Amelioration of bleomycin-induced pulmonary fibrosis via TGF-β-induced Smad and non-Smad signaling pathways in galectin-9-deficient mice and fibroblast cells

The interrelation of galectins and autophagy

Autophagy is a vital physiological process that maintains intracellular homeostasis by removing damaged organelles and senescent or misfolded molecules. However, excessive autophagy results in cell death and apoptosis, which will lead to a variety of diseases. Galectins are a type of animal lectin that binds to β-galactosides and can bind to the cell surface or extracellular matrix glycans, affecting a variety of immune processes in vivo and being linked to the development of many diseases. In many cases, galectins and autophagy both play important regulatory roles in the cellular life course, yet our understanding of the relationship between them is still incomplete. Galectins and autophagy may share common etiological cofactors for some diseases. Hence, we summarize the relationship between galectins and autophagy, aiming to draw attention to the existence of multiple associations between galectins and autophagy in a variety of physiological and pathological processes, which provide new ideas for etiological diagnosis, drug development, and therapeutic targets for related diseases.

Targeting galectin-driven regulatory circuits in cancer and fibrosis

Galectins are a family of endogenous glycan-binding proteins that have crucial roles in a broad range of physiological and pathological processes. As a group, these proteins use both extracellular and intracellular mechanisms as well as glycan-dependent and independent pathways to reprogramme the fate and function of numerous cell types. Given their multifunctional roles in both tissue fibrosis and cancer, galectins have been identified as potential therapeutic targets for these disorders. Here, we focus on the therapeutic relevance of galectins, particularly galectin 1 (GAL1), GAL3 and GAL9 to tumour progression and fibrotic diseases. We consider an array of galectin-targeted strategies, including small-molecule carbohydrate inhibitors, natural polysaccharides and their derivatives, peptides, peptidomimetics and biological agents (notably, neutralizing monoclonal antibodies and truncated galectins) and discuss their mechanisms of action, selectivity and therapeutic potential in preclinical models of fibrosis and cancer. We also review the results of clinical trials that aim to evaluate the efficacy of galectin inhibitors in patients with idiopathic pulmonary fibrosis, nonalcoholic steatohepatitis and cancer. The rapid pace of glycobiology research, combined with the acute need for drugs to alleviate fibrotic inflammation and overcome resistance to anticancer therapies, will accelerate the translation of anti-galectin therapeutics into clinical practice.

Proteomics reveals antiviral host response and NETosis during acute COVID-19 in high-risk patients

SARS-CoV-2 remains an acute threat to human health, endangering hospital capacities worldwide. Previous studies have aimed at informing pathophysiologic understanding and identification of disease indicators for risk assessment, monitoring, and therapeutic guidance. While findings start to emerge in the general population, observations in high-risk patients with complex pre-existing conditions are limited. We addressed the gap of existing knowledge with regard to a differentiated understanding of disease dynamics in SARS-CoV-2 infection while specifically considering disease stage and severity. We biomedically characterized quantitative proteomics in a hospitalized cohort of COVID-19 patients with mild to severe symptoms suffering from different (co)-morbidities in comparison to both healthy individuals and patients with non-COVID related inflammation. Deep clinical phenotyping enabled the identification of individual disease trajectories in COVID-19 patients. By the use of the individualized disease phase assignment, proteome analysis revealed a severity dependent general type-2-centered host response side-by-side with a disease specific antiviral immune reaction in early disease. The identification of phenomena such as neutrophil extracellular trap (NET) formation and a pro-coagulatory response characterizing severe disease was successfully validated in a second cohort. Together with the regulation of proteins related to SARS-CoV-2-specific symptoms identified by proteome screening, we not only confirmed results from previous studies but provide novel information for biomarker and therapy development.

Plasma Galectin-9 Is a Useful Biomarker for Predicting Renal Function in Patients Undergoing Native Kidney Biopsy

CONTEXT.—

Galectin-9 reduces tissue damage in certain immune-mediated glomerular diseases. However, its role in structural and functional renal changes in patients with varying types of chronic kidney disease (CKD) is less clear.

OBJECTIVE.—

To investigate the association between plasma galectin-9 levels, proteinuria, tubulointerstitial lesions, and renal function in different CKD stages.

DESIGN.—

We measured plasma galectin-9 levels in 243 patients undergoing renal biopsy for determining the CKD etiology. mRNA and protein expression levels of intrarenal galectin-9 were assessed by quantitative real-time polymerase chain reaction and immunostaining. Relationships between plasma galectin-9, clinical characteristics, and tubulointerstitial damage were analyzed with logistic regression. We investigated galectin-9 expression patterns in vitro in murine J774 macrophages treated with differing stimuli.

RESULTS.—

To analyze the relationship between galectin-9 and clinical features, we divided the patients into 2 groups according to median plasma galectin-9 levels. The high galectin-9 group tended to be older and to have decreased renal function, higher proteinuria, and greater interstitial fibrosis. After multivariable adjustment, elevated plasma galectin-9 levels were independently associated with stage 3b or higher CKD. An analysis of gene expression in the tubulointerstitial compartment in the biopsy samples showed a significant positive correlation between intrarenal galectin-9 mRNA expression and plasma galectin-9 levels. Immunohistochemistry confirmed increased galectin-9 expression in the renal interstitium of patients with advanced CKD, and most galectin-9-positive cells were macrophages, as determined by double-immunofluorescence staining. In vitro experiments showed that galectin-9 expression in macrophages was significantly increased after interferon-γ stimulation.

CONCLUSIONS.—

Our findings suggest that plasma galectin-9 is a good biomarker for diagnosing advanced CKD.

Possible important roles of galectins in the healing of human fetal membranes

The fetal membranes healing is a complex and dynamic process of replacing devitalized and missing cellular structures and tissue layers. Multiple cells and extracellular matrices, and cell differentiation, migration and proliferation may participate in restoring the integrity of damaged tissue, however this process still remains unclear. Therefore, there is a need to identify and integrate new ideas and methods to design a more effective dressing to accelerate fetal membrane healing. This review explores the function and role of galectins in the inflammatory, epithelial mesenchymal transition, proliferative migration, and remodeling phases of fetal membrane healing. In conclusion, the preliminary findings are promising. Research on amnion regeneration is expected to provide insight into potential treatment strategies for premature rupture of membranes.

Abnormal ADAM17 expression causes airway fibrosis in chronic obstructive asthma

Patients with chronic obstructive asthma (COA) develop airflow obstruction caused by subepithelial fibrosis. Although a disintegrin and metalloproteinase 17 (ADAM17) has been implicated in lung inflammation and tissue fibrosis, its role in airway fibrosis in COA has not been explored. Here, we found marked overexpression of ADAM17, phosphorylated ADAM17, and connective tissue growth factor (CTGF) in human airway fibroblasts from COA patients, compared with those of normal subjects. Similarly, levels of ADAM17, CTGF, α-smooth muscle actin (α-SMA), and collagen were increased in endobronchial biopsies from COA patients, but not in controls. In an ovalbumin-challenge asthma model, airway fibrosis was inhibited in ADAM17^f/f/Cre⁺ mice compared to control mice. TGF-β- and thrombin-induced fibrotic protein expression was reduced by ADAM17 small interfering (si)RNA, TAPI-0 (an ADAM17 inhibitor), and EGFR siRNA. In addition, exogenous HB-EGF reversed fibrotic response in ADAM17 knockdown human lung fibroblasts. ADAM17 causes subepithelial fibrosis through regulation of enhanced extracellular matrix production and fibroblast differentiation and is the common pathway for airway fibrosis mediated by TGF-β and thrombin through an aberrant ADAM17/EGFR signalling pathway.

Emerging role of galectin family in inflammatory autoimmune diseases

Galectin family is a group of glycan-binding proteins. Members in this family are expressed in different tissues, immune or non-immune cells. These molecules are important regulators in innate and adaptive immune response, performing significantly in a broad range of cellular and pathophysiological functions, such as cell proliferation, adhesion, migration, and invasion. Findings have shown that expression of galectins is abnormal in many inflammatory autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, osteoarthritis, sjögren's syndrome, systemic sclerosis. Galectins also function as intracellular and extracellular disease regulators mainly through the binding of their carbohydrate recognition domain to glycoconjugates. Here, we review the state-of-the-art of the role that different galectin family members play in immune cells, contributing to the complex inflammatory diseases. Hopefully collection of the information will provide a preliminary theoretical basis for the exploration of new targets for treatment of the disorders.

Galectin-9 regulates follicular helper T cells to inhibit humoral autoimmunity-induced pulmonary fibrosis

Interstitial pneumonia with autoimmune features (IPAF) is an unexplained disease state characterized by autoimmunity and pulmonary fibrosis. Exploring the pathogenesis of IPAF is helpful for the treatment of interstitial pneumonia and idiopathic pulmonary fibrosis. In this study, we observed that the lung Galectin-9 (Gal-9) of IPAF patients was significantly reduced, which was significantly related to lung dysfunction and abnormal humoral immunity. Moreover, an overreactive germinal center (GC) reaction in the lung lymph nodes (LNs) of Gal-9-deficient mice was found to be related to abnormally active follicular helper T cells (Tfh) cells. The lack of Gal-9 ligand in Tfh cells can lead to excessive transcriptional programming and differentiation and help GC B cells. Gal-9 deficiency caused an abnormal humoral immune response in mice, leading to excessive deposition of nonspecific autoantibodies in mice and chronic lung fibrosis. Our research reveals the important regulatory role of gal-9 in Tfh cells and a possible target for the treatment of IPAF.

Latest progress on the molecular mechanisms of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a serious life-threatening lung disease, and the median survival period of PF patients after diagnosis is only 2.5-3.5 years. At present, there are no effective drugs or therapeutics to reverse or even inhibit IPF. The main pathological characteristics of pulmonary fibrosis (PF) include damage to alveolar epithelial cells, fibroblast activation and extracellular matrix accumulation, which gradually lead to damage to the lung structure and decreased lung function. It is important to understand the cellular and molecular mechanisms of PF comprehensively and clearly. In this paper, critical signaling pathways related to PF were reviewed to present updates on the molecular mechanisms of PF.

The therapeutic potential of galectin-3 inhibition in fibrotic disease

Galectin-3 is a beta-galactoside-binding mammalian lectin and part of the 15 member galectin family that are evolutionarily highly conserved. It is the only chimeric protein with a C-terminal carbohydrate recognition domain (CRD) linked to a proline, glycine, and tyrosine rich additional N-terminal domain. Galectin-3 binds several cell surface glycoproteins via its CRD domain as well as undergoing oligomerization, via binding at the N-terminal or the CRD, resulting in the formation of a galectin-3 lattice on the cell surface. The galectin-3 lattice has been regarded as being a crucial mechanism whereby extracellular galectin-3 modulates cellular signalling by prolonging retention time or retarding lateral movement of cell surface receptors in the plasma membrane. As such galectin-3 can regulate various cellular functions such as diffusion, compartmentalization and endocytosis of plasma membrane glycoproteins and glycolipids and the functionality of membrane receptors. In multiple models of organ fibrosis, it has been demonstrated that galectin-3 is potently pro-fibrotic and modulates the activity of fibroblasts and macrophages in chronically inflamed organs. Increased galectin-3 expression also activates myofibroblasts resulting in scar formation and may therefore impact common fibrotic pathways leading to fibrosis in multiple organs. Over the last decade there has been a marked increase in the scientific literature investigating galectin-3 in a range of fibrotic diseases as well as the clinical development of new galectin-3 inhibitors. In this review we will examine the role of galectin-3 in fibrosis, the therapeutic strategies for inhibiting galectin-3 in fibrotic disease and the clinical landscape to date.

In ovo very early-in-life exposure to diesel exhaust induced cardiopulmonary toxicity in a hatchling chick model

Diesel exhaust (DE) had been associated with cardiopulmonary toxicity and developmental toxicity. However, neonatal very early-in-life exposure had not been extensively studied previously. To investigate the potential effects of neonatal very early-in-life exposure to DE, a brand-new chicken embryo in ovo exposure model had been established, with which the cardiopulmonary effects of DE exposure via air cell infusion at embryonic day 18/19 (ED18/19) were assessed in hatchling chicks post-hatch 0-, 1-, or 2-weeks. Heart rates were assessed with electrocardiography. Cardiac and pulmonary morphologies were investigated with histopathological methods. Cardiopulmonary effects were explored with immunohistochemistry for alpha smooth muscle actin (alpha-SMA). In further investigations, the expression levels of phosphorylated AhR, serum levels of TGF-β1, phosphorylated SMAD2/3 and phosphorylated p38MAPK were assessed in the lung tissues. Significantly elevated heart rates, increased right ventricular wall thickness and cardiac collagen deposition were observed in the hearts of exposed hatchling chicks. Significantly increased collagen deposition as well as increased vascular alpha-SMA layer thickness/decreased cavity area were observed in exposed animal lungs. These effects persisted up to two weeks post-hatch. Mechanistic studies revealed elevated phosphorylated AhR expression levels in 0-week and 1-week chicken lungs, while phosphorylated SMAD2/3 levels significantly increased in 0-week chicken lungs but decreased in 2-week chicken lungs following DE exposure. Phosphorylation of p38MAPK did not remarkably increase until 2-week post-hatch. In summary, the novel chicken neonatal very early-in-life exposure model effectively exposed the chicken embryos during the neonatal initial breathing, resulting in cardiopulmonary toxicity, which is associated with AHR, TGF-β1 and MAPK signaling.