The Macrophage Mannose Receptor Regulate Mannan-Induced Psoriasis, Psoriatic Arthritis, and Rheumatoid Arthritis-Like Disease Models

Impacts of monosaccharide composition on immunomodulation by cello-pentaose, manno-pentaose, and xylo-pentaose: Unraveling the underlying molecular mechanisms

Different types of functional oligosaccharides exhibit varying degrees of immune-enhancing effects, which might be attributable to differences in their glycosyl structures. The differences in the immunomodulatory action of three functional oligosaccharides with distinct glycosyl compositions: cello-oligosaccharides (COS), manno-oligosaccharides (MOS), and xylo-oligosaccharides (XOS), were investigated in mouse-derived macrophage RAW264.7. Moreover, the immune enhancement mechanism of oligosaccharides with diverse glycosyl compositions was investigated from a molecular interaction perspective. The TLR4-dependent immunoregulatory effect of functional oligosaccharides was shown by measuring the levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in RAW264.7 cells treated with different functional oligosaccharides, both with and without Resatorvid [TAK-242] (a Toll-like receptor 4 [TLR4] inhibitor). Western blot analysis showed that binding of the three oligosaccharides to TLR4 activated the downstream signaling pathway and consequently enhanced the immune response. The fluorescence spectra and molecular docking results revealed that the main mechanisms by which these oligosaccharides attach to the TLR4 active pocket are hydrogen bonds and van der Waals forces. Functional oligosaccharides were ranked according to their affinity for TLR4, as follows: MOS > COS > XOS, indicating that oligosaccharides or polysaccharides containing mannose units may confer significant advantages for immune enhancement.

Soluble mannose receptor: A potential biomarker in Gaucher disease

PURPOSE

Soluble mannose receptor (sMR) relates to mannose receptor expression on macrophages, and is elevated in inflammatory disorders. Gaucher disease (GD) has altered macrophage function and utilises mannose receptors for enzyme replacement therapy (ERT) endocytosis. sMR has not previously been studied in GD.

METHODS

sMR was measured by ELISA and correlated with GD clinical features including spleen and liver volume, haemoglobin and platelet count, bone marrow burden (BMB) scores and immunoglobulin levels. sMR was compared with biomarkers of GD: chitotriosidase, lyso-GL1, PARC, CCL3, CCL4, osteoactivin, serum ACE and ferritin.

RESULTS

Median sMR in untreated GD patients was 303.0 ng/mL compared to post-treatment 190.9 ng/mL (p = .02) and healthy controls 202 ng/mL. Median sMR correlated with median spleen volume 455 mL (r = .70, p = .04), liver volume 2025 mL (r = .64, p = .04), BMB 7 (r = .8, p = .03), IgA 1.9 g/L (r = .54, p = .036), IgG 9.2 g/L (r = .57, p = .027), IgM 1.45 g/L (r = .86, p < .0001), with inverse correlation to median platelet count of 125 × 109/L (r = -.47, p = .08) and haemoglobin of 137 g/L (r = -.77, p = .0008). sMR correlated with established biomarkers: osteoactivin 107.8 ng/mL (r = .58, p = .0006), chitotriosidase 3042 nmol/mL/h (r = .52, p = .0006), PARC 800 ng/mL (r = .67, p = .0068), ferritin 547 μg/L (r = .72, p = .002) and CCL3 50 pg/mL (r = .67, p = .007).

CONCLUSIONS

sMR correlates with clinical features and biomarkers of GD and reduces following therapy.

Exploring the Predictive Value of Gut Microbiome Signatures for Therapy Intensification in Patients With Inflammatory Bowel Disease: A 10-Year Follow-up Study

BACKGROUND

Inflammatory bowel diseases (IBDs) pose a significant challenge due to their diverse, often debilitating, and unpredictable clinical manifestations. The absence of prognostic tools to anticipate the future complications that require therapy intensification presents a substantial burden to patient private life and health. We aimed to explore whether the gut microbiome is a potential biomarker for future therapy intensification in a cohort of 90 IBD patients.

METHODS

We conducted whole-genome metagenomics sequencing on fecal samples from these patients, allowing us to profile the taxonomic and functional composition of their gut microbiomes. Additionally, we conducted a retrospective analysis of patients' electronic records over a period of 10 years following the sample collection and classified patients into (1) those requiring and (2) not requiring therapy intensification. Therapy intensification included medication escalation, intestinal resections, or a loss of response to a biological treatment. We applied gut microbiome diversity analysis, dissimilarity assessment, differential abundance analysis, and random forest modeling to establish associations between baseline microbiome profiles and future therapy intensification.

RESULTS

We identified 12 microbial species (eg, Roseburia hominis and Dialister invisus) and 16 functional pathways (eg, biosynthesis of L-citrulline and L-threonine) with significant correlations to future therapy intensifications. Random forest models using microbial species and pathways achieved areas under the curve of 0.75 and 0.72 for predicting therapy intensification.

CONCLUSIONS

The gut microbiome is a potential biomarker for therapy intensification in IBD patients and personalized management strategies. Further research should validate our findings in other cohorts to enhance the generalizability of these results.

Engineering extracellular vesicles with macrophage membrane fusion for ameliorating imiquimod-induced psoriatic skin inflammation

INTRODUCTION

Herein, we developed an engineered extracellular vehicle (EV)-based method for ameliorating inflammatory responses in psoriasis.

METHODS

EVs, derived from annexin A1 (ANXA1) overexpressing T cells, were co-extruded with M2 macrophage membrane to obtain engineered EVs. In vitro, the effect of engineered EVs on macrophage polarization was evaluated by real-time PCR. In imiquimod (IMQ)-induced psoriasis-like mouse model, the efficacy of engineered EVs in ameliorating psoriatic inflammation was evaluated by Psoriasis Area and Severity Index (PASI) score and immunohistochemistry staining after subcutaneous injection of EVs.

RESULTS

The engineered EVs not only preserved the high stability of M2 macrophage membrane but also retained the macrophage reprogramming potential of ANXA1 overexpressed in T cells. In the psoriasis-like mouse model, subcutaneous injection of engineered EVs successfully reduced the PASI score and the levels of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α. Along with high biosafety, the administration of EVs also rescued the histomorphological changes of spleen, liver, and kidney.

CONCLUSIONS

The engineered EVs exhibited the potential to alleviate inflammation of psoriasis, providing new insights and potential strategies for the immunotherapies of psoriasis.

Mannose-doped metal-organic frameworks induce tumor cell pyroptosis via the PERK pathway

BACKGROUND

The implementation of pyroptosis exhibits significant potential as a tactic to enhance tumor immune microenvironments. Previous applications of pyroptosis inducers have encountered various limitations, such as the development of drug resistance, manifestation of toxic side effects, and a deficiency in targeting capabilities. As a result, there is a growing demand for tumor therapeutic molecules that can overcome these obstacles. Therefore, the objective of this study is to develop a multifunctional nanospheres that addresses these challenges by enabling high-precision targeting of tumor cells and inducing effective pyroptosis.

RESULTS

We prepared a mannose-modified MOF called mannose-doped Fe3O4@NH2-MIL-100 (M-FNM). M-FNM could enter CAL27 cells through MR-mediated endocytosis, which caused in a significant increase in the level of intracellular ROS. This increase subsequently triggered ER stress and activated the PERK-eIF2α-ATF4-CHOP signaling pathway. CHOP then mediated the downstream cascade of Caspase-1, inducing pyroptosis. In in vivo experiments, M-FNM demonstrated excellent targeting ability and exhibited anti-tumor effects. Additionally, M-FNM reshaped the immune microenvironment by promoting the infiltration of anti-tumor immune cells, primarily T lymphocytes.

CONCLUSIONS

M-FNM significantly decreased tumor growth. This novel approach to induce pyroptosis in tumor cells using M-FNM may offer new avenues for the development of effective immunotherapies against cancer.

The Conundrum of Psoriatic Arthritis: a Pathogenetic and Clinical Pattern at the Midpoint of Autoinflammation and Autoimmunity

Psoriatic arthritis (PsA) is a chronic inflammatory condition characterized by psoriasis, synovitis, enthesitis, spondylitis, and the possible association with other extra-articular manifestations and comorbidities. It is a multifaceted and systemic disorder sustained by complex pathogenesis, combining aspects of autoinflammation and autoimmunity. Features of PsA autoinflammation include the role of biomechanical stress in the onset and/or exacerbation of the disease; the evidence of involvement of the innate immune response mediators in the skin, peripheral blood and synovial tissue; an equal gender distribution; the clinical course which may encounter periods of prolonged remission and overlapping features with autoinflammatory syndromes. Conversely, the role of autoimmunity is evoked by the association with class I major histocompatibility complex alleles, the polyarticular pattern of the disease which sometimes resembles rheumatoid arthritis and the presence of serum autoantibodies. Genetics also provide important insights into the pathogenesis of PsA, particularly related to class I HLA being associated with psoriasis and PsA. In this review, we provide a comprehensive review of the pathogenesis, genetics and clinical features of PsA that endorse the mixed nature of a disorder at the crossroads of autoinflammation and autoimmunity.

Challenges and opportunities in animal models of psoriatic arthritis

OBJECTIVE

To review the preparation, characteristics and research progress of different PsA animal models.

METHODS

Computerized searches were conducted in CNKI, PubMed and other databases to classify and discuss the relevant studies on PsA animal models. The search keywords were "PsA and animal model(s), PsA and animal(s), PsA and mouse, PsA and mice, PsA and rat(s), PsA and rabbit(s), PsA and dog(s)" RESULTS: The experimental animals currently used to study PsA are mainly rodents, including mice and rats. According to the different methods of preparing the models, the retrieved animal models were classified into spontaneous or genetic mutation, transgenic and induced animal models. These PsA animal models involve multiple pathogenesis, some experimental animals' lesions appear in a short and comprehensive cycle, some have a high success rate in molding, and some are complex and less reproducibility. This article summarizes the preparation methods, advantages and disadvantages of different models.

CONCLUSIONS

The animal models of PsA aim to mimic the clinicopathological alterations of PsA patients through gene mutation, transgenesis or targeted proinflammatory factor and to reveal new pathogenic pathways and therapeutic targets by exploring the pathological features and clinical manifestations of the disease. This work will have very far-reaching implications for the in-depth understanding of PsA and the development of new drugs.

Discovery of CLEC2B as a diagnostic biomarker and screening of celastrol as a candidate drug for psoriatic arthritis through bioinformatics analysis

BACKGROUND

Psoriatic arthritis (PSA) is a chronic, immune-mediated inflammatory joint disease that is liked to mortality due to cardiovascular disease. Diagnostic markers and effective therapeutic options for PSA remain limited due to the lack of understanding of the pathogenesis. We aimed to identify potential diagnostic markers and screen the therapeutic compounds for PSA based on bioinformatics analysis.

METHODS

Differentially expressed genes (DEGs) of PSA were identified from the GSE61281 dataset. WGCNA was used to identify PSA-related modules and prognostic biomarkers. Clinical samples were collected to validate the expression of the diagnostic gene. These DEGs were subjected to the CMap database for the identification of therapeutic candidates for PSA. Potential pathways and targets for drug candidates to treat PSA were predicted using Network Pharmacology. Molecular docking techniques were used to validate key targets.

RESULTS

CLEC2B was identified as a diagnostic marker for PSA patients (AUC > 0.8) and was significantly upregulated in blood samples. In addition, celastrol was identified as a candidate drug for PSA. Subsequently, the network pharmacology approach identified four core targets (IL6, TNF, GAPDH, and AKT1) of celastrol and revealed that celastrol could treat PSA by modulating inflammatory-related pathways. Finally, molecular docking demonstrated stable binding of celastrol to four core targets in the treatment of PSA. Animal experiments indicated celastrol alleviated inflammatory response in the mannan-induced PSA.

CONCLUSION

CLEC2B was a diagnostic marker for PSA patients. Celastrol was identified as a potential therapeutic drug for PSA via regulating immunity and inflammation.

A New Galactoglucomannan from the Mycelium of the Medicinal Parasitic Fungus Cordyceps cicadae and Its Immunomodulatory Activity In Vitro and In Vivo

A new galactoglucomannan (C-0-1) was purified from the medicinal parasitic fungus of Cordyceps cicadae using an anion-exchange column and gel permeation column. The results of high-performance liquid chromatography and high-performance gel permeation chromatography indicated that C-0-1 consists of galactose, glucose, and mannose in a ratio of 5:1:4 and has a molecular weight of 23.3 kDa. The combined structural elucidation analysis methods including partial acid hydrolysis, methylation analysis, and NMR experiments revealed that C-0-1 was a comb-like polysaccharide with a core structure including (1→2)-α-D-Manp residues in the backbone and branches at O-6 of the main chain. (1→4)-α-D-Glcp, (1→2)-β-D-Galf, (1→2,6)-β-D-Galf, and terminal β-Galf were located at the side chains. An in vitro experiment using RAW 264.7 cells indicated that C-0-1 exhibits good immunomodulatory activity by enhancing inducible nitric oxide synthase secretion and the production of some major inflammatory cytokines. On inhibiting the cytokine production using anti-pattern recognition receptors antibodies, it was revealed that the activation of macrophages is mainly carried out by C-0-1 through the mannose receptor. Toll-like receptor 4 and Toll-like receptor 2 were also involved in this identification process. An in vivo experiment on immunosuppressive mice treated with cyclophosphamide indicated that C-0-1 improves the secretion of serum-related cytokines (IFN-γ, TNF-α, IL-2, IL-4, and IL-10) and affects the balance of T helper cells Th1/Th2. Given the structural and bioactivity similarity between Cordyceps cicadae and Cordyceps sinensis, we can conclude that Cordyceps cicadae could be used as an important medicinal fungus like Cordyceps sinensis.

Comparative studies on mannan and imiquimod induced experimental plaque psoriasis inflammation in inbred mice

Psoriasis is a genetically determined, environmentally triggered, immune system-mediated autoimmune disease. Different animal models are needed to investigate the complex pathological mechanisms underlying this disease. Therefore, we established mannan-induced psoriasis model and compared with the most commonly used imiquimod-induced psoriasis in terms of disease, induction of innate immune cells, expression of cytokines, and the effect of dexamethasone treatment. Mannan significantly induced more severe psoriasis with better disease relapsing feature than imiquimod (IMQ). As determined by immunohistochemistry, IMQ induced significantly more infiltration of CD11c+ and F4/80+ cells than mannan in the skin. However, cytometric analysis showed a significant increase in the percentage of Gr-1+ neutrophils in the spleen and lymph nodes as well as F4/80+ macrophages in the spleen after mannan exposure. Variation in the percentage of significantly increased Vγ4 T cells was also found to be dependent on the lymphoid organs tested. However, there is a clear difference between these models in terms of expression of certain cytokine genes: IL-22, IL-23, IL-17E, and IL-17F were expressed more predominantly in mannan-induced inflammation, while IL-6 and IL-17A expressions were significantly higher in IMQ model. Interestingly, dexamethasone treatment strongly reduced epidermal thickness and histological scores induced by mannan than IMQ. Despite inducing psoriasis-like inflammation, certain differences and similarities were observed in the immune responses induced by mannan and IMQ. However, mannan-induced psoriasis model is relatively more simple, economical and less harmful to mice with an increased possibility to develop a chronic psoriasis model by exposing mice to mannan.

Mannose-mediated nanodelivery of methotrexate to macrophages augments rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is a chronic autoimmune disease that gravely jeopardizes the quality of life of numerous people. Methotrexate (MTX) is a disease-modifying anti-rheumatic drug commonly used in clinics; however, it suffers from slow onset, moderate efficacy, and adverse reactions such as renal dysfunction, myelosuppression, and bone erosion after long-term treatment. Here, we explored macrophage targeted delivery of MTX using mannose-installed chimaeric polymersomes (Man-PMTX) as an advanced treatment for RA. Man-PMTX exhibited high (∼18 wt%) and robust loading of MTX, uniform size of 51-55 nm, minimal hemolytic activity, and glutathione-actuated drug release property. Man-PMTX showed better uptake by activated macrophages than PMTX, and more repolarization of bone marrow-derived macrophages (BMDMs) to anti-inflammatory M2 type macrophages and less secretion of TNF-α and IL-1β compared with free MTX and PMTX. In vivo studies revealed that Man-PMTX showed significantly higher accumulation in inflammatory joints than in healthy joints and effectively treated RA by relieving inflammation, repolarizing macrophages from M1 type to M2 type, and mitigating proinflammatory cytokines. Accordingly, Man-PMTX effectively protected the synovium and bone from damage. Mannose-mediated nanodelivery of methotrexate to macrophages appears to be an attractive strategy to augment rheumatoid arthritis therapy.

Phospholipase A1 Member A Deficiency Alleviates Mannan-Induced Psoriatic Arthritis in Mice Model

Synovial fluids from rheumatoid and psoriatic arthritis patients have high levels of PLA1A. The current study was to understand PLA1A functions in the pathophysiology of rheumatic diseases. We generated Pla1a−/− mice to assess their phenotype and the impact of PLA1A deficiency on the development of mannan-induced psoriatic arthritis (MIP). Mice were evaluated routinely for the induced symptoms. On the day of sacrifice, blood samples were collected for hematology analysis and prepared for plasma. Livers were collected. Lymph node immune cells were analyzed using flow cytometry. We performed μCT scans of hind paws from naïve and mannan-induced female mice. Cytokines/chemokines were quantified using Luminex in hind paw tissues and plasma of female mice. Pla1a−/− mice showed a slight increase in circulating and lymph node lymphocytes. CD4+ T cells contributed most to this increase in lymph nodes (p = 0.023). In the MIP model, the lymph node ratios of CD3+ to CD19+ and CD4+ to CD8+ were higher in Pla1a−/− mice. Pla1a−/− mice were less susceptible to MIP (p < 0.001) and showed reduced bone erosions. Pla1a−/− mice also showed reduced IL-17, KC, IP-10, MIP-1β, LIF, and VEGF in hind paw tissues as compared to WT mice (p < 0.05). These findings indicated that PLA1A deficiency protected from the development of the MIP disease. The data suggested that PLA1A could contribute to MIP through increased activation of lymphocytes, possibly those producing IL-17.

The Role of Reactive Oxygen Species in the Rheumatoid Arthritis-Associated Synovial Microenvironment

Rheumatoid arthritis (RA) is an inflammatory disease that begins with a loss of tolerance to modified self-antigens and immune system abnormalities, eventually leading to synovitis and bone and cartilage degradation. Reactive oxygen species (ROS) are commonly used as destructive or modifying agents of cellular components or they act as signaling molecules in the immune system. During the development of RA, a hypoxic and inflammatory situation in the synovium maintains ROS generation, which can be sustained by increased DNA damage and malfunctioning mitochondria in a feedback loop. Oxidative stress caused by abundant ROS production has also been shown to be associated with synovitis in RA. The goal of this review is to examine the functions of ROS and related molecular mechanisms in diverse cells in the synovial microenvironment of RA. The strategies relying on regulating ROS to treat RA are also reviewed.

Variants of beta-glucan polysaccharides downregulate autoimmune inflammation

Common infections and polysaccharides, from bacteria and yeasts, could trigger psoriasis and psoriatic arthritis (PsA), and possibly rheumatoid arthritis (RA). The objective of this study was to investigate the effects of β-glucan polysaccharides in the effector phase of arthritis and as regulators of psoriasis and PsA-like symptoms in mice. Collagen antibody induced arthritis was studied as a model of RA and mannan-induced psoriasis (MIP) was used as model for psoriasis and PsA, using mice with a mutation of Ncf1 on the B10.Q genetic background, making them highly disease susceptible. The mice were exposed to three common variants: 1,6-β-glucan, 1,3-β-glucan and 1,3-1,6-β-glucan. These β-glucans down-regulated disease in mice if administered simultaneously, before or after mannan. Interestingly, the protection was macrophage mannose receptor (MMR/CD206) dependent with a more pronounced protection long-term than short-term. The number of resident peritoneal macrophages decreased after in vivo challenge with β-glucan and mannan compared to mannan alone, whereas the numbers of infiltrating cells correspondingly increased, further indicating macrophages as key for β-glucan mediated regulation. At the doses tested, β-glucans could not induce arthritis, psoriasis or PsA in wild-type mice. However, β-glucans could ameliorate the PsA-like symptoms representing a new unforeseen possibility to explore for future clinical treatment.

β-glucan exerted anti-inflammatory activities in a murine model of psoriasis and psoriatic arthritis is, at least in part, mediated via the activation of CD206 on macrophages

Transcriptome and metabolome analyses of the immune response to light stress in the hybrid grouper (Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀)

Light intensity is an important environmental factor that affects fish growth and health through multiple physiological activities and metabolism and eventually impacts aquaculture harvest. There is a need to evaluate the fish stress response to light intensities, which will benefit aquaculture. Here, hybrid grouper (Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀) was treated with three light intensities for evaluation of the light stress response, including high light intensity (1 250 lx), low light intensity (10 lx) and moderate light intensity (250 lx). Transcriptome analysis showed that a total of 71 318 unigene sequences were obtained with an N50 of 2 589 bp. Compared to the control group (250 lx), 1 697 differentially expressed genes (DEGs), a considerable quantity, were detected in the 1 250 lx group. Among those genes, 548 were upregulated, and the remaining 149 genes showed decreased expression. Comparatively small numbers of DEGs were detected in the 10 lx group; 54 out of 103 genes exhibited upregulated expression, and 49 genes showed downregulation. For further KEGG analysis, 82 DEGs were enriched in nine common signalling pathways in immunity, of which 73 DEGs were significantly inhibited in the 1 250 lx group. In contrast, only 11 DEGs were enriched in three immunity pathways, with nine DEGs showing a significant increase in the 10 lx group. The metabolome analysis revealed 59 and 44 differential metabolites (DMs) from the 1 250 lx and 10 lx groups, respectively. Of note, those DMs from the 1 250 lx-treated group were tendentiously involved in amino acid metabolism and lipid metabolism pathways, while the purine metabolism, amino acid metabolism and lipid metabolism pathways were mostly found in the 10 lx treatment group. In summary, our data indicated that high light intensity significantly inhibited the immune response in hybrid grouper, while low light intensity presented low stimulation of immune activity. In addition, both high and low light intensity could inhibit protein synthesis and amino acid metabolism. Taken together, hybrid grouper exhibited a much milder stress response to low light intensity than to high light intensity.

Novel positron emission tomography tracers for imaging of rheumatoid arthritis

Positron emission tomography (PET) is a nuclear imaging modality that relies on visualization of molecular targets in tissues, which is nowadays combined with a structural imaging modality such as computed tomography (CT) or Magnetic Resonance Imaging (MRI) and referred to as hybrid PET imaging. This technique allows to image specific immunological targets in rheumatoid arthritis (RA). Moreover, quantification of the PET signal enables highly sensitive monitoring of therapeutic effects on the molecular target. PET may also aid in stratification of the immuno-phenotype at baseline in order to develop personalized therapy. In this systematic review we will provide an overview of novel PET tracers, investigated in the context of RA, either pre-clinically, or clinically, that specifically visualize immune cells or stromal cells, as well as other factors and processes that contribute to pathology. The potential of these tracers in RA diagnosis, disease monitoring, and prediction of treatment outcome will be discussed. In addition, novel PET tracers established within the field of oncology that may be of use in RA will also be reviewed in order to expand the future opportunities of PET imaging in RA.

Critical role of synovial tissue-resident macrophage niche in joint homeostasis and suppression of chronic inflammation

Little is known about the mechanisms regulating the transition of circulating monocytes into pro- or anti-inflammatory macrophages in chronic inflammation. Here, we took advantage of our novel mouse model of rheumatoid arthritis, in which Flip is deleted under the control of a CD11c promoter (HUPO mice). During synovial tissue homeostasis, both monocyte-derived F4/80^int and self-renewing F4/80^hi tissue-resident, macrophage populations were identified. However, in HUPO mice, decreased synovial tissue-resident macrophages preceded chronic arthritis, opened a niche permitting the influx of activated monocytes, with impaired ability to differentiate into F4/80^hi tissue-resident macrophages. In contrast, Flip-replete monocytes entered the vacated niche and differentiated into tissue-resident macrophages, which suppressed arthritis. Genes important in macrophage tissue residency were reduced in HUPO F4/80^hi macrophages and in leukocyte-rich rheumatoid arthritis synovial tissue monocytes. Our observations demonstrate that the macrophage tissue-resident niche is necessary for suppression of chronic inflammation and may contribute to the pathogenesis of rheumatoid arthritis.

Differential expression patterns of glycosphingolipids and C-type lectin receptors on immune cells in absence of functional regulatory T cells

Background

Glycosylation is a common and complex type of protein posttranslational modification. Altered glycosylation of immunoglobulins in autoimmune diseases has led to the “altered glycan hypothesis” postulating existence of a unique glycan signature on immune cells and extracellular proteins characterized by site‐specific relative abundances of individual glycan structures and glycosylation patterns. However, it is not clear how glycosylation on leukocyte subpopulations differ between states of health or inflammation.

Hypothesis

Glycosphingolipid patterns on immune cells of forkhead‐box‐P3‐deficient scurfy mice differs from those on wild‐type immune cells.

Methods

T cells and dendritic cells were isolated from spleens of either wild‐type or age‐matched scurfy mice. Glycosphingolipids of CD4⁺ T cells and splenic dendritic cells from wild‐type and scurfy mice were then analyzed by multiplexed capillary gel electrophoresis coupled to laser‐induced fluorescence detection (xCGE‐LIF). In addition, flow cytometry and ChipCytometry were used to access expression patterns of various C‐type lectin receptors on antigen‐presenting cells from various organs of both wild‐type and scurfy mice.

Results

We, hereby report differential expression of glycosphingolipids in health and under inflammatory conditions as reflected in wild‐type and scurfy mice. Furthermore, we observed that the absence of functional regulatory T cells correlated with elevated expression of CLEC‐7A and CD205 but a reduction in levels of CLEC12A and CD206 on antigen‐presenting cells.

Conclusion

We hereby show that the absence of functional regulatory T cells affects expression pattern and quantities of glycosphingolipids on immune cells. Thus, glycosphingolipids could serve as biomarkers for mapping genetical and homeostatic perturbances such as those resulting from a diseased condition.

Mouse CD163 deficiency strongly enhances experimental collagen-induced arthritis

The scavenger receptor CD163 is highly expressed in macrophages in sites of chronic inflammation where it has a not yet defined role. Here we have investigated development of collagen-induced arthritis (CIA) and collagen antibody-induced arthritis (CAIA) in CD163-deficient C57BL/6 mice. Compared to wild-type mice, the CIA in CD163-deficient mice had a several-fold higher arthritis score with early onset, prolonged disease and strongly enhanced progression. Further, the serum anti-collagen antibody isotypes as well as the cytokine profiles and T cell markers in the inflamed joints revealed that CD163-deficient mice after 52 days had a predominant Th2 response in opposition to a predominant Th1 response in CD163+/+ mice. Less difference in disease severity between the CD163+/+ and CD163-/- mice was seen in the CAIA model that to a large extent induces arthritis independently of T-cell response and endogenous Th1/Th2 balance. In conclusion, the present set of data points on a novel strong anti-inflammatory role of CD163.

Transcriptome analysis reveals new insights into immune response to hypoxia challenge of large yellow croaker (Larimichthys crocea)

Fish live in direct contact with aquatic environment, which exhibits much wider temporal and spatial variations in oxygen content. The molecular mechanisms underlying fish response to hypoxia have become a subject of great concern in recent years. In the present study, we performed transcriptome analysis of spleen and head kidney tissues from large yellow croaker (Larimichthys crocea) at 6 h, 24 h and 48 h after hypoxia challenge. A total of 2,499 and 3,685 differentially expressed genes (DEGs) were obtained in spleen and head kidney, respectively. The expression changes of 10 selected genes in each tissue were further validated by quantitative real-time PCR. Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichments revealed that numerous DEGs were immune genes, involved in multiple immune-relevant pathways. In spleen, several pattern recognition receptors (PRRs), including Toll-like receptors (TLR1, TLR2-1, TLR2-2, TLR5 and TLR8), Fucolectins (FUCL1, FUCL4 and FUCL5) and macrophage mannose receptor (MRC1), were significantly down-regulated, suggesting that the immune processes mediated by these PRRs may be suppressed by hypoxia stress. However, some PRRs (FUCL4, FUCL5 and MRC1) and other innate immunity genes, such as C-type lectin domain gene family members, chemokines, chemokine receptors and complement components were up-regulated in head kidney, which may be due to the increases in phagocytosis and cytokine secretion by macrophages after hypoxic stimulus. The expression of genes involved in B cell receptor signaling pathway, Natural killer cell-mediated cytotoxicity and NF-κB signaling pathway decreased rapidly, but regained normal or increased over time, suggesting an early adjustment pattern of fish immune response to cope with hypoxia stress. Moreover, the anaerobic ATP-generating pathway was activated and energy consumption processes were repressed concurrently in both spleen and head kidney. These data provide valuable information for understanding the tissue-specific and temporal changes of immune gene expression in hypoxic large yellow croakers.

Shikimic acid, a mannose bioisostere, promotes hair growth with the induction of anagen hair cycle

Shikimic acid (SA) has recently been found to be a major component of plant stem cells. The exact effects of SA on human hair follicles (HFs) is unknown. The purpose of this study was to examine the effects of SA on hair growth. We investigated the effect of SA on an in vivo C57BL/6 mouse model. We examined the expression of mannose receptor (MR), which is a known receptor of SA, in human HFs and the effect of SA on human dermal papilla cells (hDPCs), outer root sheath cells (hORSCs), and on ex vivo human hair organ culture. SA significantly prolonged anagen hair growth in the in vivo mouse model. We confirmed expression of the MR in human HFs, and that SA increased the proliferation of hDPCs and hORSCs. It was found that SA enhanced hair shaft elongation in an ex vivo human hair organ culture. SA treatment of hDPCs led to increased c-myc, hepatocyte growth factor, keratinocyte growth factor and vascular endothelial growth factor levels and upregulation of p38 MAPK and cAMP response element-binding protein levels. Our results show that SA promotes hair growth and may serve as a new therapeutic agent in the treatment of alopecia.

Glucan and Mannan-Two Peas in a Pod

In recent decades, various polysaccharides isolated from algae, mushrooms, yeast, and higher plants have attracted serious attention in the area of nutrition and medicine. The reasons include their low toxicity, rare negative side effects, relatively low price, and broad spectrum of therapeutic actions. The two most and best-studied polysaccharides are mannan and glucan. This review focused on their biological properties.

TanshinoneIIA Alleviates Inflammatory Response and Directs Macrophage Polarization in Lipopolysaccharide-Stimulated RAW264.7 Cells

TanshinoneIIA (TanIIA) has been demonstrated to possess numerous biological effects. However, the specific effect of TanIIA on macrophage polarization has not been reported. In this study, it was revealed that TanIIA might play a pivotal role in macrophage polarization. As our results indicated, cell morphology was changed in RAW264.7 cells which were treated with LPS or LPS/TanIIA (0.1 μM, 1 μM, 10 μM). Subsequently, pro-inflammatory cytokine TNF-α and anti-inflammatory cytokine IL-10 were measured by ELISA kits. Furthermore, TanIIA enhanced the expression of M2 macrophage markers (Arg1 and FIZZ1) and decreased the expression of markers associated with M1 macrophage polarization (iNOS and IL-1β). Increased expression of CD206 was also detected by flow cytometry in TanIIA-treated groups. Mechanistically, it was revealed that TanIIA modulated macrophage polarization by ameliorating mitochondrial function and regulating TLR4-HMGB1/CEBP-β pathway. In addition, increased expression of miR-155 was observed in RAW264.7 cells incubated with LPS and were effectively inhibited by TanIIA. Taken together, it was suggested that TanIIA inhibits inflammatory response and promotes macrophage polarization toward an M2 phenotype, which provides new evidence for the anti-inflammation activity of TanIIA.

Myeloid C-type lectin receptors in skin/mucoepithelial diseases and tumors

Myeloid C‐type lectin receptors (CLRs), which consist of an extracellular carbohydrate recognition domain and intracellular signal transducing motif such as the immunoreceptor tyrosine‐based activation motif (ITAM) or immunoreceptor tyrosine‐based inhibitory motif (ITIM), are innate immune receptors primarily expressed on myeloid lineage cells such as dendritic cells (DCs) and Mϕs. CLRs play important roles in host defense against infection by fungi and bacteria by recognizing specific carbohydrate components of these pathogens. However, these immune receptors also make important contributions to immune homeostasis of mucosa and skin in mammals by recognizing components of microbiota, as well as by recognizing self‐components such as alarmins from dead cells and noncanonical non‐carbohydrate ligands. CLR deficiency not only induces hypersensitivity to infection, but also causes dysregulation of muco‐cutaneous immune homeostasis, resulting in the development of allergy, inflammation, autoimmunity, and tumors. In this review, we introduce recent discoveries regarding the roles of myeloid CLRs in the immune system exposed to the environment, and discuss the roles of these lectin receptors in the development of colitis, asthma, psoriasis, atopic dermatitis, and cancer. Although some CLRs are suggested to be involved in the development of these diseases, the function of CLRs and their ligands still largely remain to be elucidated.

Rapid spread of mannan to the immune system, skin and joints within 6 hours after local exposure

Psoriasis (Ps), psoriatic arthritis (PsA) and rheumatoid arthritis (RA) are common diseases dependent on environmental factors that activate the immune system in unknown ways. Mannan is a group of polysaccharides common in the environment; they are potentially pathogenic, because at least some of them induce Ps-, PsA- and RA-like inflammation in mice. Here, we used positron emission tomography/computed tomography to examine in-vivo transport and spread of mannan labelled with fluorine-18 [¹⁸ F]. The results showed that mannan was transported to joints (knee) and bone marrow (tibia) of mice within 6 h after intraperitoneal injection. The time it took to transport mannan, and its presence in blood, indicated cellular transport of mannan within the circulatory system. In addition, mannan was filtered mainly through the spleen and liver. [¹⁸ F]fluoromannan was excreted via kidneys, small intestine and, to some extent, the mouth. In conclusion, mannan reaches joints rapidly after injection, which may explain why mannan-induced inflammatory disease is targeted to these tissues.

An improved genome assembly for Larimichthys crocea reveals hepcidin gene expansion with diversified regulation and function

Larimichthys crocea (large yellow croaker) is a type of perciform fish well known for its peculiar physiological properties and economic value. Here, we constructed an improved version of the L. crocea genome assembly, which contained 26,100 protein-coding genes. Twenty-four pseudo-chromosomes of L. crocea were also reconstructed, comprising 90% of the genome assembly. This improved assembly revealed several expansions in gene families associated with olfactory detection, detoxification, and innate immunity. Specifically, six hepcidin genes (LcHamps) were identified in L. crocea, possibly resulting from lineage-specific gene duplication. All LcHamps possessed similar genomic structures and functional domains, but varied substantially with respect to expression pattern, transcriptional regulation, and biological function. LcHamp1 was associated specifically with iron metabolism, while LcHamp2s were functionally diverse, involving in antibacterial activity, antiviral activity, and regulation of intracellular iron metabolism. This functional diversity among gene copies may have allowed L. crocea to adapt to diverse environmental conditions.

Sulforaphane Inhibits Inflammatory Responses of Primary Human T-Cells by Increasing ROS and Depleting Glutathione

The activity and function of T-cells are influenced by the intra- and extracellular redox milieu. Oxidative stress induces hypo responsiveness of untransformed T-cells. Vice versa increased glutathione (GSH) levels or decreased levels of reactive oxygen species (ROS) prime T-cell metabolism for inflammation, e.g., in rheumatoid arthritis. Therefore, balancing the T-cell redox milieu may represent a promising new option for therapeutic immune modulation. Here we show that sulforaphane (SFN), a compound derived from plants of the Brassicaceae family, e.g., broccoli, induces a pro-oxidative state in untransformed human T-cells of healthy donors or RA patients. This manifested as an increase of intracellular ROS and a marked decrease of GSH. Consistently, increased global cysteine sulfenylation was detected. Importantly, a major target for SFN-mediated protein oxidation was STAT3, a transcription factor involved in the regulation of TH17-related genes. Accordingly, SFN significantly inhibited the activation of untransformed human T-cells derived from healthy donors or RA patients, and downregulated the expression of the transcription factor RORγt, and the TH17-related cytokines IL-17A, IL-17F, and IL-22, which play a major role within the pathophysiology of many chronic inflammatory/autoimmune diseases. The inhibitory effects of SFN could be abolished by exogenously supplied GSH and by the GSH replenishing antioxidant N-acetylcysteine (NAC). Together, our study provides mechanistic insights into the mode of action of the natural substance SFN. It specifically exerts TH17 prone immunosuppressive effects on untransformed human T-cells by decreasing GSH and accumulation of ROS. Thus, SFN may offer novel clinical options for the treatment of TH17 related chronic inflammatory/autoimmune diseases such as rheumatoid arthritis.

Proteome and microbiota analysis reveals alterations of liver-gut axis under different stocking density of Peking ducks

This study aimed to determine the impact of stocking density on the liver proteome and cecal microbiota of Peking ducks. A total of 1,200 21-day-old ducks were randomly assigned to 5 stocking density groups of 5, 6, 7, 8 and 9 ducks/m², with 6 replicates for each group. At 40 days of age, duck serum and pectorals were collected for biochemical tests; liver and cecal contents of ducks were gathered for proteome and microbiota analysis, respectively. Serum MDA increased while pectorals T-AOC reduced linearly with enhancing stocking density. Duck lipid metabolism was altered under different stocking density as well. Serum LDL-C increased linearly with increasing stocking density. Proteome analysis revealed fatty acid biosynthesis proteins such as acyl-CoA synthetase family member 2 and fatty acid oxidation related proteins including acyl-CoA dehydrogenase long chain and acyl-coenzyme A oxidase were enriched in high stocking density group. Additionally, high stocking density increased oxidative response associated proteins such as DDRGK domain containing 1. Furthermore, increasing stocking density diminished proteins of anti-oxidant capacity including regucalcin and catalase. 16S rDNA analysis revealed that higher stocking density was accompanied with decreased microbial diversity, as well as depletion of anti-inflammatory bacterial taxa, including Bacteroidales, Butyricimonas and Alistipe. Besides, reduced bile acid metabolism-associated bacteria such as Ruminococcaceae, Clostridiales and Desulfovibrionaceae were found in the high-density group. Both proteome and 16S rDNA results showed inflammation and chronic liver disease trend in the high-density group, which suggests the involvement of the liver-gut axis in oxidative stress.

Chronic Active Arthritis Driven by Macrophages Without Involvement of T Cells: A Novel Experimental Model of Rheumatoid Arthritis

OBJECTIVE

To develop a new chronic rheumatoid arthritis model that is driven by the innate immune system.

METHODS

Injection of a cocktail of 4 monoclonal antibodies against type II collagen, followed on days 5 and 60 by intraperitoneal injections of mannan (from Saccharomyces cerevisiae), was used to induce development of chronic arthritis in B10.Q mice. The role of the innate immune system as compared to the adaptive immune system in this arthritis model was investigated using genetically modified mouse strains.

RESULTS

A new model of chronic relapsing arthritis was characterized in B10.Q mice, in which a persistently active, chronic disease was found. This relapsing disease was driven by macrophages lacking the ability to mount a reactive oxygen species response against pathogens, and was associated with the classical/alternative pathway, but not the lectin pathway, of complement activation. The disease was independent of Fcγ receptor type III, and also independent of the activity of adaptive immune cells (B and T cells), indicating that the innate immune system, involving complement activation, could be the sole driver of chronicity.

CONCLUSION

Chronic active arthritis can be driven innately by macrophages without the involvement of T and B cells in the adaptive immune system.

Mannan-induced Nos2 in macrophages enhances IL-17-driven psoriatic arthritis by innate lymphocytes

Previous identification of the inducible nitric oxide synthase (NOS2) gene as a risk allele for psoriasis (Ps) and psoriatic arthritis (PsA) suggests a possible pathogenic role of nitric oxide (NO). Using a mouse model of mannan-induced Ps and PsA (MIP), where macrophages play a regulatory role by releasing reactive oxygen species (ROS), we found that NO was detectable before disease onset in mice, independent of a functional nicotinamide adenine dinucleotide phosphate oxidase 2 complex. MIP was suppressed by either deletion of Nos2 or inhibition of NO synthases with NG-nitro-l-arginine methyl ester, demonstrating that Nos2-derived NO is pathogenic. NOS2 expression was also up-regulated in lipopolysaccharide- and interferon-γ-stimulated monocyte subsets from patients with PsA compared to healthy controls. Nos2-dependent interleukin-1α (IL-1α) release from skin macrophages was essential for arthritis development by promoting IL-17 production of innate lymphoid cells. We conclude that Nos2-derived NO by tissue macrophages promotes MIP, in contrast to the protective effect by ROS.

Systemic Inflammation and Cardiovascular Comorbidity in Psoriasis Patients: Causes and Consequences

Psoriasis is a common inflammatory skin disease characterized by the appearance of red scaly plaques that can affect any part of the body. High prevalence, chronicity, disfiguration, disability, and associated comorbidity make it a challenge for clinicians of multiple specialties. Likewise, its complex pathogenesis, comprising inflammation, hyperproliferation, and angioneogenesis, intrigues numerous scientific disciplines, namely, immunology. From a clinical perspective, the severity of psoriasis is highlighted by its increased mortality, with cardiovascular diseases contributing the highest excess risk. From a scientific point of view, psoriasis has to be considered a systemic inflammatory condition, as blood biomarkers of inflammation are elevated and imaging techniques document sites of inflammation beyond the skin. While the association of psoriasis with cardiovascular diseases is now widely accepted, causes and consequences of this association are controversially discussed. This review comments on epidemiologic, genetic, and mechanistic studies that analyzed the relation between psoriasis and cardiovascular comorbidity. The hypothesis of psoriasis potentially being an independent cardiovascular risk factor, driving atherosclerosis via inflammation-induced endothelial dysfunction, will be discussed. Finally, consequences for the management of psoriasis with the objective to reduce the patients’ excess cardiovascular risk will be pointed out.