Production of complement components by cells of the immune system

C5a/C5aR regulates Th1/Th2 imbalance in sepsis-associated lung injury by promoting neutrophil activation to increase PAD4 expression

OBJECTIVE

Multi-organ failure frequently complicates sepsis, with lungs being the primary target. T helper (Th) cell activation and phenotypic imbalance among them contribute significantly to sepsis-associated lung injury. Additionally, the complement system could regulate the polarized phenotype of T lymphocytes. Therefore, this study investigated the effect of C5a/C5a receptor (C5aR)/Peptidylarginine deiminase 4 (PAD4) on the Th1/Th2 ratio in sepsis-induced lung injury.

METHODS

ELISA was used to detect the expression of PAD4, HBP, MPO, IL-1β, IL-10, IL-6, IL-4, syndecan-1, endocan and H3Cit. An LPS-induced septic lung injury mouse model was constructed, with HE and PAS stains evaluating lung damage. BCA kit quantified BALF total protein, Western blot examined C5aR, syndecan-1, endocan, PAD4 levels, while TUNEL and flow cytometry assessed tissue cellular apoptosis. Furthermore, flow cytometry was used to detect the +Th1 and Th2 cells proportion in peripheral blood, and CCK-8 was used to detect BEAS-2B activity.

RESULTS

The results indicated that PAD4 and inflammatory factors were increased in lesion samples compared with controls. In sepsis-induced lung injury mice, addition of GSK484, a PAD4 inhibitor, effectively alleviated sepsis-induced lung edema and inflammatory responses. GSK484 was found to inhibit C5a/C5aR expression and suppress apoptosis and lung injury. Furthermore, GSK484 markedly inhibited Th1 cell phenotypes in vitro. Additionally, GSK484 intervention on Th1 cell phenotype further affected lung epithelial cell injury.

CONCLUSION

In summary, we revealed the mechanism of C5a/C5aR-induced PAD4 upregulation via neutrophil activation in sepsis-associated lung injury, causing a Th1/Th2 imbalance and lung injury, providing a novel approach for sepsis-associated lung injuries treatment.

PTX3 Deficiency Aggravates Periodontitis by the Complement C5a-C5aR1 Axis

Dysregulation of the complement system plays a critical role in periodontitis progression. In addition to the harmful effects of biofilm, aberrant expression of complement regulatory proteins is also a potential cause of periodontitis. Pentraxin 3 (PTX3) is involved in complement activation and regulation, seeking a balance between amplifying complement-mediated immune responses and avoiding complement-mediated tissue damage. However, its role in periodontitis remains unexplored. This study aimed to investigate the effects of PTX3 on inflammation onset and resolution, with a particular emphasis on its complement regulatory function. We found that PTX3 is predominantly expressed in human and mouse inflammatory monocytes and is significantly upregulated during periodontitis. In vivo experiments showed that PTX3 deficiency led to the accumulation of complement C5a, massive infiltration of inflammatory monocytes, and alveolar bone loss in a ligation-induced mouse periodontitis model. Inhibition of C5a signaling with PMX53 or NLRP3 inflammasome with MCC950 significantly alleviated these adverse effects. In addition, PTX3 deficiency delayed the resolution of inflammation and alveolar bone repair during the recovery phase of periodontitis. In vitro studies showed that PTX3 deficiency promoted C5a conversion and release in monocytes, thereby activating the NLRP3 inflammasome via the C5a-C5aR1 axis-mediated mitogen-activated protein kinase and nuclear factor κB signaling in an inflammatory environment. In conclusion, these data elucidate the link between PTX3 in regulating complement activation and periodontitis progression, providing a potential target for innate immune-based therapy of periodontitis.

Regulation of the terminal complement cascade in adipose tissue for control of its volume, cellularity, and fibrosis

White adipose tissue (WAT) is a reservoir for various pathogens and their products, such as lipopolysaccharides. Therefore, it must be equipped with a defense mechanism connected with the activation of innate immunity. This explains the phenomenon that adipocytes express components of the classical and alternative complement pathways, which can be activated even in the absence of opportunistic pathogens. Terminal stages of the complement pathway are related to the production of membrane attack complexes and, thus, can cause lysis of pathogens, as well as autolysis of host adipocytes, contributing to the regulation of the cellularity in WAT. Complement-induced autolysis of adipocytes is counteracted by a number of cellular defense mechanisms. This versatility of activation and suppression processes enables a broad range of adaptability to physiological contexts, ranging from the development of hypertrophic WAT to lipodystrophy. Pathogen-induced activation of the complement pathway in WAT also induces a profibrotic phenotype. These processes may also be involved in the regulation of insulin resistance in adipocytes. This explains the dual immune/metabolic role of the complement pathway in WAT: the pathway is an integral part of the immune response but also potently involved in the control of volume and cellularity of WAT under both physiological and pathological conditions.

Protective immune response against Rhodococcus equi: An innate immunity-focused review

Rhodococcus equi causes pyogranulomatous pneumonia in foals and immunocompromised people. Despite decades of research efforts, no vaccine is available against this common cause of disease and death in foals. The purpose of this narrative review is to summarise the current understanding of interactions between R. equi and the host innate immune system, to describe features of the immune response that are associated with resistance or susceptibility to R. equi infection, and help guide strategies for developing novel approaches for preventing R. equi infections. Virulence of R. equi in foals has been attributed to the virulence associated protein A which allows intracellular survival in macrophages by preventing acidification of R. equi-containing vacuole. Additionally, foal susceptibility to R. equi infection is associated with immaturity and naivety of innate and adaptive immune systems, while adult horses with fully functional immune system are resistant to pneumonia. Specific interaction between R. equi and innate immune cells can result in bacterial survival or death; learning how to manipulate these responses to control infection is critical to prevent pneumonia in foals. Administration of live vaccines and stimulation of innate immune responses appears to improve foals' immune response and has the potential to overcome the challenges of foal active vaccination and elicit protection against pneumonia.

Peripheral protein inflammatory biomarkers in bipolar disorder and major depressive disorder: A systematic review and meta-analysis

OBJECTIVES

Bipolar disorder (BD) and major depressive disorder (MDD) are mood disorders. The most frequent clinical presentation of BD and MDD is depression, which contributes to high rates of misdiagnosis between disorders. To support diagnostic discrimination and therapeutic stratification, we aim to perform a systematic review and meta-analysis evaluating peripheral protein inflammatory biomarkers between BD and MDD, with a focus on the depressive state.

METHODS

We conducted a literature search on PubMed, PsycInfo and Embase with no year/language restrictions. Original studies including human participants with a BD or MDD diagnosis which directly compared levels of peripheral protein inflammatory biomarkers between groups were included. A random effects meta-analysis was performed.

RESULTS

35 studies were included in the systematic review. 9 studies were included in the meta-analysis. The meta-analysis showed IL-7 (p < 0.01) levels were significantly decreased in BD, and IL-9 (p < 0.01), CCL3 (p = 0.03), CCL4 (p = 0.01), CCL5 (p = 0.02) and CCL11 (p = 0.04) levels were significantly increased in BD.

LIMITATIONS

High heterogeneity and limited dataset size restricted our meta-analysis to a small subset of biomarkers and limited our exploration of the effects of moderator variables.

CONCLUSION

This study found differences in IL-7, IL-9, CCL3, CCL4, CCL5 and CCL11 between BD and MDD in a depressive state. These findings support the notion that inflammation is associated with mood disorder pathophysiology, particularly with respect to T-cell network dysregulation. Further studies can assist in better understanding differences between disorders and work towards clinical applications.

Immunomodulatory and cardio-protective effects of differentially originated multipotent mesenchymal stroma cells during polymicrobial sepsis in mice

PURPOSE

Sepsis is a life-threatening condition with cardiac complications being an independent predictor of poor outcome. Although their mechanisms have been widely investigated, therapeutic options remain limited. One promising therapeutic tool are mesenchymal stromal cells (MSCs). The aim of this study is to investigate the immunomodulatory effects of human MSCs from two different sources (bone marrow/BMMSC and adipose tissue/ASC) and to evaluate their cardioprotective potential.

METHODS

60 adult male C57BL/6 mice were divided into sham, sepsis (cecal ligation puncture (CLP)) and two i.v. treatment groups CLP + human BMMSC and CLP + human ASC with 5 animals in each group. The observation periods were 8, 24 and 72 h. Left ventricular tissue was analyzed histologically, by qPCR (C3ar, C5ar1, Il-1b, Il-6, Il-10, Tlr2, Tlr4, Tnfa, and Nlrp3) and western blot. Cardiac damage markers troponin I and heart fatty acid binding protein (HFABP) were detected in serum by ELISA.

RESULTS

Troponin I and HFABP were significantly increased in CLP group after 8 h compared to sham. In cardiac tissue the expression of C3ar, C5ar1, Il-1b, Il-6, Il-10, Tlr2, Tlr4, Tnfa and Nlrp3 inflammasome was upregulated up to 24h after CLP compared to sham. After BMMSC treatment, C3ar as well as C5ar, Tlr2 and Il-10 mRNA expression in left ventricle was downregulated compared to CLP, whereas ASC treatment was associated with the downregulation of Il-6 and Nlrp3.

CONCLUSIONS

CLP-induced polymicrobial sepsis in mice was associated with cardiac damage and increased inflammation in left ventricular tissue. Therapeutic systemic application of human BMMSC and ASC ameliorated damage and inflammation in the heart.

Proteomic and In Silico Analyses Highlight Complement System's Role in Bladder Cancer Immune Regulation

Background and Objectives: Bladder cancer (BLCA), intimately associated with the immune system, represents a substantial global health burden due to its high recurrence rates and limited therapeutic effectiveness. Although immunotherapy shows promise, challenges persist due to the lack of reliable therapeutic targets. This study aims to investigate potential immune-related biomarkers that could influence the tumor microenvironment in BLCA, using proteomic and in silico approaches. Materials and Methods: Tissue samples from BLCA patients (n = 27) and controls (n = 27) were collected from Şişli Hamidiye Etfal Training and Research Hospital. Proteomic analysis was performed by liquid chromatography/mass spectrometry (LC-MS)/MS to reveal the identities of differentially regulated proteins. Protein network analysis and hub protein detection were performed using Cytoscape (v.3.10.3), while functional annotation was carried out using EnrichR. The immunological analysis of hub proteins was performed in Sangerbox platform, and prognostic associations were evaluated through the Kaplan-Meier Plotter tool. Results: LC-MS/MS analysis identified 120 differentially regulated immune-related proteins. STRING analysis, using an immune response dataset (GO:0006955), highlighted the complement cascade as a significantly enriched pathway (p < 0.05). Proteins, namely C4A, CFB, C4B, C8B, CFH, CFI, C5, C4BPA, C3, and C2, that are known to play key roles in the complement system were identified. Immunological analysis with these proteins revealed the phenomena of immune infiltration and immune checkpoint gene associations (p < 0.05). Four hub genes-CFB, C4B, CFI, and C2-demonstrated a significant prognostic value for BLCA (p < 0.05). Conclusions: This study highlights the pivotal role of the complement system in the immune regulation of BLCA. CFI, C4A, and C4B emerged as potential target proteins for BLCA treatment, particularly in immunotherapy, for enhancing survival. Future research on these proteins and the complement system specifically focusing on BLCA may facilitate the development of targeted immunotherapies, ultimately improving treatment outcomes.

Innate immunity of the lungs in homeostasis and disease

Humans breathe thousands of litres of non-sterile air each day containing bacteria, viruses, and fungi, as well as pollutants, allergens, and other particles. The continual exposure to foreign particles is juxtaposed with the vast surface area of the blood-air-barrier which becomes extremely thin to allow for efficient gas exchange. To prevent infection and injury, the healthy lung relies on a robust innate immune system to protect itself. Critically, this innate immune system must clear insults while maintaining immune tolerance and minimizing inflammation to avoid disrupting the lung's vital gas exchange function. In this review, we discuss how the innate immune system protects the lung from its environment.

Transcriptomic characterization of human pancreatic CD206- and CD206 + macrophages

Macrophages reside in all organs and participate in homeostatic- and immune regulative processes. Little is known about pancreatic macrophage gene expression. In the present study, global gene expression was characterized in human pancreatic macrophage subpopulations. CD206- and CD206 + macrophages were sorted separately from pancreatic islets and exocrine tissue to high purity using flow cytometry, followed by RNA-seq analysis. Comparing CD206- with CD206 + macrophages, CD206- showed enrichment in histones, proliferation and cell cycle regulation, glycolysis and SPP1-associated immunosuppressive polarization while CD206 + showed enrichment in complement and coagulation-, IL-10 and IL-2RA immune regulation, as well as scavenging-related gene sets. Comparing islet CD206- with exocrine CD206-, enrichments in islet samples included two sets involved in immune regulation, while enrichments in exocrine samples included sets related to extracellular matrix and immune activation. Fewer differences were found between CD206 + macrophages, with enrichments in islet samples including two IL2-RA related gene sets, while enrichments in exocrine samples included sets related to extracellular matrix and immune activation. Comparing macrophages between individuals with normoglycemia, elevated HbA1c or type 2 diabetes, only a few diverse differentially expressed genes were identified. This work characterizes global gene expression and identifies differences between CD206- and CD206 + macrophage populations within the human pancreas.

Fibroblast heterogeneity and its role in generating protective immunity in the secondary lymphoid organs

Fibroblasts are cells of mesenchymal origin with a range of phenotypic diversity and heterogeneity. One of the major functions of fibroblasts is the formation and turnover of the extracellular matrix and establishing a tissue structure by forming a matrisome from embryonic development to the adult stage. It plays an indispensable role in extracellular matrix remodeling during injury, repair, and infection, providing a scaffold for cell-to-cell interaction. Despite their important pathophysiological roles, molecular markers for tissue-resident fibroblasts are only now being identified. Fibroblasts acquire molecular signatures based on anatomical locations, thus impacting their phenotypic heterogeneity despite their overlapping morphology. Fibroblasts are now recognized as key immune sentinel cells, capable of regulating the inflammatory milieu through their distinct functional subsets that are designed to respond differently with unique immune signatures. Fibroblasts can detect pathogenic and danger signals through their diverse pattern recognition receptors (PRRs) and release soluble mediators that can modulate the immune infiltrates at the site of tissue injury and repair. This review discusses the diversity and heterogeneity of fibroblasts in secondary lymphoid organs such as lymph nodes, spleen, and Peyer's patches, and their contributions to a range of pathological and physiological processes. The role of trans-differentiated effector fibroblast phenotypes that modulate the expression and function of various innate immune components (PRRs, cytokines, chemokines, and complement) in maintaining homeostasis has also been discussed.

Aortic aneurysm and dissection: complement and precision medicine in aortic disease

Aortic disease encompasses life-threatening conditions such as aortic aneurysm and dissection, which are associated with high prevalence, morbidity, and mortality. The complement system, a key component of innate immunity, not only defends against pathogens but also maintains tissue homeostasis. Recent discoveries have expanded its role beyond immunity, linking complement dysregulation to numerous diseases and positioning it as a target for pharmacotherapy. Complement-based treatments for precision medicine are emerging, with several pharmaceuticals either already approved or under investigation. In aortic disease, complement activation and dysregulation have unveiled novel mechanisms and clinical implications. Human and experimental studies suggest that all three complement pathways contribute to disease pathophysiology. The complement system induces direct cellular damage via the membrane attack complex, as well as matrix-metalloproteinase (MMP)-associated tissue damage by promoting MMP-2 and MMP-9 expression. The anaphylatoxins C3a and C5a exacerbate disease by recruiting immune cells and triggering proinflammatory responses. Examples include neutrophil extracellular trap formation and cytokine release by polymorphonuclear neutrophils. These findings highlight the complement system as a promising novel diagnostic and therapeutic target in aortic disease with potential for individualized treatment. However, gaps remain, emphasizing the need for standardized multisite preclinical studies to improve reproducibility and translation. Biomarker studies must also be validated across diverse patient cohorts for clinical applicability. This review examines current knowledge regarding complement in aortic disease, aiming to evaluate its potential for innovative diagnostic and personalized treatment strategies.

Complement-mediated enhancement of SARS-CoV-2 antibody neutralisation potency in vaccinated individuals

With the continued emergence of SARS-CoV-2 variants and concerns of waning immunity, there is a need for better defined correlates of protection to aid future vaccine and therapeutic developments. Whilst neutralising antibody titres are associated with protection, these are typically determined in the absence of the complement system, which has the potential to enhance neutralisation titres and strengthen correlates with protection in vivo. Here we show that replenishment of the complement system in neutralisation assays can significantly enhance neutralisation titres, with up to an ~83-fold increase in neutralisation of the BA.1.1.529 strain using cross-reactive sera from vaccination against the ancestral strain. The magnitude of enhancement significantly varies between individuals, viral strains (wild-type/VIC01 and Omicron/BA.1), and cell lines (Vero E6 and Calu-3), and is abrogated following heat-inactivation of the complement source. Utilising ACE2 competition assays, we show that the mechanism of action is partially mediated by reducing ACE2-spike interactions. Through the addition of compstatin (a C3 inhibitor) to live virus neutralisation assays, the complement protein C3 is shown to be required for maximum efficiency. These findings further our understanding of SARS-CoV-2 immunity and neutralisation, with implications for protection against emerging variants and assessing future vaccine and therapeutic developments.

Prospects for potential therapy targeting immune‑associated factors in endometriosis (Review)

Endometriosis (EM) is a chronic inflammatory disease that is one of the most common causes of gynecological systemic lesions in women before menopause. The most representative histological feature of EM is that the endometrium appears outside of the uterine cavity, often in the ovary. Although it is generally accepted that the epithelial and stromal cells of the ectopic endometrium are not malignant, they still have numerous similarities to malignant tumors, including considerable changes to the immune microenvironment (immune monitoring disorder), the creation of a specific hormone environment, high levels of oxidative stress, chronic inflammation and abnormal immune cell regulation. The pathogenesis of EM is not fully understood, which makes it difficult to identify specific biomarkers and potential therapeutic targets for early disease diagnosis and effective treatment. However, considerable progress has been made in this field over the past few decades. The purpose of the present review is to summarize the confirmed and potential biomarkers for EM, and to identify potential therapeutic targets based on changes in immunological factors (including natural killer cells, macrophages, the complement system, miRNA and P‑selectin) in the ectopic endometrial tissue. It is hoped that this work can be used as the basis for identifying accurate diagnostic markers for EM and developing personalized immune‑targeted therapy.

Factor B as a therapeutic target for the treatment of complement-mediated diseases

The complement system, consisting of three initiating pathways-classical, lectin and alternative, is an important part of innate immunity. Dysregulation of the complement system is implicated in the pathogenesis of several autoimmune and inflammatory diseases. Therapeutic inhibition of the complement system has been recognized as a viable approach to drug development and has been successful with the approval of a small number of complement inhibitors for diseases such as paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, neuromyelitis optica, myasthenia gravis and geographic atrophy. More recently, therapies selectively targeting the alternative pathway (AP), which drives the amplification of the complement responses, are being evaluated for these complement-mediated diseases. Complement Factor B, a serine protease, is a unique component of the AP that is essential for the catalytic activity of AP C3 convertase and AP C5 convertase. Inhibition of Factor B blocks the activity of the alternative pathway and the amplification loop, and subsequent generation of the membrane attack complex downstream; however, it has no effect on the initial activation mediated by the classical and lectin complement pathways. Therefore, Factor B is an attractive target for diseases in which the AP is overactivated. In this review, we provide an overview of Factor B and its critical role in the AP, discuss the benefit-risk of Factor B inhibition as a targeted therapeutic strategy, and describe the various Factor B inhibitors that are approved and/or in clinical development.

Modelling protein-protein interactions for the design of vaccine chimeric antigens with protective epitopes

Ticks and tick-borne diseases are a growing burden worldwide and vaccines are effective control interventions. Vaccine formulations with tick antigens such as BM86/BM95 (BM) and Subolesin (SUB) have shown reduction in tick fitness and infestation in immunized hosts. However, antigen combination is a challenging approach to improve vaccine efficacy (E) against multiple tick species. Herein, in silico and in music algorithms were integrated to model BM-SUB protein-protein interactions to apply a quantum vaccinology approach for combining protective epitopes or immunological quantum in the chimeric antigen Q38-95. Cattle immunized with Q38-95 and infested with African blue tick Rhipicephalus decoloratus showed an 82% E similar to BM86 and higher than SUB. The immune mechanisms activated in cattle in response to vaccination with Q38-95 were mediated by anti-BM/SUB antibodies that interfered with BM-SUB interactions and through activation of other innate and adaptive immune pathways. The results support modelling protein-protein interactions affecting E to identify and combine candidate protective epitopes in chimeric antigens.

AI-Based Prediction of Protein Corona Composition on DNA Nanostructures

DNA nanotechnology has emerged as a powerful approach to engineering biophysical tools, therapeutics, and diagnostics because it enables the construction of designer nanoscale structures with high programmability. Based on DNA base pairing rules, nanostructure size, shape, surface functionality, and structural reconfiguration can be programmed with a degree of spatial, temporal, and energetic precision that is difficult to achieve with other methods. However, the properties and structure of DNA constructs are greatly altered in vivo due to spontaneous protein adsorption from biofluids. These adsorbed proteins, referred to as the protein corona, remain challenging to control or predict, and subsequently, their functionality and fate in vivo are difficult to engineer. To address these challenges, we prepared a library of diverse DNA nanostructures and investigated the relationship between their design features and the composition of their protein corona. We identified protein characteristics important for their adsorption to DNA nanostructures and developed a machine-learning model that predicts which proteins will be enriched on a DNA nanostructure based on the DNA structures' design features and protein properties. Our work will help to understand and program the function of DNA nanostructures in vivo for biophysical and biomedical applications.

A comprehensive transcriptional reference for severity and progression in spinal cord injury reveals novel translational biomarker genes

Spinal cord injury (SCI) is a devastating condition that leads to motor, sensory, and autonomic dysfunction. Current therapeutic options remain limited, emphasizing the need for a comprehensive understanding of the underlying SCI-associated molecular mechanisms. This study characterized distinct SCI phases and severities at the gene and functional levels, focusing on biomarker gene identification. Our approach involved a systematic review, individual transcriptomic analysis, gene meta-analysis, and functional characterization. We compiled a total of fourteen studies with 273 samples, leading to the identification of severity- and phase-specific biomarker genes that allow the precise classification of transcriptomic profiles. We investigated the potential transferability of severity-specific biomarkers and identified a twelve-gene signature that predicted injury prognosis from human blood samples. We also report the development of MetaSCI-app - an interactive web application designed for researchers - that allows the exploration and visualization of all generated results ( https://metasci-cbl.shinyapps.io/metaSCI ). Overall, we present a transcriptomic reference and provide a comprehensive framework for assessing SCI considering severity and time perspectives, all integrated into a user-friendly tool.

The role and treatment potential of the complement pathway in chronic pain

The role of the complement system in pain syndromes has garnered attention on the back of preclinical and clinical evidence supporting its potential as a target for new analgesic pharmacotherapies. Of the components that make up the complement system, component 5a (C5a) and component 3a (C3a) are most strongly and consistently associated with pain. Receptors for C5a are widely found in immune resident cells (microglia, astrocytes, sensory neuron-associated macrophages (sNAMs)) in the central nervous system (CNS) as well as hematogenous immune cells (mast cells, macrophages, T-lymphocytes, etc.). When active, as is often observed in chronic pain conditions, these cells produce various inflammatory mediators including pro-inflammatory cytokines. These events can trigger nervous tissue inflammation (neuroinflammation) which coexists with and potentially maintains peripheral and central sensitization. C5a has a likely critical role in initiating this process highlighting its potential as a promising non-opioid target for treating pain. This review summarizes the most up-to-date research on the role of the complement system in pain with emphasis on the C5 pathway in peripheral tissue, dorsal root ganglia (DRG) and the CNS, and explores advances in complement-targeted drug development and sex differences. A perspective on the optimal application of different C5a inhibitors for different types (e.g., neuropathic, post-surgical and chemotherapy-induced pain, osteoarthritis pain) and stages (e.g., acute, subacute, chronic) of pain is also provided to help guide future clinical trials. PERSPECTIVE: This review highlights the role and mechanisms of complement components and their receptors in physiological and pathological pain. The potential of complement-targeted therapeutics for the treatment of chronic pain is also explored with a focus on C5a inhibitors to help guide future clinical trials.

Impacts of an organophosphate pesticide and water restriction on physiology and immunity in the passerine Zonotrichia capensis

Climate change, specifically rising temperatures and increased frequency of droughts will increase the level of exposure of organisms to chemical pollution. Notably, the impact of increased frequency and duration of drought events and subsequent dehydration on pesticide toxicity remains largely unknown. We evaluated the combined effects of exposure to the pesticide Chlorpyrifos (CPF) and water restriction (WR) on the enzymatic activities of three plasma esterases (acetylcholinesterase, butyrylcholinesterase and carboxylesterase), basal metabolic rate (BMR), leukocyte profile (proportion of heterophils to lymphocytes; H:L ratio), and bactericidal capacity of plasma in the rufous-collared sparrow (Zonotrichia capensis), a common passerine bird in Chile. The activity of the enzyme carboxylesterase decreased in birds exposed only to CPF and birds exposed to both the CPF and WR. In the group exposed to both stressors, the butyrylcholinesterase activity was also reduced. The BMR exhibited an increase in both groups exposed to CPF, with a higher rise observed in the group exposed to both CPF and WR, while the group subjected to WR showed no change. The bactericidal capacity of the plasma decreased significantly in birds exposed to CPF and in those exposed to both the pesticide and WR, while a marginal effect was observed in the group only subjected to WR. The H:L ratio increased in all groups, with the most pronounced effect in birds exposed to both stressors. These results suggest a shift in the energy budget of Z. capensis, favoring the detoxification of the pesticide through esterase activities, at the expense of reduced immunocompetence.

The role of complement in tumor immune tolerance and drug resistance: a double-edged sword

The domain of cancer treatment has persistently been confronted with significant challenges, including those associated with recurrence and drug resistance. The complement system, which serves as the foundation of the innate immune system, exhibits intricate and nuanced dual characteristics in the evolution of tumors. On the one hand, the complement system has the capacity to directly inhibit cancer cell proliferation via specific pathways, thereby exerting a beneficial anti-tumor effect. Conversely, the complement system can also facilitate the establishment of an immune escape barrier for cancer cells through non-complement-mediated mechanisms, thereby protecting them from eradication. Concurrently, the complement system can also be implicated in the emergence of drug resistance through a multitude of complex mechanisms, directly or indirectly reducing the efficacy of therapeutic interventions and facilitating the progression of cancer. This paper analyses the role of the complement system in tumors and reviews recent research advances in the mechanisms of tumor immune tolerance and drug resistance.

Candidiasis: Insights into Virulence Factors, Complement Evasion and Antifungal Drug Resistance

Invasive fungal infections constitute a substantial global health burden, with invasive candidiasis representing approximately 70% of reported cases worldwide. The emergence of antifungal resistance among Candida species has further exacerbated this challenge to healthcare systems. Recent epidemiological studies have documented a concerning shift towards non-albicans Candida species, exhibiting reduced antifungal susceptibility, in invasive candidiasis cases. The complement system serves as a crucial first-line defence mechanism against Candida infections. These fungal pathogens can activate the complement cascade through three conventional pathways-classical, lectin, and alternative-in addition to activation through the coagulation system. While these pathways are initiated by distinct molecular triggers, they converge at C3 convertase formation, ultimately generating biologically active products and the membrane attack complex. Candida species have evolved sophisticated mechanisms to evade complement-mediated host defence, including the masking of cell wall components, proteolytic cleavage and inhibition of complement proteins, recruitment of complement regulators, and acquisition of host proteins. This review examines the intricate interplay between Candida species and the host complement system, with emphasis on complement evasion strategies. Furthermore, we highlight the importance of exploring the crosstalk between antifungal resistance and immune evasion strategies employed by Candida species. Understanding these interactions may facilitate the development of novel therapeutic approaches and strategies to overcome treatment failures in Candida species infections.

Proteomic characterization of molecular mechanisms of paraquat-induced lung injury in a mouse model

BACKGROUND

We sought to explore the molecular mechanisms underpinning acute lung injury (ALI) caused by poisoning with paraquat (PQ).

METHODS

Selection mice were intraperitoneally injected with PQ at 40 mg/kg, whereas controls were injected with sterile saline. On days 2, 7, and 14 after administration, mice were anesthetized and sacrificed, and lung tissue was removed. Lung pathological changes were observed with conventional staining techniques. Lung tissue components were assessed with tandem mass spectrometry tag technology, and differentially expressed proteins (DEPs) were bioinformatically analyzed and investigated with parallel reaction monitoring.

RESULTS

The expression of 91, 160, and 78 proteins was significantly altered at days 2, 7, and 14, respectively. Gene Ontology analyses revealed that the DEPs in the PQ-2d and PQ-7d groups were involved primarily in humoral immunity and coagulation-related reactions, whereas those in the PQ-14d group were implicated primarily in chemotactic and regulatory responses. Kyoto Encyclopedia of Genes and Genomes analyses indicated that complement and coagulation cascades were key pathways in the PQ-2d and PQ-7d groups, whereas xenobiotic metabolism by cytochrome P450 was a key pathway in the PQ-14d group. Nine proteins at PQ-2d and eight proteins at PQ-7d were validated through parallel reaction monitoring (PRM).

CONCLUSIONS

PQ-induced ALI depends on over-activation of immune responses by damaged alveolar/endothelial cells, and the complement/coagulation cascade pathway plays a key role during this process. The proteins identified herein might provide new therapeutic targets or biomarkers for PQ poisoning.

Shedding light on the role of complement C4 activation in cancer

Complement C4 is a key component in the activation of classical and lectin complement pathways, which are observed in both animal tumor models and cancer patients. While its role in autoimmune disorders has been extensively studied, the functions of complement C4 and its activation in cancer have received inadequate consideration. Recent studies have detected C4 activation in animal tumor models and cancer patients, with its fragment C4d found in cancer tissues and lymph nodes. Elevated C4d levels could be a useful biomarker for detecting various cancers. This review aims to summarize recent developments on the role of complement C4 activation in promoting an immunosuppressive tumor microenvironment, thereby supporting tumor progression and metastasis; C4d as a biomarker; and its potential as a target for cancer immunotherapy. We also conduct a critical evaluation of methods used to measure complement C4 and its activation products, highlighting possible pitfalls and areas for improvement in existing research.

Inherent immunity and adaptive immunity: Mechanism and role in AECOPD

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is the leading cause of hospitalization and mortality in COPD patients. The occurrence of antibiotic resistance and the progression of non-infectious diseases contribute to poor patient outcomes. Thus, a comprehensive understanding of the mechanisms underlying AECOPD is essential for effective prevention. It is widely acknowledged that the immune system plays a fundamental role in pathogen clearance and the development of inflammation. Immune dysregulation, either due to deficiency or hyperactivity, has been implicated in AECOPD pathogenesis. Therefore, the purpose of this review is to investigate the possible mechanisms underlying dysregulated immune function and disease progression in COPD patients, specifically focusing on the innate and adaptive immune responses. The ultimate aim is to provide new insights for clinical prevention and treatment strategies targeting AECOPD.

Environmental signatures and fish proteomics: A multidisciplinary study to identify the major stressors in estuaries located in French agricultural watersheds

Watersheds and estuaries are impacted by multiple anthropogenic stressors that affect their biodiversity and functioning. Assessing their ecological quality has consequently remained challenging for scientists and stakeholders. In this paper, we propose a multidisciplinary approach to identify the stressors in seven small French estuaries located in agricultural watersheds. We collected data from landscape (geography, hydrobiology) to estuary (pollutant chemistry) and fish individual scales (environmental signatures, proteomics). This integrative approach focused on the whole hydrosystems, from river basins to estuaries. To characterize each watershed, we attempted to determine the land use considering geographic indicators (agricultural and urbanised surfaces) and landscape patterns (hedges density and riparian vegetation). Juveniles of European flounder (Platichthys flesus) were captured in September, after an average residence of five summer months in the estuary. Analyses of water, sediments and biota allowed to determine the concentrations of dissolved inorganic nitrogen species, pesticides and trace elements in the systems. Environmental signatures were also measured in flounder tissues. These environmental parameters were used to establish a typology of the watersheds. Furthermore, data from proteomics on fish liver were combined with environmental signatures to determine the responses of fish to stressors in their environments. Differential protein abundances highlighted a dysregulation related to the detoxification of xenobiotics (mainly pesticides) in agricultural watersheds, characterized by intensive cereal and vegetable crops and high livestock. Omics also revealed a dysregulation of proteins associated with the response to hypoxia and heat stress in some estuaries. Furthermore, we highlighted a dysregulation of proteins involved in urea cycle, immunity and metabolism of fatty acids in several systems. Finally, the combination of environmental and molecular signatures appears to be a relevant method to identify the major stressors operating within hydrosystems.

Metabolism and immune responses of striped hamsters to ectoparasite challenges: insights from transcriptomic analysis

Introduction

The striped hamster, often parasitized by ectoparasites in nature, is an ideal model for studying host-ectoparasite molecular interactions. Investigating the response to ectoparasites under laboratory conditions helps elucidate the mechanism of host adaptations to ectoparasite pressure.

Methods

Using transcriptome sequencing, we analyzed gene expression in striped hamsters after short-term (3 days) and long-term (28 days) flea (Xenopsylla cheopis) parasitism. Differentially expressed genes (DEGs) were identified and subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Hub genes were pinpointed using protein-protein interaction (PPI) network analysis and the MCODE in Cytoscape. Gene Set Enrichment Analysis (GSEA) was used to further clarify the functional pathways of these hub genes. Validation of DEGs was performed via RT-qPCR. Additionally, the concentrations of reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were determined using specific enzyme-linked immunosorbent assay (ELISA) detection kits for hamsters.

Results

GO analysis revealed that during early parasitism, hosts primarily responded to the ectoparasites by adjusting the expression of genes related to metabolic functions. As parasitism persisted, the immune response became prominent, activating various immune pathways against ectoparasites. KEGG analysis confirmed the ongoing roles of metabolism and immunity. Notably, the chemical carcinogenesis - reactive oxygen species pathway was upregulated during flea parasitism, with downregulation of hub genes ATP5MC1 and ATP5MC2, highlighting the importance of mitochondrial function in oxidative stress. ELISA findings revealed that on day 3, flea parasitism groups showed elevated ROS expression and reduced SOD and CAT levels compared to the control group. By day 28, only SOD expression showed a significant decrease in both parasitism groups.

Conclusion

This study uncovered the dynamic changes in metabolism and immune responses of striped hamsters parasitized by Xenopsylla cheopis. Hosts adjust their physiological and immune states to optimize survival strategies during different ectoparasite stages, enhancing our understanding of host-ectoparasite interactions. This also paves the way for further research into how hosts regulate complex biological processes in response to ectoparasite challenges.

Complement System and Adhesion Molecule Skirmishes in Fabry Disease: Insights into Pathogenesis and Disease Mechanisms

Fabry disease is a rare X-linked lysosomal storage disorder caused by mutations in the galactosidase alpha (GLA) gene, resulting in the accumulation of globotriaosylceramide (Gb3) and its deacetylated form, globotriaosylsphingosine (Lyso-Gb3) in various tissues and fluids throughout the body. This pathological accumulation triggers a cascade of processes involving immune dysregulation and complement system activation. Elevated levels of complement 3a (C3a), C5a, and their precursor C3 are observed in the plasma, serum, and tissues of patients with Fabry disease, correlating with significant endothelial cell abnormalities and vascular dysfunction. This review elucidates how the complement system, particularly through the activation of C3a and C5a, exacerbates disease pathology. The activation of these pathways leads to the upregulation of adhesion molecules, including vascular cell adhesion molecule 1 (VCAM1), intercellular adhesion molecule 1 (ICAM1), platelet and endothelial cell adhesion molecule 1 (PECAM1), and complement receptor 3 (CR3) on leukocytes and endothelial cells. This upregulation promotes the excessive recruitment of leukocytes, which in turn exacerbates disease pathology. Targeting complement components C3a, C5a, or their respective receptors, C3aR (C3a receptor) and C5aR1 (C5a receptor 1), could potentially reduce inflammation, mitigate tissue damage, and improve clinical outcomes for individuals with Fabry disease.

Role of Complement in Liver Diseases

This review aims to summarize recent research using animal models, cell models, and human data regarding the role of complement in liver disease. Complement is part of the innate immune system and was initially characterized for its role in control of pathogens. However, evidence now indicates that complement also plays an important role in the response to cellular injury that is independent of pathogens. The liver is the main organ responsible for producing circulating complement. In response to liver injury, complement is activated and likely plays a dual role, both contributing to and protecting from injury. In uncontrolled complement activation, cell injury and liver inflammation occur, contributing to progression of liver disease. Complement activation is implicated in the pathogenesis of multiple liver diseases, including alcohol-associated liver disease, metabolic dysfunction-associated steatotic liver disease, fibrosis and cirrhosis, hepatocellular carcinoma, and autoimmune hepatitis. However, the mechanisms by which complement is overactivated in liver diseases are still being unraveled.

Circulating levels of endogenous complement inhibitors correlate inversely with complement consumption in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is marked by excessive complement activation, contributing to tissue damage. Complement activation can be detected in many organs including the skin, kidney, and brain. The involvement of the central nervous system is particularly relevant to understanding neuropsychiatric SLE (NPSLE), one of the poorest understood manifestations of SLE for which no biomarkers are available. We studied the levels of complement inhibitors in SLE in relation to disease activity and as possible biomarkers to identify NPSLE. Serum levels of complement inhibitors C1-inhibitor (C1-INH), C4b-binding protein (C4BP), Factor I, and Factor H were measured in 345 SLE patients (including 102 with NPSLE) and 108 healthy controls. Compared with controls, SLE patients had higher C1-INH and C4BP but lower Factor I and H levels. All inhibitors positively correlated with total C3 and C4 levels. While correlating with the SLE Disease Activity Index (SLEDAI), no distinction in inhibitor levels was found between SLE and NPSLE patients. Over time, C1-INH and Factor H levels normalized, but no significant changes were observed for C4BP and Factor I. In SLE the levels of circulating complement inhibitors are inversely correlated to complement consumption but do not serve as biomarkers for NPSLE.

Understanding dental pulp inflammation: from signaling to structure

The pulp is a unique tissue within each tooth that is susceptible to painful inflammation, known as pulpitis, triggered by microbial invasion from carious lesions or trauma that affect many individuals. The host response involves complex immunological processes for pathogen defense and dentin apposition at the site of infection. The interplay of signaling between the immune and non-immune cells via cytokines, chemokines, neuropeptides, proteases, and reactive nitrogen and oxygen species leads to tissue reactions and structural changes in the pulp that escalate beyond a certain threshold to irreversible tissue damage. If left untreated, the inflammation, which is initially localized, can progress to pulpal necrosis, requiring root canal treatment and adversely affecting the prognosis of the tooth. To preserve pulp vitality and dental health, a deeper understanding of the molecular and cellular mechanisms of pulpitis is imperative. In particular, elucidating the links between signaling pathways, clinical symptoms, and spatiotemporal spread is essential to develop novel therapeutic strategies and push the boundaries of vital pulp therapy.

The Complement System as a Part of Immunometabolic Post-Exercise Response in Adipose and Muscle Tissue

The precise molecular processes underlying the complement's activation, which follows exposure to physical stress still remain to be fully elucidated. However, some possible mechanisms could play a role in initiating changes in the complement's activity, which are observed post-exposure to physical stress stimuli. These are mainly based on metabolic shifts that occur in the microenvironment of muscle tissue while performing its function with increased intensity, as well as the adipose tissue's role in sterile inflammation and adipokine secretion. This review aims to discuss the current opinions on the possible link between the complement activation and diet, age, sex, and health disorders with a particular emphasis on endocrinopathies and, furthermore, the type of physical activity and overall physical fitness. It has been indicated that regular physical activity incorporated into therapeutic strategies potentially improves the management of particular diseases, such as, e.g., autoimmune conditions. Moreover, it represents a favorable influence on immunoaging processes. A better understanding of the complement system's interaction with physical activity will support established clinical therapies targeting complement components.

The Emerging Role of Immunoglobulins and Complement in the Stimulation of Neuronal Activity and Repair: Not as Simple as We Thought

Neurologic disorders such as traumatic brain injury, multiple sclerosis, Alzheimer's disease, and drug-resistant epilepsy have a high socioeconomic impact around the world. Current therapies for these disorders are often not effective. This creates a demand for the development of new therapeutic approaches to treat these disorders. Recent data suggest that autoreactive naturally occurring immunoglobulins produced by subsets of B cells, called B1 B cells, combined with complement, are actively involved in the processes of restoration of neuronal functions during pathological conditions and remyelination. The focus of this review is to discuss the possibility of creating specific therapeutic antibodies that can activate and fix complement to enhance neuronal survival and promote central nervous system repair after injuries associated with many types of neurodegenerative diseases.

Humanized CXCL12 antibody delays onset and modulates immune response in alopecia areata mice: insights from single-cell RNA sequencing

It has been demonstrated that CXCL12 inhibits hair growth via CXCR4, and its neutralizing antibody (Ab) increases hair growth in alopecia areata (AA). However, the molecular mechanisms have not been fully elucidated. In the present study, we further prepared humanized CXCL12 Ab for AA treatment and investigated underlying molecular mechanisms using single-cell RNA sequencing. Subcutaneous injection of humanized CXCL12 Ab significantly delayed AA onset in mice, and dorsal skin was analyzed. T cells and dendritic cells/macrophages were increased in the AA model, but decreased after CXCL12 Ab treatment. Pseudobulk RNA sequencing identified 153 differentially expressed genes that were upregulated in AA model and downregulated after Ab treatment. Gene ontology analysis revealed that immune cell chemotaxis and cellular response to type II interferon were upregulated in AA model but downregulated after Ab treatment. We further identified key immune cell-related genes such as Ifng, Cd8a, Ccr5, Ccl4, Ccl5, and Il21r, which were colocalized with Cxcr4 in T cells and regulated by CXCL12 Ab treatment. Notably, CD8+ T cells were significantly increased and activated via Jak/Stat pathway in the AA model but inactivated after CXCL12 Ab treatment. Collectively, these results indicate that humanized CXCL12 Ab is promising for AA treatment via immune modulatory effects.

Expression of CREBBP and EP300 Associated With Tumor Volume in Patients With Grade-3 Glioma: A Retrospective Analysis

Background

Reliable predictive data are crucial for making accurate treatment decisions in glioma patients, but it can be challenging to obtain due to limited information in many cases. Numerous research studies have indicated the involvement of cyclic adenosine monophosphate (cAMP)-response element binding protein (CREBBP) and E1A binding protein p300 (EP300) in tumorigenesis and tumor progression across various types.

Methods

The messenger RNA (mRNA) expression levels of CREBBP and EP300 were retrospectively analyzed in 17 grade-3 glioma patients. The SYBR Green real-time polymerase chain reaction (RT-PCR) technique was employed for mRNA expression analysis, with the glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH) used as a reference gene for data normalization. In addition, the relationship between CREBBP, EP300 expression and patients' clinical information, imaging features, histologic features, immune factors, and overall survival was assessed through univariate analyses.

Results

The analysis of the data unveiled a statistically significant upregulation of CREBBP and EP300 mRNA expression levels in large gliomas as compared with their smaller counterparts (P < .05). Histological examination using hematoxylin and eosin (H&E) staining exhibited marked cellular heterogeneity, with heightened cell density observed specifically within tumors displaying elevated CREBBP expression levels. In contrast, there was a substantial downregulation of complement 3 and complement 4 within larger tumor volumes when compared with smaller ones (P < .05). However, these findings do not serve as clinically relevant prognostic indicators for glioma.

Conclusions

It is suggested that higher expression levels of CREBBP and EP300 are positively associated with increased tumor volume. Inhibition of CREBBP and EP300 enhances local immunogenicity, leading to the recruitment of immune cells and release of cytokines for effective tumor eradication, ultimately resulting in the inhibition of tumor growth.

C1q Levels: A Reliable Biomarker for Differentiating Active and Latent Tuberculosis Infection

BACKGROUND

Tuberculosis (TB) poses a significant public health challenge, particularly because it can exist in an asymptomatic latent phase. Latent TB infection indicates the presence of Mycobacterium tuberculosis without clinical symptoms. Effectively distinguishing between active and latent TB is essential, especially in regions with high TB prevalence, as it may help reduce transmission rates. This study aims to evaluate C1q as a potential biomarker for differentiating active TB from latent forms.

METHODS

This prospective cross-sectional study was conducted from January 2017 to February 2018, involving HIV-negative adults aged 18 and older attending TB clinics. Participants were categorized based on clinical symptoms, imaging results, and laboratory tests into active or latent TB. Blood samples were collected to assess serum C1q levels, which were then compared between the two groups.

RESULTS

Out of 81 patients referred for TB evaluation, 38 were diagnosed with active TB. The overall median C1q level was 6.46 μg/ml (interquartile range 4.66-10). The active TB group exhibited significantly elevated C1q levels (10.21 μg/ml) compared to the latent TB group (6.03 μg/ml, P < 0.001). The area under the receiver operating characteristic curve for C1q in distinguishing active from latent TB was 0.74 (95% confidence interval, 0.63-0.85), with sensitivity varying between 61% and 82% at different threshold values.

CONCLUSIONS

C1q shows potential as a reliable and easily obtainable biomarker for differentiating active TB from latent infection, demonstrating high sensitivity. These results underscore the need for further research to explore the clinical application of C1q in TB diagnostics.

DNA methylome analysis reveals epigenetic alteration of complement genes in advanced metabolic dysfunction-associated steatotic liver disease

BACKGROUND/AIMS

Blocking the complement system is a promising strategy to impede the progression of metabolic dysfunction-associated steatotic liver disease (MASLD). However, the interplay between complement and MASLD remains to be elucidated. This comprehensive approach aimed to investigate the potential association between complement dysregulation and the histological severity of MASLD.

METHODS

Liver biopsy specimens were procured from a cohort comprising 106 Korean individuals, which included 31 controls, 17 with isolated steatosis, and 58 with metabolic dysfunction-associated steatohepatitis (MASH). Utilizing the Infinium Methylation EPIC array, thorough analysis of methylation alterations in 61 complement genes was conducted. The expression and methylation of nine complement genes in a murine MASH model were examined using quantitative RT-PCR and pyrosequencing.

RESULTS

Methylome and transcriptome analyses of liver biopsies revealed significant (P<0.05) hypermethylation and downregulation of C1R, C1S, C3, C6, C4BPA, and SERPING1, as well as hypomethylation (P<0.0005) and upregulation (P<0.05) of C5AR1, C7, and CD59, in association with the histological severity of MASLD. Furthermore, DNA methylation and the relative expression of nine complement genes in a MASH diet mouse model aligned with human data.

CONCLUSION

Our research provides compelling evidence that epigenetic alterations in complement genes correlate with MASLD severity, offering valuable insights into the mechanisms driving MASLD progression, and suggests that inhibiting the function of certain complement proteins may be a promising strategy for managing MASLD.

Nephrotic Syndrome Throughout Childhood: Diagnosing Podocytopathies From the Womb to the Dorm

The etiologies of podocyte dysfunction that lead to pediatric nephrotic syndrome (NS) are vast and vary with age at presentation. The discovery of numerous novel genetic podocytopathies and the evolution of diagnostic technologies has transformed the investigation of steroid-resistant NS while simultaneously promoting the replacement of traditional morphology-based disease classifications with a mechanistic approach. Podocytopathies associated with primary and secondary steroid-resistant NS manifest as diffuse mesangial sclerosis, minimal change disease, focal segmental glomerulosclerosis, and collapsing glomerulopathy. Molecular testing, once an ancillary option, has become a vital component of the clinical investigation and when paired with kidney biopsy findings, provides data that can optimize treatment and prognosis. This review focuses on the causes including selected monogenic defects, clinical phenotypes, histopathologic findings, and age-appropriate differential diagnoses of nephrotic syndrome in the pediatric population with an emphasis on podocytopathies.

AI-based Prediction of Protein Corona Composition on DNA Nanostructures

DNA nanotechnology has emerged as a powerful approach to engineering biophysical tools, therapeutics, and diagnostics because it enables the construction of designer nanoscale structures with high programmability. Based on DNA base pairing rules, nanostructure size, shape, surface functionality, and structural reconfiguration can be programmed with a degree of spatial, temporal, and energetic precision that is difficult to achieve with other methods. However, the properties and structure of DNA constructs are greatly altered in vivo due to spontaneous protein adsorption from biofluids. These adsorbed proteins, referred to as the protein corona, remain challenging to control or predict, and subsequently, their functionality and fate in vivo are difficult to engineer. To address these challenges, we prepared a library of diverse DNA nanostructures and investigated the relationship between their design features and the composition of their protein corona. We identified protein characteristics important for their adsorption to DNA nanostructures and developed a machine-learning model that predicts which proteins will be enriched on a DNA nanostructure based on the DNA structures' design features and protein properties. Our work will help to understand and program the function of DNA nanostructures in vivo for biophysical and biomedical applications.

Circulating pancreatic enzyme levels are a causal biomarker of type 1 diabetes

Novel biomarkers of type 1 diabetes (T1D) are needed for earlier detection of disease and identifying therapeutic targets. We identified biomarkers of T1D by combining plasma cis and trans protein QTLs (pQTLs) for 2,922 proteins in the UK Biobank with a T1D genome-wide association study (GWAS) in 157k samples. T1D risk variants at over 20% of known loci colocalized with cis or trans pQTLs, and distinct sets of T1D loci colocalized with immune, pancreatic secretion, or gut-related proteins. We identified 23 proteins with evidence for a causal role in using pQTLs as genetic instruments in Mendelian Randomization which included multiple sensitivity analyses. Proteins increasing T1D risk were involved in immune processes (e.g. HLA-DRA) and, more surprisingly, T1D protective proteins were enriched in pancreatic secretions (e.g. CPA1), cholesterol metabolism (e.g. APOA1), and gut homeostasis. Genetic variants associated with plasma levels of T1D-protective pancreatic enzymes such as CPA1 were enriched in cis-regulatory elements in pancreatic exocrine and gut enteroendocrine cells, and the protective effects of CPA1 and other enzymes on T1D were consistent when using instruments specific to acinar cells. Finally, pancreatic enzymes had decreased acinar expression in T1D, including CPA1 which was altered prior to onset. Together, these results reveal causal biomarkers and highlight processes in the exocrine pancreas, immune system, and gut that modulate T1D risk.

Novel insights: crosstalk with non-puerperal mastitis and immunity

The two primary types of non-puerperal mastitis (NPM) are granulomatous lobular mastitis (GLM) and plasma cell mastitis (PCM). Existing research indicates that immune inflammatory response is considered to be the core of the pathogenesis of GLM and PCM, and both innate and adaptive immune responses play an important role in the pathophysiology of PCM and GLM. However, the regulatory balance between various immune cells in these diseases is still unclear. Consequently, we present a comprehensive summary of the immune-related variables and recent advances in GLM and PCM.

Fish decay-accelerating factor (DAF) regulates intestinal complement pathway and immune response to bacterial challenge

Decay-accelerating factor (DAF) is an essential member of the complement regulatory protein family that plays an important role in immune response and host homeostasis in mammals. However, the immune function of DAF has not been well characterized in bony fish. In this study, a complement regulatory protein named CiDAF was firstly characterized from Ctenopharyngodon idella and its potential roles were investigated in intestine following bacterial infection. Similar to mammalian DAFs, CiDAF has multiple complement control protein (CCP) functional domains, suggesting the evolutionary conservation of DAFs. CiDAF was broadly expressed in all tested tissues, with a relatively high expression level detected in the spleen and kidney. In vivo immune challenge experiments revealed that CiDAF strongly responded to bacterial pathogens (Aeromonas hydrophila and Aeromonas veronii) and PAMPs (lipopolysaccharide (LPS) or muramyl dipeptide (MDP)) challenges. In vitro RNAi experiments indicated that knockdown of CiDAF could upregulate the expression of complement genes (C4b, C5 and C7) and inflammatory cytokines (TNF-α, IL-1β and IL-8). Moreover, 2000 ng/mL of CiDAF agonist progesterone effectively alleviated LPS- or MDP-induced intestinal inflammation by regulating expression of complement factors, TLR/PepT1 pathway genes and inflammatory cytokines. Overall, these findings revealed that CiDAF may act as a negative regulator of intestinal complement pathway and immune response to bacterial challenge in grass carp.

Myeloproliferative Neoplasms Transcriptome Reveals Pro-Inflammatory Signature and Enrichment in Peripheral Blood Monocyte-Related Genes

Myeloproliferative neoplasms (MPN) are hematological diseases associated with genetic driver mutations in the JAK2, CALR, and MPL genes and exacerbated oncoinflammatory status. Analyzing public microarray data from polycythemia vera (n = 41), essential thrombocythemia (n = 21), and primary myelofibrosis (n = 9) patients' peripheral blood by in silico approaches, we found that pro-inflammatory and monocyte-related genes were differentially expressed in MPN patients' transcriptome. Genes related to cell activation, secretion of pro-inflammatory and pro-angiogenic mediators, activation of neutrophils and platelets, coagulation, and interferon pathway were upregulated in monocytes compared to controls. Together, our results suggest that molecular alterations in monocytes may contribute to oncoinflammation in MPN.

Apical tubular complement activation and the loss of kidney function in proteinuric kidney diseases

Many kidney diseases are associated with proteinuria. Since proteinuria is independently associated with kidney function loss, anti-proteinuric medication, often in combination with dietary salt restriction, comprises a major cornerstone in the prevention of progressive kidney failure. Nevertheless, complete remission of proteinuria is very difficult to achieve, and most patients with persistent proteinuria slowly progress toward kidney failure. It is well-recognized that proteinuria leads to kidney inflammation and fibrosis via various mechanisms. Among others, complement activation at the apical side of the proximal tubular epithelial cells is suggested to play a crucial role as a cause of progressive loss of kidney function. However, hitherto limited attention is given to the pathophysiological role of tubular complement activation relative to glomerular complement activation. This review aims to summarize the evidence for tubular epithelial complement activation in proteinuric kidney diseases in relation to loss of kidney function.

Mast cells and ocular surface: An update review

Mast cells (MCs), traditionally viewed as key players in IgE-mediated allergic responses, are increasingly recognized for their versatile roles. Situated at critical barrier sites such as the ocular surface, these sentinel cells participate in a broad array of physiological and pathological processes. This review presents a comprehensive update on the immune pathophysiology of MCs, with a particular focus on the mechanisms underlying innate immunity. It highlights their roles at the ocular surface, emphasizing their participation in allergic reactions, maintenance of corneal homeostasis, neovascularization, wound healing, and immune responses in corneal grafts. The review also explores the potential of MCs as therapeutic targets, given their significant contributions to disease pathogenesis and their capacity to modulate immunity. Through a thorough examination of current literature, we aim to elucidate the immune pathophysiology and multifaceted roles of MCs in ocular surface health and disease, suggesting directions for future research and therapeutic innovation.

Local complement activation and modulation in mucosal immunity

The complement system is an evolutionarily conserved arm of innate immunity, which forms one of the first lines of host response to pathogens and assists in the clearance of debris. A deficiency in key activators/amplifiers of the cascade results in recurrent infection, whereas a deficiency in regulating the cascade predisposes to accelerated organ failure, as observed in colitis and transplant rejection. Given that there are over 60 proteins in this system, it has become an attractive target for immunotherapeutics, many of which are United States Food and Drug Administration-approved or in multiple phase 2/3 clinical trials. Moreover, there have been key advances in the last few years in the understanding of how the complement system operates locally in tissues, independent of its activities in circulation. In this review, we will put into perspective the abovementioned discoveries to optimally modulate the spatiotemporal nature of complement activation and regulation at mucosal surfaces.

The Interactions of the Complement System with Human Cytomegalovirus

The complement system is an evolutionarily ancient component of innate immunity that serves as an important first line of defense against pathogens, including viruses. In response to infection, the complement system can be activated by three distinct yet converging pathways (classical, lectin, and alternative) capable of engaging multiple antiviral host responses to confront acute, chronic, and recurrent viral infections. Complement can exert profound antiviral effects via multiple mechanisms including the induction of inflammation and chemotaxis to sites of infection, neutralization/opsonization of viruses and virally infected cells, and it can even shape adaptive immune responses. With millions of years of co-evolution and the ability to establish life-long infections, herpesviruses have evolved unique mechanisms to counter complement-mediated antiviral defenses, thus enabling their survival and replication within humans. This review aims to comprehensively summarize how human herpesviruses engage with the complement system and highlight our understanding of the role of complement in human cytomegalovirus (HCMV) infection, immunity, and viral replication. Herein we describe the novel and unorthodox roles of complement proteins beyond their roles in innate immunity and discuss gaps in knowledge and future directions of complement and HCMV research.

Supervised discovery of interpretable gene programs from single-cell data

Factor analysis decomposes single-cell gene expression data into a minimal set of gene programs that correspond to processes executed by cells in a sample. However, matrix factorization methods are prone to technical artifacts and poor factor interpretability. We address these concerns with Spectra, an algorithm that combines user-provided gene programs with the detection of novel programs that together best explain expression covariation. Spectra incorporates existing gene sets and cell-type labels as prior biological information, explicitly models cell type and represents input gene sets as a gene-gene knowledge graph using a penalty function to guide factorization toward the input graph. We show that Spectra outperforms existing approaches in challenging tumor immune contexts, as it finds factors that change under immune checkpoint therapy, disentangles the highly correlated features of CD8+ T cell tumor reactivity and exhaustion, finds a program that explains continuous macrophage state changes under therapy and identifies cell-type-specific immune metabolic programs.

Reward system activation improves recovery from acute myocardial infarction

Psychological processes have a crucial role in the recovery from acute myocardial infarction (AMI), yet the underlying mechanisms of these effects remain elusive. Here we demonstrate the impact of the reward system, a brain network associated with motivation and positive expectations, on the clinical outcomes of AMI in mice. Chemogenetic activation of dopaminergic neurons in the reward system improved the remodeling processes and vascularization after AMI, leading to enhanced cardiac performance compared to controls. These effects were mediated through several physiological mechanisms, including alterations in immune activity and reduced adrenergic input to the liver. We further demonstrate an anatomical connection between the reward system and the liver, functionally manifested by altered transcription of complement component 3, which in turn affects vascularization and recovery from AMI. These findings establish a causal connection between a motivational brain network and recovery from AMI, introducing potential therapeutic avenues for intervention.

The complement system and diabetic retinopathy

Diabetic retinopathy (DR) is one of the common microvascular complications of diabetes mellitus and is the main cause of visual impairment in diabetic patients. The pathogenesis of DR is still unclear. The complement system, as an important component of the innate immune system in addition to defending against the invasion of foreign microorganisms, is involved in the occurrence and development of DR through 3 widely recognized complement activation pathways, the complement regulatory system, and many other pathways. Molecules such as C3a, C5a, and membrane attacking complex, as important molecules of the complement system, are involved in the pathologenesus of DR, either through direct damaging effects or by activating cells (microglia, macroglia, etc.) in the retinal microenvironment to contribute to the pathological damage of DR indirectly. We review the integral association of the complement system and DR to further understand the pathogenesis of DR and possibly provide a new strategy for itstreatment.