Intracellular immune sensing promotes inflammation via gasdermin D-driven release of a lectin alarmin.

Inflammatory caspase sensing of cytosolic lipopolysaccharide (LPS) triggers pyroptosis and the concurrent release of damage-associated molecular patterns (DAMPs). Collectively, DAMPs are key determinants that shape the aftermath of inflammatory cell death. However, the identity and function of the individual DAMPs released are poorly defined. Our proteomics study revealed that cytosolic LPS sensing triggered the release of galectin-1, a ß-galactoside-binding lectin. Galectin-1 release is a common feature of inflammatory cell death, including necroptosis. In vivo studies using galectin-1-deficient mice, recombinant galectin-1 and galectin-1-neutralizing antibody showed that galectin-1 promotes inflammation and plays a detrimental role in LPS-induced lethality. Mechanistically, galectin-1 inhibition of CD45 (Ptprc) underlies its unfavorable role in endotoxin shock. Finally, we found increased galectin-1 in sera from human patients with sepsis. Overall, we uncovered galectin-1 as a bona fide DAMP released as a consequence of cytosolic LPS sensing, identifying a new outcome of inflammatory cell death.

Gal-1 (Galectin-1) Upregulation Contributes to Abdominal Aortic Aneurysm Progression by Enhancing Vascular Inflammation.

OBJECTIVE: Abdominal aortic aneurysm (AAA) is a vascular degenerative disease causing sudden rupture of aorta and significant mortality in elders. Nevertheless, no prognostic and therapeutic target is available for disease management. Gal-1 (galectin-1) is a ß-galactoside-binding lectin constitutively expressed in vasculature with roles in maintaining vascular homeostasis. This study aims to investigate the potential involvement of Gal-1 in AAA progression. Approach and Results: Gal-1 was significantly elevated in circulation and aortic tissues of Ang II (angiotensin II)-infused apoE-deficient mice developing AAA. Gal-1 deficiency reduced incidence and severity of AAA with lower expression of aortic MMPs (matrix metalloproteases) and proinflammatory cytokines. TNFα (tumor necrosis factor alpha) induced Gal-1 expression in cultured vascular smooth muscle cells and adventitial fibroblasts. Gal-1 deletion enhanced TNFα-induced MMP9 expression in fibroblasts but not vascular smooth muscle cells. Cysteinyl-labeling assay demonstrated that aortic Gal-1 exhibited susceptibility to oxidation in vivo. Recombinant oxidized Gal-1 induced expression of MMP9 and inflammatory cytokines to various extents in macrophages, vascular smooth muscle cells, and fibroblasts through activation of MAP (mitogen-activated protein) kinase signaling. Clinically, serum MMP9 level was significantly higher in both patients with AAA and coronary artery disease than in control subjects, whereas serum Gal-1 level was elevated in patients with AAA but not coronary artery disease when compared with controls. CONCLUSIONS: Gal-1 is highly induced and contributes to AAA by enhancing matrix degradation activity and inflammatory responses in experimental model. The pathological link between Gal-1 and AAA is also observed in human patients. These findings support the potential of Gal-1 as a disease biomarker and therapeutic target of AAA.

Galectin-1 expression in the serum and placenta of pregnant women with fetal growth restriction and its significance.

BACKGROUND: This study aims to investigate galectin-1 (Gal-1) expression in the serum and placenta of pregnant women with fetal growth restriction (FGR) and its significance. METHODS: Thirty-one pregnant women with single-birth FGR but without comorbidities, eight pregnant women with FGR and preeclampsia (PE), and eight pregnant women with FGR and gestational diabetes mellitus (GDM) were enrolled as the study group, while 20 pregnant women with normal singleton pregnancy in the same period were enrolled as the control group. The serum Gal-1 level was detected using an enzyme-linked immunosorbent assay (ELISA), and Gal-1 expression in the placenta was detected by western blot. RESULTS: The results revealed that, compared with the control group, the serum Gal-1 level decreased in the women with FGR without comorbidities, and the difference was statistically significant (P < 0.001). Compared with the control group, the difference in serum Gal-1 expression in the FGR-PE group was not statistically significant (P = 0.29). The peripheral serum Gal-1 level decreased in the FGR-GDM group compared with the control group, and the difference was statistically significant (P < 0.001). The serum Gal-1 level was positively correlated with birth weight (r2 = 0.172, P < 0.01). Compared with the control group, the Gal-1 expression level decreased in the placenta of the pregnant women with FGR without comorbidities (P < 0.05). CONCLUSIONS: Gal-1 exhibits low expression in the serum and placenta of pregnant women with FGR. In addition, Gal-1 may be involved in the pathogenesis of FGR and could represent a new diagnostic marker of the disease.

Galectin-3 is associated with severe heart failure and death: A hospital-based study in Chinese patients.

Heart failure (HF) is a serious disease syndrome characterized by elevated pro-inflammatory cytokines and inflammatory mediators presume to have significant contribution on disease progression. Galectins are carbohydrate-binding proteins responsible of various physiological functions. Role of galectins in heart failure has been ill-defined. In the present case-controls study, 136 patients clinically diagnosed with heart failure and 125 healthy Chinese controls were recruited. Levels of galectins (Gal-1, 3 and 9) and cytokines (IFN-γ, IL-17A, IL-4 and TGF-ß) were quantified by ELISA. Increased levels of galectin-1 and 3 was observed in HF patients and associated with clinical severity. In addition, pro-inflammatory cytokines such as IFN-γ and IL-17A were increased in patients whereas, anti-inflammatory TGFß was decreased. Galectin-3 was positively correlated with IFN-γ, IL-17A and inversely with TGF-ß. Furthermore, ROC curve analysis suggested galectin-3 as a promising biomarker for diagnosis and HF and clinical severity. Interestingly, a two-year follow-up indicated significant association of elevated galectin-3 with mortality due to HF. In conclusion, galectin-3 associated with HF and clinical manifestations possibly by inducing pro-inflammatory cytokines and could be a possible biomarker of HF and severe clinical conditions.

Galectin-1 and Galectin-3 Levels in Patients with Schizophrenia and their Unaffected Siblings.

Many hypothesis suggest that inflammation plays an important role in schizophrenia. Galectins can regulate inflammatory response in central nervous system. The relation between galectins and neuropsyhchiatric diseases and schizophrenia is unclear. The present study compared levels of Gal-1 and Gal-3 of patients with schizophrenia to that of first-degree relatives without the disease and healthy controls in order to evaluate any possible association. Sixty-two patients with schizophrenia, fifty-five unaffected siblings and fifty-eight age- and sex-matched healthy controls enrolled. Serum Gal-1, Gal-3 and CRP levels were measured. PANNS and CGI-S were used to evaluate the severity of disease. There was a statistically significant difference in serum Gal-1 levels among the patient, sibling, and control groups. There were no statistically significant correlations between serum CRP ​​and serum Gal-1 or Gal-3 levels. Gal-1 values were significantly higher in the unaffected siblings compared to both the patient group and the healthy control group. Gal-3 levels were elevated in the sibling group relative to the patient group. In the literature, the relationship between galectins and schizophrenia is very limited and appears to be a new field of study. Future studies are needed to evaluate the protective roles of galectins.

Both serum and tissue Galectin-1 levels are associated with adverse clinical features in neuroblastoma.

BACKGROUND: Neuroblastoma is one of the most common pediatric solid tumors. Although the 5-year overall survival rate has increased over the past few decades, high-risk patients still have a poor prognosis due to a lack of biomonitoring therapy. This study was performed to investigate the role of Galectin-1 in neuroblastoma biomonitoring therapy. PROCEDURE: A tissue microarray containing 37 neuroblastoma tissue samples was used to evaluate the correlation between Galectin-1 expression and clinical features. Blood samples were examined to better understand whether serum Galectin-1 (sGalectin-1) could be used for biomonitoring therapy. Kaplan-Meier analysis and ROC analysis was conducted to distinguish the outcome associated with high or low expression of Galectin-1 in patients with neuroblastoma. RESULTS: Increased Galectin-1 expression was found in neuroblastoma and it was further demonstrated that elevated tissue Galectin-1 expression was related to INSS stage, histology, bone marrow metastasis, and poor survival. sGalectin-1 levels were higher in newly diagnosed patients with neuroblastoma than healthy subjects. Patients with elevated sGalectin-1 through treatment cycles correlated with the poor chemo-responses and tended to have worse outcomes, such as metastasis or stable tumor size, whereas gradually decreasing sGalectin-1 levels correlated with no observed progression in clinical symptoms. CONCLUSIONS: Tissue and serum Galectin-1 levels were associated with adverse clinical features in patients with neuroblastoma, and sGalectin-1 could be a potential biomarker for monitoring therapy.

Integrated Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC) and Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) Quantitative Proteomic Analysis Identifies Galectin-1 as a Potential Biomarker for Predicting Sorafenib Resistance in Liver Cancer.

Sorafenib has become the standard therapy for patients with advanced hepatocellular carcinoma (HCC). Unfortunately, most patients eventually develop acquired resistance. Therefore, it is important to identify potential biomarkers that could predict the efficacy of sorafenib. To identify target proteins associated with the development of sorafenib resistance, we applied stable isotope labelling with amino acids in cell culture (SILAC)-based quantitative proteomic approach to analyze differences in protein expression levels between parental HuH-7 and sorafenib-acquired resistance HuH-7 (HuH-7(R)) cells in vitro, combined with an isobaric tags for relative and absolute quantitation (iTRAQ) quantitative analysis of HuH-7 and HuH-7(R) tumors in vivo. In total, 2,450 quantified proteins were identified in common in SILAC and iTRAQ experiments, with 81 showing increased expression (>2.0-fold) with sorafenib resistance and 75 showing decreased expression (<0.5-fold). In silico analyses of these differentially expressed proteins predicted that 10 proteins were related to cancer with involvements in cell adhesion, migration, and invasion. Knockdown of one of these candidate proteins, galectin-1, decreased cell proliferation and metastasis in HuH-7(R) cells and restored sensitivity to sorafenib. We verified galectin-1 as a predictive marker of sorafenib resistance and a downstream target of the AKT/mTOR/HIF-1α signaling pathway. In addition, increased galectin-1 expression in HCC patients' serum was associated with poor tumor control and low response rate. We also found that a high serum galectin-1 level was an independent factor associated with poor progression-free survival and overall survival. In conclusion, these results suggest that galectin-1 is a possible biomarker for predicting the response of HCC patients to treatment with sorafenib. As such, it may assist in the stratification of HCC and help direct personalized therapy.

Biomarkers for evaluation of treatment response in classical Hodgkin lymphoma: comparison of sGalectin-1, sCD163 and sCD30 with TARC.

Soluble Galectin-1 (sGal-1, also termed LGALS1), soluble CD163 (sCD163) and soluble CD30 (sCD30) have been reported to be elevated in plasma or serum of patients with classical Hodgkin lymphoma (cHL). We aimed to determine the clinical utility of these biomarkers for evaluation of treatment response compared to thymus and activation regulated chemokine (TARC, also termed CCL17). Plasma or serum samples were prospectively collected among 103 newly diagnosed cHL patients before and after treatment. Levels of sGal-1, sCD163, sCD30 and TARC were correlated with disease characteristics and clinical treatment response. Elevated plasma levels of sGal-1, sCD163, sCD30 and TARC were found in 67%, 21%, 91% and 93% of cHL patients respectively. Mean plasma levels of sGal-1 and sCD30 decreased after treatment but sCD163 did not decrease after treatment. There was no correlation with change of these markers and clinical treatment response in individual patients. TARC levels strongly correlated with disease characteristics and metabolic volume. TARC remained high in 6 out of 7 non-responsive patients and dramatically decreased in 95 out of 96 responsive patients. In summary, elevated pre-treatment levels of sGal-1, sCD163, sCD30 and TARC can be found in patients with cHL. However, only plasma TARC accurately reflects disease activity and correlates with clinical treatment response.

Circulating and tissue galectin-1 and galectin-3 in colorectal carcinoma: association with clinicopathological parameters, serum CEA, IL-17 and IL23.

PURPOSE: Galectins are modulators of many processes critical for tumor progression and metastasis but their clinical significance is still unclear. The objective of this study was to analyze the clinical significance of Galectin-1 and Galectin-3 in the tissue and sera of patients with colorectal carcinoma (CRC). Examined were also their association with serum CEA, IL-17 and IL-23 in CRC patients. METHODS: One hundred and twenty patients with CRC were included in this study. The expression of Galectin-1 and Galectin-3 in biopsy samples of CRC was determined using immunohistochemistry (N=120). The concentrations of Galectin-1, Galectin-3, IL-17 and IL-23 in the sera of CRC patients (N=38) were determined by Enzyme Linked Immunosorbent Assay (ELISA). RESULTS: Serum Galectin-1 concentrations positively correlated with parameters of malignancy including perineural invasion (p=0.016), lymph node involvement and distant metastases (p=0.029). Higher expression of peritumoral Galectin-1 was associated with both presence of perineural invasion and poor differentiation of CRC. Serum CEA levels positively correlated with circulating Galectin-1, but inversely correlated with peritumoral Galectin-1 expression. There was no correlation between Galectin-3 and clinicopathological parameters of CRC, but it was found that Galectin-3 expression in the tumor tissue positively correlated with serum IL-17 and IL-23. Circulating Galectin-3 levels significantly correlated with IL-17 (p=0.042), but not with IL-23 in the sera of CRC patients. CONCLUSIONS: This study suggests that Galectin-1 and Galectin-3 exhibit protumorigenic activity in CRC by affecting different aspects of tumor progression. Galectin-1 facilitates tumor invasion and metastasis while Galectin-3 preferentially modulates tumor-associated inflammatory processes.

Galectin-1 serum levels reflect tumor burden and adverse clinical features in classical Hodgkin lymphoma.

Galectin-1 (Gal1) is a member of a highly conserved family of carbohydrate-binding proteins. It modulates innate and adaptive immune responses and fosters tumor-immune escape. Hodgkin lymphoma (HL) Reed-Sternberg cells overexpress and secrete Gal1, which selectively kills T helper (Th)1 and Th17 cells and cytotoxic T cells and promotes the immunosuppressive Th2/regulatory T-cell-predominant HL microenvironment. We developed a sandwich enzyme-linked immunosorbent assay and assessed serum Gal1 levels in 293 newly diagnosed, previously untreated patients with classical HL (cHL) enrolled in 3 risk-adapted clinical trials. Serum Gal1 levels were significantly higher in patients with cHL than in normal controls (P < .0001). Gal1 serum levels also increased with Ann Arbor stage (P = .012), areas of nodal involvement (P < .0001), and the International Prognostic Score (2-7, P = .019). We conclude that Gal1 serum levels are significantly associated with tumor burden and related clinical features in newly diagnosed cHL patients.

Cord blood galectin-1 and -3 concentrations in term pregnancies with normal restricted and increased fetal growth.

OBJECTIVE: To determine levels of galectins (gal)-1 and -3 (implicated in angiogenesis/immunologic mechanisms) in intrauterine growth restricted (IUGR), large (LGA) and appropriate for gestational age (AGA) pregnancies, as these groups differ in fat mass, angiogenic patterns and immune responses. METHODS: Cord-blood (UC) gal-1 and -3 concentrations were measured in 30 IUGR, 30 LGA and 20 AGA singleton full-term infants and their mothers (MS). RESULTS: IUGR, LGA and AGA groups did not differ in gal-1 and -3 concentrations. UC gal-1 levels were lower when mothers were older [b=-0.651, CI 95% -1.186 (-0.116), P=0.018] and UC gal-3 levels were increased when mothers presented gestational diabetes [b=9.836, CI 95% 3.833- (15.839), P=0.002]. In IUGRs MS gal-3 and in LGAs UC gal-1 were decreased in multiparas [b=-5.372, CI 95% -9.584- (-1.161), P=0.014], and [b=-7.540, CI 95% -14.606- (-0.473), P=0.037], respectively. No correlations were found between MS or UC gal-1 and gal-3 concentrations. CONCLUSIONS: Lower UC gal-1 levels, when mothers were older, and increased UC gal-3 levels in cases of gestational diabetes, possibly reflect angiogenic activity. In multiparas, decreased MS gal-3 and UC gal-1 levels in IUGR/LGA, respectively, might imply inflammatory response against immunosuppression expected in subsequent pregnancies, as compared to the first one.

Serum Galectin-1, Galectin-9, and YKL-40 levels in bipolar disorder and their relationship with cognitive functions.

PURPOSE: The number of studies conducted on the role of neuroinflammation in the etiopathogenesis of bipolar disorder has been increasing in recent years. The role of Galectin-1, Galectin-9, and YKL-40, which are considered to play roles in neuroinflammation and the etiopathogenesis of bipolar disorder, and the relationship of these parameters with cognitive functions were investigated in the present study. METHOD: Serum Galectin-1, Galectin-9, and YKL-40 levels were measured with the ELISA Method in 64 bipolar euthymic patients and 64 healthy controls. The Stroop and trail-making tests were administered to assess cognitive functions in all participants. RESULTS: Serum Galectin-1, Galectin-9, and YKL-40 levels were statistically and significantly lower in the patient group when compared to the healthy control group. The scores of the Stroop test and trail-making tests were statistically higher in the patient group than in the healthy control group. There was a weak and positive correlation between serum Galectin-1, Galectin-9, and YKL-40 levels and cognitive performance in all participants. DISCUSSION AND CONCLUSION: Statistically significant low levels of serum Galectin-1, Galectin-9, and YKL-40 detected in the patient group suggest that these parameters have important roles in neuroinflammation. The statistically higher Stroop and trail-making test scores of the patient group compared to the control group indicates that the cognitive performance of the patient group was weaker. Also, the positive correlation between Galectin-1, Galectin-9, and YKL-40 levels and cognitive performance suggests that these molecules may have a neuroprotective role. We think that the present study will contribute to this field where there is very limited data in the literature.

Correlation Analysis of Genetic Mutations and Galectin Levels in Breast Cancer Patients.

Galectins are innate immune system regulators associated with disease progression in cancer. This paper aims to investigate the correlation between mutated cancer-critical genes and galectin levels in breast cancer patients to determine whether galectins and genetic profiles can be used as biomarkers for disease and potential therapy targets. Prisma Health Cancer Institute's Biorepository provided seventy-one breast cancer samples, including all four stages spanning the major molecular subtypes and histologies. Hotspot mutation statuses of cancer-critical genes were determined using multiplex PCR in tumor samples from the same patients by Precision Genetics and the University of South Carolina Functional Genomics Core Facility. The galectin-1, -3, and -9 levels in patients' sera were analyzed using Enzyme-linked Immunosorbent Assay (ELISA). An analysis was performed using JMP software to compare mean and median serum galectin levels between samples with and without specific cancer-critical genes, including pooled t-test, Wilcoxon Rank Sum Test, ANOVA, and Steel Dwass Test (α=0.05). Our analysis indicates that KIT mutations correlate with elevated serum levels of galectin-9 in patients with breast cancer. In patients with Luminal A subtype, FLT3 mutation correlates with lower serum galectin-1 and -9 levels and TP53 mutations correlate with higher serum galectin-3 levels. Patients with invasive ductal carcinoma had significantly higher serum galectin-3 levels than patients with ductal carcinoma in situ. Patients with both TP53 and PIK3CA mutations exhibit elevated serum galectin-3 levels, while patients with one or neither mutation show no significant difference in serum galectin-3 levels. In addition, metastatic breast cancer samples were more likely to have a KIT or PIK3CA mutation compared to primary breast cancer samples. The relationship between genetic mutations and galectin levels has the potential to identify appropriate candidates for combined therapy, targeting genetic mutations and galectins. Further understanding of the effect of genetic mutations and galectin levels on cancer progression and metastasis could aid in the search for biomarkers for breast cancer diagnosis, disease progression, and prognosis.

Galectin-1 influences trophoblast immune evasion and emerges as a predictive factor for the outcome of pregnancy.

Galectin-1 (gal-1) is expressed at the feto-maternal interface and plays a role in regulating the maternal immune response against placental alloantigens, contributing to pregnancy maintenance. Both decidua and placenta contribute to gal-1 expression and may be important for the maternal immune regulation. The expression of gal-1 within the placenta is considered relevant to cell-adhesion and invasion of trophoblasts, but the role of gal-1 in the immune evasion machinery exhibited by trophoblast cells remains to be elucidated. In this study, we analyzed gal-1 expression in preimplantation human embryos and first-trimester decidua-placenta specimens and serum gal-1 levels to investigate the physiological role played by this lectin during pregnancy. The effect on human leukocyte antigen G (HLA-G) expression in response to stimulation or silencing of gal-1 was also determined in the human invasive, proliferative extravillous cytotrophoblast 65 (HIPEC65) cell line. Compared with normal pregnant women, circulating gal-1 levels were significantly decreased in patients who subsequently suffered a miscarriage. Human embryos undergoing preimplantation development expressed gal-1 on the trophectoderm and inner cell mass. Furthermore, our in vitro experiments showed that exogenous gal-1 positively regulated the membrane-bound HLA-G isoforms (HLA-G1 and G2) in HIPEC65 cells, whereas endogenous gal-1 also induced expression of the soluble isoforms (HLA-G5 and -G6). Our results suggest that gal-1 plays a key role in pregnancy maternal immune regulation by modulating HLA-G expression on trophoblast cells. Circulating gal-1 levels could serve as a predictive factor for pregnancy success in early human gestation.

Binding of galectin-1 to αIIbß3 integrin triggers "outside-in" signals, stimulates platelet activation, and controls primary hemostasis.

Understanding noncanonical mechanisms of platelet activation represents an important challenge for the identification of novel therapeutic targets in bleeding disorders, thrombosis, and cancer. We previously reported that galectin-1 (Gal-1), a ß-galactoside-binding protein, triggers platelet activation in vitro. Here we investigated the molecular mechanisms underlying this function and the physiological relevance of endogenous Gal-1 in hemostasis. Mass spectrometry analysis, as well as studies using blocking antibodies against the anti-α(IIb) subunit ofα(IIb)ß(3) integrin or platelets from patients with Glanzmann's thrombasthenia syndrome (α(IIb)ß(3) deficiency), identified this integrin as a functional Gal-1 receptor in platelets. Binding of Gal-1 to platelets triggered the phosphorylation of ß(3)-integrin, Syk, MAPKs, PI3K, PLCγ2, thromboxane (TXA(2)) release, and Ca(2+) mobilization. Not only soluble but also immobilized Gal-1 promoted platelet activation. Gal-1-deficient (Lgals1(-/-)) mice showed increased bleeding time (P<0.0002, knockout vs. wild type), which was not associated with an abnormal platelet count. Lgals1(-/-) platelets exhibited normal aggregation to PAR4, ADP, arachidonic acid, or collagen but abnormal ATP release at low collagen concentrations. Impaired spreading on fibrinogen and clot retraction with normal levels of α(IIb)ß(3) was also observed in Lgals1(-/-) platelets, indicating a failure in the "outside-in" signaling through this integrin. This study identifies a noncanonical mechanism, based on galectin-integrin interactions, for regulating platelet activation.

Altered galectin-1 serum levels in patients diagnosed with high-grade glioma.

High-grade gliomas (HGG) are the most common and most aggressive intrinsic human brain tumors in adults. Galectin-1, a glycan-binding protein that is overexpressed in HGG, has been shown to contribute significantly to the aggressive nature of HGG. It is unknown whether increased galectin-1 expression levels are exclusively found at the tumor site or whether galectin-1 can also be detected in the serum of HGG patients. Galectin-1 serum levels were analyzed in a prospective dataset of 43 healthy controls and 125 patients with newly diagnosed or recurrent HGG. Samples were taken at the moment of surgical resection and/or 2-3 weeks after surgery. Galectin-1 serum levels were determined using an ELISA for galectin-1. Galectin-1 serum levels depended significantly on age and sex in the control group. Age- and sex-adjusted galectin-1 serum levels were significantly higher in all patient subgroups compared to healthy controls with a high discriminative ability that increased with age. We did not observe a significant decrease in the galectin-1 serum levels upon surgical resection of the tumor. Collectively, the data presented here may represent a first step to establish galectin-1 as a biomarker in HGG disease monitoring. Further longitudinal evaluation is required and ongoing to investigate the value of galectin-1 serum levels in HGG patients as an additional diagnostic marker, but more importantly as a predictor of treatment response and prognosis. Furthermore, galectin-1 serum levels could also provide an important tool for the identification of HGG patients that could benefit from galectin-1 directed therapies that are currently under development.

A decrease in galectin-1 (Gal-1) levels correlates with an increase in anti-Gal-1 antibodies at the synovial level in patients with rheumatoid arthritis.

BACKGROUND: Several studies have confirmed that galectin-1 (Gal-1) plays a role in controlling the immune response because of its pro-apoptotic effect. Although studies based on a rheumatoid arthritis (RA) mouse model have suggested a crucial role for Gal-1 in inflammation, clinical data are lacking. We have detected the presence of autoantibodies against galectins in blood, but their physiological meaning remains unknown. OBJECTIVES: To compare plasma and synovial levels of Gal-1 in RA patients and in healthy controls, and correlate them with clinical parameters. METHODS: Plasma and synovial (non-arthritic knee effusion) samples were collected from RA patients and healthy donors. All patients were receiving treatment with steroids and/or disease-modifying anti-rheumatic drugs (DMARDs). A blood sample was taken at a baseline visit to determine plasma anti-cyclic citrullinated peptide (anti-CCP) antibodies, tumour necrosis factor alpha (TNF-α), Gal-1, and anti-Gal-1 autoantibodies. RESULTS: Although plasma levels of Gal-1 were similar in patients and controls, the concentration of Gal-1 was significantly reduced in the synovial fluid of patients with RA. This reduction was not correlated with TNF-α or C-reactive protein (CRP) levels. However, the decrease in synovial Gal-1 correlated with a significant increase in anti-Gal-1 autoantibodies and anti-CCP antibody titres, suggesting a physiological effect of autoantibodies limiting the amount Gal-1 and potentially blocking its biological effect in RA patients. CONCLUSION: Gal-1 levels were significant reduced at the synovial level in RA patients, possibly as a consequence of the increase in anti-Gal-1 autoantibodies.

Identification of galectin-1 and galectin-3 as novel partners for von Willebrand factor.

OBJECTIVE: Although von Willebrand factor (VWF) is a heavily glycosylated protein, its potential to associate with glycan-binding proteins is poorly investigated. Here, we explored its interaction with the glycan-binding proteins galectin-1 and galectin-3. METHODS AND RESULTS: Immunofluorescence analysis using Duolink proximity ligation assays revealed that VWF colocalizes with galectin-1 and galectin-3 in endothelial cells, both before and after stimulation of endothelial cells. Moreover, galectin-1 was found along the typical VWF bundles that are released by endothelial cells. Galectin-1 and galectin-3 could be coprecipitated with VWF from plasma in immunoprecipitation assays, whereas plasma levels of galectin-1 and galectin-3 were significantly reduced in VWF-deficient mice. Binding studies using purified proteins confirmed that VWF could directly interact with both galectins, predominantly via its N-linked glycans. In search of the physiological relevance of the VWF-galectin interaction, we found that inhibition of galectins in in vitro perfusion assays was associated with increased VWF-platelet string formation, a phenomenon that was reproduced in galectin-1/galectin-3 double-deficient mice. These mice were also characterized by a more rapid formation of initial thrombi following ferric chloride-induced injury. CONCLUSIONS: We have identified galectin-1 and galectin-3 as novel partners for VWF, and these proteins may modulate VWF-mediated thrombus formation.

Potential tumor markers of renal cell carcinoma: α-enolase for postoperative follow up, and galectin-1 and galectin-3 for primary detection.

The diagnosis of renal cell carcinoma is currently based on imaging techniques, mainly because there is no blood marker available for its detection. Thus, there is still the need for the development of novel tumor markers. We examined plasma levels of eight proteins in 15 renal cell carcinoma patients before and after surgery, and in 51 healthy controls using enzyme-linked immunosorbent assay. Plasma levels of α-enolase, calnexin, galectin-1, galectin-3 and lectin mannose-binding 2 were significantly higher in renal cell carcinoma patients than in controls (P < 0.05). Among these proteins, the sensitivities for galectin-1 and galectin-3 were higher than those for calnexin and lectin mannose-binding 2 in the specificity range from 80% to 100%. A combined use of galectin-1 and galectin-3 showed 98% specificity and 47% sensitivity. In addition, the assays showed that plasma α-enolase levels decreased significantly 4 weeks after nephrectomy (P = 0.0034), and this tendency continued until 12 weeks after nephrectomy (P = 0.0156). These findings suggest that α-enolase could be used in the postoperative follow up of renal cell carcinoma patients, whereas the combined use of galectin-1 and galectin-3 might represent a useful tool for primary detection.