-γ, and IP-10 secretion in human peripheral blood mononuclear cells (PBMCs) exposed to peptides derived from the HPV-16 capsid (HPV16(L1)). This could reflect an increase in the immune activity toward HPV-16. At the same time, some active substances reduced the lympho-proliferation and the expression of T-cell activation markers. Finally, some of the MIM actives displayed antiproliferative effects in CC-derived HeLa cells under serum-starvation conditions. Altogether, this body of data highlighted for the first time the dual effect of MIM in the framework of HR-HPV infections as a potential (i) immune modulator of HPV16(L1)-treated PBMCs and (ii) antiproliferative agent of HPV-positive CC cells.

Treatment success in cats with chronic enteropathy is associated with a decrease in fecal calprotectin concentrations.

Feline chronic enteropathies (FCE) are challenging to diagnose and monitor for progression and response to treatment. Fecal calprotectin might be a useful non-invasive marker to evaluate clinical endpoints of therapeutic monitoring in FCE. We evaluated fecal calprotectin concentrations in cats with FCE before and after initiation of treatment comprised of immunomodulation and/or dietary intervention. Included were 17 cats with FCE and 18 healthy controls. Clinical investigation of FCE cases included clinical severity grading (feline chronic enteropathy activity index, FCEAI) in all cats, abdominal ultrasonography in 15 cats, and gastrointestinal biopsies in 6 cats. Fecal calprotectin was measured in samples from 12 cats with FCE before treatment, all 17 FCE cats ≥6 weeks after treatment initiation, and all healthy controls. Fecal calprotectin concentrations in FCE cases before treatment (median: 61 μg/g) were significantly higher than after treatment initiation (median: 15 μg/g; p = 0.0098) and compared to controls (median: 6 μg/g; p = 0.0235) and correlated with the FCEAI scores (ρ = 0.54, p = 0.0316). Fecal calprotectin concentrations after treatment initiation were higher with more severe duodenal/proximal jejunal pathology (ρ = 0.83, p = 0.0427) and shorter intervals between sampling time points (ρ = -0.54, p = 0.0250). Relevant decreases in initially increased fecal calprotectin concentrations are seen in cats with FCE on varying treatment strategies that significantly improve or have remission of clinical signs. This supports the utility of fecal calprotectin as a surrogate biomarker to assess disease severity in FCE cases. Further studies need to evaluate fecal calprotectin concentrations longitudinally in relation to mucosal healing vs. clinical response.

CD4+ Regulatory T Cells in Human Cancer: Subsets, Origin, and Molecular Regulation.

CD4+CD25hiFOXP3+ regulatory T cells (Treg) play major roles in the maintenance of immune tolerance, prevention of inflammation, and tissue homeostasis and repair. In contrast with these beneficial roles, Tregs are abundant in virtually all tumors and have been mechanistically linked to disease progression, metastases development, and therapy resistance. Tregs are thus recognized as a major target for cancer immunotherapy. Compared with other sites in the body, tumors harbor hyperactivated Treg subsets whose molecular characteristics are only beginning to be elucidated. Here, we describe current knowledge of intratumoral Tregs and discuss their potential cellular and tissue origin. Furthermore, we describe currently recognized molecular regulators that drive differentiation and maintenance of Tregs in cancer, with a special focus on those signals regulating their chronic immune activation, with relevant implications for cancer progression and therapy.

Clonal hematopoiesis in people with advanced HIV and associated inflammatory syndromes.

People with HIV (PWH) have a higher age-adjusted mortality due to chronic immune activation and age-related comorbidities. PWH also have higher rates of clonal hematopoiesis (CH) than age-matched non-HIV cohorts; however, risk factors influencing the development and expansion of CH in PWH remain incompletely explored. We investigated the relationship between CH, immune biomarkers, and HIV-associated risk factors (CD4+ and CD8+ T cells, nadir CD4+ count, opportunistic infections [OIs], and immune reconstitution inflammatory syndrome [IRIS]) in a diverse cohort of 197 PWH with median age of 42 years, using a 56-gene panel. Seventy-nine percent had a CD4+ nadir below 200 cells/μL, 58.9% had prior OIs, and 34.5% had a history of IRIS. The prevalence of CH was high (27.4%), even in younger individuals, and CD8+ T cells and nadir CD4+ counts strongly associated with CH after controlling for age. A history of IRIS was associated with CH in a subgroup analysis of patients 35 years of age and older. Inflammatory biomarkers were higher in CH carriers compared with noncarriers, supporting a dysregulated immune state. These findings suggest PWH with low nadir CD4+ and/or inflammatory complications may be at high risk of CH regardless of age and represent a high-risk group that could benefit from risk reduction and potentially targeted immunomodulation.

The Activity Management Inventory for Pain (AMI-P): Initial Development and Validation of a Questionnaire Based on Operant Learning and Energy Conservation Models of Activity Management.

Activity management is an important treatment component in chronic pain programs. However, there are shortcomings in measures of this construct, leading to inconsistencies in research findings. Here, we describe the development of the Activity Management Inventory for Pain (AMI-P). The AMI-P was developed by a group of international researchers with extensive expertise in both chronic pain and activity management. The initial evaluation of the AMI-P items included 2 studies that were both conducted in Canadian tertiary pain care centers. The resulting 20-item measure has 3 behavior scales (Rest, Alternating Activity, and Planned Activity), and 4 goal scales (Feel Less Pain, Get More Done, Complete the Task, and Save Energy). The behavior scales evidenced marginal to good internal consistency and test-retest reliability, and a moderate positive association with an existing pacing measure. The Rest and Alternating Activity scales were associated with greater pain interference, the Alternating Activity and Planned Activity scales were associated with less satisfaction with social roles, and the Planned Activity scale was associated with fewer depressive symptoms. The Alternating Activity scale increased significantly from pretreatment to posttreatment. All goal scales were positively associated with all behavior scales. The Feel Less Pain goal scale was positively associated with measures of avoidance and pain interference, while the Get More Done goal scale was negatively associated with measures of depressive symptoms and overdoing. The findings support the reliability and validity of the AMI-P scales, while also highlighting the complexity and multidimensional aspects of activity management.

Influence of Chronic Forced Immobilization and Consumption of a High-Fat and High-Carbohydrate Diet Containing Cholesterol on Lipid and Cholesterol Metabolism in Male Wistar Rats.

We studied the effect of separate and combined influence of chronic forced physical activity reduction and high-fat and high-carbohydrate diet containing cholesterol on some indicators of carbohydrate, lipid, and cholesterol metabolism in growing male Wistar rats. Used combination of factors simulating a sedentary lifestyle and unhealthy diet did not have a synergistic effect on the selected biomarkers. On the contrary, the effect was antagonistic: body weight and appetite decreased and insulin resistance increased. The obtained results indicate certain prospects of hypercholesterolemia model using in preclinical studies of specialized food products to optimize the diet of individuals with disorders of carbohydrate and lipid metabolism.

Long-Term Consequences of PTI Activation and Its Manipulation by Root-Associated Microbiota.

In nature, plants are constantly colonized by a massive diversity of microbes engaged in mutualistic, pathogenic or commensal relationships with the host. Molecular patterns present in these microbes activate pattern-triggered immunity (PTI), which detects microbes in the apoplast or at the tissue surface. Whether and how PTI distinguishes among soil-borne pathogens, opportunistic pathogens, and commensal microbes within the soil microbiota remains unclear. PTI is a multimodal series of molecular events initiated by pattern perception, such as Ca2+ influx, reactive oxygen burst, and extensive transcriptional and metabolic reprogramming. These short-term responses may manifest within minutes to hours, while the long-term consequences of chronic PTI activation persist for days to weeks. Chronic activation of PTI is detrimental to plant growth, so plants need to coordinate growth and defense depending on the surrounding biotic and abiotic environments. Recent studies have demonstrated that root-associated commensal microbes can activate or suppress immune responses to variable extents, clearly pointing to the role of PTI in root-microbiota interactions. However, the molecular mechanisms by which root commensals interfere with root immunity and root immunity modulates microbial behavior remain largely elusive. Here, with a focus on the difference between short-term and long-term PTI responses, we summarize what is known about microbial interference with host PTI, especially in the context of root microbiota. We emphasize some missing pieces that remain to be characterized to promote the ultimate understanding of the role of plant immunity in root-microbiota interactions.

Recent advances in understanding the biology of follicular lymphoma.

Follicular lymphoma (FL), the most common indolent B-cell lymphoma, develops over decades before manifesting as overt disease. BCL2 overexpression by t(14;18) confers a survival advantage to B cells during the germinal center reaction, and abnormalities in epigenetic modifier genes lead to desynchronization of gene expression changes in germinal center B cells. Studies in mouse models have shown that BCL2 overexpression and epigenetic deregulation in B cells cooperatively promote lymphomagenesis. The immune microenvironment also plays an essential role in the biology of FL, and many molecular prognostic indicators based on the immune microenvironment have been proposed. However, high-risk gene signatures do not appear to be consistent between patients receiving different chemotherapies. FL cells frequently carry N-linked glycosylation motifs within the immunoglobulin gene, leading to chronic activation of the B-cell receptor (BCR). Recent evidence suggests that this chronic BCR signaling drives FL polarization toward a dark-zone phenotype and promotes clonal evolution. Since both epigenetic and post-transcriptional modifications of B cells have been implicated in the early stage of FL development, it may be possible to use novel non-chemotherapeutic approaches that interfere with the immunobiology in treatment or early prevention of FL.

Mitochondrial Dysfunction as the Major Basis of Brain Aging.

The changes in the properties of three biological events that occur with cerebral aging are discussed. These adverse changes already begin to develop early in mid-life and gradually become more pronounced with senescence. Essentially, they are reflections of the progressive decline in effectiveness of key processes, resulting in the deviation of essential biochemical trajectories to ineffective and ultimately harmful variants of these programs. The emphasis of this review is the major role played by the mitochondria in the transition of these three important processes toward more deleterious variants as brain aging proceeds. The immune system: the shift away from an efficient immune response to a more unfocused, continuing inflammatory condition. Such a state is both ineffective and harmful. Reactive oxygen species are important intracellular signaling systems. Additionally, microglial phagocytic activity utilizing short lived reactive oxygen species contribute to the removal of aberrant or dead cells and bacteria. These processes are transformed into an excessive, untargeted, and persistent generation of pro-oxidant free radicals (oxidative stress). The normal efficient neural transmission is modified to a state of undirected, chronic low-level excitatory activity. Each of these changes is characterized by the occurrence of continuous activity that is inefficient and diffused. The signal/noise ratio of several critical biological events is thus reduced as beneficial responses are gradually replaced by their impaired and deleterious variants.

Abstract 2704: cGAS-STING drives myeloid inflammation in chromosomally unstable esophageal cancer

Abstract Esophageal adenocarcinoma (EAC) is an aggressive disease characterized by chromosomal instability (CIN), whereby cells continuously acquire chromosomal abnormalities that promote therapeutic resistance, immune evasion and metastasis. CIN in cancers also fuels the misplacement of genomic DNA in the form of structural abnormalities of the nucleus, such as micronuclei (MN), that lead to chronic activation of the cytosolic DNA sensing cGAS-STING pathway. However, how chronic cGAS-STING pathway activation is tolerated and shapes the tumor landscape of CINhigh EAC cancers is poorly understood. Using publicly available RNA-seq and genome sequencing data of EAC tumours and esophageal cancer cell lines as well as a panel of EAC cell lines, we demonstrate that the core cGAS-STING pathway machinery is rarely inactivated in EAC despite high levels of baseline CIN and aneuploidy. Through transcriptomic profiling of an isogenic EAC precursor cell line model of variable CIN and cGASKO/WT EAC cell lines we show that both chronic and transient CIN-driven cGAS-STING activation converge on the expression of CXCR1/2 ligands and other pro-inflammatory cytokines and chemokines rather than typical anti-tumor type I interferon signalling in EAC cells. Indeed, a novel transcriptional signature of cGAS+ micronuclear burden-correlated genes correlates with orthogonal measures of CIN in EAC tumours and esophagogastric cancer cell lines and is associated with an enrichment in myeloid-derived cells as well as poor prognosis. Correspondingly, using multiplexed immunofluorescence (IF) we find that a high preponderance of cGAS+MN and STING expression in human EAC samples is associated with decreased tumor purity, increased myeloid cell and macrophage infiltration, and increased peripheral blood neutrophil counts, indicative of tumor-promoting myeloid inflammation. Ongoing multiplexed IF and single-nuclei RNAseq analysis of cGAS+MNhigh and cGAS+MNlow EAC tumors will further help characterise the components that comprise the CIN EAC tumor microenvironment (TME) and the CIN- and cGAS-STING-dependent cell-cell interactions that govern it. Taken together, our findings provide an explanation for the observed maintenance of cGAS and STING in EAC and identify disruption of cGAS-STING-dependent myeloid cell inflammation and recruitment as a potential therapeutic target for CINhigh EAC. Citation Format: Bruno Beernaert, Erkin Erdal, Rose Clark, Tong Liu, Ester M. Hammond, Eileen E. Parkes. cGAS-STING drives myeloid inflammation in chromosomally unstable esophageal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2704.