Obesity-induced DNA released from adipocytes stimulates chronic adipose tissue inflammation and insulin resistance

A systematic review on the applicability of cell-free DNA level as an obesity biomarker

Obesity has become a global health concern in recent decades. Utilizing biomarkers presents a promising approach to comprehensively monitor the progress of obesity and its associated health conditions. This review aims to synthesize the available evidence on the correlation between cfDNA level and obesity and to provide insights into the applicability of using cfDNA level as a tool for monitoring progression of obesity. Searches were performed in PubMed and Embase on April 1, 2022. Data and other relevant information were extracted and compiled into a structured table for further analysis. Among 1170 articles screened, 11 articles were included in this review and assessed qualitatively. The results demonstrated that existing evidence mainly focused on three populations, including healthy individuals, cancer patients and pregnant women. Majority of the studies on healthy individuals identified a significant association between cfDNA level and body weight status but not among cancer patients. Varying results were observed among pregnant women at different gestational trimesters. Our review summarized some preliminary evidence on the association between cfDNA level and obesity. More cohort studies in larger scale with comprehensive assessment have to be conducted to examine the applicability of cfDNA as a biomarker for severity and disease progression of obesity.

Association of fetal fraction and cell-free fetal DNA with adverse pregnancy outcomes: A systematic review

BACKGROUND

Adverse pregnancy outcomes, which can be caused by multiple factors, present a significant threat to the health of mothers and their babies. Cell-free fetal DNA (cffDNA) from placental trophoblast cells might be able to reflect placental and fetal status. Previous studies have yielded controversial results regarding the association of FF or cffDNA with various adverse pregnancy outcomes. A previous study has attempted to systematically assess the association between low fetal fraction (FF) and adverse pregnancy outcomes, but it failed to perform quantitative analyses due to the few studies included. In the present study, we attempted to quantitatively assess the association of FF (or cffDNA) with adverse pregnancy outcomes and further analyze the causes of heterogeneity.

OBJECTIVES

To investigate the association of high/low FF or cffDNA with adverse pregnancy outcomes.

SEARCH STRATEGY

We searched the databases of PubMed, Embase, Cochrane, and Web of Science from January 1, 1990, to June 15, 2022 in this meta-analysis.

SELECTION CRITERIA

Studies on the relationships of adverse pregnancy outcomes in women with FF or cell free DNA were included. Non-English literature was excluded.

DATA COLLECTION AND ANALYSIS

Data about pregnancy outcomes and cell free DNA were extracted and meta-analyzed. Subgroup analysis was performed by different outcomes.

MAIN RESULTS

There were 11 studies included involving 8280 participants. No significant heterogeneity was observed among the studies (I2 = 27%, 25%), and a fixed-effect model was used for weighted quantitative analysis. The results revealed that the FF or cffDNA during pregnancy was significantly associated with adverse pregnancy outcomes in pregnant women (OR = 1.57, 95% CI [1.24, 1.99], P = 0.233). The overall incidence of the maternal adverse outcomes was 8% (95% CI: 5-13). Subgroup analysis of different outcomes showed an evident association between low FF or cffDNA and hypertensive disorders of pregnancy (HDP) (OR = 1.76, 95% CI [1.36, 2.27], P = 0.581). There was no evidence that the occurrence of spontaneous preterm birth (sPTB) and placental abnormality was associated with FF or cffDNA. No association was observed between low FF or cffDNA during pregnancy and adverse outcomes in fetuses (OR = 1.39, 95% CI [0.99, 1.94], P = 0.242). The overall incidence of adverse outcomes in fetuses was 8% (95% CI: 6-11). There were controversies over the association between high FF or cffDNA and HDP, and sPTB and small for gestational age infant, among different studies.

CONCLUSIONS

Pregnant women with low FF or cffDNA during the first or second trimester of pregnancy have an overall increased risk of adverse pregnancy outcomes, especially HDP. However, the association between FF and various pregnancy outcomes needs to be further explored by more prospective studies.

Tlr9 deficiency in B cells leads to obesity by promoting inflammation and gut dysbiosis

Toll-like receptor 9 (TLR9) recognizes bacterial, viral and self DNA and play an important role in immunity and inflammation. However, the role of TLR9 in obesity is less well-studied. Here, we generate B-cell-specific Tlr9-deficient (Tlr9fl/fl/Cd19Cre+/-, KO) B6 mice and model obesity using a high-fat diet. Compared with control mice, B-cell-specific-Tlr9-deficient mice exhibited increased fat tissue inflammation, weight gain, and impaired glucose and insulin tolerance. Furthermore, the frequencies of IL-10-producing-B cells and marginal zone B cells were reduced, and those of follicular and germinal center B cells were increased. This was associated with increased frequencies of IFNγ-producing-T cells and increased follicular helper cells. In addition, gut microbiota from the KO mice induced a pro-inflammatory state leading to immunological and metabolic dysregulation when transferred to germ-free mice. Using 16 S rRNA gene sequencing, we identify altered gut microbial communities including reduced Lachnospiraceae, which may play a role in altered metabolism in KO mice. We identify an important network involving Tlr9, Irf4 and Il-10 interconnecting metabolic homeostasis, with the function of B and T cells, and gut microbiota in obesity.

Polyester Nanoparticles with Controlled Topography for Peroral Drug Delivery Using Insulin as a Model Protein

Receptor-mediated polyester drug delivery systems have tremendous potential for improving the clinical performance of existing pharmaceutical drugs. Despite significant progress made in this area, it remains unclear how and to what extent the polyester nanoparticle surface topography would affect the in vitro, ex vivo and in vivo performance of a drug, and if there exists a correlation between in vitro and in vivo, as well as healthy versus pathophysiological states. Herein, we report a systematic investigation of the interactions between ligands and receptors as a function of the linker length, two-carbon (2C) versus four-carbon (4C). The in vitro, ex vivo and in vivo in healthy models validate the hypothesis that 4C has better reach and binding to the receptors. The results indicate that 4C offered better performance over 2C in vivo in improving the oral bioavailability of insulin (INS) by 1.1-fold (3.5-fold compared to unfunctionalized nanoparticles) in a healthy rat model. Similar observations were made in pathophysiological models; however, the effects were less prominent compared to those in healthy models. Throughout, ligand decorated nanoparticles outperformed unfunctionalized nanoparticles. Finally, a semimechanistic pharmacokinetic and pharmacodynamic (PKPD) model was developed using the experimental data sets to quantitatively evaluate the effect of P2Ns-GA on oral bioavailability and efficacy of insulin. The study presents a sophisticated oral delivery system for INS or hydrophilic therapeutic cargo, highlighting the significant impact on bioavailability that minor adjustments to the surface chemistry can have.

Human omentin-1 reduces vascular insulin resistance and hypertension in Otsuka Long-Evans Tokushima Fatty rats

PURPOSE

Hypertension is one of the major risk factors for renal failure and cardiovascular diseases, and is caused by various abnormalities including the contractility of blood vessels. Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which mimic human type 2 diabetes, are frequently used to study obesity-induced insulin resistance (IR) and hypertension. Human omentin-1 is one of the recently identified adipocytokines. We previously demonstrated that human omentin-1 not only caused vasodilation in rat isolated blood vessels, but also prevented inflammatory responses, a possible mechanism relating IR, in human vascular endothelial cells. Taken together, we hypothesized that human omentin-1 may reduce obesity-induced IR and hypertension in OLETF rats.

METHODS

OLETF rats were intraperitoneally administered with human omentin-1 for 7 days.

RESULTS

Human omentin-1 had no influence on overweight, hyperglycemia, urinary glucose extraction, hyperinsulinemia, and systemic IR in OLETF rats. Human omentin-1 decreased systolic blood pressure in OLETF rats. The measurement of isometric contraction revealed that human omentin-1 had no influence on the agonist-induced contractile and relaxant responses in isolated thoracic aorta from OLETF rats. However, the relaxant response mediated by human insulin was converted into the contractile response in thoracic aorta from OLETF rats, which was prevented by human omentin-1. The Western blotting revealed that human omentin-1 improved the decrease in endothelial nitric oxide synthase activation in isolated thoracic aorta from OLETF rats.

CONCLUSION

In summary, we for the first time revealed that human omentin-1 partly reduces vascular IR and thereby inhibits hypertension in OLETF rats.

Enhancing fetal outcomes in GCK-MODY pregnancies: a precision medicine approach via non-invasive prenatal GCK mutation detection

Background

Mutations in the GCK gene cause Maturity Onset Diabetes of the Young (GCK-MODY) by impairing glucose-sensing in pancreatic beta cells. During pregnancy, managing this type of diabetes varies based on fetal genotype. Fetuses carrying a GCK mutation can derive benefit from moderate maternal hyperglycemia, stimulating insulin secretion in fetal islets, whereas this may cause macrosomia in wild-type fetuses. Modulating maternal glycemia can thus be viewed as a form of personalized prenatal therapy, highly beneficial but not justifying the risk of invasive testing. We therefore developed a monogenic non-invasive prenatal diagnostic (NIPD-M) test to reliably detect the transmission of a known maternal GCK mutation to the fetus.

Methods

A small amount of fetal circulating cell-free DNA is present in maternal plasma but cannot be distinguished from maternal cell-free DNA. Determining transmission of a maternal mutation to the fetus thus implies sequencing adjacent polymorphisms to determine the balance of maternal haplotypes, the transmitted haplotype being over-represented in maternal plasma.

Results

Here we present a series of such tests in which fetal genotype was successfully determined and show that it can be used to guide therapeutic decisions during pregnancy and improve the outcome for the offspring. We discuss several potential hurdles inherent to the technique, and strategies to overcome these.

Conclusion

Our NIPD-M test allows reliable determination of the presence of a maternal GCK mutation in the fetus, thereby allowing personalized in utero therapy by modulating maternal glycemia, without incurring the risk of miscarriage inherent to invasive testing.

New Horizons: Epidemiology of Obesity, Diabetes Mellitus, and Cancer Prognosis

The global prevalence of obesity and diabetes mellitus has increased in parallel with increasing cancer incidence, due to environmental and lifestyle factors and population aging. Metabolic diseases are associated with increased cancer risk, so a growing number of patients with cancer have coexistent obesity and/or diabetes mellitus. In this narrative review, we highlight recent evidence on the clinical impact of obesity and diabetes mellitus on the prognosis of prostate, breast, and colorectal cancer, and provide an overview of the underlying mechanisms. There is evidence that obesity is associated with increased risk of recurrence, and all-cause and cancer-specific mortality among adults with prostate, breast, and colorectal cancer. Diabetes mellitus is associated with increased all-cause and cancer-specific mortality for these 3 cancers, beyond any impact of obesity. Evidence also suggests increased risk of colorectal cancer recurrence in patients with diabetes mellitus. The underlying mechanisms are multifactorial and likely include hormonal imbalances and chronic inflammation that promote cancer cell growth. Obesity and diabetes mellitus are associated with increased risk of complications and side effects of cancer treatment. Associated comorbidities such as impaired kidney function, cardiovascular disease, and neuropathies may preclude the use of guideline cancer treatment and are competing causes of death. Cancer patients with metabolic diseases require a designated clinical program and a multidisciplinary approach involving oncologists, endocrinologists, surgeons, nutritionists, and physiotherapists, to ensure coordinated and optimized patient care.

Impact of diabetes mellitus and triglyceride glucose index on mortality and cardiovascular outcomes in patients with chronic coronary syndrome undergoing coronary computed tomography angiography

Background

There is limited knowledge regarding whether an elevated triglyceride glucose (TyG) index can serve as a prognostic marker for mortality and cardiovascular outcomes, independent of diabetes mellitus (DM) and plaque burden, in patients with chronic coronary syndrome (CCS).

Methods

Patients with CCS (n = 684) were categorized into subgroups based on the presence of DM, and patients without DM were further divided into two groups based on presence or absence of an elevation of TyG index >8.8. Coronary plaque burden was evaluated using coronary computed tomography angiography. Major cardiovascular adverse event (MACE) was defined as a composite event of nonfatal myocardial infarction, unstable angina or unplanned coronary revascularization, stroke, non-cardiovascular mortality and cardiovascular mortality.

Results

Patients without DM exhibited significantly greater plaque and epicardial adipose tissue volumes than those with DM. Multivariable Cox proportional hazards models demonstrated that DM and an elevated TyG index >8.8 were independently associated with the risk of MACE after adjusting for age, sex, and plaque volume. Patients with DM (hazard ratio, 3.74; 95% confidence interval, 1.97-7.08; p < 0.001) and patients without DM with an elevated TyG index (hazard ratio, 1.99; 95% confidence interval, 1.01-3.91; p = 0.045) had an increased risk of MACE.

Conclusion

This study indicates that DM and an elevated TyG index are predictors of MACE, independent of plaque volume, in patients with CCS.

Liquid Biopsy: A Game Changer for Type 2 Diabetes

As the burden of type 2 diabetes (T2D) continues to escalate globally, there is a growing need for novel, less-invasive biomarkers capable of early diabetes detection and monitoring of disease progression. Liquid biopsy, recognized for its minimally invasive nature, is increasingly being applied beyond oncology, and nevertheless shows its potential when the collection of the tissue biopsy is not possible. This diagnostic approach involves utilizing liquid biopsy markers such as cell-free nucleic acids, extracellular vesicles, and diverse metabolites for the molecular diagnosis of T2D and its related complications. In this context, we thoroughly examine recent developments in T2D liquid biopsy research. Additionally, we discuss the primary challenges and future prospects of employing liquid biopsy in the management of T2D. Prognosis, diagnosis and monitoring of T2D through liquid biopsy could be a game-changing technique for personalized diabetes management.

Circadian rhythm and circulating cell-free DNA release on healthy subjects

In the last decade, clinical studies have investigated the clinical relevance of circulating cell-free-DNA (ccfDNA) as a diagnostic and prognosis tool in various diseases including cancers. However, limited knowledge on ccfDNA biology restrains its full development in the clinical practice. To improve our understanding, we evaluated the impact of the circadian rhythm on ccfDNA release in healthy subjects over a 24-h period. 10 healthy female subjects underwent blood sampling at 8am and 20 healthy male subjects underwent serial blood sampling (8:00 AM, 9:00 AM, 12:00 PM, 4:00 PM, 8:00 PM, 12:00 AM, 4 AM (+ 1 Day) and 8 AM (+ 1 Day)). We performed digital droplet-based PCR (ddPCR) assays to target 2 DNA fragments (69 & 243 bp) located in the KRAS gene to determine the ccfDNA concentration and fragmentation profile. As control, half of the samples were re-analyzed by capillary miniaturized electrophoresis (BIAbooster system). Overall, we did not detect any influence of the circadian rhythm on ccfDNA release. Instead, we observed a decrease in the ccfDNA concentration after meal ingestion, suggesting either a post-prandial effect or a technical detection bias due to a higher plasma load in lipids and triglycerides. We also noticed a potential effect of gender, weight and creatinine levels on ccfDNA concentration.

Adipose cDC1s contribute to obesity-associated inflammation through STING-dependent IL-12 production

Obesity is associated with chronic low-grade white adipose tissue (WAT) inflammation that can contribute to the development of insulin resistance in mammals. Previous studies have identified interleukin (IL)-12 as a critical upstream regulator of WAT inflammation and metabolic dysfunction during obesity. However, the cell types and mechanisms that initiate WAT IL-12 production remain unclear. Here we show that conventional type 1 dendritic cells (cDC1s) are the cellular source of WAT IL-12 during obesity through analysis of mouse and human WAT single-cell transcriptomic datasets, IL-12 reporter mice and IL-12p70 protein levels by enzyme-linked immunosorbent assay. We demonstrate that cDC1s contribute to obesity-associated inflammation by increasing group 1 innate lymphocyte interferon-γ production and inflammatory macrophage accumulation. Inducible depletion of cDC1s increased WAT insulin sensitivity and systemic glucose tolerance during diet-induced obesity. Mechanistically, endocytosis of apoptotic bodies containing self-DNA by WAT cDC1s drives stimulator of interferon genes (STING)-dependent IL-12 production. Together, these results suggest that WAT cDC1s act as critical regulators of adipose tissue inflammation and metabolic dysfunction during obesity.

Cationic mesoporous silica nanoparticles alleviate osteoarthritis by targeting multiple inflammatory mediators

Osteoarthritis (OA) is a common and complex inflammatory disorder that is frequently compounded by cartilage degradation, synovial inflammation, and osteophyte formation. Damaged chondrocytes release multiple danger mediators that exacerbate synovial inflammation and accelerate the progression to OA. Conventional treatments targeting only a single mediator of OA have failed to achieve a strong therapeutic effect. Addressing the crucial role of multiple danger mediators in OA progression, we prepared polyethylenimine (PEI)-functionalized diselenide-bridged mesoporous silica nanoparticles (MSN-PEI) with cell-free DNA (cfDNA)-binding and anti-oxidative properties. In models of surgery-induced and collagenase-induced arthritis, we showed that these cationic nanoparticles attenuated cartilage degradation and provided strong chondroprotection against joint damage. Mechanistically, multiple target blockades alleviated oxidative stress and dampened cfDNA-induced inflammation by suppressing the M1 polarization of macrophages. This study suggests a beneficial direction for targeting multiple danger mediators in the treatment of intractable arthritis.

Nanopore sequencing reveals methylation changes associated with obesity in circulating cell-free DNA from Göttingen Minipigs

Profiling of circulating cell-free DNA (cfDNA) by tissue-specific base modifications, such as 5-methylcytosines (5mC), may enable the monitoring of ongoing pathophysiological processes. Nanopore sequencing allows genome-wide 5mC detection in cfDNA without bisulphite conversion. The aims of this study were: i) to find differentially methylated regions (DMRs) of cfDNA associated with obesity in Göttingen minipigs using Nanopore sequencing, ii) to validate a subset of the DMRs using methylation-specific PCR (MSP-PCR), and iii) to compare the cfDNA DMRs with those from whole blood genomic DNA (gDNA). Serum cfDNA and gDNA were obtained from 10 lean and 7 obese Göttingen Minipigs both with experimentally induced myocardial infarction and sequenced using Oxford Nanopore MinION. A total of 1,236 cfDNA DMRs (FDR<0.01) were associated with obesity. In silico analysis showed enrichment of the adipocytokine signalling, glucagon signalling, and cellular glucose homoeostasis pathways. A strong cfDNA DMR was discovered in PPARGC1B, a gene linked to obesity and type 2 diabetes. The DMR was validated using MSP-PCR and correlated significantly with body weight (P < 0.05). No DMRs intersected between cfDNA and gDNA, suggesting that cfDNA originates from body-wide shedding of DNA. In conclusion, nanopore sequencing detected differential methylation in minute quantities (0.1-1 ng/µl) of cfDNA. Future work should focus on translation into human and comparing 5mC from somatic tissues to pinpoint the exact location of pathology.

Innate Immune System Regulated by Stimulator of Interferon Genes, a Cytosolic DNA Sensor, Regulates Endothelial Function

Background Sterile inflammation caused by metabolic disorders impairs endothelial function; however, the underlying mechanism by which hyperglycemia induces inflammation remains obscure. Recent studies have suggested that stimulator of interferon genes (STING), a key cytosolic DNA sensor in the innate immune system, contributes to the pathogenesis of inflammatory diseases. This study examines the role of the STING in endothelial dysfunction in streptozotocin-induced diabetic mice. Methods and Results Injection of streptozotocin promoted the expression of STING and DNA damage markers in the aorta of wild-type mice. Streptozotocin elevated blood glucose and lipid levels in both wild-type and STING-deficient mice, which showed no statistical differences. Genetic deletion of STING ameliorated endothelial dysfunction as determined by the vascular relaxation in response to acetylcholine (P<0.001) and increased endothelial nitric oxide synthase phosphorylation in the aorta (P<0.05) in STZ-injected mice. Endothelium-independent vascular response to sodium nitroprusside did not differ. Treatment with a direct STING agonist, cyclic GMP-AMP, or mitochondrial DNA increased inflammatory molecule expression (eg, VCAM1 and IFNB) and decreased endothelial nitric oxide synthase phosphorylation in human umbilical vein endothelial cells, partially through the STING pathway. Cyclic GMP-AMP significantly impaired endothelial function of aortic segments obtained from wild-type mice, which was ameliorated in the presence of C-176, a STING inhibitor, or a neutralizing interferon-β antibody. Furthermore, the administration of C-176 ameliorated endothelial dysfunction in STZ-induced diabetic mice (P<0.01). Conclusions The DNA damage response regulated by STING impairs endothelial function. STING signaling may be a potential therapeutic target of endothelial dysfunction caused by hyperglycemia.

Excess body weight and postmenopausal breast cancer: Emerging molecular mechanisms and perspectives

Postmenopausal, obese women have a significantly higher risk of developing estrogen receptor-positive (ER+) breast tumors, that are resistant to therapies and are associated with higher recurrence and death rates. The global prevalence of overweight/obese women has reached alarming proportions and with postmenopausal ER+ breast carcinoma (BC) having the highest incidence among the three obesity-related cancers in females (i.e., breast, endometrial and ovarian), this is of significant concern. Elucidation of the precise molecular mechanisms underlying the pro-cancerous action of obesity in ER+BC is therefore critical for disease prevention and novel treatment initiatives. Interestingly, accumulating data has shown opposing relationships between obesity and cancer in either pre- or post-menopausal women. Excess body weight is associated with an increased risk of breast cancer in postmenopausal women and a decreased risk in pre-menopausal women. Moreover, excess adiposity during early life appears to be protective against postmenopausal breast cancer, including both ER+ and ER negative BC subtypes. Overall, estrogen-dependent mechanisms have been implicated as the main driving force in obesity-related breast tumorigenesis. In the present review we discuss the epidemiologic and mechanistic aspects of association between obesity and breast tumors after menopause, mainly in the context of hormone dependency. Molecular and cellular events underlying this association present as potential avenues for both therapeutic intervention as well as the prevention of BC-promoting processes linked to excess adiposity, which is proving to be vital in an increasingly obese global population.

Cell-free DNA reveals distinct pathology of multisystem inflammatory syndrome in children

Multisystem inflammatory syndrome in children (MIS-C) is a rare but life-threatening hyperinflammatory condition induced by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes pediatric COVID-19 (pCOVID-19). The relationship of the systemic tissue injury to the pathophysiology of MIS-C is poorly defined. We leveraged the high sensitivity of epigenomics analyses of plasma cell-free DNA (cfDNA) and plasma cytokine measurements to identify the spectrum of tissue injury and glean mechanistic insights. Compared with pediatric healthy controls (pHCs) and patients with pCOVID-19, patients with MIS-C had higher levels of cfDNA primarily derived from innate immune cells, megakaryocyte-erythroid precursor cells, and nonhematopoietic tissues such as hepatocytes, cardiac myocytes, and kidney cells. Nonhematopoietic tissue cfDNA levels demonstrated significant interindividual variability, consistent with the heterogenous clinical presentation of MIS-C. In contrast, adaptive immune cell-derived cfDNA levels were comparable in MIS-C and pCOVID-19 patients. Indeed, the cfDNA of innate immune cells in patients with MIS-C correlated with the levels of innate immune inflammatory cytokines and nonhematopoietic tissue-derived cfDNA, suggesting a primarily innate immunity-mediated response to account for the multisystem pathology. These data provide insight into the pathogenesis of MIS-C and support the value of cfDNA as a sensitive biomarker to map tissue injury in MIS-C and likely other multiorgan inflammatory conditions.

Regulation of Cathelicidin Antimicrobial Peptide (CAMP) Gene Expression by TNFα and cfDNA in Adipocytes

Understanding the complex interactions between metabolism and the immune system ("metaflammation") is crucial for the identification of key immunomodulatory factors as potential therapeutic targets in obesity and in cardiovascular diseases. Cathelicidin antimicrobial peptide (CAMP) is an important factor of innate immunity and is expressed in adipocytes. CAMP, therefore, might play a role as an adipokine in metaflammation and adipose inflammation. TNFα, cell-free nucleic acids (cfDNA), and toll-like receptor (TLR) 9 are components of the innate immune system and are functionally active in adipose tissue. The aim of the present study was to investigate the impact of TNFα and cfDNA on CAMP expression in adipocytes. Since cfDNA acts as a physiological TLR9 agonist, we additionally investigated TLR9-mediated CAMP regulation in adipocytes and adipose tissue. CAMP gene expression in murine 3T3-L1 and human SGBS adipocytes and in murine and human adipose tissues was quantified by real-time PCR. Adipocyte inflammation was induced in vitro by TNFα and cfDNA stimulation. Serum CAMP concentrations in TLR9 knockout (KO) and in wildtype mice were quantified by ELISA. In primary adipocytes of wildtype and TLR9 KO mice, CAMP gene expression was quantified by real-time PCR. CAMP gene expression was considerably increased in 3T3-L1 and SGBS adipocytes during differentiation. TNFα significantly induced CAMP gene expression in mature adipocytes, which was effectively antagonized by inhibition of PI3K signaling. Cell-free nucleic acids (cfDNA) significantly impaired CAMP gene expression, whereas synthetic agonistic and antagonistic TLR9 ligands had no effect. CAMP and TLR9 gene expression were correlated positively in murine and human subcutaneous but not in intra-abdominal/visceral adipose tissues. Male TLR9 knockout mice exhibited lower systemic CAMP concentrations than wildtype mice. CAMP gene expression levels in primary adipocytes did not significantly differ between wildtype and TLR9 KO mice. These findings suggest a regulatory role of inflammatory mediators, such as TNFα and cfDNA, in adipocytic CAMP expression as a novel putative molecular mechanism in adipose tissue innate immunity.

Hepatic conversion of acetyl-CoA to acetate plays crucial roles in energy stress

Accumulating evidence indicates that acetate is increased under energy stress conditions such as those that occur in diabetes mellitus and prolonged starvation. However, how and where acetate is produced and the nature of its biological significance are largely unknown. We observed overproduction of acetate to concentrations comparable to those of ketone bodies in patients and mice with diabetes or starvation. Mechanistically, ACOT12 and ACOT8 are dramatically upregulated in the liver to convert free fatty acid-derived acetyl-CoA to acetate and CoA. This conversion not only provides a large amount of acetate, which preferentially fuels the brain rather than muscle, but also recycles CoA, which is required for sustained fatty acid oxidation and ketogenesis. We suggest that acetate is an emerging novel 'ketone body' that may be used as a parameter to evaluate the progression of energy stress.

Mitochondrial sourcing of interferogenic ligands and an autoantigen in human obesity-associated metaflammation

OBJECTIVE

Visceral adipose tissue (VAT) inflammation contributes to metabolic dysregulation in obesity. VAT recruitment and activation of plasmacytoid dendritic cells (pDCs) through toll-like receptor 9 (TLR9) recognition of self-DNA, leading to induction of type I interferons, are crucial innate triggers for this VAT inflammation. It was hypothesized that mitochondrial DNA (mtDNA) can contribute to TLR9 activation in VAT-recruited pDCs in obesity, and this study aimed to identify the carrier protein for ligand access to TLR9 and to explore whether this also provides for a source of autoantigens in this context.

METHODS

VAT samples, used for gene expression studies as well as adipose explant cultures, were collected from patients with obesity (n = 54) and lean patients (n = 10). Supernatants from human pDC cultures, treated with adipose explant culture supernatants, were used for interferon α ELISA. Venous plasma, from patients with (n = 114) and without (n = 45) obesity, was used for an ELISA for autoantibodies.

RESULTS

MtDNA from VAT in obesity, in complex with mitochondrial transcription factor A protein (TFAM), acts as interferogenic ligands for pDCs. Humoral autoreactivity against TFAM is also induced in obesity.

CONCLUSIONS

Interferogenic ligands and an autoantigen can be sourced from dysfunctional mitochondria in VAT of humans with obesity. Further therapeutic and prognostic potential for this immune mechanism in obesity warrants exploration.

Self-Propelled Proteomotors with Active Cell-Free mtDNA Clearance for Enhanced Therapy of Sepsis-Associated Acute Lung Injury

Acute lung injury (ALI) is a frequent and serious complication of sepsis with limited therapeutic options. Gaining insights into the inflammatory dysregulation that causes sepsis-associated ALI can help develop new therapeutic strategies. Herein, the crucial role of cell-free mitochondrial DNA (cf-mtDNA) in the regulation of alveolar macrophage activation during sepsis-associated ALI is identified. Most importantly, a biocompatible hybrid protein nanomotor (NM) composed of recombinant deoxyribonuclease I (DNase-I) and human serum albumin (HSA) via glutaraldehyde-mediated crosslinking is prepared to obtain an inhalable nanotherapeutic platform targeting pulmonary cf-mtDNA clearance. The synthesized DNase-I/HSA NMs are endowed with self-propulsive capability and demonstrate superior performances in stability, DNA hydrolysis, and biosafety. Pulmonary delivery of DNase-I/HSA NMs effectively eliminates cf-mtDNAs in the lungs, and also improves sepsis survival by attenuating pulmonary inflammation and lung injury. Therefore, pulmonary cf-mtDNA clearance strategy using DNase-I/HSA NMs is considered to be an attractive approach for sepsis-associated ALI.

Triad3A-Mediated K48-Linked ubiquitination and degradation of TLR9 impairs mitochondrial bioenergetics and exacerbates diabetic cardiomyopathy

INTRODUCTION

Targeted protein degradation represents a promising therapeutic approach, while diabetic cardiomyopathy (DCM) arises as a consequence of aberrant insulin secretion and impaired glucose and lipid metabolism in the heart..

OBJECTIVES

Considering that the Toll-like receptor 9 (TLR9) signaling pathway plays a pivotal role in regulating energy metabolism, safeguarding cardiomyocytes, and influencing glucose uptake, the primary objective of this study was to investigate the impact of TLR9 on diabetic cardiomyopathy (DCM) and elucidate its underlying mechanism.

METHODS

Mouse model of DCM was established using intraperitoneal injection of STZ, and mice were transfected with adeno-associated virus serotype 9-TLR9 (AAV9-TLR9) to assess the role of TLR9 in DCM. To explore the mechanism of TLR9 in regulating DCM disease progression, we conducted interactome analysis and employed multiple molecular approaches.

RESULTS

Our study revealed a significant correlation between TLR9 expression and mouse DCM. TLR9 overexpression markedly mitigated cardiac dysfunction, myocardial fibrosis, oxidative stress, and apoptosis in DCM, while inflammation levels remained relatively unaffected. Mechanistically, TLR9 overexpression positively modulated mitochondrial bioenergetics and activated the AMPK-PGC1a signaling pathway. Furthermore, we identified Triad3A as an interacting protein that facilitated TLR9's proteasomal degradation through K48-linked ubiquitination. Inhibiting Triad3A expression improved cardiac function and pathological changes in DCM by enhancing TLR9 activity.

CONCLUSIONS

The findings of this study highlight the critical role of TLR9 in maintaining cardiac function and mitigating pathological alterations in diabetic cardiomyopathy. Triad3A-mediated regulation of TLR9 expression and function has significant implications for understanding the pathogenesis of DCM. Targeting TLR9 and its interactions with Triad3A may hold promise for the development of novel therapeutic strategies for diabetic cardiomyopathy. Further research is warranted to fully explore the therapeutic potential of TLR9 modulation in the context of cardiovascular diseases.

Implication of DNA methylation during lifestyle mediated weight loss

Over the past 50 years, the number of overweight/obese people increased significantly, making obesity a global public health challenge. Apart from rare monogenic forms, obesity is a multifactorial disease, most likely resulting from a concerted interaction of genetic, epigenetic and environmental factors. Although recent studies opened new avenues in elucidating the complex genetics behind obesity, the biological mechanisms contributing to individual's risk to become obese are not yet fully understood. Non-genetic factors such as eating behaviour or physical activity are strong contributing factors for the onset of obesity. These factors may interact with genetic predispositions most likely via epigenetic mechanisms. Epigenome-wide association studies or methylome-wide association studies are measuring DNA methylation at single CpGs across thousands of genes and capture associations to obesity phenotypes such as BMI. However, they only represent a snapshot in the complex biological network and cannot distinguish between causes and consequences. Intervention studies are therefore a suitable method to control for confounding factors and to avoid possible sources of bias. In particular, intervention studies documenting changes in obesity-associated epigenetic markers during lifestyle driven weight loss, make an important contribution to a better understanding of epigenetic reprogramming in obesity. To investigate the impact of lifestyle in obesity state specific DNA methylation, especially concerning the development of new strategies for prevention and individual therapy, we reviewed 19 most recent human intervention studies. In summary, this review highlights the huge potential of targeted interventions to alter disease-associated epigenetic patterns. However, there is an urgent need for further robust and larger studies to identify the specific DNA methylation biomarkers which influence obesity.

Mitochondrial Dysfunction Associated with mtDNA in Metabolic Syndrome and Obesity

Metabolic syndrome (MetS) is a precursor to the major health diseases associated with high mortality in industrialized countries: cardiovascular disease and diabetes. An important component of the pathogenesis of the metabolic syndrome is mitochondrial dysfunction, which is associated with tissue hypoxia, disruption of mitochondrial integrity, increased production of reactive oxygen species, and a decrease in ATP, leading to a chronic inflammatory state that affects tissues and organ systems. The mitochondrial AAA + protease Lon (Lonp1) has a broad spectrum of activities. In addition to its classical function (degradation of misfolded or damaged proteins), enzymatic activity (proteolysis, chaperone activity, mitochondrial DNA (mtDNA)binding) has been demonstrated. At the same time, the spectrum of Lonp1 activity extends to the regulation of cellular processes inside mitochondria, as well as outside mitochondria (nuclear localization). This mitochondrial protease with enzymatic activity may be a promising molecular target for the development of targeted therapy for MetS and its components. The aim of this review is to elucidate the role of mtDNA in the pathogenesis of metabolic syndrome and its components as a key component of mitochondrial dysfunction and to describe the promising and little-studied AAA + LonP1 protease as a potential target in metabolic disorders.

Exploring the Synergistic Potential of Radiomics and Laboratory Biomarkers for Enhanced Identification of Vulnerable COVID-19 Patients

BACKGROUND

Severe courses and high hospitalization rates were ubiquitous during the first pandemic SARS-CoV-2 waves. Thus, we aimed to examine whether integrative diagnostics may aid in identifying vulnerable patients using crucial data and materials obtained from COVID-19 patients hospitalized between 2020 and 2021 (n = 52). Accordingly, we investigated the potential of laboratory biomarkers, specifically the dynamic cell decay marker cell-free DNA and radiomics features extracted from chest CT.

METHODS

Separate forward and backward feature selection was conducted for linear regression with the Intensive-Care-Unit (ICU) period as the initial target. Three-fold cross-validation was performed, and collinear parameters were reduced. The model was adapted to a logistic regression approach and verified in a validation naïve subset to avoid overfitting.

RESULTS

The adapted integrated model classifying patients into "ICU/no ICU demand" comprises six radiomics and seven laboratory biomarkers. The models' accuracy was 0.54 for radiomics, 0.47 for cfDNA, 0.74 for routine laboratory, and 0.87 for the combined model with an AUC of 0.91.

CONCLUSION

The combined model performed superior to the individual models. Thus, integrating radiomics and laboratory data shows synergistic potential to aid clinic decision-making in COVID-19 patients. Under the need for evaluation in larger cohorts, including patients with other SARS-CoV-2 variants, the identified parameters might contribute to the triage of COVID-19 patients.

Macrophage function in adipose tissue homeostasis and metabolic inflammation

Obesity-related metabolic organ inflammation contributes to cardiometabolic disorders. In obese individuals, changes in lipid fluxes and storage elicit immune responses in the adipose tissue (AT), including expansion of immune cell populations and qualitative changes in the function of these cells. Although traditional models of metabolic inflammation posit that these immune responses disturb metabolic organ function, studies now suggest that immune cells, especially AT macrophages (ATMs), also have important adaptive functions in lipid homeostasis in states in which the metabolic function of adipocytes is taxed. Adverse consequences of AT metabolic inflammation might result from failure to maintain local lipid homeostasis and long-term effects on immune cells beyond the AT. Here we review the complex function of ATMs in AT homeostasis and metabolic inflammation. Additionally, we hypothesize that trained immunity, which involves long-term functional adaptations of myeloid cells and their bone marrow progenitors, can provide a model by which metabolic perturbations trigger chronic systemic inflammation.

TLR9 agonist CpG ODN 2395 promotes the immune response against Leishmania donovani in obesity and undernutrition mice

As important immunomodulators, CpG ODNs have broad application prospects in the treatment and prevention of leishmaniasis. In order to explore the immunomodulatory effect of CpG ODNs on mice infected with Leishmania parasites in different nutritional status, TLR9 agonist CpG ODN 2395 or TLR9 antagonist CpG ODN 2088 was injected into normal, obesity and undernutrition BALB/c mice infected with Leishmania donovani, respectively. Subsequently, spleen and liver parasite loads, spleen and liver immune gene expression, spleen T cell subsets proportion and PD-1 expression, serum lipids, serum cytokines, and anti-Leishmania antibodies were measured to assess the immune response of mice with different nutritional status. The results displayed that at the 8th week after infection, the spleen parasite load of obesity and undernutrition mice was significantly higher than that of normal mice, but the liver parasite load showed no statistical difference among the three groups. The treatment of CpG ODN 2395 or CpG ODN 2088 significantly reduced the spleen parasite load of obesity and undernutrition infected mice, but did not reduce that of normal infected mice. In obesity infected mice, CpG ODN 2395 promoted the up-regulation of TCR, ICOS and TLR4 in spleen, promoted the secretion of IFN-γ and anti-Leishmania total IgG and IgG1 antibodies, and increased the content of serum HDL-C. In undernutrition infected mice, CpG ODN 2395 promoted the up-regulation of spleen CD28 and TLR9, increased the proportion of spleen CD3⁺ T cells, and decreased the content of serum IL-10. Our results demonstrated that CpG ODN 2395 enhanced the immune response and clearance of Leishmania parasites in obesity and undernutrition mice, which might be used as a therapeutic agent for obesity and undernutrition leishmaniasis patients in the future.

The Interaction between Circulating Cell-Free Mitochondrial DNA and Inflammatory Cytokines in Predicting Human Mental Health Issue Risk in Adolescents: An Explorative Study

Adolescence is often a challenging time in which psychiatric issues have a strong connection to mental health disorders later in life. The early identification of the problems can reduce the burden of disease. To date, the effective identification of adolescents at risk of developing mental health problems remains understudied. Altogether, the interaction between circulating cell-free mtDNA (ccf-mtDNA) and inflammatory cytokines in adolescents is insufficiently understood regarding experienced mental health difficulties. Our study selected the participants based on the Strength and Difficulty Questionnaire (SDQ) score using the cut-off points of 3 and 18 for the low and the high score groups, respectively. The answers of the SDQ at the age of 12.2-15.7 years contributed to the investigation of (i) whether ccf-mtDNA units are associated with cytokines, and (ii) if an interaction model for predicting risk of mental health issues is observed. We discovered a sex-specific correlation between the screened markers associated with mental health problems in the low and high SDQ score groups among the male participants and in the low SDQ score group among the female participants. The mitochondrial MT-ND4 and MT-CO1 genes correlated significantly with interleukin-12p70 (IL-12p70) in males and with monocyte chemoattractant protein-1 (MCP-1) in females. Due to the nature of the explorative study, the studied markers alone did not indicate statistical significance for the prediction of mental health problems. Our analysis provided new insight into potential plasma-based biomarkers to predict mental health issues.

Polycationic PAMAM ameliorates obesity-associated chronic inflammation and focal adiposity

As a surging public health crisis, obesity and overweight predispose individuals to various severe comorbidities contributed by the accompanying chronic inflammation. However, few options exist for tackling chronic inflammation in obesity or inhibiting depot-specific adiposity. Here, we report that polycationic polyamidoamine (PAMAM) treatment can improve both aspects of obesity. With the discovery that the plasma cell-free RNA (cfRNA) level is elevated in obese subjects, we applied the cationic PAMAM generation 3 (P-G3) scavenger to treat diet-induced obese (DIO) mice. Intraperitoneal delivery of P-G3 alleviated the chronic inflammation in DIO mice and reduced their body weight, resulting in improved metabolic functions. To further enhance the applicability of P-G3, we complexed P-G3 with human serum albumin (HSA) to attain a sustained release, which showed consistent benefits in treating DIO mice. Local injection of HSA-PG3 into subcutaneous fat completely restricted the distribution of the complex within the targeted depot and reduced focal adiposity. Our study illuminates a promising cationic strategy to ameliorate chronic inflammation in obesity and target local adiposity.

Severe gestational diabetes mellitus in lean dams is associated with low IL-1α levels and affects the growth of the juvenile mouse offspring

We investigated how maternal gestational diabetes (GDM) impacts the metabolic status of offspring. GDM was induced in CD1 mice consuming a fast-food diet (FFD) by repeated low-dose streptozotocin injections before mating. Offspring of normoglycemic standard chow or the FFD consuming dams served as controls. In 4-week-old offspring weaned to standard chow, plasma concentrations of extracellular DNA, inflammatory markers, and parameters of the cardiometabolic status (glycemia, liver lipid content; body, organ, and fat weight) were determined. Two-factor analysis of variance indicated that the male offspring of GDM dams manifest postnatal growth retardation and lower relative kidney weight. Regardless of sex, GDM offspring manifest the lowest IL-1α levels, and other inflammatory markers showed mild and inconsistent alterations. Offspring of dams consuming the FFD displayed higher liver triacylglycerols content. The three groups of offspring showed no significant differences in glycemia and extracellular DNA. Partial least squares-discriminant analysis indicated that male GDM offspring present lower kidney, body, and brown adipose tissue weights; lower IL-1α levels, and higher concentrations of GM-CSF and IL-10 compared with their FFD counterparts. The model failed to select discriminative variables in females. In conclusion, in mice, maternal GDM in the absence of obesity adversely affects the early growth of juvenile male offspring.

Adipose cell-free DNA in diabetes

Cancer-associated necrosis is a well-known source of cell-free DNA (cfDNA). However, the origins of cfDNA are not strictly limited to cancer. Additionally, dietary exposure induces apoptosis-induced proliferation in adipocytes, leading to the release of cfDNA. The genetic information derived from cfDNA as a result of apoptosis-induced proliferation contains specific methylation patterns in adipose tissue that can be used as a marker to detect the risk of developing Type 2 diabetes Mellitus (T2DM) in the future. cfDNA is superior to peripheral blood leukocytes (PBL) and whole blood samples for reflecting tissue pathology due to the frequent use of PBL and whole blood samples that do not match tissue pathology. The difficulty of demonstrating that cfDNA is derived from adipose tissue. We propose several promising techniques by analyzing cfDNA derived from adipose tissue to detect T2DM risk. First, adipose-specific genes such as ADIPOQ and Leptin were utilized. Second, MCTA-Seq, EpiSCORE, deconvolution, multiplexing, and automated machine learning (AutoML) were used to determine the proportion of total methylation in related genes.

Palmitic acid induces nDNA release to cytosol and promotes microglial M1 polarization via cGAS-STING signaling pathway

Palmitic acid (PA), the most common statured fatty acid in diets, is involved in peripheral as well as central inflammation. The M1 polarization of microglia plays an important role in PA-induced neuroinflammation. However, it is still unclear on the key factor and molecule mechanism of microglial polarization among it. Thus, we investigated whether the release of self-DNA into the cytoplasm of microglia was a consequence of PA treatment, as in aortic endothelial cells and adipocytes. RT-qPCR and immunofluorescence were performed to detect the status of cytosolic DNA and microglial polarization after PA treatment. We found that the content of cytosolic nDNA rather than mtDNA increased after PA treatment and the M1 polarization of microglia was associated with this. Moreover, the knockdown of cGAS in BV2 microglial cells demonstrated that the cGAS-STING pathway is involved in polarization process. Our results revealed that nDNA and cGAS-STING pathway are critically involved in PA-induced microglial M1 polarization. This mechanism may pose a new insight on targeting microglia may be a promising way to mitigate diet-induced early neuroinflammation.

Neutrophil extracellular traps in urinary tract infection

Background

Urinary tract infections (UTI) are common types of bacterial infection in children. UTI treatment is aimed to prevent complications including hypertension, proteinuria, and progression to chronic kidney disease. Activated neutrophils release chromatin-based structures associated with antimicrobial proteins called neutrophil extracellular traps (NETs). We aimed to describe the role of NET-associated markers in children with UTI as well as the role of NETs formation in a mouse model of UTI.

Materials and methods

Markers of NETs including extracellular DNA (ecDNA), myeloperoxidase (MPO) and cathelicidin were analyzed in children with febrile UTI caused by E. coli (n = 98, aged 0.3-1.3 years) and in healthy controls (n = 50, 0.5-5.2 years). Moreover, an acute experimental model of UTI was performed on PAD4 knock-out mice with diminished NETs formation (n = 18), and on wild-type mice (n = 15).

Results

Children with UTI had significantly higher urinary NETs markers including total ecDNA, nuclear DNA and mitochondrial DNA, altogether with MPO and cathelicidin. The concentrations of MPO and cathelicidin positively correlated with ecDNA (r = 0.53, p ≤ 0.001; r = 0.56, p ≤ 0.001, respectively) and the number of leukocytes in the urine (r = 0.29, p ≤ 0.05; r = 0.27, p ≤ 0.05, respectively). Moreover, urinary MPO was positively associated with cathelicidin (r = 0.61, p ≤ 0.001). In the experimental model, bacterial load in the bladder (20-fold) and kidneys (300-fold) was significantly higher in PAD4 knock-out mice than in wild-type mice.

Conclusion

Higher urinary NETs makers-ecDNA, MPO and cathelicidin and their correlation with leukocyturia in children with UTI confirmed our hypothesis about the association between NETs and UTI in children. Higher bacterial load in mice with diminished NETs formation suggests that NETs are not only a simple consequence of UTI, but might play a direct role in the prevention of pyelonephritis and other UTI complications.

Cell-Free DNA in the Pathogenesis and Therapy of Non-Infectious Inflammations and Tumors

The basic function of the immune system is the protection of the host against infections, along with the preservation of the individual antigenic identity. The process of self-tolerance covers the discrimination between self and foreign antigens, including proteins, nucleic acids, and larger molecules. Consequently, a broken immunological self-tolerance results in the development of autoimmune or autoinflammatory disorders. Immunocompetent cells express pattern-recognition receptors on their cell membrane and cytoplasm. The majority of endogenous DNA is located intracellularly within nuclei and mitochondria. However, extracellular, cell-free DNA (cfDNA) can also be detected in a variety of diseases, such as autoimmune disorders and malignancies, which has sparked interest in using cfDNA as a possible biomarker. In recent years, the widespread use of liquid biopsies and the increasing demand for screening, as well as monitoring disease activity and therapy response, have enabled the revival of cfDNA research. The majority of studies have mainly focused on the function of cfDNA as a biomarker. However, research regarding the immunological consequences of cfDNA, such as its potential immunomodulatory or therapeutic benefits, is still in its infancy. This article discusses the involvement of various DNA-sensing receptors (e.g., absent in melanoma-2; Toll-like receptor 9; cyclic GMP-AMP synthase/activator of interferon genes) in identifying host cfDNA as a potent danger-associated molecular pattern. Furthermore, we aim to summarize the results of the experimental studies that we recently performed and highlight the immunomodulatory capacity of cfDNA, and thus, the potential for possible therapeutic consideration.

Associations of genome-wide cell-free DNA fragmentation profiles with blood biochemical and hematological parameters in healthy individuals

Cell-free DNA (cfDNA), as a non-invasive approach, has been introduced in a wide range of applications, including cancer diagnosis/ monitoring, prenatal testing, and transplantation monitoring. Yet, studies of cfDNA fragmentomics in physiological conditions are lacking. In this study, we aim to explore the correlation of fragmentation patterns of cfDNA with blood biochemical and hematological parameters in healthy individuals. We addressed the impact of physiological variables and abnormal blood biochemical and hematological parameters on cfDNA fragment size distribution. We also figured and validated that hematological inflammation markers, including leukocyte, lymphocyte, neutrophil, and platelet distribution width as well as aspartate transaminase levels were significantly correlated with the genome-wide cfDNA fragmentation pattern. Our findings suggest that cfDNA fragmentation profiles were associated with physiological parameters related to cardiovascular risk factors, inflammatory response and hepatocyte injury, which may provide insights for further research on the potential role of cfDNA fragmentation in diagnosis and monitor of several disease.

Hepatocyte phosphatase DUSP22 mitigates NASH-HCC progression by targeting FAK

Nonalcoholic steatohepatitis (NASH), a common clinical disease, is becoming a leading cause of hepatocellular carcinoma (HCC). Dual specificity phosphatase 22 (DUSP22, also known as JKAP or JSP-1) expressed in numerous tissues plays essential biological functions in immune responses and tumor growth. However, the effects of DUSP22 on NASH still remain unknown. Here, we find a significant decrease of DUSP22 expression in human and murine fatty liver, which is mediated by reactive oxygen species (ROS) generation. Hepatic-specific DUSP22 deletion particularly exacerbates lipid deposition, inflammatory response and fibrosis in liver, facilitating NASH and non-alcoholic fatty liver disease (NAFLD)-associated HCC progression. In contrast, transgenic over-expression, lentivirus or adeno-associated virus (AAV)-mediated DUSP22 gene therapy substantially inhibit NASH-related phenotypes and HCC development in mice. We provide mechanistic evidence that DUSP22 directly interacts with focal adhesion kinase (FAK) and restrains its phosphorylation at Tyr397 (Y397) and Y576 + Y577 residues, subsequently prohibiting downstream activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and nuclear factor-κB (NF-κB) cascades. The binding of DUSP22 to FAK and the dephosphorylation of FAK are indispensable for DUSP22-meliorated NASH progression. Collectively, our findings identify DUSP22 as a key suppressor of NASH-HCC, and underscore the DUSP22-FAK axis as a promising therapeutic target for treatment of the disease.

Research progress on the immune microenvironment of the gallbladder in patients with cholesterol gallstones

Cholesterol gallstones are very common in hepatobiliary surgery and have been studied to a certain extent by doctors worldwide for decades. However, the mechanism of cholesterol gallstone formation is not fully understood, so there is currently no completely effective drug for the treatment and prevention of cholesterol gallstones. The formation and development of cholesterol gallstones are caused by a variety of genetic and environmental factors, among which genetic susceptibility, intestinal microflora disorders, impaired gallbladder motility, and immune disorders are important in the pathogenesis of cholesterol gallstones. This review focuses on recent advances in these mechanisms. We also discuss some new targets that may be effective in the treatment and prevention of cholesterol gallstones, which may be hot areas in the future.

Associations of circulating cell-free DNA, C-reactive protein, and cardiometabolic risk among low-active smokers with elevated depressive symptoms

Background and aims

Cell-free DNA (cfDNA) is elevated in several disease states. Metabolic syndrome is a constellation of factors associated with poor cardiometabolic outcomes. This study examined associations of cfDNA from the nucleus (cf-nDNA) and mitochondria (cf-mtDNA), C-reactive protein (CRP), and metabolic syndrome risk, in low-active smokers with depressive symptoms.

Methods

Participants (N = 109; mean age 47) self-reported medical history. Physical activity was determined by accelerometry and anthropometrics were measured. Blood was collected and analyzed for cf-nDNA, cf-mtDNA, CRP, triglycerides, high-density lipoprotein, hemoglobin A1c. A continuous metabolic syndrome composite risk score was calculated. Relationships of cf-nDNA, cf-mtDNA, CRP, and cardiometabolic risk were examined with correlations and linear regression.

Results

CRP and cf-nDNA were significantly associated with metabolic syndrome risk (r = .39 and r = .31, respectively), cf-mtDNA was not (r = .01). In a linear regression, CRP and cf-nDNA significantly predicted the metabolic syndrome risk score, findings that remained significant controlling for age, gender, nicotine dependence, and physical activity.

Conclusions

Associations of cf-nDNA with both CRP and metabolic risk suggest a role for cf-nDNA in inflammatory processes associated with metabolic syndrome. The negative findings for cf-mtDNA suggest distinct roles for cf-nDNA and cf-mtDNA in these processes.

Expanding role of deoxyribonucleic acid-sensing mechanism in the development of lifestyle-related diseases

In lifestyle-related diseases, such as cardiovascular, metabolic, respiratory, and kidney diseases, chronic inflammation plays a causal role in their pathogenesis; however, underlying mechanisms of sterile chronic inflammation are not well-understood. Previous studies have confirmed the damage of cells in these organs in the presence of various risk factors such as diabetes, dyslipidemia, and cigarette smoking, releasing various endogenous ligands for pattern recognition receptors. These studies suggested that nucleic acids released from damaged tissues accumulate in these tissues, acting as an endogenous ligand. Undamaged DNA is an integral factor for the sustenance of life, whereas, DNA fragments, especially those from pathogens, are potent activators of the inflammatory response. Recent studies have indicated that inflammatory responses such as the production of type I interferon (IFN) induced by DNA-sensing mechanisms which contributes to self-defense system in innate immunity participates in the progression of inflammatory diseases by the recognition of nucleic acids derived from the host, including mitochondrial DNA (mtDNA). The body possesses several types of DNA sensors. Toll-like receptor 9 (TLR9) recognizes DNA fragments in the endosomes. In addition, the binding of DNA fragments in the cytosol activates cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase (cGAS), resulting in the synthesis of the second messenger cyclic GMP-AMP (cGAMP). The binding of cGAMP to stimulator of interferon genes (STING) activates NF-κB and TBK-1 signaling and consequently the production of many inflammatory cytokines including IFNs. Numerous previous studies have demonstrated the role of DNA sensors in self-defense through the recognition of DNA fragments derived from pathogens. Beyond the canonical role of TLR9 and cGAS-STING, this review describes the role of these DNA-sensing mechanism in the inflammatory responses caused by endogenous DNA fragments, and in the pathogenesis of lifestyle-related diseases.

Obesity in HIV infection: host-pathogen interaction

OBJECTIVE

Both obesity and HIV infection are characterized by a state of chronic inflammation associated with increased morbidity and mortality. This review aims to assess the available literature on immune dysregulation in obesity and people with HIV infection (PWH).

DESIGN

A systematic review of peer-reviewed literature.

METHODS

We conducted a systematic literature search of PubMed, Embase, Scopus, and international conference abstracts for articles on the epidemiology of obesity in the general population and in PWH and the pathogenesis of obesity with a focus on inflammation and immune activation.

RESULTS

Of the 631 articles selected after title review, 490 met the inclusion criteria and 90 were included in the final selection. The selected studies highlight the increasing prevalence of obesity in PWH and a substantial role for antiretroviral treatment (ART) in its development. Pathogenesis of obesity and its associated inflammation derives from disturbances in adipose tissue (AT) immune function, focused on T-cell and macrophage function, with a switch to pro-inflammatory immune phenotype and resulting increases in pro-inflammatory chemokines, which contribute to the development of metabolic syndrome. Although dysregulation of these pathways is seen in both obesity and HIV, there remains a lack of human studies on AT inflammation in HIV.

CONCLUSION

Obesity is an emerging comorbidity in PWH, with a substantial overlap in immune dysregulation patterns seen in both conditions. How this immune dysfunction impacts on development of metabolic complications for both obesity and HIV infection, and whether targeting of AT-derived inflammation will improve outcomes in PWH requires further study.

The Role of B Lymphocyte Subsets in Adipose Tissue Development, Metabolism, and Aging

Adipose tissue contains resident B lymphocytes (B cells) with varying immune functions and mechanisms, depending on the adipose depot type and location. The heterogeneity of B cells and their functions affect the immunometabolism of the adipose tissue in aging and age-associated metabolic disorders. B cells exist in categorizations of subsets that have developmental or phenotypic differences with varying functionalities. Subsets can be categorized as either protective or pathogenic depending on their secretion profile or involvement in metabolic maintenance. In this article, we summarized recent finding on the B cell heterogeneity and discuss how we can utilize our current knowledge of adipose resident B lymphocytes for potential treatment for age-associated metabolic disorders. © 2022 American Physiological Society. Compr Physiol 12: 1-13, 2022.

TLR9: A friend or a foe

The innate immune system is a primary protective line in our body. It confers its protection through different pattern recognition receptors (PRRs), especially toll like receptors (TLRs). Toll like receptor 9 (TLR9) is an intracellular TLR, expressed in different immunological and non-immunological cells. Release of cellular components, such as proteins, nucleotides, and DNA confers a beneficial inflammatory response and maintains homeostasis for removing cellular debris during normal physiological conditions. However, during pathological cellular damage and stress signals, engagement between mtDNA and TLR9 acts as an alarm for starting inflammatory and autoimmune disorders. The controversial role of TLR9 in different diseases baffled scientists if it has a protective or deleterious effect after activation during insults. Targeting the immune system, especially the TLR9 needs further investigation to provide a therapeutic strategy to control inflammation and autoimmune disorders.

Esaxerenone, a selective mineralocorticoid receptor blocker, improves insulin sensitivity in mice consuming high-fat diet

BACKGROUND

Esaxerenone is a novel, non-steroidal selective mineralocorticoid receptor (MR) blocker. MR activation plays a crucial role in the development of cardiovascular and metabolic diseases. In this study, we investigated the effects of esaxerenone on various metabolic parameters in mice.

MATERIALS AND METHODS

Esaxerenone (3 mg/kg/day) was orally administered to high-fat diet (HFD)-fed male C57BL/6 mice. Mice fed a normal diet (ND) served as controls. Glucose and insulin tolerance, plasma lipid levels, and transaminase levels were assessed as metabolic parameters. Macrophage accumulation in the adipose tissue was evaluated using histological analysis. 3T3-L1 adipocytes, HepG2 cells, and C2C12 myotubes were used for in vitro experiments. Gene expression and insulin signaling were examined using quantitative RT-PCR and western blotting, respectively.

RESULTS

HFD successfully induced insulin resistance compared with that in ND. Esaxerenone ameliorated insulin resistance (P < 0.05) without altering other metabolic parameters, such as the lipid profile. Esaxerenone administration tended to decrease plasma transaminase levels compared with those in the non-treated group. In the adipose tissue, esaxerenone decreased macrophage accumulation (P < 0.05) and increased the expression levels of adiponectin and PPARγ. Aldosterone significantly decreased the expression levels of PPARγ and adiponectin in 3T3-L1 adipocytes. Furthermore, aldosterone attenuated insulin-induced Akt phosphorylation in 3T3-L1 adipocytes, HepG2 cells, and C2C12 myotubes in a dose-dependent manner (P < 0.01). These effects were ameliorated by pretreatment with esaxerenone.

CONCLUSION

Esaxerenone ameliorated insulin resistance in HFD-fed mice. Reduction of inflammation and improvement in insulin signaling may underlie the beneficial effects of esaxerenone.

IFN-I signaling in cancer: the connection with dysregulated Insulin/IGF axis

Type I interferons (IFN-Is) are prototypical inflammatory cytokines produced in response to stress. IFN-Is have a critical role in antitumor immunity by driving the activation of leukocytes and favoring the elimination of malignant cells. However, IFN-I signaling in cancer, specifically in the tumor microenvironment (TME), can have opposing roles. Sustained IFN-I stimulation can promote immune exhaustion or enable tumor cell-intrinsic malignant features. Herein, we discuss the potential impact of the insulin/insulin-like growth factor system (I/IGFs) and of metabolic disorders in aberrant IFN-I signaling in cancer. We consider the possibility that targeting I/IGFs, especially in patients with cancer affected by metabolic disorders, contributes to an effective strategy to inhibit deleterious IFN-I signaling, thereby restoring sensitivity to various cancer therapies, including immunotherapy.

Factors Modulating COVID-19: A Mechanistic Understanding Based on the Adverse Outcome Pathway Framework

Addressing factors modulating COVID-19 is crucial since abundant clinical evidence shows that outcomes are markedly heterogeneous between patients. This requires identifying the factors and understanding how they mechanistically influence COVID-19. Here, we describe how eleven selected factors (age, sex, genetic factors, lipid disorders, heart failure, gut dysbiosis, diet, vitamin D deficiency, air pollution and exposure to chemicals) influence COVID-19 by applying the Adverse Outcome Pathway (AOP), which is well-established in regulatory toxicology. This framework aims to model the sequence of events leading to an adverse health outcome. Several linear AOPs depicting pathways from the binding of the virus to ACE2 up to clinical outcomes observed in COVID-19 have been developed and integrated into a network offering a unique overview of the mechanisms underlying the disease. As SARS-CoV-2 infectibility and ACE2 activity are the major starting points and inflammatory response is central in the development of COVID-19, we evaluated how those eleven intrinsic and extrinsic factors modulate those processes impacting clinical outcomes. Applying this AOP-aligned approach enables the identification of current knowledge gaps orientating for further research and allows to propose biomarkers to identify of high-risk patients. This approach also facilitates expertise synergy from different disciplines to address public health issues.

Toll-like Receptor 7 (TLR7) Is Expressed in Adipocytes and the Pharmacological TLR7 Agonist Imiquimod and Adipocyte-Derived Cell-Free Nucleic Acids (cfDNA) Regulate Adipocyte Function

Endosome-localized Toll-like receptors (TLRs) 3 and 9 are expressed and functionally active in adipocytes. The functionality and role of TLR7 in adipocyte biology and innate immunity of adipose tissue (AT) is poorly characterized. We analyzed TLR7 mRNA and protein expression in murine 3T3-L1 and primary adipocytes, in co-cultures of 3T3-L1 adipocytes with murine J774A.1 monocytes and in human AT. The effects of TLR7 agonists imiquimod (IMQ) and cell-free nucleic acids (cfDNA) on adipokine concentration in cell-culture supernatants and gene expression profile were investigated. We found that TLR7 expression is strongly induced during adipocyte differentiation. TLR7 gene expression in adipocytes and AT stroma-vascular cells (SVC) seems to be independent of TLR9. IMQ downregulates resistin concentration in adipocyte cell-culture supernatants and modulates gene expression of glucose transporter Glut4. Adipocyte-derived cfDNA reduces adiponectin and resistin in cell-culture supernatants and potentially inhibits Glut4 gene expression. The responsiveness of 3T3-L1 adipocytes to imiquimod is preserved in co-culture with J774A.1 monocytes. Obesity-related, adipocyte-derived cfDNA engages adipocytic pattern recognition receptors (PRRs), modulating AT immune and metabolic homeostasis during adipose inflammation.

Nucleic Acid-Scavenging Hydrogels Accelerate Diabetic Wound Healing

Chronic inflammation is a typical feature and a major impediment in refractory diabetic foot ulcer (DFU). High levels of extracellular cell-free nucleic acid (cfDNA) have recently been known to play a critical role in the cause of inflammation. Herein, we fabricated polyacrylamide-based cationic hydrogels and topically applied them to the ulcer of a diabetic rat model. The cfDNA level in the wound area was significantly reduced after hydrogel adsorption, and the level of inflammation was eliminated. In turn, the wound closure was significantly promoted without introducing systemic toxicity. Cationic hydrogels represent an effective material to combat uncontrolled inflammation in DFU.

Pathophysiological Role of Nucleic Acid-Sensing Pattern Recognition Receptors in Inflammatory Diseases

Pattern recognition receptors (PRRs) play critical roles in recognizing pathogen-derived nucleic acids and inducing innate immune responses, such as inflammation and type I interferon production. PRRs that recognize nucleic acids include members of endosomal Toll-like receptors, cytosolic retinoic acid inducible gene I-like receptors, cyclic GMP–AMP synthase, absent in melanoma 2-like receptors, and nucleotide binding oligomerization domain-like receptors. Aberrant recognition of self-derived nucleic acids by these PRRs or unexpected activation of downstream signaling pathways results in the constitutive production of type I interferons and inflammatory cytokines, which lead to the development of autoimmune or autoinflammatory diseases. In this review, we focus on the nucleic acid-sensing machinery and its pathophysiological roles in various inflammatory diseases.

Obesity modulates the immune macroenvironment associated with breast cancer development

Growing evidence demonstrates a strong correlation between obesity and an increased risk of breast cancer, although the mechanisms involved have not been completely elucidated. Some reports have described a crosstalk between adipocytes, cancer cells, and immune cells within the tumor microenvironment, however, it is currently unknown whether obesity can promote tumor growth by inducing systemic alterations of the immune cell homeostasis in peripheral lymphoid organs and adipose tissue. Here, we used the E0771 breast cancer cell line in a mouse model of diet-induced obesity to analyze the immune subpopulations present in the tumors, visceral adipose tissue (VAT), and spleen of lean and obese mice. Our results showed a significant reduction in the frequency of infiltrating CD8⁺ T cells and a decreased M1/M2 macrophage ratio, indicative of the compromised anti-tumoral immune response reported in obesity. Despite not finding differences in the percentage or numbers of intratumoral Tregs, phenotypic analysis showed that they were enriched in CD39⁺, PD-1⁺ and CCR8⁺ cells, compared to the draining lymph nodes, confirming the highly immunosuppressive profile of infiltrating Tregs reported in established tumors. Analysis of peripheral T lymphocytes showed that tumor development in obese mice was associated to a significant increase in the percentage of peripheral Tregs, which supports the systemic immunosuppressive effect caused by the tumor. Interestingly, evaluation of immune subpopulations in the VAT showed that the characteristic increase in the M1/M2 macrophage ratio reported in obesity, was completely reversed in tumor-bearing mice, resembling the M2-polarized profile found in the microenvironment of the growing tumor. Importantly, VAT Tregs, which are commonly decreased in obese mice, were significantly increased in the presence of breast tumors and displayed significantly higher levels of Foxp3, indicating a regulatory feedback mechanism triggered by tumor growth. Altogether, our results identify a complex reciprocal relationship between adipocytes, immune cells, and the tumor, which may modulate the immune macroenvironment that promotes breast cancer development in obesity.

Mitochondria, oxidative stress and nonalcoholic fatty liver disease: A complex relationship

According to the 'multiple-hit' hypothesis, several factors can act simultaneously in nonalcoholic fatty liver disease (NAFLD) progression. Increased nitro-oxidative (nitroso-oxidative) stress may be considered one of the main contributors involved in the development and risk of NAFLD progression to nonalcoholic steatohepatitis (NASH) characterized by inflammation and fibrosis. Moreover, it has been repeatedly postulated that mitochondrial abnormalities are closely related to the development and progression of liver steatosis and NAFLD pathogenesis. However, it is difficult to determine with certainty whether mitochondrial dysfunction or oxidative stress are primary events or a simple consequence of NAFLD development. On the one hand, increasing lipid accumulation in hepatocytes could cause a wide range of effects from mild to severe mitochondrial damage with a negative impact on cell fate. This can start the cascade of events, including an increase of cellular reactive nitrogen species (RNS) and reactive oxygen species (ROS) production that promotes disease progression from simple steatosis to more severe NAFLD stages. On the other hand, progressing mitochondrial bioenergetic catastrophe and oxidative stress manifestation could be considered accompanying events in the vast spectrum of abnormalities observed during the transition from NAFL to NASH and cirrhosis. This review updates our current understanding of NAFLD pathogenesis and clarifies whether mitochondrial dysfunction and ROS/RNS are culprits or bystanders of NAFLD progression.

Identification of Potential Biomarkers of Type 2 Diabetes Mellitus-Related Immune Infiltration Using Weighted Gene Coexpression Network Analysis

Background

Type 2 diabetes mellitus (T2DM) is characterized by chronic low-grade inflammation, showing an increasing trend. The infiltration of immune cells into adipose tissue has been shown to be an important pathogenic cause of T2DM. The purpose of this study is to use the relevant database to identify some abnormally expressed or dysfunctional genes related to diabetes from the perspective of immune infiltration.

Methods

Weighted gene coexpression network analysis (WGCNA) was employed to systematically identify the coexpressed gene modules and hub genes associated with T2DM development based on a microarray dataset (GSE23561) from the Gene Expression Omnibus (GEO) database. The key genes in modules highly related to clinical features were calculated and screened by using R software, and their participation in T2DM was determined by gene enrichment analysis. The mRNA levels of CSF1R, H2AFV, LCK, and TLR9 in pre-T2DM mice and normal wild-type mice were detected by WGCNA screening and real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR).

Results

We constructed 14 coexpressed gene modules, and the brown module was shown to be significantly related to T2DM. Through verification of the protein-protein interaction (PPI) network, four upregulated hub genes, CSF1R, H2AFV, LCK, and TLR9, were screened from the brown module and successfully distinguishedT2DM patients from healthy people. These hub genes may be used as biomarkers and important indicators for patient diagnosis. Enrichment analysis showed that these hub genes were highly associated with IL-6-related inflammatory metabolism, immune regulation, and immune cell infiltration. Finally, we verified the hub genes CSF1R, LCK, and TLR9 in a T2DM animal model and found that their mRNA levels were significantly higher in animals with T2DM than in control group mice (NC).

Conclusions

In summary, our results suggest that these hub genes (CSF1R, LCK, and TLR9) can serve as biomarkers and immunotherapeutic targets for T2DM.