Type 2 immunity in tissue repair and fibrosis

Effectiveness and safety of anti-IL-5/Rα biologics in eosinophilic granulomatosis with polyangiitis: a two-year multicenter observational study

Background

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare vasculitis characterized by asthma, systemic manifestations, and blood and tissue eosinophilia.

Objective

To assess the effectiveness and safety of mepolizumab (anti-IL-5) and benralizumab (anti-IL-5Rα) in EGPA for 24 months.

Methods

We conducted a multicenter observational study, including patients with EGPA treated with anti-IL-5/Rα biologics in 9 Italian specialized facilities. Systemic disease activity, remission and relapse rate were evaluated from 3 to 24 months after treatment initiation. Respiratory outcomes, hematological parameters, corticosteroid (OCS) and immunosuppressants consumption were also assessed.

Results

49 patients with relapsing-refractory EGPA were included [26 (53.1%) benralizumab 30mg, 20 (40.8%) mepolizumab 100mg, 3 (6.1%) mepolizumab 300mg]. Overall, 38.8% and 57.1% achieved remission after 12 and 24 months, respectively (69.2% benralizumab and 43.5% mepolizumab). Lower OCS intake and higher blood eosinophil count at baseline were associated with remission at 24 months. Both biologics exerted beneficial effects on severe asthma outcomes. Indeed, 61.2% (61.5% benralizumab and 60.8% mepolizumab) remained exacerbation-free during treatment. Lung function parameters showed improvements in the overall cohort (all p<0.05), but began to decline from month 12, especially with mepolizumab. Marked reduction in blood eosinophils was registered with mepolizumab (p<0.0001), while benralizumab depleted both eosinophils (p<0.0001) and basophils (p<0.0001). In general, 69.6% (76% benralizumab and 61.9% mepolizumab) of OCS-dependent patients lowered their daily dose by 75%, while 28.3% discontinued these drugs. Immunosuppressants were suspended in 88.2% of cases. Adverse events were reported in 8.2% of patients.

Conclusions

These real-world data suggest that anti-IL-5/Rα biologics are effective and safe in the long-term as add-on treatments for patients with EGPA.

Type 1 and type 2 cytokine-mediated immune orchestration in the tumour microenvironment and their therapeutic potential

Cancer remains the second leading cause of death worldwide despite modern breakthroughs in medicine, and novel treatments are urgently needed. The revolutionary success of immune checkpoint inhibitors in the past decade serves as proof of concept that the immune system can be effectively harnessed to treat cancer. Cytokines are small signalling proteins with critical roles in orchestrating the immune response and have become an attractive target for immunotherapy. Type 1 immune cytokines, including interferon γ (IFNγ), interleukin-12 (IL-12), and tumour necrosis factor α (TNFα), have been shown to have largely tumour suppressive roles in part through orchestrating anti-tumour immune responses mediated by natural killer (NK) cells, CD8⁺ T cells and T helper 1 (Th1) cells. Conversely, type 2 immunity involving group 2 innate lymphoid cells (ILC2s) and Th2 cells are involved in tissue regeneration and wound repair and are traditionally thought to have pro-tumoural effects. However, it is found that the classical type 2 immune cytokines IL-4, IL-5, IL-9, and IL-13 may have conflicting roles in cancer. Similarly, type 2 immunity-related cytokines IL-25 and IL-33 with recently characterised roles in cancer may either promote or suppress tumorigenesis in a context-dependent manner. Furthermore, type 1 cytokines IFNγ and TNFα have also been found to have pro-tumoural effects under certain circumstances, further complicating the overall picture. Therefore, the dichotomy of type 1 and type 2 cytokines inhibiting and promoting tumours respectively is not concrete, and attempts of utilising these for cancer immunotherapy must take into account all available evidence. This review provides an overview summarising the current understanding of type 1 and type 2 cytokines in tumour immunity and discusses the prospects of harnessing these for immunotherapy in light of previous and ongoing clinical trials.

Fibroblasts at the curtain call: from ensemble to principal dancers in immunometabolism and inflammaging

Inflammation is a necessary step in response to injuries, being vital in restoring homeostasis and facilitating tissue healing. Among the cells that play a crucial role in inflammatory responses, stromal cells, including fibroblasts, have an undeniable significance in fine-tuning the magnitude of mediators that directly affect hyper-inflammatory responses and tissue destruction. Fibroblasts, the dominant cells in the gingival connective tissue, are a very heterogeneous population of cells, and more recently they have been receiving well deserved attention as central players and often the 'principal dancers' of many pathological processes ranging from inflammation and fibrosis to altered immunity and cancer. The goal of the current investigation is to dive into the exact role of the stromal fibroblast and the responsible mechanistic factors involved in both regulation and dysregulation of the inflammatory responses. This article reviews the most recent literature on how fibroblasts, in their different activation states or subtypes, play a crucial role in contributing to inflammatory outcomes. We will focus on recent findings on inflammatory diseases. We will also provide connections regarding the stromal-immune relationship, which supports the idea of fibroblast coming out from the 'ensemble' of cell types to the protagonist role in immunometabolism and inflammaging. Additionally, we discuss the current advances in variation of fibroblast nomenclature and division into clusters with their own suggested function and particularities in gene expression. Here, we provide a perspective for the periodontal implications, discussing the fibroblast role in the infection-driven and inflammatory mediated diseases such as periodontitis.

Host Immunity and Immunization Strategies for Clostridioides difficile Infection

Clostridioides difficile infection (CDI) represents a significant challenge to public health. C. difficile-associated mortality and morbidity have led the U.S. CDC to designate it as an urgent threat. Moreover, recurrence or relapses can occur in up to a third of CDI patients, due in part to antibiotics being the primary treatment for CDI and the major cause of the disease. In this review, we summarize the current knowledge of innate immune responses, adaptive immune responses, and the link between innate and adaptive immune responses of the host against CDI. The other major determinants of CDI, such as C. difficile toxins, the host microbiota, and related treatments, are also described. Finally, we discuss the known therapeutic approaches and the current status of immunization strategies for CDI, which might help to bridge the knowledge gap in the generation of therapy against CDI.

Downregulation of fibrosis related hsa-miR-29c-3p in human CAKUT

Congenital anomalies of the kidney and urinary tract (CAKUT) represent structural and functional urinary system malformations and take place as one of the most common congenital malformations with an incidence of 1:500. Ureteral obstruction-induced hydronephrosis is associated with renal fibrosis and chronic kidney diseases in the pediatric CAKUT. We aimed to construct interaction network of previously bioinformatically associated miRNAs with CAKUT differentially expressed genes in order to prioritize those associated with fibrotic process and to experimentally validate the expression of selected miRNAs in CAKUT patients compared to control group. We constructed interaction network of hsa-miR-101-3p, hsa-miR-101-5p and hsa-miR-29c-3p that showed significant association with fibrosis. The top enriched molecular pathway was extracellular matrix-receptor interaction (adjusted p = .0000263). We experimentally confirmed expression of three miRNAs (hsa-miR-29c-3p, hsa-miR-101-3p and hsa-miR-101-5p) in obstructed ureters (ureteropelvic junction obstruction and primary obstructive megaureter) and vesicoureteral reflux. The hsa-miR-29c-3p was shown to have lower expression in both patient groups compared to controls. Relative levels of hsa-miR-101-5p and hsa-miR-101-3p showed significant positive correlations in both groups of patients. Statistically significant correlation was observed between hsa-miR-101 (-3p and -5p) and hsa-miR-29c-3p only in the obstructed group. The significant downregulation of anti-fibrotic hsa-miR-29c-3p in obstructive CAKUT could explain activation of genes involved in fibrotic processes. As miRNAs are promising candidates in therapeutic approaches our results need further measurement of fibrotic markers or assessment of extent of fibrosis and functional evaluation of hsa-miR-29c.

Tissue-resident memory T cells mediate mucosal immunity to recurrent urinary tract infection

Urinary tract infection (UTI) is one of the most prevalent human bacterial infections. New therapeutic approaches, including vaccination and immunotherapy, are urgently needed to combat the rapid global dissemination of multidrug-resistant uropathogens. Development of therapies is impeded by an incomplete understanding of memory development during UTI. Here, we found that reducing bacterial load early in infection, by reducing the inoculum or with antibiotics after infection, completely abrogated the protective memory response. We observed a mixed T helper (T_H) cell polarization, composed of T_H1, T_H2, and T_H17 T cells, among T cells infiltrating the bladder during primary infection. Thus, we hypothesized that reducing antigen load altered T_H cell polarization, leading to poor memory. Unexpectedly, however, T_H cell polarization was unchanged in these scenarios. Instead, we uncovered a population of tissue-resident memory (T_RM) T cells that was significantly reduced in the absence of sufficient antigen. Demonstrating that T_RM cells are necessary for immune memory, transfer of lymph node- or spleen-derived infection-experienced T cells to naïve animals did not confer protection against infection. Supporting that T_RM cells are sufficient to protect against recurrent UTI, animals depleted of systemic T cells, or treated with FTY720 to block memory lymphocyte migration from lymph nodes to infected tissue, were equally protected compared with unmanipulated mice against a second UTI. Thus, we uncovered an unappreciated key role for T_RM cells in the memory response to bacterial infection in the bladder mucosa, providing a target for non-antibiotic-based immunotherapy and/or new vaccine strategies to prevent recurrent UTI.

Engineered collagen polymeric materials create noninflammatory regenerative microenvironments that avoid classical foreign body responses

The efficacy and longevity of medical implants and devices is largely determined by the host immune response, which extends along a continuum from pro-inflammatory/pro-fibrotic to anti-inflammatory/pro-regenerative. Using a rat subcutaneous implantation model, along with histological and transcriptomics analyses, we characterized the tissue response to a collagen polymeric scaffold fabricated from polymerizable type I oligomeric collagen (Oligomer) in comparison to commercial synthetic and collagen-based products. In contrast to commercial biomaterials, no evidence of an immune-mediated foreign body reaction, fibrosis, or bioresorption was observed with Oligomer scaffolds for beyond 60 days. Oligomer scaffolds were noninflammatory, eliciting minimal innate inflammation and immune cell accumulation similar to sham surgical controls. Genes associated with Th2 and regulatory T cells were instead upregulated, implying a novel pathway to immune tolerance and regenerative remodeling for biomaterials.

Biomaterials-based immunomodulation enhances survival of murine vascularized composite allografts

Vascularized composite allotransplantation (VCA) is a restorative option for patients suffering from severe tissue defects not amenable to conventional reconstruction. However, the toxicities associated with life-long multidrug immunosuppression to enable allograft survival and induce immune tolerance largely limit the broader application of VCA. Here, we investigate the potential of targeted immunomodulation using CTLA4-Ig combined with a biological porcine-derived extracellular matrix (ECM) scaffold that elicits a pro-regenerative Th2 response to promote allograft survival and regulate the inflammatory microenvironment in a stringent mouse orthotopic hind limb transplantation model (BALB/c to C57BL/6). The median allograft survival time (MST) increased significantly from 15.0 to 24.5 days (P = 0.0037; Mantel-Cox test) after adding ECM to the CTLA4-Ig regimen. Characterization of the immune infiltration shows a pro-regenerative phenotype prevails over those associated with inflammation and rejection including macrophages (F4/80^hi+CD206^hi+MHCII^low), eosinophils (F4/80^lowSiglec-F⁺), and T helper 2 (Th2) T cells (CD4⁺IL-4⁺). This was accompanied by an increased expression of genes associated with a Type 2 polarized immune state such as Il4, Ccl24, Arg1 and Ym1 within the graft. Furthermore, when ECM was applied along with a clinically relevant combination of CTLA4-Ig and Rapamycin, allograft survival was prolonged from 33.0 to 72.5 days (P = 0.0067; Mantel-Cox test). These studies implicate the clinical exploration of combined regimens involving local application of pro-regenerative, immunomodulatory biomaterials in surgical wound sites with targeted co-stimulatory blockade to reduce adverse effects of immunosuppression and enhance graft survival in VCA.

Fusobacterium & Co. at the Stem of Cancer: Microbe-Cancer Stem Cell Interactions in Colorectal Carcinogenesis

Adult stem cells lie at the crossroads of tissue repair, inflammation, and malignancy. Intestinal microbiota and microbe-host interactions are pivotal to maintaining gut homeostasis and response to injury, and participate in colorectal carcinogenesis. Yet, limited knowledge is available on whether and how bacteria directly crosstalk with intestinal stem cells (ISC), particularly cancerous stem-like cells (CR-CSC), as engines for colorectal cancer initiation, maintenance, and metastatic dissemination. Among several bacterial species alleged to initiate or promote colorectal cancer (CRC), the pathobiont Fusobacterium Nucleatum has recently drawn significant attention for its epidemiologic association and mechanistic linkage with the disease. We will therefore focus on current evidence for an F. nucleatum-CRCSC axis in tumor development, highlighting the commonalities and differences between F. nucleatum-associated colorectal carcinogenesis and gastric cancer driven by Helicobacter Pylori. We will explore the diverse facets of the bacteria-CSC interaction, analyzing the signals and pathways whereby bacteria either confer "stemness" properties to tumor cells or primarily target stem-like elements within the heterogeneous tumor cell populations. We will also discuss the extent to which CR-CSC cells are competent for innate immune responses and participate in establishing a tumor-promoting microenvironment. Finally, by capitalizing on the expanding knowledge of how the microbiota and ISC crosstalk in intestinal homeostasis and response to injury, we will speculate on the possibility that CRC arises as an aberrant repair response promoted by pathogenic bacteria upon direct stimulation of intestinal stem cells.

Group 2 innate lymphoid cells constrain type 3/17 lymphocytes in shared stromal niches to restrict liver fibrosis

Group 2 innate lymphoid cells (ILC2s) cooperate with adaptive Th2 cells as key organizers of tissue type 2 immune responses, while a spectrum of innate and adaptive lymphocytes coordinate early type 3/17 immunity. Both type 2 and type 3/17 lymphocyte associated cytokines are linked to tissue fibrosis, but how their dynamic and spatial topographies may direct beneficial or pathologic organ remodelling is unclear. Here we used volumetric imaging in models of liver fibrosis, finding accumulation of periportal and fibrotic tract IL-5 + lymphocytes, predominantly ILC2s, in close proximity to expanded type 3/17 lymphocytes and IL-33 high niche fibroblasts. Ablation of IL-5 + lymphocytes worsened carbon tetrachloride-and bile duct ligation-induced liver fibrosis with increased niche IL-17A + type 3/17 lymphocytes, predominantly γδ T cells. In contrast, concurrent ablation of IL-5 + and IL-17A + lymphocytes reduced this progressive liver fibrosis, suggesting a cross-regulation of type 2 and type 3 lymphocytes at specialized fibroblast niches that tunes hepatic fibrosis.

Responding to ACL Injury and its Treatments: Comparative Gene Expression between Articular Cartilage and Synovium

The relationship between cartilage and synovium is a rapidly growing area of osteoarthritis research. However, to the best of our knowledge, the relationships in gene expression between these two tissues have not been explored in mid-stage disease development. The current study compared the transcriptomes of these two tissues in a large animal model one year following posttraumatic osteoarthritis induction and multiple surgical treatment modalities. Thirty-six Yucatan minipigs underwent transection of the anterior cruciate ligament. Subjects were randomized to no further intervention, ligament reconstruction, or ligament repair augmented with an extracellular matrix (ECM) scaffold, followed by RNA sequencing of the articular cartilage and synovium at 52 weeks after harvest. Twelve intact contralateral knees served as controls. Across all treatment modalities, the primary difference in the transcriptomes was that the articular cartilage had greater upregulation of genes related to immune activation compared to the synovium-once baseline differences between cartilage and synovium were adjusted for. Oppositely, synovium featured greater upregulation of genes related to Wnt signaling compared to articular cartilage. After adjusting for expression differences between cartilage and synovium seen following ligament reconstruction, ligament repair with an ECM scaffold upregulated pathways related to ion homeostasis, tissue remodeling, and collagen catabolism in cartilage relative to synovium. These findings implicate inflammatory pathways within cartilage in the mid-stage development of posttraumatic osteoarthritis, independent of surgical treatment. Moreover, use of an ECM scaffold may exert a chondroprotective effect over gold-standard reconstruction through preferentially activating ion homeostatic and tissue remodeling pathways within cartilage.

IL-4 and IL-13: Regulators and Effectors of Wound Repair

Type 2 immunity mediates protective responses to helminths and pathological responses to allergens, but it also has broad roles in the maintenance of tissue integrity, including wound repair. Type 2 cytokines are known to promote fibrosis, an overzealous repair response, but their contribution to healthy wound repair is less well understood. This review discusses the evidence that the canonical type 2 cytokines, IL-4 and IL-13, are integral to the tissue repair process through two main pathways. First, essential for the progression of effective tissue repair, IL-4 and IL-13 suppress the initial inflammatory response to injury. Second, these cytokines regulate how the extracellular matrix is modified, broken down, and rebuilt for effective repair. IL-4 and/or IL-13 amplifies multiple aspects of the tissue repair response, but many of these pathways are highly redundant and can be induced by other signals. Therefore, the exact contribution of IL-4Rα signaling remains difficult to unravel.

Novel Biomarkers, Including tcdB PCR Cycle Threshold, for Predicting Recurrent Clostridioides difficile Infection

Traditional clinical models for predicting recurrent Clostridioides difficile infection do not perform well, likely owing to the complex host-pathogen interactions involved. Accurate risk stratification using novel biomarkers could help prevent recurrence by improving underutilization of effective therapies (i.e., fecal transplant, fidaxomicin, bezlotoxumab). We used a biorepository of 257 hospitalized patients with 24 features collected at diagnosis, including 17 plasma cytokines, total/neutralizing anti-toxin B IgG, stool toxins, and PCR cycle threshold (CT) (a proxy for stool organism burden). The best set of predictors for recurrent infection was selected by Bayesian model averaging for inclusion in a final Bayesian logistic regression model. We then used a large PCR-only data set to confirm the finding that PCR CT predicts recurrence-free survival using Cox proportional hazards regression. The top model-averaged features were (probabilities of >0.05, greatest to least): interleukin 6 (IL-6), PCR CT, endothelial growth factor, IL-8, eotaxin, IL-10, hepatocyte growth factor, and IL-4. The accuracy of the final model was 0.88. Among 1,660 cases with PCR-only data, cycle threshold was significantly associated with recurrence-free survival (hazard ratio, 0.95; P < 0.005). Certain biomarkers associated with C. difficile infection severity were especially important for predicting recurrence; PCR CT and markers of type 2 immunity (endothelial growth factor [EGF], eotaxin) emerged as positive predictors of recurrence, while type 17 immune markers (IL-6, IL-8) were negative predictors. In addition to novel serum biomarkers (particularly, IL-6, EGF, and IL-8), the readily available PCR CT may be critical to augment underperforming clinical models for C. difficile recurrence.

Identification of a broadly fibrogenic macrophage subset induced by type 3 inflammation

Macrophages are central orchestrators of the tissue response to injury, with distinct macrophage activation states playing key roles in fibrosis progression and resolution. Identifying key macrophage populations found in human fibrotic tissues could lead to new treatments for fibrosis. Here, we used human liver and lung single-cell RNA sequencing datasets to identify a subset of CD9⁺TREM2⁺ macrophages that express SPP1, GPNMB, FABP5, and CD63. In both human and murine hepatic and pulmonary fibrosis, these macrophages were enriched at the outside edges of scarring and adjacent to activated mesenchymal cells. Neutrophils expressing MMP9, which participates in the activation of TGF-β1, and the type 3 cytokines GM-CSF and IL-17A coclustered with these macrophages. In vitro, GM-CSF, IL-17A, and TGF-β1 drive the differentiation of human monocytes into macrophages expressing scar-associated markers. Such differentiated cells could degrade collagen IV but not collagen I and promote TGF-β1-induced collagen I deposition by activated mesenchymal cells. In murine models blocking GM-CSF, IL-17A or TGF-β1 reduced scar-associated macrophage expansion and hepatic or pulmonary fibrosis. Our work identifies a highly specific macrophage population to which we assign a profibrotic role across species and tissues. It further provides a strategy for unbiased discovery, triage, and preclinical validation of therapeutic targets based on this fibrogenic macrophage population.

Modes of type 2 immune response initiation

Type 2 immunity defends against macro-parasites and can cause allergic diseases. Our understanding of the mechanisms governing the initiation of type 2 immunity is limited, whereas we know more about type 1 immune responses. Type 2 immunity can be triggered by a wide array of inducers that do not share common features and via diverse pathways and mechanisms. To address the complexity of the type 2 initiation pathways, we suggest a framework that conceptualizes different modes of induction of type 2 immunity. We discuss categories of type 2 inducers and their immunogenicity, types of tissue perturbations that are caused by these inducers, sensing strategies for the initiation of Th2 immune responses, and categorization of the signals that are produced in response to type 2 challenges. We describe tissue-specific examples of functional disruption that could lead to type 2 inflammation and propose that different sensing strategies that operate at the tissue level converge on the initiation of type 2 immune responses.

Skin disorders and interstitial lung disease: Part I-Screening, diagnosis, and therapeutic principles

Numerous inflammatory, neoplastic, and genetic skin disorders are associated with interstitial lung disease (ILD), the fibrosing inflammation of lung parenchyma that has significant morbidity and mortality. Therefore, the dermatologist plays a major role in the early detection and appropriate referral of patients at risk for ILD. Part 1 of this 2-part CME outlines the pathophysiology of ILD and focuses on clinical screening and therapeutic principles applicable to dermatological patients who are at risk for ILD. Patients with clinical symptoms of ILD should be screened with pulmonary function tests and high-resolution chest computed tomography. Screening for pulmonary hypertension should be considered in high-risk patients. Early identification and elimination of pulmonary risk factors, including smoking and gastroesophageal reflux disease, are essential in improving respiratory outcomes. First-line treatment interventions for ILD in a dermatological setting include mycophenolate mofetil, but the choice of therapeutic agents depends on the nature of the primary disease, the severity of ILD, and comorbidities and should be the result of a multidisciplinary assessment. Better awareness of ILD among medical dermatologists and close interdisciplinary collaborations are likely to prevent treatment delays improving long-term outcomes.

Interleukin-2 family cytokines: An overview of genes, expression, signaling and functional roles in teleost

The interleukin-2 (IL-2) family cytokines include IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21, which share γ chain (γc) subunit in receptors. The IL-2 family cytokines have unique biological effects that regulate differentiation, survival and activation of multiple lymphocyte lineages. Deficiency of IL-2 family signaling pathway in mammals prevents CD4⁺ T cells from developing effector functions and CD8⁺ T cells from developing immunological memory. In the present review, we addressed available information from teleost IL-2 family cytokines and discussed implications in teleost immunity. Also, we described and discussed their expression profiles, receptors, signaling transductions and functions. In teleost, IL-2 family has 5 members (IL-2, IL-4/13, IL-7, IL-15, IL-21) without IL-9, and their receptors share a common γc subunit and include other 6 subunits (IL-2Rβ1/2, IL-4Rα1/2, IL-13Rα1/2, IL-7Rα, IL-15Rα, and IL-21Rα1/2). Some paralogues have changes in domain structure and show differential expression, modulation, functions. IL-2 family cytokines constitutively express in many immune associated tissues and are largely induced after pathogenic microbial stimulation. In general, there are relatively conserved functions in the IL-2 family throughout vertebrates, and many of the key IL-2 family members are important in lymphocyte proliferation and differentiation, development, inflammation from fishes to mammals. This review will give an update on the effective information of teleost IL-2 family cytokines. Thus, it will provide a source of reference for other researchers/readers and inspire further interest.

Helminth-associated changes in host immune phenotype connect top-down and bottom-up interactions during co-infection

1. Within-host parasite interactions can be mediated by the host and changes in host phenotypes often serve as indicators of the presence or intensity of parasite interactions. 2. Parasites like helminths induce a range of physiological, morphological, and immunological changes in hosts that can drive bottom-up (resource-mediated) or top-down (immune-mediated) interactions with co-infecting parasites. Although top-down and bottom-up interactions are typically studied in isolation, the diverse phenotypic changes induced by parasite infection may serve as a useful tool for understanding if, and when, these processes act in concert. 3. Using an anthelmintic treatment study of African buffalo (Syncerus caffer), we tracked changes in host immunological and morphological phenotypes during helminth-coccidia co-infection to investigate their role in driving independent and combinatorial bottom-up and top-down parasite interactions. We also examined repercussions for host fitness. 4. Clearance of a blood-sucking helminth, Haemonchus, from the host gastrointestinal tract induced a systemic Th2 immune phenotype, while clearance of a tissue-feeding helminth, Cooperia, induced a systemic Th1 phenotype. Furthermore, the Haemonchus-associated systemic Th2 immune phenotype drove simultaneous top-down and bottom-up effects that increased coccidia shedding by changing the immunological and morphological landscapes of the intestine. 5. Higher coccidia shedding was associated with lower host body condition, a lower chance of pregnancy, and older age at first pregnancy, suggesting that coccidia infection imposed significant condition and reproductive costs on the host. 6. Our findings suggest that top-down and bottom-up interactions may commonly co-occur and that tracking key host phenotypes that change in response to infection can help uncover complex pathways by which parasites interact.

Effect of CCR2 Knockout on Tendon Biomechanical Properties in a Mouse Model of Delayed Rotator Cuff Repair

BACKGROUND

The high incidence of incomplete or failed healing after rotator cuff repair (RCR) has led to an increased focus on the biologic factors that affect tendon-to-bone healing. Inflammation plays a critical role in the initial tendon-healing response. C-C chemokine receptor type 2 (CCR2) is a chemokine receptor linked to the recruitment of monocytes in early inflammatory stages and is associated with an increase in pro-inflammatory macrophages. The purpose of this study was to evaluate the role of CCR2 in tendon healing following RCR in C57BL/6J wildtype (WT) and CCR2-/- knockout (CCR2KO) mice in a delayed RCR model.

METHODS

Fifty-two 12-week-old, male mice were allocated to 2 groups (WT and CCR2KO). All mice underwent unilateral supraspinatus tendon (SST) detachment at the initial surgical procedure, followed by a delayed repair 2 weeks later. The primary outcome measure was biomechanical testing. Secondary measures included histology, gene expression analysis, flow cytometry, and gait analysis.

RESULTS

The mean load-to-failure was 1.64 ± 0.41 N in the WT group and 2.50 ± 0.42 N in the CCR2KO group (p = 0.030). The mean stiffness was 1.43 ± 0.66 N/mm in the WT group and 3.00 ± 0.95 N/mm in the CCR2KO group (p = 0.008). Transcriptional profiling demonstrated 7 differentially expressed genes (DEGs) when comparing the CCR2KO and WT groups (p < 0.05) and significant differences in Type-I and Type-II interferon pathway scores (p < 0.01). Flow cytometry demonstrated significant differences between groups for the percentage of macrophages present (8.1% for the WT group compared with 5.8% for the CCR2KO group; p = 0.035). Gait analysis demonstrated no significant differences between groups.

CONCLUSIONS

CCR2KO may potentially improve tendon biomechanical properties by decreasing macrophage infiltration and/or by suppressing inflammatory mediator pathways in the setting of delayed RCR.

CLINICAL RELEVANCE

CCR2 may be a promising target for novel therapeutics that aim to decrease failure rates following RCR.

Dietary gluten worsens hepatic steatosis by increasing inflammation and oxidative stress in ApoE-/- mice fed a high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disorder in the world. We have seen that gluten intake exacerbated obesity and atherosclerosis in apolipoprotein E knockout (ApoE-/-) mice. In this study, we investigated the effect of gluten consumption on inflammation and oxidative stress in the liver of mice with NAFLD. Male ApoE-/- mice were fed a gluten-free (GF-HFD) or gluten-containing (G-HFD) high-fat diet for 10 weeks. Blood, liver, and spleen were collected to perform the analyses. The animals of the gluten group had increased hepatic steatosis, followed by increased serum AST and ALT. Gluten intake increased hepatic infiltration of neutrophils, macrophages, and eosinophils, as well as the levels of chemotaxis-related factors CCL2, Cxcl2, and Cxcr3. The production of the TNF, IL-1β, IFNγ, and IL-4 cytokines in the liver was also increased by gluten intake. Furthermore, gluten exacerbated the hepatic lipid peroxidation and nitrotyrosine deposition, which were associated with increased production of ROS and nitric oxide. These effects were related to increased expression of NADPH oxidase and iNOS, as well as decreased activity of superoxide dismutase and catalase enzymes. There was an increased hepatic expression of the NF-κB and AP1 transcription factors, corroborating the worsening effect of gluten on inflammation and oxidative stress. Finally, we found an increased frequency of CD4+FOXP3+ lymphocytes in the spleen and increased gene expression of Foxp3 in the livers of the G-HFD group. In conclusion, dietary gluten aggravates NAFLD, exacerbating hepatic inflammation and oxidative stress in obese ApoE-deficient mice.

Myofibroblast Ccn3 is regulated by Yap and Wwtr1 and contributes to adverse cardiac outcomes

Introduction

While Yap and Wwtr1 regulate resident cardiac fibroblast to myofibroblast differentiation following cardiac injury, their role specifically in activated myofibroblasts remains unexplored.

Methods

We assessed the pathophysiological and cellular consequence of genetic depletion of Yap alone (Yap fl/fl ;Postn MCM ) or Yap and Wwtr1 (Yap fl/fl ;Wwtr1 fl/+ ;Postn MCM ) in adult mouse myofibroblasts following myocardial infarction and identify and validate novel downstream factors specifically in cardiac myofibroblasts that mediate pathological remodeling.

Results

Following myocardial infarction, depletion of Yap in myofibroblasts had minimal effect on heart function while depletion of Yap/Wwtr1 resulted in smaller scars, reduced interstitial fibrosis, and improved ejection fraction and fractional shortening. Single cell RNA sequencing of interstitial cardiac cells 7 days post infarction showed suppression of pro-fibrotic genes in fibroblasts derived from Yap fl/fl ,Wwtr1 fl/+ ;Postn MCM hearts. In vivo myofibroblast depletion of Yap/Wwtr1 as well in vitro knockdown of Yap/Wwtr1 dramatically decreased RNA and protein expression of the matricellular factor Ccn3. Administration of recombinant CCN3 to adult mice following myocardial infarction remarkably aggravated cardiac function and scarring. CCN3 administration drove myocardial gene expression of pro-fibrotic genes in infarcted left ventricles implicating CCN3 as a novel driver of cardiac fibrotic processes following myocardial infarction.

Discussion

Yap/Wwtr1 depletion in myofibroblasts attenuates fibrosis and significantly improves cardiac outcomes after myocardial infarction and we identify Ccn3 as a factor downstream of Yap/Wwtr1 that contributes to adverse cardiac remodeling post MI. Myofibroblast expression of Yap, Wwtr1, and Ccn3 could be further explored as potential therapeutic targets for modulating adverse cardiac remodeling post injury.

Salmonella typhimurium exacerbates injuries but resolves fibrosis in liver and spleen during Schistosoma mansoni infection

BACKGROUND

In most developing or undeveloped countries, patients are often co-infected with multiple pathogens rather than a single pathogen. While different pathogens have their impact on morbidity and mortality, co-infection of more than one pathogen usually made the disease outcome different. Many studies reported the co-infection of Schistosoma with Salmonella in pandemic areas. However, the link or the underlying mechanism in the pathogenesis caused by Schistosoma-Salmonella co-infection is still unknown.

METHODS

In this study, Salmonella typhimurium (S. typhimurium) was challenged to Schistosoma mansoni (S. mansoni)-infected mice. Further experiments such as bacterial culture, histopathological examination, western blotting, and flow cytometry were performed to evaluate the outcomes of the infection. Cytokine responses of the mice were also determined by ELISA and real-time quantitative PCR.

RESULTS

Our results demonstrated that co-infected mice resulted in higher bacterial excretion in the acute phase but higher bacterial colonization in the chronic phase. Lesser egg burden was also observed during chronic schistosomiasis. Infection with S. typhimurium during schistosomiasis induces activation of the inflammasome and apoptosis, thereby leading to more drastic tissue damage. Interestingly, co-infected mice showed a lower fibrotic response in the liver and spleen. Further, co-infection alters the immunological functioning of the mice, possibly the reason for the observed pathological outcomes.

CONCLUSION

Collectively, our findings here demonstrated that S. mansoni-infected mice challenged with S. typhimurium altered their immunological responses, thereby leading to different pathological outcomes.

Stromal Reprogramming through Dual PDGFRα/β Blockade Boosts the Efficacy of Anti-PD-1 Immunotherapy in Fibrotic Tumors

Excess stroma and cancer-associated fibroblasts (CAF) enhance cancer progression and facilitate immune evasion. Insights into the mechanisms by which the stroma manipulates the immune microenvironment could help improve cancer treatment. Here, we aimed to elucidate potential approaches for stromal reprogramming and improved cancer immunotherapy. Platelet-derived growth factor C (PDGFC) and D expression were significantly associated with a poor prognosis in patients with gastric cancer, and PDGF receptor beta (PDGFRβ) was predominantly expressed in diffuse-type gastric cancer stroma. CAFs stimulated with PDGFs exhibited markedly increased expression of CXCL1, CXCL3, CXCL5, and CXCL8, which are involved in polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC) recruitment. Fibrotic gastric cancer xenograft tumors exhibited increased PMN-MDSC accumulation and decreased lymphocyte infiltration, as well as resistance to anti-PD-1. Single-cell RNA sequencing and spatial transcriptomics revealed that PDGFRα/β blockade reversed the immunosuppressive microenvironment through stromal modification. Finally, combining PDGFRα/β blockade and anti-PD-1 treatment synergistically suppressed the growth of fibrotic tumors. These findings highlight the impact of stromal reprogramming on immune reactivation and the potential for combined immunotherapy for patients with fibrotic cancer.

SIGNIFICANCE

Stromal targeting with PDGFRα/β dual blockade reverses the immunosuppressive microenvironment and enhances the efficacy of immune checkpoint inhibitors in fibrotic cancer. See related commentary by Tauriello, p. 655.

Molecular methods to study protein trafficking between organs

Interorgan communication networks are key regulators of organismal homeostasis, and their dysregulation is associated with a variety of pathologies. While mass spectrometry proteomics identifies circulating proteins and can correlate their abundance with disease phenotypes, the tissues of origin and destinations of these secreted proteins remain largely unknown. In vitro approaches to study protein secretion are valuable, however, they may not mimic the complexity of in vivo environments. More recently, the development of engineered promiscuous BirA* biotin ligase derivatives has enabled tissue-specific tagging of cellular secreted proteomes in vivo. The use of biotin as a molecular tag provides information on the tissue of origin and destination, and enables the enrichment of low-abundance hormone proteins. Therefore, promiscuous protein biotinylation is a valuable tool to study protein secretion in vivo.

Peripheral Immunophenotype in IgG4-Related Disease and Its Association with Clinical Phenotypes and Disease Activity

Diverse immune cell subsets have been described in IgG4-related disease (IgG4-RD). If there is a different immunophenotype according to clinical phenotype and activity status is not known. Levels of IL-4-, IL-13-, IL-5-, and IL-21-producing CD4+ T cells (Th2 subsets), CD4+ cytotoxic T lymphocytes (CD4+CTLs), T helper 9 cells, T follicular helper cells (Tfh; Tfh1/Tfh2/Tfh17/Tf regulatory [Tfr]), Foxp3+ regulatory T cells, Type 1 regulatory T cells (Tr1), T helper 3 regulatory cells (Th3), IL-10-producing regulatory B cells (Bregs), IL-10-expressing regulatory plasmacytoid dendritic (pDC IL-10+) cells, and M1 and M2 monocytes were determined by flow cytometry in 43 IgG4-RD patients and 12 controls. All immune subsets were higher in patients vs. controls. CD4+/IL-4+, CD4+/IL-5+, CD4+CTLs, Tfh2, Tfh17, Tfr, and M1 monocyte cell number was different among IgG4-RD clinical phenotypes. The pancreato-hepato-biliary phenotype was characterized by a higher CD4+CTLs, Tfh17, Tfh2, and Tfr and lower M1 cell number. An increased CD4+CTLs and Th3 cell number distinguished the head and neck-limited phenotype, while the retroperitoneal/aortic and Mikulicz/systemic phenotypes were characterized by increased Th2 subsets. Tfh17, Tr1, Th3, pDC, M1, and M2 monocytes were augmented in active patients. In summary, the clinical heterogeneity of IgG4-RD might be driven by the participation of different immunophenotypes and, consequently, by a different fibroinflammatory process.

The extracellular matrix and the immune system: A mutually dependent relationship

For decades, immunologists have studied the role of circulating immune cells in host protection, with a more recent appreciation of immune cells resident within the tissue microenvironment and the intercommunication between nonhematopoietic cells and immune cells. However, the extracellular matrix (ECM), which comprises at least a third of tissue structures, remains relatively underexplored in immunology. Similarly, matrix biologists often overlook regulation of complex structural matrices by the immune system. We are only beginning to understand the scale at which ECM structures determine immune cell localization and function. Additionally, we need to better understand how immune cells dictate ECM complexity. This review aims to highlight the potential for biological discovery at the interface of immunology and matrix biology.

Role of Nasal Fibroblasts in Airway Remodeling of Chronic Rhinosinusitis: The Modulating Functions Reexamined

Chronic rhinosinusitis (CRS) is a multifactorial inflammatory disease of the nose and sinuses that affects more than 10% of the adult population worldwide. Currently, CRS is classified into endotypes according to the inflammatory response (Th1, Th2, and Th17) or the distribution of immune cells in the mucosa (eosinophilic and non-eosinophilic). CRS induces mucosal tissue remodeling. Extracellular matrix (ECM) accumulation, fibrin deposition, edema, immune cell infiltration, and angiogenesis are observed in the stromal region. Conversely, epithelial-to-mesenchymal transition (EMT), goblet cell hyperplasia, and increased epithelial permeability, hyperplasia, and metaplasia are found in the epithelium. Fibroblasts synthesize collagen and ECM, which create a structural skeleton of tissue and play an important role in the wound-healing process. This review discusses recent knowledge regarding the modulation of tissue remodeling by nasal fibroblasts in CRS.

Bioengineered liver crosslinked with nano-graphene oxide enables efficient liver regeneration via MMP suppression and immunomodulation

Decellularized extracellular matrix scaffold, widely utilized for organ engineering, often undergoes matrix decomposition after transplantation and produces byproducts that cause inflammation, leading to clinical failure. Here we propose a strategy using nano-graphene oxide to modify the biophysical properties of decellularized liver scaffolds. Notably, we demonstrate that scaffolds crosslinked with nano-graphene oxide show high resistance to enzymatic degradation via direct inhibition of matrix metalloproteinase activity and increased mechanical rigidity. We find that M2-like macrophage polarization is promoted within the crosslinked scaffolds, which reduces graft-elicited inflammation. Moreover, we show that low activities of matrix metalloproteinases, attributed to both nano-graphene oxide and tissue inhibitors of metalloproteinases expressed by M2c, can protect the crosslinked scaffolds against in vivo degradation. Lastly, we demonstrate that bioengineered livers fabricated with the crosslinked scaffolds remain functional, thereby effectively regenerating damaged livers after transplantation into liver failure mouse models. Overall, nano-graphene oxide crosslinking prolongs allograft survival and ultimately improves therapeutic effects of bioengineered livers, which offer an alternative for donor organs.

Review: Research progress of adipose-derived stem cells in the treatment of chronic wounds

Although methods are used to treat wounds clinically, there are still many challenges in the treatment of chronic wounds due to excessive inflammatory response, difficulties in epithelialization, vascularization, and other factors. With the increasing research on adipose-derived stem cells (ADSCs) in recent years, accumulating evidence has shown that ADSCs scan promotes the healing of chronic wounds by regulating macrophage function and cellular immunity and promoting angiogenesis and epithelialization. The present study reviewed the difficulties in the treatment of chronic wounds, as well as the advantages and the mechanism of ADSCs in promoting the healing of chronic wounds, to provide a reference for the stem cell therapy of chronic wounds.

Remodeling and Restraining Lung Tissue Damage Through the Regulation of Respiratory Immune Responses

Tissue damage caused by various stimuli under certain conditions, such as biological and environmental cues, can actively induce systemic and/or local immune responses. Therefore, understanding the immunological perspective would be critical to not only regulating homeostasis of organs and tissues but also to restrict and remodel their damage. Lungs serve as one of the key immunological organs, and thus, in the present article, we focus on the innate and adaptive immune systems involved in remodeling and engineering lung tissue. Innate immune cells are known to react immediately to damage. Macrophages, one of the most widely studied types of innate immune cells, are known to be involved in tissue damage and remodeling, while type 2 innate lymphoid cells (ILC2s) have recently been revealed as an important cell type responsible for tissue remodeling. On the other hand, adaptive immune cells are also involved in damage control. In particular, resident memory T cells in the lung prevent prolonged disease that causes tissue damage. In this review, we first outlined the structure of the respiratory system with biological and environmental cues and the innate/adaptive immune responses in the lung. It is our hope that understanding an immunological perspective for tissue remodeling and damage control in the lung will be beneficial for stakeholders in this area.

The contradictory roles of macrophages in non-alcoholic fatty liver disease and primary liver cancer-Challenges and opportunities

Chronic liver diseases from varying etiologies generally lead to liver fibrosis and cirrhosis. Among them, non-alcoholic fatty liver disease (NAFLD) affects roughly one-quarter of the world population, thus representing a major and increasing public health burden. Chronic hepatocyte injury, inflammation (non-alcoholic steatohepatitis, NASH) and liver fibrosis are recognized soils for primary liver cancer, particularly hepatocellular carcinoma (HCC), being the third most common cause for cancer-related deaths worldwide. Despite recent advances in liver disease understanding, therapeutic options on pre-malignant and malignant stages remain limited. Thus, there is an urgent need to identify targetable liver disease-driving mechanisms for the development of novel therapeutics. Monocytes and macrophages comprise a central, yet versatile component of the inflammatory response, fueling chronic liver disease initiation and progression. Recent proteomic and transcriptomic studies performed at singular cell levels revealed a previously overlooked diversity of macrophage subpopulations and functions. Indeed, liver macrophages that encompass liver resident macrophages (also named Kupffer cells) and monocyte-derived macrophages, can acquire a variety of phenotypes depending on microenvironmental cues, and thus exert manifold and sometimes contradictory functions. Those functions range from modulating and exacerbating tissue inflammation to promoting and exaggerating tissue repair mechanisms (i.e., parenchymal regeneration, cancer cell proliferation, angiogenesis, fibrosis). Due to these central functions, liver macrophages represent an attractive target for the treatment of liver diseases. In this review, we discuss the multifaceted and contrary roles of macrophages in chronic liver diseases, with a particular focus on NAFLD/NASH and HCC. Moreover, we discuss potential therapeutic approaches targeting liver macrophages.

Immunomodulatory Biomaterials and Emerging Analytical Techniques for Probing the Immune Micro-Environment

After implantation of a biomaterial, both the host immune system and properties of the material determine the local immune response. Through triggering or modulating the local immune response, materials can be designed towards a desired direction of promoting tissue repair or regeneration. High-throughput sequencing technologies such as single-cell RNA sequencing (scRNA-seq) emerging as a powerful tool for dissecting the immune micro-environment around biomaterials, have not been fully utilized in the field of soft tissue regeneration. In this review, we first discussed the procedures of foreign body reaction in brief. Then, we summarized the influences that physical and chemical modulation of biomaterials have on cell behaviors in the micro-environment. Finally, we discussed the application of scRNA-seq in probing the scaffold immune micro-environment and provided some reference to designing immunomodulatory biomaterials. The foreign body response consists of a series of biological reactions. Immunomodulatory materials regulate immune cell activation and polarization, mediate divergent local immune micro-environments and possess different tissue engineering functions. The manipulation of physical and chemical properties of scaffolds can modulate local immune responses, resulting in different outcomes of fibrosis or tissue regeneration. With the advancement of technology, emerging techniques such as scRNA-seq provide an unprecedented understanding of immune cell heterogeneity and plasticity in a scaffold-induced immune micro-environment at high resolution. The in-depth understanding of the interaction between scaffolds and the host immune system helps to provide clues for the design of biomaterials to optimize regeneration and promote a pro-regenerative local immune micro-environment.

Decreased Th1 Cells and Increased Th2 Cells in Peripheral Blood Are Associated with Idiopathic Inflammatory Myopathies Patients with Interstitial Lung Disease

Interstitial lung disease (ILD) is a highly fatal manifestation of idiopathic inflammatory myopathies (IIMs). Th cells play important roles in the initiation of ILD. Here, we investigated the clinical significance of peripheral blood Th cells in IIMs-ILD patients. Eleven healthy controls (HC) and 53 patients diagnosed with IIMs were included, including 30 with ILD (IIMs-ILD) and 23 without ILD (IIMs-non-ILD). Circulating Th1, Th2, Th17, and Treg cells were examined by flow cytometry, and their correlation with clinical and laboratory findings was analyzed by Spearman's correlation and logistic regression. The proportion of Th1 cells decreased and Th2 cells increased in IIMs-ILD compared with IIMs-non-ILD (median (quartile): 2.99 (1.59-5.39) vs. 6.91 (3.48-10.04), p < 0.001; 2.67 (1.79-4.67) vs. 1.62 (0.85-2.66), p = 0.006) and correlated with disease activity. The Th1-cell proportion decreased in anti-MDA5 antibody-positive patients, while the Th2 cell proportion increased in patients with nonspecific interstitial pneumonia compared with IIMs-non-ILD (2.66 (1.06-4.35) vs. 6.91 (3.48-10.04), p = 0.002; 3.09 (2.03-5.72) vs. 1.62 (0.85-2.66), p = 0.016). Univariate analysis showed that a lower Th1 proportion, higher Th2 proportion increased, lower CK level, positivity for ARS, or anti-Ro52 antibodies (OR = 0.7122; OR = 1.679; OR = 0.9993; OR = 9.188; and OR = 6.161, respectively) were associated with the occurrence of ILD in IIMs patients. Decreased Th1 cells and elevated Th2 cells in peripheral blood may be involved in the pathogenesis of ILD in IIMs patients and have different effects on different serological and imaging subtypes.

Mesenchymal stem cells in fibrotic diseases-the two sides of the same coin

Fibrosis is caused by extensive deposition of extracellular matrix (ECM) components, which play a crucial role in injury repair. Fibrosis attributes to ~45% of all deaths worldwide. The molecular pathology of different fibrotic diseases varies, and a number of bioactive factors are involved in the pathogenic process. Mesenchymal stem cells (MSCs) are a type of multipotent stem cells that have promising therapeutic effects in the treatment of different diseases. Current updates of fibrotic pathogenesis reveal that residential MSCs may differentiate into myofibroblasts which lead to the fibrosis development. However, preclinical and clinical trials with autologous or allogeneic MSCs infusion demonstrate that MSCs can relieve the fibrotic diseases by modulating inflammation, regenerating damaged tissues, remodeling the ECMs, and modulating the death of stressed cells after implantation. A variety of animal models were developed to study the mechanisms behind different fibrotic tissues and test the preclinical efficacy of MSC therapy in these diseases. Furthermore, MSCs have been used for treating liver cirrhosis and pulmonary fibrosis patients in several clinical trials, leading to satisfactory clinical efficacy without severe adverse events. This review discusses the two opposite roles of residential MSCs and external MSCs in fibrotic diseases, and summarizes the current perspective of therapeutic mechanism of MSCs in fibrosis, through both laboratory study and clinical trials.

Diminished Tubule Epithelial Farnesoid X Receptor Expression Exacerbates Inflammation and Fibrosis Response in Aged Rat Kidney

The age-associated functional decline of the kidney is accompanied by structural changes including glomerular sclerosis and interstitial fibrosis. Aging kidneys also exhibit increased vulnerability in stressful environmental conditions. In this study, we assessed the differences in responses between young and aged animals to folic acid (FA)-induced renal fibrosis. To monitor the effects of aging on FA-induced kidney fibrosis, we administered FA (250 mg/kg) to young (6-month old) and aged (20-month old) rats. The development of severe fibrosis was only detected in aged rat kidneys, which was accompanied by increased kidney injury and inflammation. Furthermore, we found that FA-treated aged rats had significantly lower farnesoid X receptor (FXR) expression in the tubular epithelial cells than the rats not treated with FA. Interestingly, the extent of inflammation was severe in the kidneys of aged rat, where the FXR expression was low. To explore the role of FXR in kidney inflammation, in vitro studies were performed using NRK52E kidney tubule epithelial cells. NF-κB activation by lipopolysaccharide treatment induces chemokine production in NRK52E cells. The activation of FXR by obeticholic acid significantly reduced the transcriptional activity of NF-κB and chemokine production. In contrast, FXR knockdown increased LPS-induced chemokine production in NRK52E cells. Finally, FXR-knockout mice that were administered FA showed increased inflammation and severe fibrosis. In summary, we demonstrated that diminished FXR expression in the epithelial cells of the renal tubules exacerbated the fibrotic response in aged rat kidneys by upregulating pro-inflammatory NF-κB activation.

Clonorchis sinensis aggravates biliary fibrosis through promoting IL-6 production via toll-like receptor 2-mediated AKT and p38 signal pathways

Clonorchis sinensis is an important food-borne zoonotic parasite which has been linked to biliary fibrosis and cholangiocarcinoma. However, the details of the pathogenesis of C. sinensis were unclear. To explore the role and regulatory mechanism of toll-like receptor 2 (TLR2) in C. sinensis-induced biliary fibrosis, we established the C. sinensis-infected C57BL/6 mouse model with TLR2-/- and wild type (WT) mice. The mortality rate, liver lesions, TLR2 and TGF-β1 expression, phosphorylation of Smad2/3, AKT, p38, ERK and p65, and cytokine productions were analyzed. Furthermore, similar parameters were examined in mouse biliary epithelial cells (BECs) co-cultured with C. sinensis excretory/secretory proteins (ESPs). The results showed that TLR2 expression was enhanced significantly in C. sinensis-infected WT mice and mouse BECs. C. sinensis-infected TLR2-/- mice exhibited an increased weight and a decreased mortality rate; significantly alleviated liver lesions and biliary fibrosis, reduced numbers of myofibroblasts; decreased expression of TGF-β1 and phosphorylation level of AKT, p38 and Smad2/3; significantly decreased production of IL-6, TNF-α and IL-4, while increased production of IFN-γ compared with C. sinensis-infected WT mice. Furthermore, C. sinensis ESPs could activate TLR2-mediated AKT and p38 pathways to increase the production of IL-6 in mouse BECs. In conclusion, these data indicate that C. sinensis infection activated TGF-β1-Smad2/3 through TLR2-mediated AKT and p38 pathways to promote IL-6 production, which resulted in myofibroblast activation and aggravating biliary fibrosis in mice.

The Wound Healing Potential of Lignosus rhinocerus and Other Ethno-myco Wound Healing Agents

Wound care has become increasingly important over the years. Various synthetic products for wound care treatment have been reported to cause toxic side effects and therefore natural products are in significant demand as they have minimal side effects. The presence of bioactive compounds in medicinal mushrooms contributes to various biological activities which assist in the early inflammatory phase, keratinocyte proliferation, and its migration enhancement which are pertinent to wound rehabilitation. Lignosus rhinocerus (tiger milk mushroom) can reduce the inflammation phase in wound healing by fighting off bacterial infection and modulating pro-inflammatory cytokines expression in the early stage to avoid prolonged inflammation and tissue damage. The antibacterial, immunomodulating, and anti-inflammatory activities exhibited by most macrofungi play a key role in enhancing wound healing. Several antibacterial and antifungal compounds sourced from traditional botanicals/products may prevent further complications and reoccurrence of injury to a wounded site. Scientific studies are actively underway to ascertain the potential use of macrofungi as a wound healing agent.

Immunology of Giant Cell Arteritis

Giant cell arteritis is an autoimmune disease of medium and large arteries, characterized by granulomatous inflammation of the three-layered vessel wall that results in vaso-occlusion, wall dissection, and aneurysm formation. The immunopathogenesis of giant cell arteritis is an accumulative process in which a prolonged asymptomatic period is followed by uncontrolled innate immunity, a breakdown in self-tolerance, the transition of autoimmunity from the periphery into the vessel wall and, eventually, the progressive evolution of vessel wall inflammation. Each of the steps in pathogenesis corresponds to specific immuno-phenotypes that provide mechanistic insights into how the immune system attacks and damages blood vessels. Clinically evident disease begins with inappropriate activation of myeloid cells triggering the release of hepatic acute phase proteins and inducing extravascular manifestations, such as muscle pains and stiffness diagnosed as polymyalgia rheumatica. Loss of self-tolerance in the adaptive immune system is linked to aberrant signaling in the NOTCH pathway, leading to expansion of NOTCH1+CD4+ T cells and the functional decline of NOTCH4+ T regulatory cells (Checkpoint 1). A defect in the endothelial cell barrier of adventitial vasa vasorum networks marks Checkpoint 2; the invasion of monocytes, macrophages and T cells into the arterial wall. Due to the failure of the immuno-inhibitory PD-1 (programmed cell death protein 1)/PD-L1 (programmed cell death ligand 1) pathway, wall-infiltrating immune cells arrive in a permissive tissues microenvironment, where multiple T cell effector lineages thrive, shift toward high glycolytic activity, and support the development of tissue-damaging macrophages, including multinucleated giant cells (Checkpoint 3). Eventually, the vascular lesions are occupied by self-renewing T cells that provide autonomy to the disease process and limit the therapeutic effectiveness of currently used immunosuppressants. The multi-step process deviating protective to pathogenic immunity offers an array of interception points that provide opportunities for the prevention and therapeutic management of this devastating autoimmune disease.

Unveiling IL-33/ST2 Pathway Unbalance in Cardiac Remodeling Due to Obesity in Zucker Fatty Rats

Obesity is an epidemic condition linked to cardiovascular disease severity and mortality. Fat localization and type represent cardiovascular risk estimators. Importantly, visceral fat secretes adipokines known to promote low-grade inflammation that, in turn, modulate its secretome and cardiac metabolism. In this regard, IL-33 regulates the functions of various immune cells through ST2 binding and-following its role as an immune sensor to infection and stress-is involved in the pro-fibrotic remodeling of the myocardium. Here we further investigated the IL-33/ST2 effects on cardiac remodeling in obesity, focusing on molecular pathways linking adipose-derived IL-33 to the development of fibrosis or hypertrophy. We analyzed the Zucker Fatty rat model, and we developed in vitro models to mimic the adipose and myocardial relationship. We demonstrated a dysregulation of IL-33/ST2 signaling in both adipose and cardiac tissue, where they affected Epac proteins and myocardial gene expression, linked to pro-fibrotic signatures. In Zucker rats, pro-fibrotic effects were counteracted by ghrelin-induced IL-33 secretion, whose release influenced transcription factor expression and ST2 isoforms balance regulation. Finally, the effect of IL-33 signaling is dependent on several factors, such as cell types' origin and the balancing of ST2 isoforms. Noteworthy, it is reasonable to state that considering IL-33 to have a unique protective role should be considered over-simplistic.

Analysis of ferroptosis-associated genes in Crohn's disease based on bioinformatics

Background

Ferroptosis, a novel mode of apoptosis has recently been shown to be associated with fibrosis, tumor, cardiovascular, and other diseases. In this study, using bioinformatic analysis, we identified ferroptosis genes associated with Crohn's disease (CD) and performed biological function analysis, identified potential drug targets, and provided new directions for the future treatment of CD.

Methods

Differential expression analysis was performed using the GSE186582 dataset from the Gene Expression Omnibus (GEO) database. Ferroptosis-associated genes were downloaded from the FerrDB database, and overlapping genes associated with CD and ferroptosis were extracted. Then, we performed functional enrichment analysis, constructed a protein-protein interaction network (PPI), identified the correlation between hub genes and immune infiltration, performed external validation using a second and third dataset (GSE102133, GSE95095), and identified potential therapeutic agents. Finally, we validated the protein expression levels of the identified hub genes by immunohistochemical staining in the colon tissues from CD and healthy participants.

Results

A total of 28 ferroptosis-associated genes associated with CD were identified in our analysis, which included 22 up-regulated and 6 down-regulated genes. Gene Ontology (GO) analysis showed that these genes are essential for the apical plasma membrane and amide transport, and Metascape analysis showed that these genes mainly act on IL-4 and IL-13 signaling pathways. Five hub genes, PTGS2, IL6, IL1B, NOS2, and IDO1, were identified by a protein interaction network, and external validation of these hub genes showed statistically significant differences in expression between the CD patients and normal participants (p < 0.05), and all AUC values were greater than 0.8. Further, we predicted the top 10 drugs used to treat CD. Immune infiltration results suggest that Hub gene is related to T cells, macrophages, dendritic cells, and other immune cells. Finally, the results of immunohistochemical experiments showed that the protein expression of the hub gene was higher in CD colon tissue than in normal subjects (p < 0.05).

Conclusion

Bioinformatics analysis showed that ferroptosis is closely related to the development of CD, and the prediction of potential drugs provides new targets for the treatment of CD. Moreover, five hub genes identified are potentially new and effective markers for the diagnosis of CD.

Epithelial-intrinsic defects in TGFβR signaling drive local allergic inflammation manifesting as eosinophilic esophagitis

Allergic diseases are a global health challenge. Individuals harboring loss-of-function variants in transforming growth factor-β receptor (TGFβR) genes have an increased prevalence of allergic disorders, including eosinophilic esophagitis. Allergic diseases typically localize to mucosal barriers, implicating epithelial dysfunction as a cardinal feature of allergic disease. Here, we describe an essential role for TGFβ in the control of tissue-specific immune homeostasis that provides mechanistic insight into these clinical associations. Mice expressing a TGFβR1 loss-of-function variant identified in atopic patients spontaneously develop disease that clinically, immunologically, histologically, and transcriptionally recapitulates eosinophilic esophagitis. In vivo and in vitro, TGFβR1 variant-expressing epithelial cells are hyperproliferative, fail to differentiate properly, and overexpress innate proinflammatory mediators, which persist in the absence of lymphocytes or external allergens. Together, our results support the concept that TGFβ plays a fundamental, nonredundant, epithelial cell-intrinsic role in controlling tissue-specific allergic inflammation that is independent of its role in adaptive immunity.

A potential three-gene-based diagnostic signature for idiopathic pulmonary fibrosis

Background: Idiopathic pulmonary fibrosis (IPF) is a life-threatening disease whose etiology remains unknown. This study aims to explore diagnostic biomarkers and pathways involved in IPF using bioinformatics analysis. Methods: IPF-related gene expression datasets were retrieved and downloaded from the NCBI Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened, and weighted correlation network analysis (WGCNA) was performed to identify key module and genes. Functional enrichment analysis was performed on genes in the clinically significant module. Then least absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine-recursive feature elimination (SVM-RFE) algorithms were run to screen candidate biomarkers. The expression and diagnostic value of the biomarkers in IPF were further validated in external test datasets (GSE110147). Results: 292 samples and 1,163 DEGs were screened to construct WGCNA. In WGCNA, the blue module was identified as the key module, and 59 genes in this module correlated highly with IPF. Functional enrichment analysis of blue module genes revealed the importance of extracellular matrix-associated pathways in IPF. IL13RA2, CDH3, and COMP were identified as diagnostic markers of IPF via LASSO and SVM-RFE. These genes showed good diagnostic value for IPF and were significantly upregulated in IPF. Conclusion: This study indicates that IL13RA2, CDH3, and COMP could serve as diagnostic signature for IPF and might offer new insights in the underlying diagnosis of IPF.

IL-10 is not anti-fibrotic but pro-fibrotic in endometriosis: IL-10 treatment of endometriotic stromal cells in vitro promotes myofibroblast proliferation and collagen type I protein expression

STUDY QUESTION

Is interleukin-10 (IL-10) anti-fibrotic in endometriosis?

SUMMARY ANSWER

IL-10 is not anti-fibrotic but pro-fibrotic in endometriosis, because IL-10 treatment of endometriotic stromal cells in vitro promotes myofibroblast proliferation and collagen type I protein expression.

WHAT IS KNOWN ALREADY

We previously showed that persistent activation of signal transducer and activator of transcription 3 (STAT3) via IL-6 trans-signaling promotes fibrosis of endometriosis. Studies showed marked anti-fibrotic effects of IL-10 via the STAT3 signaling pathway, which is generally considered to be anti-inflammatory, in various organs.

STUDY DESIGN, SIZE, DURATION

Endometrial and/or endometriotic samples of 54 patients who had histological evidence of deep endometriosis, and endometrial samples from 30 healthy fertile women were analyzed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The effects of IL-10/STAT3 signaling as well as inhibition of STAT3 activation by knockdown of STAT3 gene on the pro-fibrotic phenotype in endometrial and endometriotic stromal cells in vitro were investigated. Then, the effects of various time points of IL-10 treatment in combination with transforming growth factor (TGF)-β1 and/or IL-6/soluble IL-6 receptor (sIL-6R) on the profibrotic phenotype of endometrial and endometriotic stromal cells were investigated.

MAIN RESULTS AND THE ROLE OF CHANCE

IL-10 induced pro-fibrotic phenotype (cell proliferation, collagen type I synthesis, α-smooth muscle actin positive stress fibers and collagen gel contraction) of endometriotic stromal cells. Knockdown of STAT3 gene decreased the IL-10 induced pro-fibrotic phenotype of endometriotic stromal cells. In contrast, IL-10 had no significant effects on pro-fibrotic phenotype of endometrial stromal cells of healthy women. Sequential IL-10 treatment with or without TGF-β1 and/or IL-6/sIL-6R induced persistent activation of STAT3 and significantly increased proliferation of myofibroblasts (cells with α-smooth muscle actin positive stress fibers) and protein expression of collagen type I in endometriotic stromal cells. TGF-β1 and/or IL-6/sIL6RIL-6/sIL6R treatment significantly increased tissue inhibitor of metalloproteinase 1 (TIMP1) protein expression, whereas IL-10 had no significant effects. Knockdown of STAT3 gene significantly decreased the TGF-β1 and/or IL-6/sIL6R induced TIMP1 protein expression. In contrast, pre-treatment with IL-10 before TGF-β1 and/or IL-6/sIL-6R treatment and sequential IL-10 treatment with or without TGF-β1 and/or IL-6/sIL-6R significantly decreased proliferation of fibroblasts (cells without α-smooth muscle actin positive stress fibers) and collagen type I protein expression in endometrial stromal cells of healthy women.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Given the large number of complex interactions and signaling pathways of pro- and anti-inflammatory mediators that are involved in the pathophysiology of endometriosis, the present study investigated only a very small portion of the whole. Further in vivo studies are required to validate the present findings.

WIDER IMPLICATIONS OF THE FINDINGS

Inflammatory mediators in the pathophysiology of endometriosis have been extensively investigated as potential therapeutic targets. However, the present study showed that anti-inflammatory signals of IL-10 and IL-6 through persistent STAT3 activation may promote endometriosis fibrosis. Therapeutic strategies, such as suppression of 'inflammation', might dysregulate the cross-regulation of 'pro- and anti-inflammatory mediators', leading to detrimental effects in patients with endometriosis, such as fibrosis. To develop new, but not deleterious, therapeutic strategies, studies are required to investigate whether, how and what 'anti-inflammatory mediators' along with pro-inflammatory mediators are involved in individual patients with endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported in part by KARL STORZ SE & Co. KG (Tuttlingen, Germany). The authors have no conflict of interest to disclose.

The Role of Myofibroblasts in Physiological and Pathological Tissue Repair

Myofibroblasts are the construction workers of wound healing and repair damaged tissues by producing and organizing collagen/extracellular matrix (ECM) into scar tissue. Scar tissue effectively and quickly restores the mechanical integrity of lost tissue architecture but comes at the price of lost tissue functionality. Fibrotic diseases caused by excessive or persistent myofibroblast activity can lead to organ failure. This review defines myofibroblast terminology, phenotypic characteristics, and functions. We will focus on the central role of the cell, ECM, and tissue mechanics in regulating tissue repair by controlling myofibroblast action. Additionally, we will discuss how therapies based on mechanical intervention potentially ameliorate wound healing outcomes. Although myofibroblast physiology and pathology affect all organs, we will emphasize cutaneous wound healing and hypertrophic scarring as paradigms for normal tissue repair versus fibrosis. A central message of this review is that myofibroblasts can be activated from multiple cell sources, varying with local environment and type of injury, to either restore tissue integrity and organ function or create an inappropriate mechanical environment.

Emerging role for branched-chain amino acids metabolism in fibrosis

Fibrosis is a common pathological feature of organ diseases resulting from excessive production of extracellular matrix, which accounts for significant morbidity and mortality. However, there is currently no effective treatment targeting fibrogenesis. Recently, metabolic alterations are increasingly considered as essential factors underlying fibrogenesis, and especially research on metabolic regulation of amino acids is flourishing. Among them, branched-chain amino acids (BCAAs) are the most abundant essential amino acids, including leucine, isoleucine and valine, which play significant roles in the substance and energy metabolism and their regulation. Dysregulation of BCAAs metabolism has been proven to contribute to numerous diseases. In this review, we summarize the metabolic regulation of fibrosis and the changes in BCAAs metabolism secondary to fibrosis. We also review the effects and mechanisms of the BCAAs intervention, and its therapeutic targeting in hepatic, renal and cardiac fibrosis, with a focus on the fibrosis in liver and associated hepatocellular carcinoma.

Distinct T helper cell-mediated antitumor immunity: T helper 2 cells in focus

The adaptive arm of the immune system is crucial for appropriate antitumor immune responses. It is generally accepted that clusters of differentiation 4+ (CD4+) T cells, which mediate T helper (Th) 1 immunity (type 1 immunity), are the primary Th cell subtype associated with tumor elimination. In this review, we discuss evidence showing that antitumor immunity and better prognosis can be associated with distinct Th cell subtypes in experimental mouse models and humans, with a focus on Th2 cells. The aim of this review is to provide an overview and understanding of the mechanisms associated with different tumor outcomes in the face of immune responses by focusing on the (1) site of tumor development, (2) tumor properties (i. e., tumor metabolism and cytokine receptor expression), and (3) type of immune response that the tumor initially escaped. Therefore, we discuss how low-tolerance organs, such as lungs and brains, might benefit from a less tissue-destructive immune response mediated by Th2 cells. In addition, Th2 cells antitumor effects can be independent of CD8+ T cells, which would circumvent some of the immune escape mechanisms that tumor cells possess, like low expression of major histocompatibility-I (MHC-I). Finally, this review aims to stimulate further studies on the role of Th2 cells in antitumor immunity and briefly discusses emerging treatment options.

TH17 cell heterogeneity and its role in tissue inflammation

Since their discovery almost two decades ago, interleukin-17-producing CD4+ T cells (TH17 cells) have been implicated in the pathogenesis of multiple autoimmune and inflammatory disorders. In addition, TH17 cells have been found to play an important role in tissue homeostasis, especially in the intestinal mucosa. Recently, the use of single-cell technologies, along with fate mapping and various mutant mouse models, has led to substantial progress in the understanding of TH17 cell heterogeneity in tissues and of TH17 cell plasticity leading to alternative T cell states and differing functions. In this Review, we discuss the heterogeneity of TH17 cells and the role of this heterogeneity in diverse functions of TH17 cells from homeostasis to tissue inflammation. In addition, we discuss TH17 cell plasticity and its incorporation into the current understanding of T cell subsets and alternative views on the role of TH17 cells in autoimmune and inflammatory diseases.

Spatiotemporal Regulation of the Bone Immune Microenvironment via Dam-Like Biphasic Bionic Periosteum for Bone Regeneration

The bone immune microenvironment (BIM) regulates bone regeneration and affects the prognosis of fractures. However, there is currently no effective strategy that can precisely modulate macrophage polarization to improve BIM for bone regeneration. Herein, a hybridized biphasic bionic periosteum, inspired by the BIM and functional structure of the natural periosteum, is presented. The gel phase is composed of genipin-crosslinked carboxymethyl chitosan and collagen self-assembled hybrid hydrogels, which act as the "dam" to intercept IL-4 released during the initial burst from the bionic periosteum fiber phase, thus maintaining the moderate inflammatory response of M1 macrophages for mesenchymal stem cell recruitment and vascular sprouting at the acute fracture. With the degradation of the gel phase, released IL-4 cooperates with collagen to promote the polarization towards M2 macrophages, which reconfigure the local microenvironment by secreting PDGF-BB and BMP-2 to improve vascular maturation and osteogenesis twofold. In rat cranial defect models, the controlled regulation of the BIM is validated with the temporal transition of the inflammatory/anti-inflammatory process to achieve faster and better bone defect repair. This strategy provides a drug delivery system that constructs a coordinated BIM, so as to break through the predicament of the contradiction between immune response and bone tissue regeneration.