Circulating cell-free DNA indicates M1/M2 responses during septic peritonitis

Reduced host cell-free DNA as a biomarker in latent tuberculosis infection among tuberculosis contacts

OBJECTIVES

Circulating cell-free DNA (cfDNA), including mitochondrial cfDNA (mt-cfDNA) and nuclear cfDNA (nu-cfDNA), are potential biomarkers for infectious diseases. However, cfDNA variations in TB contacts with latent tuberculosis infection (LTBI) and their potential link to a predominance of M1 monocyte polarization in LTBI remain unexplored.

METHODS

Contacts of TB patients were screened for LTBI using the Interferon gamma (IFN-γ) release assay. Blood cfDNA was extracted, and mt-cfDNA and nu-cfDNA copy numbers were quantified by qPCR. cfDNA levels in the supernatant of M1-polarized THP-1-derived macrophages were measured.

RESULTS

Levels of mt-cfDNA and nu-cfDNA were lower in the LTBI group (n = 76) than in the uninfected group (n = 58) (p = 0.012, and p < 0.001). The results were consistent in an age- and sex-matched analysis (n = 41 pairs). mt-cfDNA and nu-cfDNA levels were negatively associated with the TB-specific IFN-γ response (p = 0.009, p < 0.001). In the LTBI group, mt-cfDNA was negatively associated with the index case's bacterial burden (p = 0.045). In cell model, mt-cfDNA and nu-cfDNA levels in the supernatant from M1-polarized macrophage were lower than those from M2-polarized cells (p = 0.030, p = 0.045).

CONCLUSIONS

TB contacts with LTBI had lower cfDNA levels, which correlated with index case infectivity. Reduced cfDNA in M1-polarized macrophages warrants further investigation into the mechanisms of cfDNA reduction in LTBI.

Intranasal PAMAM-G3 scavenges cell-free DNA attenuating the allergic airway inflammation

Allergic airway inflammation (AAI), including allergic rhinitis (AR) and allergic asthma, is driven by epithelial barrier dysfunction and type 2 inflammation. However, the underlying mechanism remains uncertain and available treatments are constrained. Consequently, we aim to explore the role of cell-free DNA (cfDNA) in AAI and assess the potential alleviating effects of cationic polymers (CPs) through cfDNA elimination. Levels of cfDNA were evaluated in AR patients, allergen-stimulated human bronchial epithelium (BEAS-2B cells) and primary human nasal epithelium from both AR and healthy control (HC), and AAI murine model. Polyamidoamine dendrimers-generation 3 (PAMAM-G3), a classic type of cationic polymers, were applied to investigate whether the clearance of cfDNA could ameliorate airway epithelial dysfunction and inhibit AAI. The levels of cfDNA in the plasma and nasal secretion from AR were higher than those from HC (P < 0.05). Additionally, cfDNA levels in the exhaled breath condensate (EBC) were positively correlated with Interleukin (IL)-5 levels in EBC (R = 0.4191, P = 0.0001). Plasma cfDNA levels negatively correlated with the duration of allergen immunotherapy treatment (R = -0.4297, P = 0.006). Allergen stimulated cfDNA secretion in vitro (P < 0.001) and in vivo (P < 0.0001), which could be effectively scavenged with PAMAM-G3. The application of PAMAM-G3 inhibited epithelial barrier dysfunction in vitro and attenuated the development of AAI in vivo. This study elucidates that cfDNA, a promising biomarker for monitoring disease severity, aggravates AAI and the application of intranasal PAMAM-G3 could potentially be a novel therapeutic intervention for AAI. Allergen stimulates the secretion of cell-free DNA (cfDNA) in both human and mouse airway. Intranasal polyamidoamine dendrimers-generation 3 (PAMAM-G3) scavenges cfDNA and alleviates allergic airway inflammation.

Exploring the Role of Cell-Free Nucleic Acids and Peritoneal Dialysis: A Narrative Review

INTRODUCTION

Cell-free nucleic acids (cf-NAs) represent a promising biomarker of various pathological and physiological conditions. Since its discovery in 1948, cf-NAs gained prognostic value in oncology, immunology, and other relevant fields. In peritoneal dialysis (PD), blood purification is performed by exposing the peritoneal membrane. Relevant sections: Complications of PD such as acute peritonitis and peritoneal membrane aging are often critical in PD patient management. In this review, we focused on bacterial DNA, cell-free DNA, mitochondrial DNA (mtDNA), microRNA (miRNA), and their potential uses as biomarkers for monitoring PD and its complications. For instance, the isolation of bacterial DNA in early acute peritonitis allows bacterial identification and subsequent therapy implementation. Cell-free DNA in peritoneal dialysis effluent (PDE) represents a marker of stress of the peritoneal membrane in both acute and chronic PD complications. Moreover, miRNA are promising hallmarks of peritoneal membrane remodeling and aging, even before its manifestation. In this scenario, with multiple cytokines involved, mtDNA could be considered equally meaningful to determine tissue inflammation.

CONCLUSIONS

This review explores the relevance of cf-NAs in PD, demonstrating its promising role for both diagnosis and treatment. Further studies are necessary to implement the use of cf-NAs in PD clinical practice.

Admixture Mapping of Sepsis in European Individuals With African Ancestries

Sepsis is a severe systemic inflammatory response to infections that is accompanied by organ dysfunction. Although the ancestral genetic background is a relevant factor for sepsis susceptibility, there is a lack of studies using the genetic singularities of a recently admixed population to identify loci involved in sepsis susceptibility. Here we aimed to discover new sepsis loci by completing the first admixture mapping study of sepsis in Canary Islanders, leveraging their distinctive genetic makeup as a mixture of Europeans and African ancestries. We used a case-control approach and inferred local ancestry blocks from genome-wide data from 113,414 polymorphisms genotyped in 343 patients with sepsis and 410 unrelated controls, all ascertained for grandparental origin in the Canary Islands (Spain). Deviations in local ancestries between cases and controls were tested using logistic regressions, followed by fine-mapping analyses based on imputed genotypes, in silico functional assessments, and gene expression analysis centered on the region of interest. The admixture mapping analysis detected that local European ancestry in a locus spanning 1.2 megabases of chromosome 8p23.1 was associated with sepsis (lowest p = 1.37 × 10⁻⁴; Odds Ratio [OR] = 0.51; 95%CI = 0.40–0.66). Fine-mapping studies prioritized the variant rs13249564 within intron 1 of MFHAS1 gene associated with sepsis (p = 9.94 × 10⁻⁴; OR = 0.65; 95%CI = 0.50–0.84). Functional and gene expression analyses focused on 8p23.1 allowed us to identify alternative genes with possible biological plausibility such as defensins, which are well-known effector molecules of innate immunity. By completing the first admixture mapping study of sepsis, our results revealed a new genetic locus (8p23.1) harboring a number of genes with plausible implications in sepsis susceptibility.

Ubiquitylation of MFHAS1 by the ubiquitin ligase praja2 promotes M1 macrophage polarization by activating JNK and p38 pathways

Sepsis is a systemic inflammation caused by infection. The balance between M1–M2 macrophage polarization has an essential role in the pathogenesis of sepsis. However, the exact mechanism underlying macrophage polarization is unclear. We previously showed that levels of malignant fibrous histiocytoma amplified sequence 1 (MFHAS1) were significantly elevated in septic patients compared with those in nonseptic patients, and involved in the activation of Toll-like receptor (TLR) 2/c-Jun N-terminal kinase (JNK)/nuclear factor (NF)-κB pathway. In the present study, we explored whether MFHAS1 was involved in macrophage polarization and determined the effect of MFHAS1 on inflammation. We performed in vitro pulldown assays and in vivo co-immunoprecipitation assays and found that E3 ubiquitin ligase praja2 could directly bind to MFHAS1. In situ immunostaining analysis confirmed the colocalization of endogenous praja2 with MFHAS1. We first reported that praja2 promotes the accumulation of ubiquitylated MFHAS1 but does not degrade it. Moreover, our results indicate that MFHAS1 ubiquitylation by praja2 positively regulates TLR2-mediated JNK/p38 pathway and promotes M1 macrophage polarization, M2 to M1 macrophage transformation and inflammation.

Enhanced activity of macrophage M1/M2 phenotypes in periodontitis

OBJECTIVE

Monocytes/macrophages play a key role in mobilizing host defense against microbial infection. The selectivity of gene expression can turn macrophages into M1- or M2-type and the plasticity and differentiation of both M1 and M2 macrophages may play important roles in the development of periodontal disease. Our research aimed to study the association between the ratio of M1/M2 macrophage and inflammatory cytokines IL-1β, MMP-9, and investigate the expressions of M1-and M2-type macrophages in gingivitis and chronic periodontitis.

METHODS

Forty specimens were collected from gingivitis individuals (n=20) and chronic periodontitis (n=20). Probing depth (PD), clinical attachment level (CAL), plaque index (PI) and bleeding on probing (BOP) were recorded. The expressions of M1- and M2-type macrophages are detected with immunohistochemical method and the relative expressions of M1-, M2-type macrophage, IL-1β and MMP-9 were assayed using real-time polymerase chain reactions.

RESULTS

The M1 and M2 peptide were mainly observed in the cytoplasm of gingival connective tissue. The ratio of M1/M2 was significant higher in chronic periodontitis group compared with that in gingivitis one. In addition, the relative expressions of IL-1β and MMP-9 also increased in periodontitis group and was correlated with the ratios of M1/M2. Meanwhile, PD was positively correlated with ratios of M1/M2.

CONCLUSIONS

Periodontal inflammation associates with an enhancement of ratio of M1/M2 phenotypes of macrophages. M1/M2 ratio could provide useful information on the periodontal tissue health status.