Identification of monocyte-associated pathways participated in the pathogenesis of pulmonary arterial hypertension based on omics-data

Pulmonary arterial hypertension (PAH) is one kind of chronic and uncurable diseases that can cause heart failure. Immune microenvironment plays a significant role in PAH. The aim of this study was to assess the role of immune cell infiltration in the pathogenesis of PAH. Differentially expressed genes based on microarray data were enriched in several immune-related pathways. To evaluate the immune cell infiltration, based on the microarray data sets in the GEO database, we used both ssGSEA and the CIBERSORT algorithm. Additionally, single-cell RNA sequencing (scRNA-seq) data was used to further explicit the specific role and intercellular communications. Then receiver operating characteristic curves and least absolute shrinkage and selection operator were used to discover and test the potential diagnostic biomarkers for PAH. Both the immune cell infiltration analyses based on the microarray data sets and the cell proportion in scRNA-seq data exhibited a significant downregulation in the infiltration of monocytes in PAH. Then, the intercellular communications showed that the interaction weighs of most immune cells, including monocytes changed between the control and PAH groups, and the ITGAL-ITGB2 and ICAM signaling pathways played critical roles in this process. In addition, ITGAM and ICAM2 displayed good diagnosis values in PAH. This study implicated that the change of monocyte was one of the key immunologic features of PAH. Monocyte-associated ICAM-1 and ITGAL-ITGB2 signaling pathways might be involved in the pathogenesis of PAH.

CAR-T Cells in the Treatment of Ovarian Cancer: A Promising Cell Therapy

Ovarian cancer (OC) is among the most common gynecologic malignancies with a poor prognosis and a high mortality rate. Most patients are diagnosed at an advanced stage (stage III or IV), with 5-year survival rates ranging from 25% to 47% worldwide. Surgical resection and first-line chemotherapy are the main treatment modalities for OC. However, patients usually relapse within a few years of initial treatment due to resistance to chemotherapy. Cell-based therapies, particularly adoptive T-cell therapy and chimeric antigen receptor T (CAR-T) cell therapy, represent an alternative immunotherapy approach with great potential for hematologic malignancies. However, the use of CAR-T-cell therapy for the treatment of OC is still associated with several difficulties. In this review, we comprehensively discuss recent innovations in CAR-T-cell engineering to improve clinical efficacy, as well as strategies to overcome the limitations of CAR-T-cell therapy in OC.

EMILIN-1 deficiency promotes chronic inflammatory disease through TGFβ signaling alteration and impairment of the gC1q/α4β1 integrin interaction

Alterations in extracellular matrix (ECM) components that modulate inflammatory cell behavior have been shown to serve as early starters for multifactorial diseases such as fibrosis and cancer. Here, we demonstrated that loss of the ECM glycoprotein EMILIN-1 alters the inflammatory context in skin during IMQ-induced psoriasis, a disease characterized by a prominent inflammatory infiltrate and alteration of vessels that appear dilated and tortuous. Abrogation of EMILIN-1 expression or expression of the EMILIN-1 mutant E933A impairs macrophage polarization and leads to imbalanced tissue homeostasis. We found that EMILIN-1 deficiency is associated with dilated lymphatic vessels, increased macrophage recruitment and psoriasis severity. Importantly, the null or mutant EMILIN-1 background was characterized by the induction of a myofibroblast phenotype, which in turn drove macrophages towards the M1 phenotype. By using the transgenic mouse model carrying the E933A mutation in the gC1q domain of EMILIN-1, which abolishes the interaction with α4- and α9-integrins, we demonstrated that the observed changes in TGFβ signaling were due to both the EMI and gC1q domains of EMILIN-1. gC1q may exert multiple functions in psoriasis, in the context of a final, more consistent inflammatory condition by controlling skin homeostasis via interaction with both keratinocytes and fibroblasts, influencing non-canonical TGFβ signaling, and likely acting on lymphatic vessel structure and function. The analyses of human psoriatic lesions, in which lower levels of EMILIN-1 were present with a very rare association with lymphatic vessels, support the multifaceted role of this ECM component in the skin inflammatory scenario.

Fibroblast pathology in inflammatory joint disease

Rheumatoid arthritis is an immune-mediated inflammatory disease in which fibroblasts contribute to both joint damage and inflammation. Fibroblasts are a major cell constituent of the lining of the joint cavity called the synovial membrane. Under resting conditions, fibroblasts have an important role in maintaining joint homeostasis, producing extracellular matrix and joint lubricants. In contrast, during joint inflammation, fibroblasts contribute to disease pathology by producing pathogenic levels of inflammatory mediators that drive the recruitment and retention of inflammatory cells within the joint. Recent advances in single-cell profiling techniques have transformed our ability to examine fibroblast biology, leading to the identification of specific fibroblast subsets, defining a previously underappreciated heterogeneity of disease-associated fibroblast populations. These studies are challenging the previously held dogma that fibroblasts are homogeneous and are providing unique insights into their role in inflammatory joint pathology. In this review, we discuss the recent advances in our understanding of how fibroblast heterogeneity contributes to joint pathology in rheumatoid arthritis. Finally, we address how these insights could lead to the development of novel therapies that directly target selective populations of fibroblasts in the future.

Insights Into Leukocyte Trafficking in Inflammatory Arthritis - Imaging the Joint

The inappropriate accumulation and activation of leukocytes is a shared pathological feature of immune-mediated inflammatory diseases (IMIDs), such as rheumatoid arthritis (RA) and psoriatic arthritis (PsA). Cellular accumulation is therefore an attractive target for therapeutic intervention. However, attempts to modulate leukocyte entry and exit from the joint have proven unsuccessful to date, indicating that gaps in our knowledge remain. Technological advancements are now allowing real-time tracking of leukocyte movement through arthritic joints or in vitro joint constructs. Coupling this technology with improvements in analyzing the cellular composition, location and interactions of leukocytes with neighboring cells has increased our understanding of the temporal dynamics and molecular mechanisms underpinning pathological accumulation of leukocytes in arthritic joints. In this review, we explore our current understanding of the mechanisms leading to inappropriate leukocyte trafficking in inflammatory arthritis, and how these evolve with disease progression. Moreover, we highlight the advances in imaging of human and murine joints, along with multi-cellular ex vivo joint constructs that have led to our current knowledge base.

Persistent inflammatory and non-inflammatory mechanisms in refractory rheumatoid arthritis

Despite nearly three decades of advances in the management of rheumatoid arthritis (RA), a substantial minority of patients are exposed to multiple DMARDs without necessarily benefitting from them; a group of patients variously designated as having 'difficult to treat', 'treatment-resistant' or 'refractory' RA. This Review of refractory RA focuses on two types of patients: those for whom multiple targeted therapies lack efficacy and who have persistent inflammatory pathology, which we designate as persistent inflammatory refractory RA (PIRRA); and those with supposed refractory RA who have continued disease activity that is predominantly independent of objective evidence of inflammation, which we designate as non-inflammatory refractory RA (NIRRA). These two types of disease are not mutually exclusive, but identifying those individuals with predominant PIRRA or NIRRA is important, as it informs distinct treatment and management approaches. This Review outlines the clinical differences between PIRRA and NIRRA, the genetic and epigenetic mechanisms and immune pathways that might contribute to the immunopathogenesis of recalcitrant synovitis in PIRRA, and a possible basis for non-inflammatory symptomatology in NIRRA. Future approaches towards the definition of refractory RA and the application of single-cell and integrated omics technologies to the identification of refractory RA endotypes are also discussed.

Multispectral imaging detects gastritis consistently in mouse model and in humans

Gastritis constitutes the initial step of the gastric carcinogenesis process. Gastritis diagnosis is based on histological examination of biopsies. Non-invasive real-time methods to detect mucosal inflammation are needed. Tissue optical properties modify reemitted light, i.e. the proportion of light that is emitted by a tissue after stimulation by a light flux. Analysis of light reemitted by gastric tissue could predict the inflammatory state. The aim of our study was to investigate a potential association between reemitted light and gastric tissue inflammation. We used two models and three multispectral analysis methods available on the marketplace. We used a mouse model of Helicobacter pylori infection and included patients undergoing gastric endoscopy. In mice, the reemitted light was measured using a spectrometer and a multispectral camera. We also exposed patient’s gastric mucosa to specific wavelengths and analyzed reemitted light. In both mouse model and humans, modifications of reemitted light were observed around 560 nm, 600 nm and 640 nm, associated with the presence of gastritis lesions. These results pave the way for the development of improved endoscopes in order to detect real-time gastritis without the need of biopsies. This would allow a better prevention of gastric cancer alongside with cost efficient endoscopies.

Role of Adiponectin in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic chronic inflammatory autoimmune joint disease, characterized by progressive articular damage and joint dysfunction. One of the symptoms of this disease is persistent inflammatory infiltration of the synovial membrane, the principle site of inflammation in RA. In the affected conditions, the cells of the synovial membrane, fibroblast-like synoviocytes and macrophage-like synovial cells, produce enzymes degrading cartilage and underlining bone tissue, as well as cytokines increasing the infiltration of immune cells. In patients with RA, higher levels of adiponectin are measured in the serum and synovial fluid. Adiponectin, a secretory product that is mainly white adipose tissue, is a multifunctional protein with dual anti-inflammatory and pro-inflammatory properties. Several studies underline the fact that adiponectin can play an important pro-inflammatory role in the pathophysiology of RA via stimulating the secretion of inflammatory mediators. This narrative review is devoted to the presentation of recent knowledge on the role played by one of the adipokines produced by adipose tissue—adiponectin—in the pathogenesis of rheumatoid arthritis.

IL6/sIL6R regulates TNFα-inflammatory response in synovial fibroblasts through modulation of transcriptional and post-transcriptional mechanisms

Introduction

The clinical efficacy of specific interleukin-6 inhibitors has confirmed the central role of IL6 in rheumatoid arthritis (RA). However the local role of IL6, in particular in synovial fibroblasts (SF) as a direct cellular target to IL6/sIL6R signal is not well characterized. The purpose of the study was to characterize the crosstalk between TNFα and IL6/sIL6R signaling to the effector pro-inflammatory response of SF.

Methods

SF lines were stimulated with either TNFα, IL6/sIL6R, or both together, for the time and dose indicated for each experiment, and where indicated, cells were treated with inhibitors actinomycin D, adalimumab, ruxolitinib and cycloheximide. mRNA expression of cytokines, chemokines and matrix metalloproteases (MMPs) were analyzed by quantitative RT-PCR. Level of IL8/CXCL8 and CCL8 in culture supernatants was measured by ELISA. Mononuclear and polymorphonuclear cells migration assays were assessed by transwell using conditioned medium from SF cultures. Statistical analyses were performed as indicated in the corresponding figure legends and a p-value < 0.05 was considered statistically significant.

Results

The stimulation of SF with IL6/sIL6R and TNFα, cooperatively promotes the expression of mono- and lymphocytic chemokines such as IL6, CCL8 and CCL2, as well as matrix degrading enzymes such as MMP1, while inhibiting the induction of central neutrophil chemokines such as IL8/CXCL8. These changes in the pattern of chemokines expression resulted in reduced polymorphonuclear (PMN) and increased mononuclear cells (MNC) chemoattraction by SF. Mechanistic analyses of the temporal expression of genes demonstrated that the cooperative regulation mediated by these two factors is mostly induced through de novo transcriptional mechanisms activated by IL6/sIL6R. Furthermore, we also demonstrate that TNFα and IL6/sIL6R cooperation is partially mediated by the expression of secondary factors signaling through JAK/STAT pathways.

Conclusions

These results point out to a highly orchestrated response to IL6 in TNFα-induced SF and provide additional insights into the role of IL6/sIL6R in the context of RA, highlighting the contribution of IL6/sIL6R to the interplay of SF with other inflammatory cells.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12860-020-00317-7.

Innovative CAR-T Cell Therapy for Solid Tumor; Current Duel between CAR-T Spear and Tumor Shield

Novel engineered T cells containing chimeric antigen receptors (CAR-T cells) that combine the benefits of antigen recognition and T cell response have been developed, and their effect in the anti-tumor immunotherapy of patients with relapsed/refractory leukemia has been dramatic. Thus, CAR-T cell immunotherapy is rapidly emerging as a new therapy. However, it has limitations that prevent consistency in therapeutic effects in solid tumors, which accounts for over 90% of all cancer patients. Here, we review the literature regarding various obstacles to CAR-T cell immunotherapy for solid tumors, including those that cause CAR-T cell dysfunction in the immunosuppressive tumor microenvironment, such as reactive oxygen species, pH, O₂, immunosuppressive cells, cytokines, and metabolites, as well as those that impair cell trafficking into the tumor microenvironment. Next-generation CAR-T cell therapy is currently undergoing clinical trials to overcome these challenges. Therefore, novel approaches to address the challenges faced by CAR-T cell immunotherapy in solid tumors are also discussed here.

Human Cardiac Mesenchymal Stromal Cells From Right and Left Ventricles Display Differences in Number, Function, and Transcriptomic Profile

BACKGROUND

Left ventricle (LV) and right ventricle (RV) are characterized by well-known physiological differences, mainly related to their different embryological origin, hemodynamic environment, function, structure, and cellular composition. Nevertheless, scarce information is available about cellular peculiarities between left and right ventricular chambers in physiological and pathological contexts. Cardiac mesenchymal stromal cells (C-MSC) are key cells affecting many functions of the heart. Differential features that distinguish LV from RV C-MSC are still underappreciated.

AIM

To analyze the physiological differential amount, function, and transcriptome of human C-MSC in LV versus (vs.) RV.

METHODS

Human cardiac specimens of LV and RV from healthy donors were used for tissue analysis of C-MSC number, and for C-MSC isolation. Paired LV and RV C-MSC were compared as for surface marker expression, cell proliferation/death ratio, migration, differentiation capabilities, and transcriptome profile.

RESULTS

Histological analysis showed a greater percentage of C-MSC in RV vs. LV tissue. Moreover, a higher C-MSC amount was obtained from RV than from LV after isolation procedures. LV and RV C-MSC are characterized by a similar proportion of surface markers. Functional studies revealed comparable cell growth curves in cells from both ventricles. Conversely, LV C-MSC displayed a higher apoptosis rate and RV C-MSC were characterized by a higher migration speed and collagen deposition. Consistently, transcriptome analysis showed that genes related to apoptosis regulation or extracellular matrix organization and integrins were over-expressed in LV and RV, respectively. Besides, we revealed additional pathways specifically associated with LV or RV C-MSC, including energy metabolism, inflammatory response, cardiac conduction, and pluripotency.

CONCLUSION

Taken together, these results contribute to the functional characterization of RV and LV C-MSC in physiological conditions. This information suggests a possible differential role of the stromal compartment in chamber-specific pathologic scenarios.

The incorporation of cationic property and immunopotentiator in poly (lactic acid) microparticles promoted the immune response against chronic hepatitis B

Biodegradable microparticles (MPs) as vaccine adjuvants have sparked the passion of researchers in recent decades. However, it is still a huge challenge to develop an efficient vaccine delivery system to reverse chronic hepatitis B (CHB). Herein, we integrated a physiochemical merit and an immunopotentiator property in poly (lactic acid) (PLA) MPs and verified the therapeutic effect on CHB model mice. We prepared uniform MPs with insertion of cationic lipid didodecyldimethylammonium bromide (DDAB), which endowed a physiochemical merit for MPs. Such a DDAB-PLA (DP) group raised the recruitment of immune cells to the injection site along with the secretion of chemokines and pro-inflammatory cytokines, promoting the activation of antigen-presenting cells (APCs). Further combination of stimulator of interferon genes (STING) agonist 5,6-dimethylxanthenone-4-acetic acid (DMXAA) (DP-D) elevated 5.8-fold higher interferon regulatory factor 7 (IRF-7) expression compared to that for DP group. The DP group showed preferred lysosome escape advantage, which was in line with the DMXAA release behavior and the intracellular target of DMXAA. In addition, DP-D vaccine augmented the IFN-γ secreting splenocytes and motivated Th1-biased antibodies in a more efficient way than that for the DP group. In the CHB model, the MPs based vaccines achieved 50% HBsAg seroconversion rate, and HBcAg in the liver also got a reduction. DP-D produced higher amount of memory T/B cells to confer protection in a sustained manner. Present work thus provided a promising strategy, via integrating a fine-tuned physiochemical property and an immunopotentiator virtue in the MPs, which synergistically reinforced both humoral and cellular immune responses against CHB.

A Clinical Approach for the Use of VIP Axis in Inflammatory and Autoimmune Diseases

The neuroendocrine and immune systems are coordinated to maintain the homeostasis of the organism, generating bidirectional communication through shared mediators and receptors. Vasoactive intestinal peptide (VIP) is the paradigm of an endogenous neuropeptide produced by neurons and endocrine and immune cells, involved in the control of both innate and adaptive immune responses. Exogenous administration of VIP exerts therapeutic effects in models of autoimmune/inflammatory diseases mediated by G-protein-coupled receptors (VPAC1 and VPAC2). Currently, there are no curative therapies for inflammatory and autoimmune diseases, and patients present complex diagnostic, therapeutic, and prognostic problems in daily clinical practice due to their heterogeneous nature. This review focuses on the biology of VIP and VIP receptor signaling, as well as its protective effects as an immunomodulatory factor. Recent progress in improving the stability, selectivity, and effectiveness of VIP/receptors analogues and new routes of administration are highlighted, as well as important advances in their use as biomarkers, contributing to their potential application in precision medicine. On the 50th anniversary of VIP's discovery, this review presents a spectrum of potential clinical benefits applied to inflammatory and autoimmune diseases.

Characterization of inflammatory cytokine profiles in cerebrospinal fluid of hand, foot, and mouth disease children with enterovirus 71-related encephalitis in Hangzhou, Zhejiang, China

Enterovirus 71 (EV71) is an important etiological agent of hand, foot, and mouth disease (HFMD), which can also lead to severe neurological complications (eg, encephalitis) in young children. Although a series of reports on EV71 infection have been published, the pathogenic mechanism of EV71 infection is still not fully understood.We evaluated the cerebrospinal fluid (CSF) levels of the inflammatory cytokines interleukin (IL)-8, IL-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α, and IL-12p70 in 88 children with EV71-related encephalitis and 19 children with febrile convulsion (FC) with the use of commercial cytometric bead array kits.The levels of IL-8, IL-1β, IL-6, and IL-10 in CSF were significantly higher in encephalitis group when compared with those observed in FC group, while no significant changes were noted in the levels of TNF-α and IL-12p70. In addition, significant and positive correlations among CSF IL-8, IL-1β, IL-6, and IL-10 were observed in encephalitis group. Furthermore, receiver operator characteristic analysis determined a cut-off value of 10.62 pg/mL for IL-6 to discriminate encephalitis patients from FCs with the sensitivity and specificity of 89.8% and 84.2%, respectively. Moreover, logistic regression analyses revealed that IL-6 was an independent predictor of EV71-related encephalitis (odds ratio = 23.241, P < .001).Our results indicate that 4 inflammatory cytokines (IL-8, IL-1β, IL-6, and IL-10) play important roles in the pathogenesis of EV71 infection. IL-6 may be used for the evaluation of EV71-related encephalitis and as a potential therapy candidate for EV71 infection.

Osteoinductive Material to Fine-Tune Paracrine Crosstalk of Mesenchymal Stem Cells With Endothelial Cells and Osteoblasts

While stem cell/biomaterial studies provide solid evidences that biomaterial intrinsic cues deeply affect cell fate, current strategies tend to neglect their effects on mesenchymal stem cells (MSCs) secretory activities and resulting cell-crosstalks. The present study aims to investigate the impact of bone-mimetic material (B-MM), with intrinsic osteoinductive property, on MSCs mediator secretions; and to explore underlying effects on cells involved in bone regeneration. Human MSCs were cultured, on B-MM, made from inorganic calcium phosphate supplemented with chitosan and hyaluronic acid biopolymers. Collected MSCs culture media were assessed for mediators release quantification and used further to stimulate endothelial cells (ECs) and alveolar bone derived osteoblasts (OBs). Without osteogenic supplements, MSCs committed into bone lineage forming thus 3D bone-like nodules after 21 days. Despite a weak percentage of cell commitment, our data elucidate new aspects of osteoinductive material effect on MSCs functions through the regulation of the secretion of mediators involved in bone regeneration and subsequently the MSCs/ECs indirect crosstalk with osteogenesis-boosting effect. Using MSCs culture media, we demonstrate a large potential of osteoinductive materials and MSCs in bone regenerative medicine. Such strategies could help to address some insights in cell-free therapies using MSCs derived media.

CaMKII Activity in the Inflammatory Response of Cardiac Diseases

Inflammation is a physiological process by which the body responds to external insults and stress conditions, and it is characterized by the production of pro-inflammatory mediators such as cytokines. The acute inflammatory response is solved by removing the threat. Conversely, a chronic inflammatory state is established due to a prolonged inflammatory response and may lead to tissue damage. Based on the evidence of a reciprocal regulation between inflammation process and calcium unbalance, here we described the involvement of a calcium sensor in cardiac diseases with inflammatory drift. Indeed, the Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) is activated in several diseases with an inflammatory component, such as myocardial infarction, ischemia/reperfusion injury, pressure overload/hypertrophy, and arrhythmic syndromes, in which it actively regulates pro-inflammatory signaling, among which includes nuclear factor kappa-B (NF-κB), thus contributing to pathological cardiac remodeling. Thus, CaMKII may represent a key target to modulate the severity of the inflammatory-driven degeneration.

Imaging the Dynamic Interaction Between Sprouting Microvessels and the Extracellular Matrix

Thorough understanding of growth and evolution of tissue vasculature is fundamental to many fields of medicine including cancer therapy, wound healing, and tissue engineering. Angiogenesis, the growth of new vessels from existing ones, is dynamically influenced by a variety of environmental factors, including mechanical and biophysical factors, chemotactic factors, proteolysis, and interaction with stromal cells. Yet, dynamic interactions between neovessels and their environment are difficult to study with traditional fixed time imaging techniques. Advancements in imaging technologies permit time-series and volumetric imaging, affording the ability to visualize microvessel growth over 3D space and time. Time-lapse imaging has led to more informative investigations of angiogenesis. The environmental factors implicated in angiogenesis span a wide range of signals. Neovessels advance through stromal matrices by forming attachments and pulling and pushing on their microenvironment, reorganizing matrix fibers, and inducing large deformations of the surrounding stroma. Concurrently, neovessels secrete proteolytic enzymes to degrade their basement membrane, create space for new vessels to grow, and release matrix-bound cytokines. Growing neovessels also respond to a host of soluble and matrix-bound growth factors, and display preferential growth along a cytokine gradient. Lastly, stromal cells such as macrophages and mesenchymal stem cells (MSCs) interact directly with neovessels and their surrounding matrix to facilitate sprouting, vessel fusion, and tissue remodeling. This review highlights how time-lapse imaging techniques advanced our understanding of the interaction of blood vessels with their environment during sprouting angiogenesis. The technology provides means to characterize the evolution of microvessel behavior, providing new insights and holding great promise for further research on the process of angiogenesis.

The Adipokine Network in Rheumatic Joint Diseases

Rheumatic diseases encompass a diverse group of chronic disorders that commonly affect musculoskeletal structures. Osteoarthritis (OA) and rheumatoid arthritis (RA) are the two most common, leading to considerable functional limitations and irreversible disability when patients are unsuccessfully treated. Although the specific causes of many rheumatic conditions remain unknown, it is generally accepted that immune mechanisms and/or uncontrolled inflammatory responses are involved in their etiology and symptomatology. In this regard, the bidirectional communication between neuroendocrine and immune system has been demonstrated to provide a homeostatic network that is involved in several pathological conditions. Adipokines represent a wide variety of bioactive, immune and inflammatory mediators mainly released by adipocytes that act as signal molecules in the neuroendocrine-immune interactions. Adipokines can also be synthesized by synoviocytes, osteoclasts, osteoblasts, chondrocytes and inflammatory cells in the joint microenvironment, showing potent modulatory properties on different effector cells in OA and RA pathogenesis. Effects of adiponectin, leptin, resistin and visfatin on local and systemic inflammation are broadly described. However, more recently, other adipokines, such as progranulin, chemerin, lipocalin-2, vaspin, omentin-1 and nesfatin, have been recognized to display immunomodulatory actions in rheumatic diseases. This review highlights the latest relevant findings on the role of the adipokine network in the pathophysiology of OA and RA.

Distinct fibroblast subsets drive inflammation and damage in arthritis

The identification of lymphocyte subsets with non-overlapping effector functions has been pivotal to the development of targeted therapies in immune-mediated inflammatory diseases (IMIDs)1,2. However, it remains unclear whether fibroblast subclasses with non-overlapping functions also exist and are responsible for the wide variety of tissue-driven processes observed in IMIDs, such as inflammation and damage3-5. Here we identify and describe the biology of distinct subsets of fibroblasts responsible for mediating either inflammation or tissue damage in arthritis. We show that deletion of fibroblast activation protein-α (FAPα)+ fibroblasts suppressed both inflammation and bone erosions in mouse models of resolving and persistent arthritis. Single-cell transcriptional analysis identified two distinct fibroblast subsets within the FAPα+ population: FAPα+THY1+ immune effector fibroblasts located in the synovial sub-lining, and FAPα+THY1- destructive fibroblasts restricted to the synovial lining layer. When adoptively transferred into the joint, FAPα+THY1- fibroblasts selectively mediate bone and cartilage damage with little effect on inflammation, whereas transfer of FAPα+ THY1+ fibroblasts resulted in a more severe and persistent inflammatory arthritis, with minimal effect on bone and cartilage. Our findings describing anatomically discrete, functionally distinct fibroblast subsets with non-overlapping functions have important implications for cell-based therapies aimed at modulating inflammation and tissue damage.

Assessment of tumor-associated immune cells in laryngeal squamous cell carcinoma

PURPOSE

This study investigated the characteristics of tumor-associated immune cells (TAICs) in laryngeal squamous cell carcinoma (LSCC) and their correlation with clinicopathological variables.

METHODS

The immune cell infiltrates of 71 specimens of stages I-IV LSCC were examined. The density of TAICs expressing CD3, CD4, CD8, CD68, and CD163 was assessed using immunohistochemical staining and image analysis in peritumoral and intratumoral regions.

RESULTS

Higher densities of CD3+ and CD8+ cell and lower densities of CD68+ and CD163+ cell infiltrations were found in early tumor stages than in late tumor stages. A higher percentage of patients with strong CD3+ and CD8+ immune cell infiltration and weak CD68+ cell infiltration in both tumor regions presented with T1 stage tumors compared with T4 stage tumors. Further, strong CD68+ cells infiltration in both regions was observed in a greater number of patients who had a relapse, while a weak CD3+ cells infiltration in both regions was found in a greater number of patients with nodal lymphatic metastasis. The univariate analysis showed that a high density of peritumoral CD3+ and CD8+ immune cells in both regions was significantly associated with a favorable overall survival (OS) (P = 0.004; P = 0.006; P = 0.042). In contrast, a high density of intratumoral CD68+ cells and peritumoral CD163+ cells was significantly associated with poor OS durations (P = 0.026; P = 0.030). The multivariate analysis demonstrated that a high density of peritumoral CD163+ cells correlated with poor OS after adjusting for tumor stage, recurrence, and nodal lymphatic metastasis (P = 0.034). This study found different patterns of TAIC infiltration in LSCC. The density and location of TAICs infiltration correlated with the clinicopathological characteristics of LSCC.

CONCLUSION

A combined analysis of the density of TAICs and their location may help predict patient survival and response to checkpoint inhibitors.

Defective Induction of COX-2 Expression by Psoriatic Fibroblasts Promotes Pro-inflammatory Activation of Macrophages

Fibroblasts play an important role as members of the innate immune system through the secretion of COX-2-derived inflammatory mediators such as prostaglandin E₂ (PGE₂). However, it has been described that dermal fibroblasts behave like mesenchymal stem cells reducing lymphocyte recruitment and dendritic cell activation through PGE₂ release. As the role of fibroblasts in psoriasis remains poorly characterized, in the present study we have evaluated the possible influence of PGE₂ derived from dermal fibroblasts as modulator of the immune response in psoriatic skin. Our results indicate that under inflammatory conditions, psoriatic fibroblasts showed defective induction of COX-2, which resulted in diminished production of PGE₂, in contrast to healthy fibroblasts. This phenotype correlated with deficient c-Jun N-terminal kinase (JNK) activation, in accordance with the hypothesis that alterations in members of the JNK pathway are associated with psoriasis. Furthermore, conditioned medium from psoriatic fibroblasts promoted the polarization of monocytic cells toward a pro-inflammatory profile, effect that was mimicked in healthy fibroblasts after pre-incubation with indomethacin. These results are consistent with a prominent role of dermal fibroblasts in the regulation of inflammatory response through the participation of COX-derived metabolites. This resolutive behavior seems to be defective in psoriatic fibroblasts, offering a possible explanation for the chronification of the disease and for the exacerbation triggered by nonsteroidal anti-inflammatory drugs (NSAIDS) such as indomethacin.

Triggering the Resolution of Immune Mediated Inflammatory Diseases: Can Targeting Leukocyte Migration Be the Answer?

Leukocyte recruitment is a pivotal process in the regulation and resolution of an inflammatory episode. It is vital for the protective responses to microbial infection and tissue damage, but is the unwanted reaction contributing to pathology in many immune mediated inflammatory diseases (IMIDs). Indeed, it is now recognized that patients with IMIDs have defects in at least one, if not multiple, check-points regulating the entry and exit of leukocytes from the inflamed site. In this review, we will explore our understanding of the imbalance in recruitment that permits the accumulation and persistence of leukocytes in IMIDs. We will highlight old and novel pharmacological tools targeting these processes in an attempt to trigger resolution of the inflammatory response. In this context, we will focus on cytokines, chemokines, known pro-resolving lipid mediators and potential novel lipids (e.g., sphingosine-1-phosphate), along with the actions of glucocorticoids mediated by 11-beta hydroxysteroid dehydrogenase 1 and 2.

An Overview of VPAC Receptors in Rheumatoid Arthritis: Biological Role and Clinical Significance

The axis comprised by the Vasoactive Intestinal Peptide (VIP) and its G protein-coupled receptors (GPCRs), VPAC1, and VPAC2, belong to the B1 family and signal through Gs or Gq proteins. VPAC receptors seem to preferentially interact with Gs in inflammatory cells, rather than Gq, thereby stimulating adenylate cyclase activity. cAMP is able to trigger various downstream pathways, mainly the canonical PKA pathway and the non-canonical cAMP-activated guanine nucleotide exchange factor (EPAC) pathway. Classically, the presence of VPACs has been confined to the plasma membrane; however, VPAC1 location has been described in the nuclear membrane in several cell types such as activated Th cells, where they are also functional. VPAC receptor signaling modulates a number of biological processes by tipping the balance of inflammatory mediators in macrophages and other innate immune cells, modifying the expression of TLRs, and inhibiting MMPs and the expression of adhesion molecules. Receptor signaling also downregulates coagulation factors and acute-phase proteins, promotes Th2 over Th1, stimulates Treg abundance, and finally inhibits a pathogenic Th17 profile. Thus, the VIP axis signaling regulates both the innate and adaptive immune responses in several inflammatory/autoimmune diseases. Rheumatoid arthritis (RA) is a complex autoimmune disease that develops on a substrate of genetically susceptible individuals and under the influence of environmental factors, as well as epigenetic mechanisms. It is a heterogeneous disease with different pathogenic mechanisms and variable clinical forms between patients with the same diagnosis. The knowledge of VIP signaling generated in both animal models and human ex vivo studies can potentially be translated to clinical reality. Most recently, the beneficial effects of nanoparticles of VIP self-associated with sterically stabilized micelles have been reported in a murine model of RA. Another novel research area is beginning to define the receptors as biomarkers in RA, with their expression levels shown to be associated with the activity of the disease and patients-reported impairment. Therefore, VPAC expression together VIP genetic variants could allow patients to be stratified at the beginning of the disease with the purpose of guiding personalized treatment decisions.

Stroma: the forgotten cells of innate immune memory

All organisms are exposed constantly to a variety of infectious and injurious stimuli. These induce inflammatory responses tailored to the threat posed. While the innate immune system is the front line of response to each stimulant, it has been considered traditionally to lack memory, acting in a generic fashion until the adaptive immune arm can take over. This outmoded simplification of the roles of innate and acquired arms of the immune system has been challenged by evidence of myeloid cells altering their response to subsequent encounters based on earlier exposure. This concept of 'innate immune memory' has been known for nearly a century, and is accepted among myeloid biologists. In recent years other innate immune cells, such as natural killer cells, have been shown to display memory, suggesting that innate immune memory is a trait common to several cell types. During the last 30 years, evidence has slowly accumulated in favour of not only haematopoietic cells, but also stromal cells, being imbued with memory following inflammatory episodes. A recent publication showing this also to be true in epithelial cells suggests innate immune memory to be widespread, if under-appreciated, in non-haematopoietic cells. In this review, we will examine the evidence supporting the existence of innate immune memory in stromal cells. We will also discuss the ramifications of memory in long-lived tissue-resident cells. Finally, we will pose questions we feel to be important in the understanding of these forgotten cells in the field of innate memory.

Mesenchymal Stem Cells as Endogenous Regulators of Inflammation

This chapter discusses the regulatory role of endogenous mesenchymal stem cells (MSC) during an inflammatory response. MSC are a heterogeneous population of multipotent cells that normally contribute towards tissue maintenance and repair but have garnered significant scientific interest for their potent immunomodulatory potential. It is through these physicochemical interactions that MSC are able to exert an anti-inflammatory response on neighbouring stromal and haematopoietic cells. However, the impact of the chronic inflammatory environment on MSC function remains to be determined. Understanding the relationship of MSC between resolution of inflammation and autoimmunity will both offer new insights in the use of MSC as a therapeutic, and also their involvement in the pathogenesis of inflammatory disorders.

Atelocollagen-based Hydrogels Crosslinked with Oxidised Polysaccharides as Cell Encapsulation Matrix for Engineered Bioactive Stromal Tissue

Tissue stroma is responsible for extracellular matrix (ECM) formation and secretion of factors that coordinate the behaviour of the surrounding cells through the microenvironment created. It's inability to spontaneously regenerate makes it a good candidate for research studies such as testing various tissue engineered products capable of replacing the stroma in order to assure normal tissue regeneration and function. In this study, a bioactive stroma was obtained considering two main components: 1) the artificial ECM formed using atelocollagen-oxidized polysaccharides hydrogels in which the polysaccharide compound (oxidised gellan or pullulan) has the role of crosslinker and 2) encapsulated stromal cells (dermal fibroblasts, ovarian theca-interstitial and granulosa cells). The cell-hosting ability of the hydrogels is demonstrated by a good diffusion of globular proteins (albumin) while the fibrillar morphology proves to be optimal for cell adhesion. These structural properties and cytocompatibility of the components maintain good cell viability and cell encapsulation for more than 12 days. Nevertheless, the results indicate some differences favouring the gellan crosslinked hydrogels. Ovarian stromal cells functionality was maintained as indicated by hormone secretion, confirming cell-cell signalling in encapsulated and co-culture conditions. In vivo implantation shows the regenerative potential of the cell-populated hydrogels as they are integrated into the natural tissue. The possibility of cryopreserving the hydrogel-cell system, while maintaining both cell viability and hydrogel structural integrity underlines the potential of these ready-to-use hydrogels as bioactive stroma for multipurpose tissue regeneration.

Identification of a transitional fibroblast function in very early rheumatoid arthritis

OBJECTIVES

Synovial fibroblasts actively regulate the inflammatory infiltrate by communicating with neighbouring endothelial cells (EC). Surprisingly, little is known about how the development of rheumatoid arthritis (RA) alters these immunomodulatory properties. We examined the effects of phase of RA and disease outcome (resolving vs persistence) on fibroblast crosstalk with EC and regulation of lymphocyte recruitment.

METHODS

Fibroblasts were isolated from patients without synovitis, with resolving arthritis, very early RA (VeRA; symptom ≤12 weeks) and established RA undergoing joint replacement (JRep) surgery. Endothelial-fibroblast cocultures were formed on opposite sides of porous filters. Lymphocyte adhesion from flow, secretion of soluble mediators and interleukin 6 (IL-6) signalling were assessed.

RESULTS

Fibroblasts from non-inflamed and resolving arthritis were immunosuppressive, inhibiting lymphocyte recruitment to cytokine-treated endothelium. This effect was lost very early in the development of RA, such that fibroblasts no longer suppressed recruitment. Changes in IL-6 and transforming growth factor beta 1 (TGF-β₁) signalling appeared critical for the loss of the immunosuppressive phenotype. In the absence of exogenous cytokines, JRep, but not VeRA, fibroblasts activated endothelium to support lymphocyte.

CONCLUSIONS

In RA, fibroblasts undergo two distinct changes in function: first a loss of immunosuppressive responses early in disease development, followed by the later acquisition of a stimulatory phenotype. Fibroblasts exhibit a transitional functional phenotype during the first 3 months of symptoms that contributes to the accumulation of persistent infiltrates. Finally, the role of IL-6 and TGF-β₁ changes from immunosuppressive in resolving arthritis to stimulatory very early in the development of RA. Early interventions targeting 'pathogenic' fibroblasts may be required in order to restore protective regulatory processes.

Adipogenic Differentiation of Mesenchymal Stem Cells Alters Their Immunomodulatory Properties in a Tissue-Specific Manner

Chronic inflammation is associated with formation of ectopic fat deposits that might represent damage-induced aberrant mesenchymal stem cell (MSC) differentiation. Such deposits are associated with increased levels of inflammatory infiltrate and poor prognosis. Here we tested the hypothesis that differentiation from MSC to adipocytes in inflamed tissue might contribute to chronicity through loss of immunomodulatory function. We assessed the effects of adipogenic differentiation of MSC isolated from bone marrow or adipose tissue on their capacity to regulate neutrophil recruitment by endothelial cells and compared the differentiated cells to primary adipocytes from adipose tissue. Bone marrow derived MSC were immunosuppressive, inhibiting neutrophil recruitment to TNFα-treated endothelial cells (EC), but MSC-derived adipocytes were no longer able to suppress neutrophil adhesion. Changes in IL-6 and TGFβ1 signalling appeared critical for the loss of the immunosuppressive phenotype. In contrast, native stromal cells, adipocytes derived from them, and mature adipocytes from adipose tissue were all immunoprotective. Thus disruption of normal tissue stroma homeostasis, as occurs in chronic inflammatory diseases, might drive "abnormal" adipogenesis which adversely influences the behavior of MSC and contributes to pathogenic recruitment of leukocytes. Interestingly, stromal cells programmed in native fat tissue retain an immunoprotective phenotype. Stem Cells 2017;35:1636-1646.

Monocyte Subsets Coregulate Inflammatory Responses by Integrated Signaling through TNF and IL-6 at the Endothelial Cell Interface

Two major monocyte subsets, CD14⁺CD16⁻ (classical) and CD14^+/dimCD16⁺ (nonclassical/intermediate), have been described. Each has different functions ascribed in its interactions with vascular endothelial cells (EC), including migration and promoting inflammation. Although monocyte subpopulations have been studied in isolated systems, their influence on EC and on the course of inflammation has been ignored. In this study, using unstimulated or cytokine-activated EC, we observed significant differences in the recruitment, migration, and reverse migration of human monocyte subsets. Associated with this, and based on their patterns of cytokine secretion, there was a difference in their capacity to activate EC and support the secondary recruitment of flowing neutrophils. High levels of TNF were detected in cocultures with nonclassical/intermediate monocytes, the blockade of which significantly reduced neutrophil recruitment. In contrast, classical monocytes secreted high levels of IL-6, the blockade of which resulted in increased neutrophil recruitment. When cocultures contained both monocyte subsets, or when conditioned supernatant from classical monocytes cocultures (IL-6^hi) was added to nonclassical/intermediate monocyte cocultures (TNF^hi), the activating effects of TNF were dramatically reduced, implying that when present, the anti-inflammatory activities of IL-6 were dominant over the proinflammatory activities of TNF. These changes in neutrophil recruitment could be explained by regulation of E-selectin on the cocultured EC. This study suggests that recruited human monocyte subsets trigger a regulatory pathway of cytokine-mediated signaling at the EC interface, and we propose that this is a mechanism for limiting the phlogistic activity of newly recruited monocytes.

Introduction: T Cell Trafficking in Inflammation and Immunity

T cell migration across vascular endothelium is essential for T cell responses, as through the expression of specific tissue-homing receptors, these cells then access peripheral tissues, with the goal of eliminating invading pathogens and/or tumor cells. However, aberrant trafficking of T cells to peripheral tissues contributes to the development of most chronic inflammatory diseases. Very little is known about the mechanisms by which T cell trafficking is regulated during inflammation, and it is thus difficult to target this aspect of pathology for the development of new therapies. It is therefore important to understand the pathways involved in regulating the recruitment of immune cells.

The Spectrum of Renal Allograft Failure

Background

Causes of “true” late kidney allograft failure remain unclear as study selection bias and limited follow-up risk incomplete representation of the spectrum.

Methods

We evaluated all unselected graft failures from 2008–2014 (n = 171; 0–36 years post-transplantation) by contemporary classification of indication biopsies “proximate” to failure, DSA assessment, clinical and biochemical data.

Results

The spectrum of graft failure changed markedly depending on the timing of allograft failure. Failures within the first year were most commonly attributed to technical failure, acute rejection (with T-cell mediated rejection [TCMR] dominating antibody-mediated rejection [ABMR]). Failures beyond a year were increasingly dominated by ABMR and ‘interstitial fibrosis with tubular atrophy’ without rejection, infection or recurrent disease (“IFTA”). Cases of IFTA associated with inflammation in non-scarred areas (compared with no inflammation or inflammation solely within scarred regions) were more commonly associated with episodes of prior rejection, late rejection and nonadherence, pointing to an alloimmune aetiology. Nonadherence and late rejection were common in ABMR and TCMR, particularly Acute Active ABMR. Acute Active ABMR and nonadherence were associated with younger age, faster functional decline, and less hyalinosis on biopsy. Chronic and Chronic Active ABMR were more commonly associated with Class II DSA. C1q-binding DSA, detected in 33% of ABMR episodes, were associated with shorter time to graft failure. Most non-biopsied patients were DSA-negative (16/21; 76.1%). Finally, twelve losses to recurrent disease were seen (16%).

Conclusion

This data from an unselected population identifies IFTA alongside ABMR as a very important cause of true late graft failure, with nonadherence-associated TCMR as a phenomenon in some patients. It highlights clinical and immunological characteristics of ABMR subgroups, and should inform clinical practice and individualised patient care.

Chasing the recipe for a pro-regenerative immune system

Identification of the key ingredients and essential processes required to achieve perfect tissue regeneration in humans has so far remained elusive. Injury in vertebrates induces an obligatory wound response that will precede or overlap any regeneration specific program or scarring outcome. This process shapes the cellular and molecular landscape of the tissue, influencing the success of endogenous repair pathways or for potential clinical intervention. The involvement of immune cells is also required for aspects of development extending beyond the initial inflammatory phase of wounding. It has now become clear from amphibian, fish and mammalian models of tissue injury that the type of immune response and the profile of immune cells attending the site of injury can act as the gatekeepers that determine wound repair quality. The heterogeneity among innate and adaptive immune cell populations, along with the developmental origin of these cells, form key ingredients affecting the potential for downstream repair and the suppression of fibrosis. Cell-to-cell interactions between immune cells, such as macrophages and T cells, with stem cells and mesenchymal cells are critically important for shaping this process and these exchanges, are in turn influenced by the type of injury, tissue location and developmental stage of the organism. Developmentally, mouse cardiac regeneration is restricted to early stages of postnatal life where the balance of innate to adaptive immune cells may be poised towards regeneration. In the injured adult mouse liver, specific macrophage subsets improve repair while other bone marrow derived cells can exacerbate injury. Other studies using genetically diverse mice have shown enhanced regeneration in certain strains, restricted to specific tissues. This enhanced repair is linked with expression of genes such as Insulin-like Growth Factor- 1 (IGF-1) and activin (Act 1), that both play important roles in shaping the immune system. Immune cells are now appreciated to have powerful influences on critical cell types required for regeneration success. The winning recipe for tissue regeneration is likely to be found ultimately by identifying the genetic elements and specific cell populations that limit or allow intrinsic potential. This will be essential for developing therapeutic strategies for tissue regeneration in humans.

Human dermal fibroblasts in psychiatry research

In order to decipher the disease etiology, progression and treatment of multifactorial human brain diseases we utilize a host of different experimental models. Recently, patient-derived human dermal fibroblast (HDF) cultures have re-emerged as promising in vitro functional system for examining various cellular, molecular, metabolic and (patho)physiological states and traits of psychiatric disorders. HDF studies serve as a powerful complement to postmortem and animal studies, and often appear to be informative about the altered homeostasis in neural tissue. Studies of HDFs from patients with schizophrenia (SZ), depression, bipolar disorder (BD), autism, attention deficit and hyperactivity disorder and other psychiatric disorders have significantly advanced our understanding of these devastating diseases. These reports unequivocally prove that signal transduction, redox homeostasis, circadian rhythms and gene*environment (G*E) interactions are all amenable for assessment by the HDF model. Furthermore, the reported findings suggest that this underutilized patient biomaterial, combined with modern molecular biology techniques, may have both diagnostic and prognostic value, including prediction of response to therapeutic agents.

Cellular Barriers after Extravasation: Leukocyte Interactions with Polarized Epithelia in the Inflamed Tissue

During the inflammatory response, immune cells egress from the circulation and follow a chemotactic and haptotactic gradient within the tissue, interacting with matrix components in the stroma and with parenchymal cells, which guide them towards the sites of inflammation. Polarized epithelial cells compartmentalize tissue cavities and are often exposed to inflammatory challenges such as toxics or infections in non-lymphoid tissues. Apicobasal polarity is critical to the specialized functions of these epithelia. Indeed, a common feature of epithelial dysfunction is the loss of polarity. Here we review evidence showing that apicobasal polarity regulates the inflammatory response: various polarized epithelia asymmetrically secrete chemotactic mediators and polarize adhesion receptors that dictate the route of leukocyte migration within the parenchyma. We also discuss recent findings showing that the loss of apicobasal polarity increases leukocyte adhesion to epithelial cells and the consequences that this could have for the inflammatory response towards damaged, infected or transformed epithelial cells.

Differential development of oil granulomas induced by pristane injection in galectin-3 deficient mice

Background

Galectin-3 is known to be a lectin that plays an important role in inflammatory processes, acting as pro-inflammatory mediator in activation and migration of neutrophils and macrophages, as well as in the phagocytic function of these cells. The injection of mineral oils into the peritoneal cavity of mice, such as 2, 6, 10, 14-tetramethylpentadecane (pristane), induce a chronic granulomatous inflammatory reaction which is rich in macrophages, B cells and peritoneal plasma cells known as oil granuloma. In addition, this inflammatory microenvironment provided by oil granulomas is also an important site of plasmacytoma induction, which are dependent on cytokine production and cellular mobilization.

Here, we have analyzed the role of galectin-3 in inflammatory cells mobilization and organization after pristane injection characterizing granulomatous reaction through the formation of oil granulomas.

Results

In galectin-3 deficient mice (gal-3^−/−), the mobilization of inflammatory cells, between peritoneal cavity and bone marrow, was responsible for the formation of disorganized oil granulomas, which presented scattered cells, large necrotic areas and low amounts of extracellular matrix. The production of inflammatory cytokines partially explained the distribution of cells through peritoneal cavity, since high levels of IL-6 in gal-3^−/− mice led to drastically reduction of B1 cells. The previous pro-inflammatory status of these animals also explains the excess of cell death and disruption of oil granulomas architecture.

Conclusions

Our data indicate, for the first time, that the disruption in the inflammatory cells migration in the absence of galectin-3 is a crucial event in the formation and organization of oil granulomas.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-015-0133-9) contains supplementary material, which is available to authorized users.

Hepatic myofibroblasts derived from Schistosoma mansoni-infected mice are a source of IL-5 and eotaxin: controls of eosinophil populations in vitro

Background

Hepatic myofibroblasts are relevant for pathogenesis of S. mansoni infection. In normal liver, these perisinusoidal cells are quiescent, express the lipocyte phenotype, and are located in the Disse’s space, being the major site of vitamin A storage. When activated, they convert to myofibroblasts and contribute to granulomatous and diffuse liver fibrosis. In the present work, we observed that myofibroblasts obtained from granulomatous periovular inflammatory reactions in schistosome-infected mice (GR-MF) produce in vitro immunomodulatory cytokines for eosinophil activation: IL-5 and eotaxin.

Methods and results

The secretory activity of GR-MF was detected after TGF-β and IL-13 stimulation using 2D and 3D cell culture systems. In a mixed co-culture system using GR-MF with hematopoietic bone marrow cells from infected mice, we observed eosinophil survival that was dependent upon IL-5 and eotaxin, since antibodies against this cytokines decreased eosinophil population, as measured by eosinophil peroxidase activity.

Conclusion

These results indicate that GR-MF may contribute to maintenance of local eosinophilia in schistosomal hepatic granulomas, and can function as immunoregulatory cells, besides their role in production of fibrosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-1197-3) contains supplementary material, which is available to authorized users.

Effect of equine herpesvirus type 1 (EHV-1) infection of nasal mucosa epithelial cells on integrin alpha 6 and on different components of the basement membrane

The respiratory mucosa is the common port of entry of equine herpesvirus type 1 (EHV-1) and several other alphaherpesviruses. An important prerequisite for successful host invasion of the virus is to cross the epithelial cell layer and the underlying basement membrane barrier. In the present study, an analysis was performed to see if an EHV-1 infection of nasal mucosa epithelial cells leads to damage of the underlying extracellular matrix proteins. Nasal mucosa explants were inoculated with EHV-1 and collected at 0, 24 and 48 hours post-inoculation (hpi). Then, double immunofluorescence staining was performed to detect viral-antigen-positive cells on the one hand and integrin alpha 6, laminin, collagen IV and collagen VII on the other hand. The area of these extracellular matrix proteins was measured in regions of interest (ROIs) at a magnification of 200X by means of the software imaging system ImageJ. ROIs were defined beneath uninfected and infected regions. In uninfected regions, 22-28 % of the ROI was stained for integrin alpha 6, 18-37 % for laminin, 14-38 % for collagen IV and 18-26 % for collagen VII. In infected regions, the percentage positive for integrin alpha 6 was significantly decreased to 0.1-9 % and 0.1-6 % after 24 and 48 hours of inoculation, respectively. Infection did not alter the percentages for laminin and collagen IV. For collagen VII, an increase in the percentage (from 18-26 % to 28-39 %) could be observed underneath EHV-1-infected plaques at 48 hours of inoculation. In conclusion, the results revealed a substantial impact of EHV-1 infection on integrin alpha 6 and collagen VII, two important components of the extracellular matrix, which are associated with the basement membrane and may facilitate virus penetration via hijacked leukocytes to underlying tissues.

TNF-α-stimulated fibroblasts secrete lumican to promote fibrocyte differentiation

In healing wounds and fibrotic lesions, fibroblasts and monocyte-derived fibroblast-like cells called fibrocytes help to form scar tissue. Although fibrocytes promote collagen production by fibroblasts, little is known about signaling from fibroblasts to fibrocytes. In this report, we show that fibroblasts stimulated with the fibrocyte-secreted inflammatory signal tumor necrosis factor-α secrete the small leucine-rich proteoglycan lumican, and that lumican, but not the related proteoglycan decorin, promotes human fibrocyte differentiation. Lumican competes with the serum fibrocyte differentiation inhibitor serum amyloid P, but dominates over the fibroblast-secreted fibrocyte inhibitor Slit2. Lumican acts directly on monocytes, and unlike other factors that affect fibrocyte differentiation, lumican has no detectable effect on macrophage differentiation or polarization. α2β1, αMβ2, and αXβ2 integrins are needed for lumican-induced fibrocyte differentiation. In lung tissue from pulmonary fibrosis patients with relatively normal lung function, lumican is present at low levels throughout the tissue, whereas patients with advanced disease have pronounced lumican expression in the fibrotic lesions. These data may explain why fibrocytes are increased in fibrotic tissues, suggest that the levels of lumican in tissues may have a significant effect on the decision of monocytes to differentiate into fibrocytes, and indicate that modulating lumican signaling may be useful as a therapeutic for fibrosis.

Inflammation, Innate Immunity, and the Intestinal Stromal Cell Niche: Opportunities and Challenges

Stromal cells of multiple tissues contribute to immune-mediated protective responses and, conversely, the pathological tissue changes associated with chronic inflammatory disease. However, unlike hematopoietic immune cells, tissue stromal cell populations remain poorly characterized with respect to specific surface marker expression, their ontogeny, self-renewal, and proliferative capacity within tissues and the extent to which they undergo phenotypic immunological changes during the course of an infectious or inflammatory insult. Extending our knowledge of the immunological features of stromal cells provides an exciting opportunity to further dissect the underlying biology of many important immune-mediated diseases, although several challenges remain in bringing the emerging field of stromal immunology to equivalence with the study of the hematopoietic immune cell compartment. This review highlights recent studies that have begun unraveling the complexity of tissue stromal cell function in immune responses, with a focus on the intestine, and proposes strategies for the development of the field to uncover the great potential for stromal immunology to contribute to our understanding of the fundamental pathophysiology of disease, and the opening of new therapeutic avenues in multiple chronic inflammatory conditions.

Expression of IL-8, IL-6 and IL-1β in tears as a main characteristic of the immune response in human microbial keratitis

Corneal infections are frequent and potentially vision-threatening diseases, and despite the significance of the immunological response in animal models of microbial keratitis (MK), it remains unclear in humans. The aim of this study was to describe the cytokine profile of tears in patients with MK. Characteristics of ocular lesions such as size of the epithelial defect, stromal infiltration, and hypopyon were analyzed. Immunological evaluation included determination of interleukine (IL)-1β, IL-6, IL-8, IL-10, IL-12 and tumor necrosis factor (TNF)-α in tear samples obtained from infected eyes of 28 patients with MK and compared with their contralateral non-infected eyes. Additionally, frequency of CD4⁺, CD8⁺, CD19⁺ and CD3⁻CD56⁺ cells was also determined in peripheral blood mononuclear cells in patients with MK, and compared with 48 healthy controls. Non-significant differences were observed in the size of the epithelial defect, stromal infiltration, and hypopyon. Nevertheless, we found an immunological profile apparently related to MK etiology. IL-8 > IL-6 in patients with bacterial keratitis; IL-8 > IL-6 > IL-1β and increased frequency of circulating CD3⁻CD56⁺ NK cells in patients with gram-negative keratitis; and IL-8 = IL-6 > IL-1β in patients with fungal keratitis. Characterization of tear cytokines from patients with MK could aid our understanding of the immune pathophysiological mechanisms underlying corneal damage in humans.

Formation of microvascular networks: role of stromal interactions directing angiogenic growth

In the adult, angiogenesis leads to an expanded microvascular network as new vessel segments are added to an existing microcirculation. Necessarily, growing neovessels must navigate through tissue stroma as they locate and grow toward other vessel elements. We have a growing body of evidence demonstrating that angiogenic neovessels reciprocally interact with the interstitial matrix of the stroma resulting in directed neovascular growth during angiogenesis. Given the compliance and the viscoelastic properties of collagen, neovessel guidance by the stroma is likely due to compressive strain transverse to the direction of primary tensile forces present during active tissue deformation. Similar stromal strains control the final network topology of the new microcirculation, including the distribution of arterioles, capillaries, and venules. In this case, stromal-derived stimuli must be present during the post-angiogenesis remodeling and maturation phases of neovascularization to have this effect. Interestingly, the preexisting organization of vessels prior to the start of angiogenesis has no lasting influence on the final, new network architecture. Combined, the evidence describes interplay between angiogenic neovessels and stroma that is important in directed neovessel growth and invasion. This dynamic is also likely a mechanism by which global tissue forces influence vascular form and function.

Crosstalk between mesenchymal stem cells and endothelial cells leads to downregulation of cytokine-induced leukocyte recruitment

Mesenchymal stem cells (MSC) have immunomodulatory properties, but their effects on endothelial cells (EC) and recruitment of leukocytes are unknown. We cocultured human bone marrow-derived MSC with EC and found that MSC could downregulate adhesion of flowing neutrophils or lymphocytes and their subsequent transendothelial migration. This applied for EC treated with tumor necrosis factor-α (TNF), interleukin-1β (IL-1), or TNF and interferon-γ combined. Supernatant from cocultures also inhibited endothelial responses. This supernatant had much higher levels of IL-6 than supernatant from cultures of the individual cells, which also lacked inhibitory functions. Addition of neutralizing antibody against IL-6 removed the bioactivity of the supernatant and also the immunomodulatory effects of coculture. Studies using siRNA showed that IL-6 came mainly from the MSC in coculture, and reduction in production in MSC alone was sufficient to impair the protective effects of coculture. Interestingly, siRNA knockdown of IL-6-receptor expression in MSC as well as EC inhibited anti-inflammatory effects. This was explained when we detected soluble IL-6R receptor in supernatants and showed that receptor removal reduced the potency of supernatant. Neutralization of transforming growth factor-β indicated that activation of this factor in coculture contributed to IL-6 production. Thus, crosstalk between MSC and EC caused upregulation of production of IL-6 by MSC which in turn downregulated the response of EC to inflammatory cytokines, an effect potentiated by MSC release of soluble IL-6R. These studies establish a novel mechanism by which MSC might have protective effects against inflammatory pathology and cardiovascular disease.

CD13 regulates anchorage and differentiation of the skeletal muscle satellite stem cell population in ischemic injury

CD13 is a multifunctional cell surface molecule that regulates inflammatory and angiogenic mechanisms in vitro, but its contribution to these processes in vivo or potential roles in stem cell biology remains unexplored. We investigated the impact of loss of CD13 on a model of ischemic skeletal muscle injury that involves angiogenesis, inflammation, and stem cell mobilization. Consistent with its role as an inflammatory adhesion molecule, lack of CD13 altered myeloid trafficking in the injured muscle, resulting in cytokine profiles skewed toward a prohealing environment. Despite this healing-favorable context, CD13(KO) animals showed significantly impaired limb perfusion with increased necrosis, fibrosis, and lipid accumulation. Capillary density was correspondingly decreased, implicating CD13 in skeletal muscle angiogenesis. The number of CD45-/Sca1-/α7-integrin+/β1-integrin+ satellite cells was markedly diminished in injured CD13(KO) muscles and adhesion of isolated CD13(KO) satellite cells was impaired while their differentiation was accelerated. Bone marrow transplantation studies showed contributions from both host and donor cells to wound healing. Importantly, CD13 was coexpressed with Pax7 on isolated muscle-resident satellite cells. Finally, phosphorylated-focal adhesion kinase and ERK levels were reduced in injured CD13(KO) muscles, consistent with CD13 regulating satellite cell adhesion, potentially contributing to the maintenance and renewal of the satellite stem cell pool and facilitating skeletal muscle regeneration.

Analyzing the effects of stromal cells on the recruitment of leukocytes from flow

Stromal cells regulate the recruitment of circulating leukocytes during inflammation through cross-talk with neighboring endothelial cells. Here we describe two in vitro "vascular" models for studying the recruitment of circulating neutrophils from flow by inflamed endothelial cells. A major advantage of these models is the ability to analyze each step in the leukocyte adhesion cascade in order, as would occur in vivo. We also describe how both models can be adapted to study the role of stromal cells, in this case mesenchymal stem cells (MSC), in regulating leukocyte recruitment. Primary endothelial cells were cultured alone or together with human MSC in direct contact on Ibidi microslides or on opposite sides of a Transwell filter for 24 hr. Cultures were stimulated with tumor necrosis factor alpha (TNFα) for 4 hr and incorporated into a flow-based adhesion assay. A bolus of neutrophils was perfused over the endothelium for 4 min. The capture of flowing neutrophils and their interactions with the endothelium was visualized by phase-contrast microscopy. In both models, cytokine-stimulation increased endothelial recruitment of flowing neutrophils in a dose-dependent manner. Analysis of the behavior of recruited neutrophils showed a dose-dependent decrease in rolling and a dose-dependent increase in transmigration through the endothelium. In co-culture, MSC suppressed neutrophil adhesion to TNFα-stimulated endothelium. Our flow based-adhesion models mimic the initial phases of leukocyte recruitment from the circulation. In addition to leukocytes, they can be used to examine the recruitment of other cell types, such as therapeutically administered MSC or circulating tumor cells. Our multi-layered co-culture models have shown that MSC communicate with endothelium to modify their response to pro-inflammatory cytokines, altering the recruitment of neutrophils. Further research using such models is required to fully understand how stromal cells from different tissues and conditions (inflammatory disorders or cancer) influence the recruitment of leukocytes during inflammation.

Fibroblasts secrete Slit2 to inhibit fibrocyte differentiation and fibrosis

Monocytes leave the blood and enter tissues. In healing wounds and fibrotic lesions, some of the monocytes differentiate into fibroblast-like cells called fibrocytes. In healthy tissues, even though monocytes enter the tissue, for unknown reasons, very few monocytes differentiate into fibrocytes. In this report, we show that fibroblasts from healthy human tissues secrete the neuronal guidance protein Slit2 and that Slit2 inhibits human fibrocyte differentiation. In mice, injections of Slit2 inhibit bleomycin-induced lung fibrosis. In lung tissue from pulmonary fibrosis patients with relatively normal lung function, Slit2 has a widespread distribution whereas, in patients with advanced disease, there is less Slit2 in the fibrotic lesions. These data may explain why fibrocytes are rarely observed in healthy tissues, may suggest that the relative levels of Slit2 present in healthy tissue and at sites of fibrosis may have a significant effect on the decision of monocytes to differentiate into fibrocytes, and may indicate that modulating Slit2 signaling may be useful as a therapeutic for fibrosis.

Stroma: fertile soil for inflammation

Biological therapies for the management of immune mediated inflammatory diseases such as rheumatoid arthritis have proven to be extremely successful in recent years. Despite these successes, even the most effective of therapies do not lead to cure. Why chronic inflammation persists indefinitely within the rheumatoid synovium despite an absence of continuous stimulation, and why some patients with early synovitis progress to persistent disease whilst others do not, has remained unexplained. In contrast to the paradigm that stromal cells are biochemically active but immunologically passive, there is now growing evidence that stromal components from the rheumatoid synovium play a crucial part in the immunopathology of rheumatoid arthritis. Stromal cells play a central role in the transformation of an acute, resolving to a chronic inflammatory process, and to the persistence of synovial inflammation and joint destruction through a variety of immune mechanisms. Therapeutic manipulation of the stroma is a largely unexplored, yet potentially vital area of research. Targeting pathogenic stromal cells has the potential to provide a cure for chronic inflammatory disorders such as rheumatoid arthritis.

Apicobasal polarity controls lymphocyte adhesion to hepatic epithelial cells

Loss of apicobasal polarity is a hallmark of epithelial pathologies. Leukocyte infiltration and crosstalk with dysfunctional epithelial barriers are crucial for the inflammatory response. Here, we show that apicobasal architecture regulates the adhesion between hepatic epithelial cells and lymphocytes. Polarized hepatocytes and epithelium from bile ducts segregate the intercellular adhesion molecule 1 (ICAM-1) adhesion receptor onto their apical, microvilli-rich membranes, which are less accessible by circulating immune cells. Upon cell depolarization, hepatic ICAM-1 becomes exposed and increases lymphocyte binding. Polarized hepatic cells prevent ICAM-1 exposure to lymphocytes by redirecting basolateral ICAM-1 to apical domains. Loss of ICAM-1 polarity occurs in human inflammatory liver diseases and can be induced by the inflammatory cytokine tumor necrosis factor alpha (TNF-α). We propose that adhesion receptor polarization is a parenchymal immune checkpoint that allows functional epithelium to hamper leukocyte binding. This contributes to the haptotactic guidance of leukocytes toward neighboring damaged or chronically inflamed epithelial cells that expose their adhesion machinery.

Podocytes regulate neutrophil recruitment by glomerular endothelial cells via IL-6-mediated crosstalk

Stromal cells actively modulate the inflammatory process, in part by influencing the ability of neighboring endothelial cells to support the recruitment of circulating leukocytes. We hypothesized that podocytes influence the ability of glomerular endothelial cells (GEnCs) to recruit neutrophils during inflammation. To address this, human podocytes and human GEnCs were cultured on opposite sides of porous inserts and then treated with or without increasing concentrations of TNF-α prior to addition of neutrophils. The presence of podocytes significantly reduced neutrophil recruitment to GEnCs by up to 50% when cultures were treated with high-dose TNF-α (100 U/ml), when compared with GEnC monocultures. Importantly, this phenomenon was dependent on paracrine actions of soluble IL-6, predominantly released by podocytes. A similar response was absent when HUVECs were cocultured with podocytes, indicating a tissue-specific phenomenon. Suppressor of cytokine signaling 3 elicited the immunosuppressive actions of IL-6 in a process that disrupted the presentation of chemokines on GEnCs by altering the expression of the duffy Ag receptor for chemokines. Interestingly, suppressor of cytokine signaling 3 knockdown in GEnCs upregulated duffy Ag receptor for chemokines and CXCL5 expression, thereby restoring the neutrophil recruitment. In summary, these studies reveal that podocytes can negatively regulate neutrophil recruitment to inflamed GEnCs by modulating IL-6 signaling, identifying a potential novel anti-inflammatory role of IL-6 in renal glomeruli.