CD180 Ligation Inhibits TLR7- and TLR9-Mediated Activation of Macrophages and Dendritic Cells Through the Lyn-SHP-1/2 Axis in Murine Lupus

Decoding the connection between SLE and DNA Sensors: A comprehensive review

Systemic lupus erythematosus (SLE) is recognized as a prevalent autoimmune disorder characterized by a multifaceted pathogenesis potentially influenced by a combination of environmental factors, genetic predisposition, and hormonal regulation. The continuous study of immune system activation is especially intriguing. Analysis of blood samples from individuals with SLE reveals an abnormal increase in interferon levels, along with the existence of anti-double-stranded DNA antibodies. This evidence suggests that the development of SLE may be initiated by innate immunity. The presence of abnormal dsDNA fragments can activate DNA sensors within cells, particularly immune cells, leading to the initiation of downstream signaling cascades that result in the upregulation of relevant cytokines and the subsequent initiation of adaptive immune responses, such as B cell differentiation and T cell activation. The intricate pathogenesis of SLE results in DNA sensors exhibiting a wide range of functions in innate immune responses that are subject to variation based on cell types, developmental processes, downstream effector signaling pathways and other factors. The review aims to reorganize how DNA sensors influence signaling pathways and contribute to the development of SLE according to current studies, with the aspiration of furnishing valuable insights for future investigations into the pathological mechanisms of SLE and potential treatment approaches.

MD-1 downregulation is associated with reduced cell surface CD180 expression in CLL

CD180 is a toll-like receptor that is highly expressed in complex with the MD-1 satellite molecule on the surface of B cells. In chronic lymphocytic leukaemia (CLL) however, the expression of CD180 is highly variable and overall, significantly reduced when compared to normal B cells. We have recently shown that reduced CD180 expression in CLL lymph nodes is associated with inferior overall survival. It was therefore important to better understand the causes of this downregulation through investigation of CD180 at the transcriptional and protein expression levels. Unexpectedly, we found CD180 RNA levels in CLL cells (n = 26) were comparable to those of normal B cells (n = 13), despite heterogeneously low expression of CD180 on the cell surface. We confirmed that CD180 RNA is translated into CD180 protein since cell surface CD180-negative cases presented with high levels of intracellular CD180 expression. Levels of MD-1 RNA were, however, significantly downregulated in CLL compared to normal controls. Together, these data suggest that changes in CD180 cell surface expression in CLL are not due to transcriptional downregulation, but defective post-translational stabilisation of the receptor due to MD-1 downregulation.

Selection against domestication alleles in introduced rabbit populations

Humans have moved domestic animals around the globe for thousands of years. These have occasionally established feral populations in nature, often with devastating ecological consequences. To understand how natural selection shapes re-adaptation into the wild, we investigated one of the most successful colonizers in history, the European rabbit. By sequencing the genomes of 297 rabbits across three continents, we show that introduced populations exhibit a mixed wild-domestic ancestry. We show that alleles that increased in frequency during domestication were preferentially selected against in novel natural environments. Interestingly, causative mutations for common domestication traits sometimes segregate at considerable frequencies if associated with less drastic phenotypes (for example, coat colour dilution), whereas mutations that are probably strongly maladaptive in nature are absent. Whereas natural selection largely targeted different genomic regions in each introduced population, some of the strongest signals of parallelism overlap genes associated with neuronal or brain function. This limited parallelism is probably explained by extensive standing genetic variation resulting from domestication together with the complex mixed ancestry of introduced populations. Our findings shed light on the selective and molecular mechanisms that enable domestic animals to re-adapt to the wild and provide important insights for the mitigation and management of invasive populations.

Genomic analysis in the colon tissues of omega-3 fatty acid-treated rats identifies novel gene signatures implicated in ulcerative colitis

Several long-term intervention trials only studied the ex vivo immunological function to elucidate the beneficial mechanisms of n-3 polyunsaturated fatty acids (PUFA) in the ulcerative colitis (UC). An unbiased whole-transcriptome analysis would be more valuable to obtain a comprehensive understanding of the processes and genes regulated by n-3 PUFA in vivo. In this study, we have performed microarray analysis in the colon tissues of dextran sulfate sodium (DSS)-induced UC in rats supplemented with n-6 PUFA, n-3PUFA and long-chain n-3PUFA (LC-n3PUFA). We have identified the novel gene signatures previously not linked to colitis such as Etv3, Clec4d, CD180, CD72, Megf11, and Angptl4 which are most downregulated in both n-3PUFA and LC-n3PUFA groups compared to the n-6PUFA group. The most upregulated genes were Nr1i3, Nptx2, and Zfp810 in both n-3PUFA and LC-n3PUFA groups. The RT-PCR analysis confirmed similar results. Interestingly, LPS treatment in macrophages upregulated the Megf11, Etv3, CD180, and Angptl4, and correlated with increased secretion of cytokines. Gene silencing of Etv3, Megf11, and CD180 in rats using intravascular delivery of siRNA-lipoparticles attenuated the DSS-induced ulceration and mucosal damage. Thus, our genome-wide microarray analysis identified novel genes regulated by omega-3 PUFA and offers new drug targets that could prevent or reduce UC.

Irradiation Attenuates Systemic Lupus Erythematosus-Like Morbidity in NZBWF1 Mice: Focusing on CD180-Negative Cells

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies that can induce systemic inflammation. Ultraviolet-A and X-ray irradiation have been reported to have therapeutic effects in patients with SLE. We previously demonstrated that CD180-negative cells, these are radiosensitive, contribute to the development of SLE-like morbidity in NZBWF1 mice. In this study, the effects of irradiation on SLE-like morbidity manifestations in NZBWF1 mice and on CD180-negative cells were investigated. Whole-body irradiation, excluding the head, attenuated SLE-like morbidity in vivo, as indicated by the prevention of the renal lesion development, inhibition of anti-dsDNA antibody production, reduction of urinary protein levels, and prolongation of the lifespan. Irradiation also reduced the proportion of CD180-negative cells in the spleen. Although other immune cells or molecules may be triggered because of the whole-body irradiation treatment, previous research, and the current results suggest a strong relationship between the radiation-induced decrease in CD180-negative cells and the amelioration of SLE-like morbidities. Clinical trials assessing CD180-negative cells as a therapeutic target for SLE have been hampered by the lack of validated cell markers; nonetheless, the present findings suggest that radiotherapy may be a new therapeutic strategy for managing SLE symptoms.

Functional impact of oxygen-saturated zeolite nanoparticles on macrophages in the context of glioblastoma: an in vitro and in vivo study

In the context of glioblastoma (GBM), hypoxia and inflammation are two main players of the tumor microenvironment. Hypoxia stimulates various features involves in tumor growth and also maintains a specific environment that favors protumor macrophages. Therefore, targeting hypoxia could potentially restore an anti-tumor M1 phenotype in macrophages. Besides, iron demonstrated its capacity to stimulate the polarization of macrophages towards an M1-like phenotype. In this paper we took advantages of microporous nanoparticles to co-deliver both oxygen and iron to bone marrow derived macrophages (BMDM) enabling the investigation of changes in polarization status and proteomic profiles. The nanoparticles were used in two in vivo models of glioblastoma, specifically, in both immunodeficient and immunocompetent settings. Our in vitro findings revealed that iron doped nanoparticles, saturated with oxygen were deemed safe for macrophages but did not demonstrate the capacity to change the M1 or M2 phenotypes. However, these nanoparticles induced some changes in proteomics pathways. The present study reports on in vivo experimentation that revealed the effects of nanoparticles on the hypoxic fraction, tumor volume, and macrophage phenotype in a GBM model. The findings indicated that the presence of nanoparticles led to a reduction in the hypoxic fraction in one of the GBM models, while no significant changes were observed in the tumor volume or macrophage phenotype. The present data showed that nanoparticles possess the capability of delivering both oxygen and iron to macrophages; though, they do not possess the ability to effectively repolarize M2 macrophages. Such strategies could be used in conjunction with other potent molecules to avoid M1 macrophages to inevitably differentiate to M2 macrophages.

The role of CD180 in hematological malignancies and inflammatory disorders

Toll-like receptors play a significant role in the innate immune system and are also involved in the pathophysiology of many different diseases. Over the past 35 years, there have been a growing number of publications exploring the role of the orphan toll-like receptor, CD180. We therefore set out to provide a narrative review of the current evidence surrounding CD180 in both health and disease. We first explore the evidence surrounding the role of CD180 in physiology including its expression, function and signaling in antigen presenting cells (APCs) (dendritic cells, monocytes, and B cells). We particularly focus on the role of CD180 as a modulator of other TLRs including TLR2, TLR4, and TLR9. We then discuss the role of CD180 in inflammatory and autoimmune diseases, as well as in hematological malignancies of B cell origin, including chronic lymphocytic leukemia (CLL). Based on this evidence we produce a current model for CD180 in disease and explore the potential role for CD180 as both a prognostic biomarker and therapeutic target. Throughout, we highlight specific areas of research which should be addressed to further the understanding of CD180 biology and the translational potential of research into CD180 in various diseases.

Impact of myeloid differentiation protein 1 on cardiovascular disease

Cardiovascular disease remains the leading cause of disability and mortality worldwide and a significant global burden. Many lines of evidence suggest complex remodeling responses to cardiovascular disease, such as myocardial ischemia, hypertension and valve disease, which lead to poor clinical outcomes, including heart failure, arrhythmia and sudden cardiac death (SCD). The mechanisms underlying cardiac remodeling are closely related to reactive oxygen species (ROS) and inflammation. Myeloid differentiation protein 1 (MD1) is a secreted glycoprotein known as lymphocyte antigen 86. The complex of MD1 and radioprotective 105 (RP105) is an important regulator of inflammation and is involved in the modulation of vascular remodeling and atherosclerotic plaque development. A recent study suggested that the expression of MD1 in hypertrophic cardiomyopathy (HCM) patients is decreased compared with that in donor hearts. Therefore, MD1 may play an important role in the pathological processes of cardiovascular disease and have potential clinical value. Here, this review aims to discuss the current knowledge regarding the role of MD1 in the regulation of cardiac pathophysiology.

Cell surface expression of human RP105 depends on N-glycosylation of MD-1

For its cell surface expression, radioprotective 105 (RP105) - an orphan Toll-like receptor - must form a complex with a soluble glycoprotein called myeloid differentiation 1 (MD-1). The number of RP105-negative cells is significantly increased in patients with systemic lupus erythematosus (SLE); however, to elucidate the mechanism underlying this increase, how RP105 is expressed on the cell surface depending on MD-1 should be investigated. We demonstrated that RP105 exhibits two forms depending on MD-1 and its two N-glycosylation sites, N96 and N156. Cell surface expression of RP105 decreased in the presence of mutant MD-1 (N96Q/N156Q). Nonglycosylated MD-1 decreased the de novo cell surface expression of RP105 but not pre-expressed RP105. Thus, the N-glycans of MD-1 may represent targets for SLE therapy.

Ageing-Associated Transcriptomic Alterations in Peri-Implantitis Pathology: A Bioinformatic Study

Background

Ageing is associated with increased incidence of peri-implantitis but the roles of ageing-associated biological mechanisms in the occurrence of peri-implantitis are not known. This study is aimed at performing integrative bioinformatic analysis of publically available datasets to uncover molecular mechanisms related to ageing and peri-implantitis.

Methods

Gene expression datasets related to ageing and peri-implantitis (PI) were sought, and differentially expressed genes (DEGs) were analysed. Ageing-related genes were also identified from the “Aging Atlas” database. Using intersection analysis, an age-related-PI gene set was identified. Functional enrichment analysis for enriched GO biological process and KEGG pathways, protein-protein interaction (PPI) network analysis, correlation analysis, and immune cell infiltration analysis to determine high-abundance immune cells were performed. Least absolute shrinkage and selection operator (LASSO) logistic regression identified key age-related-PI genes. Transcription factor-gene and drug-gene interactions and enriched KEGG pathways for the key age-related-PI genes were determined.

Results

A total of 52 genes were identified as age-related-PI genes and found enriched in several inflammation-associated processes including myeloid leukocyte activation, acute inflammatory response, mononuclear cell differentiation, B cell activation, NF-kappa B signalling, IL-17 signalling, and TNF signalling. LYN, CDKN2A, MAPT, BTK, and PRKCB were hub genes in the PPI network. Immune cell infiltration analysis showed activated dendritic cells, central memory CD4 T cells, immature dendritic cells, and plasmacytoid dendritic cells were highly abundant in PI and ageing. 7 key age-related PI genes including ALOX5AP, EAF2, FAM46C, GZMK, MAPT, RGS1, and SOSTDC1 were identified using LASSO with high predictive values and found to be enriched in multiple neurodegeneration-associated pathways, MAPK signalling, and Fc epsilon RI signalling. MAPT and ALOX5AP were associated with multiple drugs and transcription factors and interacted with other age-related genes to regulate multiple biological pathways.

Conclusion

A suite of bioinformatics analysis identified a 7-signature gene set highly relevant to cooccurrence of ageing and peri-implantitis and highlighted the role of neurodegeneration, autoimmune, and inflammation related pathways. MAPT and ALOX5AP were identified as key candidate target genes for clinical translation.

Age-related decline in the resistance of mice to bacterial infection and in LPS/TLR4 pathway-dependent neutrophil responses

Host defense against bacterial and fungal infections diminishes with age. In humans, impaired neutrophil responses are thought to contribute to this decline. However, it remains unclear whether neutrophil responses are also impaired in old mice. Here, we investigated neutrophil function in old mice, focusing on responses primed by lipopolysaccharide (LPS), an endotoxin released by gram-negative bacteria like E. coli, which signals through toll-like receptor (TLR) 4. We show that old mice have a reduced capacity to clear pathogenic E. coli during septic peritonitis. Neutrophil recruitment was elevated during LPS-induced but not aseptic peritonitis. Neutrophils from old mice showed reduced killing of E. coli. Their reactive oxygen species (ROS) production was impaired upon priming with LPS but not with GM-CSF/TNFα. Phagocytosis and degranulation were reduced in a partially LPS-dependent manner, whereas impairment of NET release in response to S. aureus was independent of LPS. Unexpectedly, chemotaxis was normal, as were Rac1 and Rac2 GTPase activities. LPS-primed activation of Erk and p38 Mapk was defective. PIP₃ production was reduced upon priming with LPS but not with GM-CSF/TNFα, whereas PIP₂ levels were constitutively low. The expression of 5% of neutrophil proteins was dysregulated in old age. Granule proteins, particularly cathepsins and serpins, as well as TLR-pathway proteins and membrane receptors were upregulated, whereas chromatin and RNA regulators were downregulated. The upregulation of CD180 and downregulation of MyD88 likely contribute to the impaired LPS signaling. In summary, all major neutrophil responses except chemotaxis decline with age in mice, particularly upon LPS priming. This LPS/TLR4 pathway dependence resolves previous controversy regarding effects of age on murine neutrophils and confirms that mice are an appropriate model for the decline in human neutrophil function.

Disrupting autorepression circuitry generates "open-loop lethality" to yield escape-resistant antiviral agents

Across biological scales, gene-regulatory networks employ autorepression (negative feedback) to maintain homeostasis and minimize failure from aberrant expression. Here, we present a proof of concept that disrupting transcriptional negative feedback dysregulates viral gene expression to therapeutically inhibit replication and confers a high evolutionary barrier to resistance. We find that nucleic-acid decoys mimicking cis-regulatory sites act as "feedback disruptors," break homeostasis, and increase viral transcription factors to cytotoxic levels (termed "open-loop lethality"). Feedback disruptors against herpesviruses reduced viral replication >2-logs without activating innate immunity, showed sub-nM IC50, synergized with standard-of-care antivirals, and inhibited virus replication in mice. In contrast to approved antivirals where resistance rapidly emerged, no feedback-disruptor escape mutants evolved in long-term cultures. For SARS-CoV-2, disruption of a putative feedback circuit also generated open-loop lethality, reducing viral titers by >1-log. These results demonstrate that generating open-loop lethality, via negative-feedback disruption, may yield a class of antimicrobials with a high genetic barrier to resistance.

RNA Microarray-Based Comparison of Innate Immune Phenotypes between Human THP-1 Macrophages Stimulated with Two BCG Strains

Currently, the only available vaccine against tuberculosis is Mycobacterium bovis Bacille Calmette-Guérin (BCG). Pulmonary tuberculosis protection provided by the vaccine varies depending on the strain, the patient’s age and the evaluated population. Although the adaptive immune responses induced by different BCG strains have been widely studied, little conclusive data is available regarding innate immune responses, especially in macrophages. Here, we aimed to characterize the innate immune responses of human THP-1-derived macrophages at the transcriptional level following a challenge with either the BCG Mexico (M.BCG) or Phipps (P.BCG) strains. After a brief in vitro characterization of the bacterial strains and the innate immune responses, including nitric oxide production and cytokine profiles, we analyzed the mRNA expression patterns and performed pathway enrichment analysis using RNA microarrays. Our results showed that multiple biological processes were enriched, especially those associated with innate inflammatory and antimicrobial responses, including tumor necrosis factor (TNF)-α, type I interferon (IFN-I) and IFN-γ. However, four DEGs were identified in macrophages infected with M.BCG compared to P. BCG. These findings indicated the proinflammatory stimulation of macrophages induced by both BCG strains, at the cytokine level and in terms of gene expression, suggesting a differential expression pattern of innate immune transcripts depending on the mycobacterial strain.

Where all the Roads Meet? A Crossover Perspective on Host Factors Regulating SARS-CoV-2 infection

COVID-19 caused by SARS-CoV-2 is the latest pandemic which has thrown the world into an unprecedented social and economic uncertainties along with huge loss to humanity. Identification of the host factors regulating the replication of SARS-CoV-2 in human host may help in the development of novel anti-viral therapies to combat the viral infection and spread. Recently, some research groups used genome-wide CRISPR/Cas screening to identify the host factors critical for the SARS-CoV-2 replication and infection. A comparative analysis of these significant host factors (p < 0.05) identified fifteen proteins common in these studies. Apart from ACE2 (receptor for SARS-CoV-2 attachment), other common host factors were CSNK2B, GDI2, SLC35B2, DDX51, VPS26A, ARPP-19, C1QTNF7, ALG6, LIMA1, COG3, COG8, BCOR, LRRN2 and TLR9. Additionally, viral interactome of these host factors revealed that many of them were associated with several SARS-CoV-2 proteins as well. Interestingly, some of these host factors have already been shown to be critical for the pathogenesis of other viruses suggesting their crucial role in virus-host interactions. Here, we review the functions of these host factors and their role in other diseases with special emphasis on viral diseases.

Immune Characteristics of LYN in Tumor Microenvironment of Gliomas

The prognosis of gliomas is poor and there are limited therapeutic approaches. Immunotherapy has become a promising treatment for gliomas. Here, we explored the expression pattern of Lck/yes-related protein tyrosine kinase (LYN) in gliomas and assessed its value as an immunotherapy biomarker. Transcriptional data was mined from two publicly available datasets, TCGA and CGGA, and used to investigate the correlation between LYN and clinical characteristics including patient prognosis, somatic mutation, and immune infiltrating features in gliomas. Besides, the correlation between LYN and classical immune checkpoint molecules was explored. Glioma samples obtained from the Xiangya Hospital cohort were used for immunohistochemistry staining. High expression level of LYN was observed in advanced gliomas and other cancer types, which predicted a worse prognosis. LYN stratified patients’ survival in the Xiangya cohort and was also significantly associated with infiltrating immune cell types and inflammatory activities in the tumor microenvironment. LYN was involved in tumor mutation, correlated with the regulation of oncogenic genes, and also showed a significant positive correlation with PD-L1. LYN can be a potential diagnostic marker and immunotherapy marker in gliomas.

TLR7 modulating B-cell immune responses in the spleen of C57BL/6 mice infected with Schistosoma japonicum

B cells played an important role in Schistosoma infection-induced diseases. TLR7 is an intracellular member of the innate immune receptor. The role of TLR7 on B cells mediated immune response is still unclear. Here, C57BL/6 mice were percutaneously infected by S. japonicum for 5-6 weeks. The percentages and numbers of B cells increased in the infected mice (p < 0.05), and many activation and function associated molecules were also changed on B cells. More splenic cells of the infected mice expressed TLR7, and B cells were served as the main cell population. Moreover, a lower level of soluble egg antigen (SEA) specific antibody and less activation associated molecules were found on the surface of splenic B cells from S. japonicum infected TLR7 gene knockout (TLR7 KO) mice compared to infected wild type (WT) mice (p < 0.05). Additionally, SEA showed a little higher ability in inducing the activation of B cells from naive WT mice than TLR7 KO mice (p < 0.05). Finally, the effects of TLR7 on B cells are dependent on the activation of NF-κB p65. Altogether, TLR7 was found modulating the splenic B cell responses in S. japonicum infected C57BL/6 mice.

Pyruvate kinase isoform M2 impairs cognition in systemic lupus erythematosus by promoting microglial synaptic pruning via the β-catenin signaling pathway

BACKGROUND

Neuropsychiatric systemic lupus erythematosus (NPSLE) is a severe complication, which involves pathological damage to the brain and cognitive function. However, its exact mechanism of action still remains unclear. In this study, we explored the role of microglia in the cognitive dysfunction of NPSLE mice. We also analyzed and compared the metabolites in the hippocampal tissues of the lupus model and control mice.

METHODS

MRL/MpJ-Fas^lpr (MRL/lpr) female mice were used as the NPSLE mouse model. Metabolomics was used to assess hippocampal glycolysis levels. Glucose, lactic acid, IL-6, and IL-1β of the hippocampus were detected by ELISA. Based on the glycolysis pathway, we found that pyruvate kinase isoform M2 (PKM2) in the hippocampus was significantly increased. Thus, the expression of PKM2 was detected by qRT-PCR and Western blotting, and the localization of PKM2 in microglia (IBA-1⁺) or neurons (NeuN⁺) was assessed by immunofluorescence staining. Flow cytometry was used to detect the number and phenotype of microglia; the changes in microglial phagocytosis and the β-catenin signaling pathway were detected in BV2 cells overexpressing PKM2. For in vivo experiments, MRL/lpr mice were treated with AAV9-shPKM2. After 2 months, Morris water maze and conditional fear tests were applied to investigate the cognitive ability of mice; H&E and immunofluorescence staining were used to evaluate brain damage; flow cytometry was used to detect the phenotype and function of microglia; neuronal synapse damage was monitored by qRT-PCR, Western blotting, and immunofluorescence staining.

RESULTS

Glycolysis was elevated in the hippocampus of MRL/lpr lupus mice, accompanied by increased glucose consumption and lactate production. Furthermore, the activation of PKM2 in hippocampal microglia was observed in lupus mice. Cell experiments showed that PKM2 facilitated microglial activation and over-activated microglial phagocytosis via the β-catenin signaling pathway. In vivo, AAV9-shPKM2-treated mice showed decreased microglial activation and reduced neuronal synapses loss by blocking the β-catenin signaling pathway. Furthermore, the cognitive impairment and brain damage of MRL/lpr mice were significantly relieved after microglial PKM2 inhibition.

CONCLUSION

These data indicate that microglial PKM2 have potential to become a novel therapeutic target for treating lupus encephalopathy.

The Potential Role of RP105 in Regulation of Inflammation and Osteoclastogenesis During Inflammatory Diseases

Inflammatory diseases have a negative impact on bone homeostasis via exacerbated local and systemic inflammation. Bone resorbing osteoclasts are mainly derived from hematopoietic precursors and bone marrow monocytes. Induced osteoclastogenesis during inflammation, autoimmunity, metabolic diseases, and cancers is associated with bone loss and osteoporosis. Proinflammatory cytokines, pathogen-associated molecular patterns, or endogenous pathogenic factors induce osteoclastogenic differentiation by binding to the Toll-like receptor (TLR) family expressed on surface of osteoclast precursors. As a non-canonical member of the TLRs, radioprotective 105 kDa (RP105 or CD180) and its ligand, myeloid differentiation protein 1 (MD1), are involved in several bone metabolic disorders. Reports from literature had demonstrated RP105 as an important activator of B cells, bone marrow monocytes, and macrophages, which regulates inflammatory cytokines release from immune cells. Reports from literature had shown the association between RP105 and other TLRs, and the downstream signaling mechanisms of RP105 with different “signaling-competent” partners in immune cells during different disease conditions. This review is focused to summarize: (1) the role of RP105 on immune cells’ function and inflammation regulation (2) the potential regulatory roles of RP105 in different disease-mediated osteoclast activation and the underlying mechanisms, and (3) the different “signaling-competent” partners of RP105 that regulates osteoclastogenesis.

The emerging roles of exosomes in autoimmune diseases, with special emphasis on microRNAs in exosomes

Autoimmune diseases include rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic vasculitis, dermatomyositis, systemic sclerosis (SSc), mixed connective tissue disease, autoimmune hemolytic anemia, autoimmune thyroiditis (AITD) and ulcerative colitis. Exosomes exist in body fluids, including blood, saliva, urine, cerebrospinal fluid and milk. They are mainly derived from the invagination of intracellular lysosomal particles, which are released into the extracellular matrix after fusion of the outer membrane of the exosomes with the cell membrane. Exosomes mediate intercellular communication and regulate the biological activity of receptor cells by carrying proteins, nucleic acids and lipids. Evidences show that exosomes are involved in the pathogenesis of various autoimmune diseases. In view of the important roles of exosomes in autoimmune diseases, this work systematically reviewed the effects of exosomes on the pathogenesis of autoimmune diseases, especially the regulatory roles of exosome derived microRNAs (miRNAs) in the pathogenesis of RA, SLE, dermatomyositis, SSc, AITD and ulcerative colitis. The review of the roles of exosomes in autoimmune diseases will help to clarify the pathogenesis of these diseases and explore new diagnostic markers and therapeutic targets.

Pyruvate Kinase M2 Contributes to TLR-Mediated Inflammation and Autoimmunity by Promoting Pyk2 Activation

Toll-like receptors (TLRs) play critical roles in regulating the abnormal activation of the immune cells resulting in the pathogenesis of inflammation and autoimmune diseases. Pyruvate kinase M2 (PKM2), which governs the last step of glycolysis, is involved in multiple cellular processes and pathological conditions. However, little is known about the involvement of PKM2 in regulating TLR-mediated inflammation and autoimmunity. Herein, we investigated the role of PKM2 in the activation of the TLR pathways and the pathogenesis of inflammation and autoimmune diseases. The activation of TLR4, TLR7 and TLR9 pathways was found to induce the up-regulation of PKM2 expression in macrophages, dendritic cells (DCs) and B cells. The over-expression of PKM2 promotes the activation of TLR4, TLR7 and TLR9 pathways while interference with the PKM2 expression or the addition of the PKM2 inhibitor (PKM-IN) markedly inhibited the activation of TLR4, TLR7 and TLR9 pathways. Mechanistically, PKM2 augmented the activation of TLR4, TLR7 and TLR9 pathways by promoting the activation of the proline-rich tyrosine kinase 2 (Pyk2). Intriguingly, the PKM2 inhibitor PKM2-IN significantly protected the mice from the endotoxic shock mediated by the TLR4-agonist LPS. Additionally, it alleviated the progression in the TLR7-agonist imiquimod-mediated lupus mice and spontaneous lupus MRL/lpr mice. Moreover, PKM2 expression was highly elevated in the monocytes, DCs and B cells from systemic lupus erythematous (SLE) patients compared with those from the healthy donors. Besides, the PKM2 expression level was positively correlated with the degree of activation of these immune cells. In summary, PKM2 contributed to TLR-mediated inflammation and autoimmunity and can be a valuable target to control inflammation and autoimmunity.

A THP-1 Cell Line-Based Exploration of Immune Responses Toward Heat-Treated BLG

Allergen recognition and processing by antigen presenting cells is essential for the sensitization step of food allergy. Macrophages and dendritic cells are both phagocytic antigen presenting cells and play important roles in innate immune responses and signaling between the innate and adaptive immune system. To obtain a model system with a homogeneous genetic background, we derived macrophages and dendritic cells from THP-1 monocytes. The difference between macrophages and dendritic cells was clearly shown by differences in their transcription response (microarray) and protein expression levels. Their resemblance to primary cells was analyzed by comparison to properties as described in literature. The uptake of β-lactoglobulin after wet-heating (60°C in solution) by THP-1 derived macrophages was earlier reported to be significantly increased. To analyse the subsequent immune response, we incubated THP-1 derived macrophages and dendritic cells with native and differently processed β-lactoglobulin and determined the transcription and cytokine expression levels of the cells. A stronger transcriptional response was found in macrophages than in dendritic cells, while severely structurally modified β-lactoglobulin induced a more limited transcriptional response, especially when compared to native and limitedly modified β-lactoglobulin. These results show that processing is relevant for the transcriptional response toward β-lactoglobulin of innate immune cells.

Harnessing the Complete Repertoire of Conventional Dendritic Cell Functions for Cancer Immunotherapy

The onset of checkpoint inhibition revolutionized the treatment of cancer. However, studies from the last decade suggested that the sole enhancement of T cell functionality might not suffice to fight malignancies in all individuals. Dendritic cells (DCs) are not only part of the innate immune system, but also generals of adaptive immunity and they orchestrate the de novo induction of tolerogenic and immunogenic T cell responses. Thus, combinatorial approaches addressing DCs and T cells in parallel represent an attractive strategy to achieve higher response rates across patients. However, this requires profound knowledge about the dynamic interplay of DCs, T cells, other immune and tumor cells. Here, we summarize the DC subsets present in mice and men and highlight conserved and divergent characteristics between different subsets and species. Thereby, we supply a resource of the molecular players involved in key functional features of DCs ranging from their sentinel function, the translation of the sensed environment at the DC:T cell interface to the resulting specialized T cell effector modules, as well as the influence of the tumor microenvironment on the DC function. As of today, mostly monocyte derived dendritic cells (moDCs) are used in autologous cell therapies after tumor antigen loading. While showing encouraging results in a fraction of patients, the overall clinical response rate is still not optimal. By disentangling the general aspects of DC biology, we provide rationales for the design of next generation DC vaccines enabling to exploit and manipulate the described pathways for the purpose of cancer immunotherapy in vivo. Finally, we discuss how DC-based vaccines might synergize with checkpoint inhibition in the treatment of malignant diseases.

The pathological role of B cells in systemic lupus erythematosus: From basic research to clinical

Systemic lupus erythematosus (SLE) is an autoimmune disease that often occurs in females of child-bearing age. It involves multiple systems and severely threatens human life. One of the typical characteristics of SLE is the formation of immune complexes with autoantibodies produced by B cells that target various autoantigens, thus indicating the pivotal role of B cells in the pathogenesis of SLE. Increasing evidence has shown abnormal expression of B cells in the peripheral blood of SLE patients. Moreover, numerous studies have shown that B cells in SLE patients are abnormally activated, as well as aberrantly differentiated, and are involved in the inflammatory cytokine milieu, abnormal transcription factor activity, and signalling pathways. Several biological therapies targeting B cells, such as anti-CD20 antibodies, have been intensively studied in preclinical and clinical trials. However, the results have not met expectations. Therefore, new therapies targeting B cells are in great need. This review will summarize the latest progress in basic research on B cells to better understand the pathogenesis of SLE and will discuss the outcomes of B-cell-targeting treatments that provide potential therapeutic targets and strategies for SLE. Studies have clarified high levels of IL-21 in serum from SLE patients and animal models. IL-21 promotes B cell differentiation, which results in antibodies accumulation leads to SLE. Therefore, further studies on IL-21 will give new perspectives on SLE treatments. In addition, the application of drugs targeting plasma cell depletion in SLE patients may also achieve satisfied results in treatment.

Toll-Like Receptor Mediated Activation of Natural Autoantibody Producing B Cell Subpopulations in an Autoimmune Disease Model

Altered expression and function of the Toll-like receptor (TLR) homologue CD180 molecule in B cells have been associated with autoimmune disorders. In this study, we report decreased expression of CD180 at protein and mRNA levels in peripheral blood B cells of diffuse cutaneous systemic sclerosis (dcSSc) patients. To analyze the effect of CD180 stimulation, together with CpG (TLR9 ligand) treatment, on the phenotype defined by CD19/CD27/IgD/CD24/CD38 staining, and function (CD69 and CD180 expression, cytokine and antibody secretion) of B cell subpopulations, we used tonsillar B cells. After stimulation, we found reduced expression of CD180 protein and mRNA in total B cells, and CD180 protein in B cell subpopulations. The frequency of CD180+ cells was the highest in the CD19+CD27+IgD+ non-switched (NS) B cell subset, and they showed the strongest activation after anti-CD180 stimulation. Furthermore, B cell activation via CD180 induced IL-6 and natural autoantibody secretion. Treatment with the combination of anti-CD180 antibody and CpG resulted in increased IL-6 and IL-10 secretion and natural autoantibody production of B cells. Our results support the role of CD180 in the induction of natural autoantibody production, possibly by NS B cells, and suggest an imbalance between the pathologic and natural autoantibody production in SSc patients.