Differential expression of galectin-1 and galectin-3 during first trimester human embryogenesis

Emerging Roles of Galectin-3 in Pulmonary Diseases

Galectin-3 is a multifunctional protein that is involved in various physiological and pathological events. Emerging evidence suggests that galectin-3 also plays a critical role in the pathogenesis of pulmonary diseases. Galectin-3 can be produced and secreted by various cell types in the lungs, and the overexpression of galectin-3 has been found in acute lung injury/acute respiratory distress syndrome (ALI/ARDS), pulmonary hypertension (PH), pulmonary fibrosis diseases, lung cancer, lung infection, chronic obstructive pulmonary disease (COPD), and asthma. Galectin-3 exerts diverse effects on the inflammatory response, immune cell activation, fibrosis and tissue remodeling, and tumorigenesis in these pulmonary disorders, and genetic and pharmacologic modulation of galectin-3 has therapeutic effects on the treatment of pulmonary illnesses. In this review, we summarize the structure and function of galectin-3 and the underlying mechanisms of galectin-3 in pulmonary disease pathologies; we also discuss preclinical and clinical evidence regarding the therapeutic potential of galectin-3 inhibitors in these pulmonary disorders. Additionally, targeting galectin-3 may be a very promising therapeutic approach for the treatment of pulmonary diseases.

GPNMB+ Gal-3+ hepatic parenchymal cells promote immunosuppression and hepatocellular carcinogenesis

Hepatocellular carcinoma (HCC) formation is a multi-step pathological process that involves evolution of a heterogeneous immunosuppressive tumor microenvironment. However, the specific cell populations involved and their origins and contribution to HCC development remain largely unknown. Here, comprehensive single-cell transcriptome sequencing was applied to profile rat models of toxin-induced liver tumorigenesis and HCC patients. Specifically, we identified three populations of hepatic parenchymal cells emerging during HCC progression, termed metabolic hepatocytes (HCMeta ), Epcam+ population with differentiation potential (EP+Diff ) and immunosuppressive malignant transformation subset (MTImmu ). These distinct subpopulations form an oncogenic trajectory depicting a dynamic landscape of hepatocarcinogenesis, with signature genes reflecting the transition from EP+Diff to MTImmu . Importantly, GPNMB+ Gal-3+ MTImmu cells exhibit both malignant and immunosuppressive properties. Moreover, SOX18 is required for the generation and malignant transformation of GPNMB+ Gal-3+ MTImmu cells. Enrichment of the GPNMB+ Gal-3+ MTImmu subset was found to be associated with poor prognosis and a higher rate of recurrence in patients. Collectively, we unraveled the single-cell HCC progression atlas and uncovered GPNMB+ Gal-3+ parenchymal cells as a major subset contributing to the immunosuppressive microenvironment thus malignance in HCC.

The Role of Galectin-3 in Predicting Congenital Heart Disease Outcome: A Review of the Literature

Galectin-3 (Gal-3) is a novel pro-fibrotic biomarker that can predict both right and left cardiac dysfunction caused by various cardiovascular conditions. Its expression seems to be progressively altered with evolving cardiac remodeling processes, even before the onset of heart failure. Hence, Gal-3 has been found to be an individual predictor of acute and chronic heart failure or to serve as part of an integrated biomarker panel that can foresee adverse cardiac outcomes. In congenital heart disease (CHD), Gal-3 correlates with cardiac mortality and complications in both children and adults and is proposed as a therapeutic target in order to reverse the activation of pro-fibrosis pathways that lead to heart failure. Positive associations between serum Gal-3 levels, post-operatory hospitalization rates, complications and ventricular dysfunction have also been reported within studies conducted on patients with CHD who underwent corrective surgery. Thus, this review tried to address the potential utility of Gal-3 in patients with CHD and particularly in those who undergo corrective surgery. The heterogeneity of the literature data and the lack of validation of the results obtained by the current studies on larger cohorts cannot be neglected, though. Further longitudinal research is required to establish how Gal-3 can relate to long-term outcomes in pediatric CHD.

Growth and differentiation of human induced pluripotent stem cell (hiPSC)-derived kidney organoids using fully synthetic peptide hydrogels

Human induced pluripotent stem cell (hiPSC)-derived kidney organoids have prospective applications ranging from basic disease modelling to personalised medicine. However, there remains a necessity to refine the biophysical and biochemical parameters that govern kidney organoid formation. Differentiation within fully-controllable and physiologically relevant 3D growth environments will be critical to improving organoid reproducibility and maturation. Here, we matured hiPSC-derived kidney organoids within fully synthetic self-assembling peptide hydrogels (SAPHs) of variable stiffness (storage modulus, G'). The resulting organoids contained complex structures comparable to those differentiated within the animal-derived matrix, Matrigel. Single-cell RNA sequencing (scRNA-seq) was then used to compare organoids matured within SAPHs to those grown within Matrigel or at the air-liquid interface. A total of 13,179 cells were analysed, revealing 14 distinct clusters. Organoid compositional analysis revealed a larger proportion of nephron cell types within Transwell-derived organoids, while SAPH-derived organoids were enriched for stromal-associated cell populations. Notably, differentiation within a higher G' SAPH generated podocytes with more mature gene expression profiles. Additionally, maturation within a 3D microenvironment significantly reduced the derivation of off-target cell types, which are a known limitation of current kidney organoid protocols. This work demonstrates the utility of synthetic peptide-based hydrogels with a defined stiffness, as a minimally complex microenvironment for the selected differentiation of kidney organoids.

Placental galectins regulate innate and adaptive immune responses in pregnancy

Introduction

Galectins are master regulators of maternal immune responses and placentation in pregnancy. Galectin-13 (gal-13) and galectin-14 (gal-14) are expressed solely by the placenta and contribute to maternal-fetal immune tolerance by inducing the apoptosis of activated T lymphocytes and the polarization of neutrophils toward an immune-regulatory phenotype.Furthermore, their decreased placental expression is associated with pregnancy complications, such as preeclampsia and miscarriage. Yet, our knowledge of the immunoregulatory role of placental galectins is incomplete.

Methods

This study aimed to investigate the effects of recombinant gal-13 and gal-14 on cell viability, apoptosis, and cytokine production of peripheral blood mononuclear cells (PBMCs) and the signaling pathways involved.

Results

Herein, we show that gal-13 and gal-14 bind to the surface of non-activated PBMCs (monocytes, natural killer cells, B cells, and T cells) and increase their viability while decreasing the rate of their apoptosis without promoting cell proliferation. We also demonstrate that gal-13 and gal-14 induce the production of interleukin (IL)-8, IL-10, and interferon-gamma cytokines in a concentration-dependent manner in PBMCs. The parallel activation of Erk1/2, p38, and NF-ĸB signaling evidenced by kinase phosphorylation in PBMCs suggests the involvement of these pathways in the regulation of the galectin-affected immune cell functions.

Discussion

These findings provide further evidence on how placenta-specific galectins assist in the establishment and maintenance of a proper immune environment during a healthy pregnancy.

The role of cytokeratin 19 levels in the determination of endometriosis stages

OBJECTIVE/AIM

Endometrisosis, one of the most common gynecological disease, is characterized by the presence of endometriotic tissue outside of uterine cavity. The development and the validation of a simple blood biomarker specific and sensitive for endometriosis may facilitate the rapid and the accurate diagnosis of the disease and thus early treatment. Cytokeratin expression changes during epithelial differentiation and this expression is important for the modulation and the control of cell cycle regulation, tumor cell motility and apoptosis. Cytokeratin 19 (CK-19) is expressed in most simple epithelial cells and their malignant counterparts. The aim of this study is to investigate serum CK-19 expression levels in patients with endometriosis and to determine the diagnostic role of CK-19 levels in differentiating various stage of endometriosis.

METHODS

Ctytokeratin-19 expression and level were studied in 70 endometriosis patients and 50 volunteers by ELISA and RT-PCR. ROC analysis was performed by comparing all stages with each other and with the control group.

RESULTS

The CK-19 levels were significantly higher in the endometriosis groups than that of the control group by ELISA and RT-PCR. A significant (p < .05) difference was observed in endometriosis patients according to the stages.

CONCLUSION

Based on our data, it suggests that Cytokeratin-19 may have a potential role in the development of endometriosis.

Galectin-3: a key player in microglia-mediated neuroinflammation and Alzheimer's disease

Alzheimer’s disease (AD) is the most common cause of dementia and is characterized by the deposition of extracellular aggregates of amyloid-β (Aβ), the formation of intraneuronal tau neurofibrillary tangles and microglial activation-mediated neuroinflammation. One of the key molecules involved in microglial activation is galectin-3 (Gal-3). In recent years, extensive studies have dissected the mechanisms by which Gal-3 modulates microglial activation, impacting Aβ deposition, in both animal models and human studies. In this review article, we focus on the emerging role of Gal-3 in biology and pathobiology, including its origin, its functions in regulating microglial activation and neuroinflammation, and its emergence as a biomarker in AD and other neurodegenerative diseases. These aspects are important to elucidate the involvement of Gal-3 in AD pathogenesis and may provide novel insights into the use of Gal-3 for AD diagnosis and therapy.

Galectin-3 in T cell-mediated immunopathology and autoimmunity

Galectin-3 (Gal-3) is the only member of galectin family able to form pentamers and heterodimers with chemokines. Its presence in various cells and tissues suggests variety of regulatory functions in physiological conditions, but increasing body of evidence indicates involvement of Gal-3 in pathological cascades of many diseases. Gal-3 exerts different, sometimes opposite, effects in various disorders or in different phases of the same disease. These differences in action of Gal-3 are related to the localization of Gal-3 in the cell, types of receptors through which it acts, or the types of cells that secrete it. As a regulator of immune response and T-cell activity, Gal-3 appears to have important role in development of autoimmunity mediated by T cells. Absence of Gal-3 in C57Bl6 mice favors Th2 mediated inflammatory myocarditis but attenuate fibrosis. Recent data also indicate Gal-3 involvement in development atherosclerosis. In pathogenesis of diabetes type 1 and autoimmune components of diabetes type 2 Gal-3 may have detrimental or protective role depending on its intracellular or extracellular localization. Gal-3 mediates autoimmune hepatic damage through activation of T-cells or natural killer T cells. Gal-3 is an important mediator in neurodevelopment, neuropathology and behavior due to its expression both in neurons and glial cells. All together, assessing the role of Gal-3 in immunopathology and autoimmunity it could be concluded that it is an important participant in pathogenesis, as well as promising monitoring marker and therapeutic target.

Hepatic stellate cells contribute to liver regeneration through galectins in hepatic stem cell niche

BACKGROUND

As a critical cellular component in the hepatic stem cell niche, hepatic stellate cells (HSCs) play critical roles in regulating the expansion of hepatic stem cells, liver regeneration, and fibrogenesis. However, the signaling of HSCs, particularly that involved in promoting hepatic stem cell expansion, remains unclear. While the overexpression of galectins has been identified in regenerating liver tissues, their involvement in cell-cell interactions between HSCs and hepatic stem cells remains to be elucidated.

METHODS

To generate a liver regeneration rat model and establish a hepatic oval cell microenvironment as a stem cell niche, 2-acetylaminofluorene treatment plus partial hepatectomy was performed. Immunofluorescence staining was conducted to detect the emergence of hepatic stem cells and their niche. Liver parenchymal cells, non-parenchymal cells, and HSCs were isolated for gene and protein expression analysis by qPCR or western blotting. To evaluate the effect of galectins on the colony-forming efficiency of hepatic stem cells, c-Kit^-CD29⁺CD49f^+/lowCD45^-Ter-119^- cells were cultured with recombinant galectin protein, galectin antibody, galectin-producing HSCs, and galectin-knockdown HSCs.

RESULTS

Following liver injury, the cytokeratin 19⁺ ductal cells were robustly induced together with the emergence of OV6⁺CD44⁺CD133⁺EpCAM⁺ hepatic stem cells. The activated desmin⁺ HSCs were recruited around the periportal area and markedly enriched in the galectin-positive domain compared to the other non-parenchymal cells. Notably, the HSC fraction isolated from regenerating liver was accompanied by dramatically elevated gene and protein expression of galectins. Hepatic stem cells co-cultured with HSCs significantly enhanced colony-forming efficiency. Conversely, single or double knockdown of galectin-1 and galectin-3 led into a significant function loss, impaired the co-cultured hepatic stem cells to attenuated colony size, inhibited colony frequency, and reduced total cell numbers in colonies. On the other hand, the promotive function of galectins was further confirmed by recombinant galectin protein supplementation and galectins blocking antibodies.

CONCLUSIONS

Our findings, for the first time, demonstrated that galectins from activated HSCs contribute to hepatic stem cell expansion during liver regeneration, suggesting that galectins serve as important stem cell niche components.

Value of Galectin-3 in Acute Myocardial Infarction

Galectins are an ancient family of lectins characterized by evolutionarily conserved amino acid sequences and β-galactoside recognition and binding sites. Galectin-3 (Gal-3) is one of 15 known galectins. This protein has important functions in numerous biological activities, including cardiac fibrosis and heart failure. In recent years, many studies have shown that Gal-3 is closely associated with acute myocardial infarction (AMI) and may be a promising biomarker for the assessment of severity as well as prognosis prediction in AMI patients, but controversy still exists. In this review, we summarize the latest literature on the relationship between Gal-3 and unstable plaques, the secretion kinetics of Gal-3 during the acute phase of AMI, and the value of Gal-3 in the prediction of post-AMI remodeling. Finally, the possible value of Gal-3 as a biological target for AMI therapy is examined.

Galectin-3: Roles in Neurodevelopment, Neuroinflammation, and Behavior

There is a plethora of evidence to suggest that Galectin-3 plays an important role in normal functions of mammalian cells, as well as in different pathogenic conditions. This review highlights recent data published by researchers, including our own team, on roles of Galectin-3 in the nervous system. Here, we discuss the roles of Galectin-3 in brain development, its roles in glial cells, as well as the interactions of glial cells with other neural and invading cells in pathological conditions. Galectin-3 plays an important role in the pathogenesis of neuroinflammatory and neurodegenerative disorders, such as multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. On the other hand, there is also evidence of the protective role of Galectin-3 due to its anti-apoptotic effect in target cells. Interestingly, genetic deletion of Galectin-3 affects behavioral patterns in maturing and adult mice. The results reviewed in this paper and recent development of highly specific inhibitors suggests that Galectin-3 may be an important therapeutic target in pathological conditions including the disorders of the central nervous system.

Galectins-1 and -3 in Human Intervertebral Disc Degeneration: Non-Uniform Distribution Profiles and Activation of Disease Markers Involving NF-κB by Galectin-1

Degeneration of the human intervertebral disc (IVD) is assumed to underlie severe clinical symptoms, in particular chronic back pain. Since adhesion/growth-regulatory galectins are linked to arthritis/osteoarthritis pathogenesis by activating a pro-degradative/-inflammatory gene expression signature, we hypothesized a similar functional involvement of galectins in IVD degeneration. Immunohistochemical evidence for the presence of galectins-1 and -3 in IVD is provided comparatively for specimens of spondylochondrosis, spondylolisthesis, and spinal deformity. Immunopositivity was detected in sections of fixed IVD specimens in each cellular compartment with age-, disease-, and galectin-type-related differences. Of note, presence of both galectins correlated with IVD degeneration, whereas correlation with age was seen only for galectin-3. In addition, staining profiles for these two galectins showed different distribution patterns in serial sections, an indication for non-redundant functionalities. In vitro, both galectins bound to IVD cells in a glycan-dependent manner. However, exclusively galectin-1 binding triggered a significant induction of functional disease markers (i.e., IL6, CXCL8, and MMP1/3/13) with involvement of the nuclear factor-kB pathway. This study thus gives direction to further network analyses and functional studies on galectins in IVD degeneration. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2204-2216, 2019.

Placental Galectins Are Key Players in Regulating the Maternal Adaptive Immune Response

Galectins are potent immunomodulators that regulate maternal immune responses in pregnancy and prevent the rejection of the semi-allogeneic fetus that also occurs in miscarriages. We previously identified a gene cluster on Chromosome 19 that expresses a subfamily of galectins, including galectin-13 (Gal-13) and galectin-14 (Gal-14), which emerged in anthropoid primates. These galectins are expressed only by the placenta and induce the apoptosis of activated T lymphocytes, possibly contributing to a shifted maternal immune balance in pregnancy. The placental expression of Gal-13 and Gal-14 is decreased in preeclampsia, a life-threatening obstetrical syndrome partly attributed to maternal anti-fetal rejection. This study is aimed at revealing the effects of Gal-13 and Gal-14 on T cell functions and comparing the expression of these galectins in placentas from healthy pregnancies and miscarriages. First-trimester placentas were collected from miscarriages and elective termination of pregnancies, tissue microarrays were constructed, and then the expression of Gal-13 and Gal-14 was analyzed by immunohistochemistry and immunoscoring. Recombinant Gal-13 and Gal-14 were expressed and purified, and their effects were investigated on primary peripheral blood T cells. The binding of Gal-13 and Gal-14 to T cells and the effects of these galectins on apoptosis, activation marker (CD25, CD71, CD95, HLA-DR) expression and cytokine (IL-1β, IL-6, IL-8, IL-10, IFNγ) production of T cells were examined by flow cytometry. Gal-13 and Gal-14 are primarily expressed by the syncytiotrophoblast at the maternal-fetal interface in the first trimester, and their placental expression is decreased in miscarriages compared to first-trimester controls. Recombinant Gal-13 and Gal-14 bind to T cells in a population- and activation-dependent manner. Gal-13 and Gal-14 induce apoptosis of Th and Tc cell populations, regardless of their activation status. Out of the investigated activation markers, Gal-14 decreases the cell surface expression of CD71, Gal-13 increases the expression of CD25, and both galectins increase the expression of CD95 on T cells. Non-activated T cells produce larger amounts of IL-8 in the presence of Gal-13 or Gal-14. In conclusion, these results show that Gal-13 and Gal-14 already provide an immunoprivileged environment at the maternal-fetal interface during early pregnancy, and their reduced expression is related to miscarriages.

Galectin-3-Mediated Glial Crosstalk Drives Oligodendrocyte Differentiation and (Re)myelination

Galectin-3 (Gal-3) is the only chimeric protein in the galectin family. Gal-3 structure comprises unusual tandem repeats of proline and glycine-rich short stretches bound to a carbohydrate-recognition domain (CRD). The present review summarizes Gal-3 functions in the extracellular and intracellular space, its regulation and its internalization and secretion, with a focus on the current knowledge of Gal-3 role in central nervous system (CNS) health and disease, particularly oligodendrocyte (OLG) differentiation, myelination and remyelination in experimental models of multiple sclerosis (MS). During myelination, microglia-expressed Gal-3 promotes OLG differentiation by binding glycoconjugates present only on the cell surface of OLG precursor cells (OPC). During remyelination, microglia-expressed Gal-3 favors an M2 microglial phenotype, hence fostering myelin debris phagocytosis through TREM-2b phagocytic receptor and OLG differentiation. Gal-3 is necessary for myelin integrity and function, as evidenced by myelin ultrastructural and behavioral studies from LGALS3^-/- mice. Mechanistically, Gal-3 enhances actin assembly and reduces Erk 1/2 activation, leading to early OLG branching. Gal-3 later induces Akt activation and increases MBP expression, promoting gelsolin release and actin disassembly and thus regulating OLG final differentiation. Altogether, findings indicate that Gal-3 mediates the glial crosstalk driving OLG differentiation and (re)myelination and may be regarded as a target in the design of future therapies for a variety of demyelinating diseases.

The role of Galectin-3 in modulating tumor growth and immunosuppression within the tumor microenvironment

The efficacy of cancer immunotherapy is limited, in part, by the multitude of immunosuppressive mechanisms present within the tumor microenvironment (TME). Galectin-3 (Gal-3) is a lectin that contributes to TME immunosuppression and regulates diverse functions including cellular homeostasis and cancer biology. Increased Gal-3 expression during cancer progression augments tumor growth, invasiveness, metastatic potential, and immune suppression, which highlights the potential use of Gal-3 as a therapeutic target capable of modulating anti-tumor immunity. Here, we discuss the mechanisms by which Gal-3 regulates lymphocytes, the role of Gal-3 in lung and prostate tumors, and the contribution of Gal-3 to TME immunosuppression.

Galectin-3 Activation and Inhibition in Heart Failure and Cardiovascular Disease: An Update

Galectin-3 is a versatile protein orchestrating several physiological and pathophysiological processes in the human body. In the last decade, considerable interest in galectin-3 has emerged because of its potential role as a biotarget. Galectin-3 is differentially expressed depending on the tissue type, however its expression can be induced under conditions of tissue injury or stress. Galectin-3 overexpression and secretion is associated with several diseases and is extensively studied in the context of fibrosis, heart failure, atherosclerosis and diabetes mellitus. Monomeric (extracellular) galectin-3 usually undergoes further "activation" which significantly broadens the spectrum of biological activity mainly by modifying its carbohydrate-binding properties. Self-interactions of this protein appear to play a crucial role in regulating the extracellular activities of this protein, however there is limited and controversial data on the mechanisms involved. We therefore summarize (recent) literature in this area and describe galectin-3 from a binding perspective providing novel insights into mechanisms by which galectin-3 is known to be "activated" and how such activation may be regulated in pathophysiological scenarios.

ECM-Related Myopathies and Muscular Dystrophies: Pros and Cons of Protein Therapies

Extracellular matrix (ECM) myopathies and muscular dystrophies are a group of genetic diseases caused by mutations in genes encoding proteins that provide critical links between muscle cells and the extracellular matrix. These include structural proteins of the ECM, muscle cell receptors, enzymes, and intracellular proteins. Loss of adhesion within the myomatrix results in progressive muscle weakness. For many ECM muscular dystrophies, symptoms can occur any time after birth and often result in reduced life expectancy. There are no cures for the ECM-related muscular dystrophies and treatment options are limited to palliative care. Several therapeutic approaches have been explored to treat muscular dystrophies including gene therapy, gene editing, exon skipping, embryonic, and adult stem cell therapy, targeting genetic modifiers, modulating inflammatory responses, or preventing muscle degeneration. Recently, protein therapies that replace components of the defective myomatrix or enhance muscle and/or extracellular matrix integrity and function have been explored. Preclinical studies for many of these biologics have been promising in animal models of these muscle diseases. This review aims to summarize the ECM muscular dystrophies for which protein therapies are being developed and discuss the exciting potential and possible limitations of this approach for treating this family of devastating genetic muscle diseases. © 2017 American Physiological Society. Compr Physiol 7:1519-1536, 2017.

Galectin-3: A key player in arthritis

Arthritis is more and more considered as the leading reason for the disability in the world, particularly regarding its main entities, rheumatoid arthritis and osteoarthritis. The common feature of arthritis is inflammation, which is mainly supported by synovitis (synovial inflammation), although the immune system plays a primary role in rheumatoid arthritis and a secondary one in osteoarthritis. During the inflammatory phase of arthritis, many pro-inflammatory cytokines and mediators are secreted by infiltrating immune and resident joint cells, which are responsible for cartilage degradation and excessive bone remodeling. Amongst them, a β-galactoside-binding lectin, galectin-3, has been reported to be highly expressed and secreted by inflamed synovium of rheumatoid arthritis and osteoarthritis patients. Furthermore, galectin-3 has been demonstrated to induce joint swelling and osteoarthritis-like lesions after intra-articular injection in laboratory animals. However, the mechanisms underlying its pathophysiological role in arthritis have not been fully elucidated. This review deals with the characterization of arthritis features and galectin-3 and summarizes our current knowledge of the contribution of galectin-3 to joint tissue lesions in arthritis.

Galectins: Double-edged Swords in the Cross-roads of Pregnancy Complications and Female Reproductive Tract Inflammation and Neoplasia

Galectins are an evolutionarily ancient and widely expressed family of lectins that have unique glycan-binding characteristics. They are pleiotropic regulators of key biological processes, such as cell growth, proliferation, differentiation, apoptosis, signal transduction, and pre-mRNA splicing, as well as homo- and heterotypic cell-cell and cell-extracellular matrix interactions. Galectins are also pivotal in immune responses since they regulate host-pathogen interactions, innate and adaptive immune responses, acute and chronic inflammation, and immune tolerance. Some galectins are also central to the regulation of angiogenesis, cell migration and invasion. Expression and functional data provide convincing evidence that, due to these functions, galectins play key roles in shared and unique pathways of normal embryonic and placental development as well as oncodevelopmental processes in tumorigenesis. Therefore, galectins may sometimes act as double-edged swords since they have beneficial but also harmful effects for the organism. Recent advances facilitate the use of galectins as biomarkers in obstetrical syndromes and in various malignancies, and their therapeutic applications are also under investigation. This review provides a general overview of galectins and a focused review of this lectin subfamily in the context of inflammation, infection and tumors of the female reproductive tract as well as in normal pregnancies and those complicated by the great obstetrical syndromes.

Galectin-1 links tumor hypoxia and radiotherapy

Radiation therapy is a main stay in treating solid tumors and plays a significant role in definitive and adjuvant therapy. Unfortunately, local control remains a challenge, in which the success of radiotherapy is largely dictated by tumor hypoxia, DNA damage repair and the antitumor immune response. Extensive efforts have therefore been devoted to targeting the factors that attenuate tumor radiosensitivity, although with limited success. Mounting evidence suggests that tumor and endothelial cells may utilize galectin-1 (Gal-1) for protection against radiation through several mechanisms. Targeting Gal-1 in combination with radiotherapy provides an exciting approach to address several radiation-prohibitive mechanisms.

Expression and function of galectins in the endometrium and at the human feto-maternal interface

Galectins are classified as lectins that share structural similarities and bind β-galactosides via a conserved carbohydrate recognition domain. So far 16 out of 19 identified galectins were shown to be present in humans and numerous studies revealed galectins as pivotal modulators of cell death, differentiation and growth. Galectins were highlighted to interact with both the adaptive and innate immune response. In the field of reproductive medicine and placenta research different roles for galectins have been proposed. Several galectins, being abundantly present at the human feto-maternal interphase and endometrium, were hypothesized to significantly contribute to endometrial receptivity and pregnancy physiology. Hence, this review outlines selected aspects of galectin action within endometrial function and at the feto-maternal interphase. Further current knowledge on galectins in reproductive and pregnancy disorders like endometriosis, abortion or preeclampsia is summarized.

Deficiency in galectin-3 promotes hepatic injury in CDAA diet-induced nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is increasingly recognized as a condition in which excess fat accumulates in hepatocytes. Nonalcoholic steatohepatitis (NASH), a severe form of NAFLD in which inflammation and fibrosis in the liver are noted, may eventually progress to end-stage liver disease. Galectin-3, a β-galactoside-binding animal lectin, is a multifunctional protein. This protein is involved in inflammatory responses and carcinogenesis. We investigated whether galectin-3 is involved in the development of NASH by comparing galectin-3 knockout (gal3(-/-)) mice and wild-type (gal3(+/+)) mice with choline-deficient L-amino-acid-defined (CDAA) diet-induced NAFLD/NASH. Hepatic injury was significantly more severe in the gal3(-/-) male mice, as compared to the gal3(+/+) mice. Data generated by microarray analysis of gene expression suggested that galectin-3 deficiency causes alterations in the expression of various genes associated with carcinogenesis and lipid metabolism. Through canonical pathway analysis, involvement of PDGF and IL-6 signaling pathways was suggested in galectin-3 deficiency. Significant increase of CD14, Fos, and Jun, those that were related to lipopolysaccharide-mediated signaling, was candidate to promote hepatocellular damages in galectin-3 deficiency. In conclusion, galectin-3 deficiency in CDAA diet promotes NAFLD features. It may be caused by alterations in the expression profiles of various hepatic genes including lipopolysaccharide-mediated inflammation.

Galectin-3 in cord blood of term and preterm infants

In recent years galectin-3 has gained attention as a signalling molecule, mainly in inflammatory diseases. Data on galectin-3 expression in neonates, however, are limited, and expression of this lectin in cord blood has not yet been reported. The aim of this study was to determine galectin-3 levels in cord blood of term and preterm neonates as well as galectin-3 levels in cord blood of term neonates after stimulation with the prevalent pathogen Streptococcus agalactiae. Cord blood samples were incubated for 24 h and galectin-3 levels were assessed by enzyme-linked immunosorbent assay. There is a positive correlation between gestational age and galectin-3 levels in cord blood. Expression of galectin-3 is significantly higher in cord blood of small-for-gestational-age infants compared to appropriate-for-gestational-age infants. Stimulation with an invasive but not with a colonizing strain of S. agalactiae induced expression of galectin-3. Galectin-3 is expressed constitutively in cord blood of neonates and seems to play a role in the innate immunity of this population.

Protein profiling of human nonpigmented ciliary epithelium cell secretome: the differentiation factors characterization for retinal ganglion cell line

The purpose of this paper was to characterize proteins secreted from the human nonpigmented ciliary epithelial (HNPE) cells, which have differentiated a rat retinal ganglion cell line, RGC-5. Undifferentiated RGC-5 cells have been shown to express several marker proteins characteristic of retinal ganglion cells. However, RGC-5 cells do not respond to N-methyl-D aspartate (NMDA), or glutamate. HNPE cells have been shown to secrete numbers of neuropeptides or neuroproteins also found in the aqueous humor, many of which have the ability to influence the activity of neuronal cells. This paper details the profile of HNPE cell-secreted proteins by proteomic approaches. The experimental results revealed the identification of 132 unique proteins from the HNPE cell-conditioned SF-medium. The biological functions of a portion of these identified proteins are involved in cell differentiation. We hypothesized that a differentiation system of HNPE cell-conditioned SF-medium with RGC-5 cells can induce a differentiated phenotype in RGC-5 cells, with functional characteristics that more closely resemble primary cultures of rat retinal ganglion cells. These proteins may replace harsh chemicals, which are currently used to induce cell differentiation.

Development of a nascent galectin-1 chimeric molecule for studying the role of leukocyte galectin-1 ligands and immune disease modulation

Galectin-1 (Gal-1), a β-galactoside-binding lectin, plays a profound role in modulating adaptive immune responses by altering the phenotype and fate of T cells. Experimental data showing recombinant Gal-1 (rGal-1) efficacy on T cell viability and cytokine production, nevertheless, is controversial due to the necessity of using stabilizing chemicals to help retain Gal-1 structure and function. To address this drawback, we developed a mouse Gal-1 human Ig chimera (Gal-1hFc) that did not need chemical stabilization for Gal-1 ligand recognition, apoptosis induction, and cytokine modulation in a variety of leukocyte models. At high concentrations, Gal-1hFc induced apoptosis in Gal-1 ligand(+) Th1 and Th17 cells, leukemic cells, and granulocytes from synovial fluids of patients with rheumatoid arthritis. Importantly, at low, more physiologic concentrations, Gal-1hFc retained its homodimeric form without losing functionality. Not only did Gal-1hFc-binding trigger IL-10 and Th2 cytokine expression in activated T cells, but members of the CD28 family and several other immunomodulatory molecules were upregulated. In a mouse model of contact hypersensitivity, we found that a non-Fc receptor-binding isoform of Gal-1hFc, Gal-1hFc2, alleviated T cell-dependent inflammation by increasing IL-4(+), IL-10(+), TGF-β(+), and CD25(high)/FoxP3(+) T cells, and by decreasing IFN-γ(+) and IL-17(+) T cells. Moreover, in human skin-resident T cell cultures, Gal-1hFc diminished IL-17(+) T cells and increased IL-4(+) and IL-10(+) T cells. Gal-1hFc will not only be a useful new tool for investigating the role of Gal-1 ligands in leukocyte death and cytokine stimulation, but for studying how Gal-1-Gal-1 ligand binding shapes the intensity of immune responses.

Galectin-1 and its involvement in hepatocellular carcinoma aggressiveness

Hepatocellular carcinoma is one of the most common cancers worldwide. Despite several efforts to elucidate hepatocellular carcinoma molecular pathogenesis, it is still not fully understood. To acquire further insights into the molecular mechanisms of hepatocellular carcinoma, we performed a systematic functional genomic approach on human HuH-7 and JHH-6 cells. The subsequent analysis of the differentially expressed genes in human specimens revealed a molecular signature of 11 genes from which we selected the LGALS1 gene, which was overexpressed in hepatocellular carcinoma. The expression analysis in humans of Galectin-1 (Gal-1), the protein encoded by LGALS1, showed a Gal-1 preferential accumulation in the stromal tissue around hepatocellular carcinoma tumors. Moreover, a significant association between increased expression of Gal-1 in hepatocellular carcinoma and the presence of metastasis was observed. Interestingly, Gal-1 overexpression resulted in an increase of cell migration and invasion. In conclusion, this study provides a portfolio of targets useful for future investigations into molecular marker-discovery studies on a large number of patients and functional assays. In addition, our data provide evidence that Gal-1 plays a role in hepatocellular carcinoma cell migration and invasion, and we suggest that further studies should be conducted to fully establish the role of Gal-1 in hepatocellular carcinoma pathogenesis and evaluate Gal-1 as a potential molecular therapeutic target.

Galectin-3: a novel mediator of heart failure development and progression

Galectins are a family of soluble beta-galactoside-binding lectins that play many important regulatory roles in inflammation, immunity, and cancer. Recently, a role for galectin-3 in the pathophysiology of heart failure (HF) has been suggested. Numerous studies have demonstrated the up-regulation of galectin-3 in hypertrophied hearts, its stimulatory effect on macrophage migration, fibroblast proliferation, and the development of fibrosis. The latter observation is particularly relevant as cardiac remodelling is an important determinant of the clinical outcome of HF and is linked to disease progression and poor prognosis. Because galectin-3 expression is maximal at peak fibrosis and virtually absent after recovery, routine measurement in patients with HF may prove valuable to identify those patients at highest risk for readmission or death, thus enabling physicians to tailor the level of care to individual patient needs. This review summarizes the most recent advances in galectin-3 research, with an emphasis on the role galectin-3 plays in the development and progression of HF.

Expression of galectin-1, a new component of slit diaphragm, is altered in minimal change nephrotic syndrome

Nephrin is an essential structural component of the glomerular slit diaphragm (SD), a highly organized intercellular junction that constitutes the ultrafiltration barrier of the kidney. Recent studies have identified two additional nephrin-interacting SD proteins (NEPH1 and NEPH2), suggesting that the zipper-like pattern of the SD is formed through complex intra- and intermolecular interactions of these proteins. However, the complexity of the SD structure suggests that additional SD components remain to be discovered. In this study, we identified galectin-1 (Gal-1) as a new component of the SD, binding to the ectodomain of nephrin. Using dual-immunofluorescence and confocal microscopy and dual-immunoelectron microscopy, we found Gal-1 co-localizing with the ectodomain of nephrin at the SD in normal human kidney. By immunoprecipitation and surface plasmon resonance, we confirmed a direct molecular interaction between Gal-1 and nephrin. Moreover, recombinant Gal-1 induced tyrosine phosphorylation of the cytoplasmic domain of nephrin and activation of the extracellular signal-regulated kinase 1/2 in podocytes. We also showed that podocytes are a major site of biosynthesis of Gal-1 in the glomerulus and that the normal expression patterns and levels of Gal-1 are altered in patients with minimal change nephrotic syndrome. Finally, in puromycin aminonucleoside-induced rat nephrosis, an apparent reduction in the levels of Gal-1 and nephrin around the onset of heavy proteinuria was also revealed. Our data present Gal-1 as a new extracellular ligand of nephrin localized at the glomerular SD, and provide further insight into the complex molecular organization, interaction, and structure of the SD, which is an active site of intracellular signaling necessary for podocyte function.

Immunohistochemical study of galectin-3 in mature and immature bull testis and epididymis

Galectin-3, a member of the β-galactoside-binding protein family, has been implicated in mammalian sperm maturation. We examined galectin-3 expression in the testis and epididymis of sexually mature and immature bulls. Western blot analysis showed varying levels of galectin-3 in the bull testis and epididymis, and galectin-3 immunoreactivity was higher in the mature testis and epididymis than in immature organs. Galectin-3 was primarily localized in interstitial cells of the immature bull testis and in the peritubular myoid and interstitial cells of the mature testis. In the immature epididymis head, galectin-3 was primarily in the principal and basal cells of the epithelium. In the mature epididymis head, moderate levels of galectin-3 were detected in the sperm, while low levels were found in the stereocilia, epithelium and connective tissue. In the immature epididymis body, moderate protein levels were detected in the principal cells, while lower levels were found in the basal cells. The mature epididymis body showed moderate levels of galectin-3 immunostaining in the stereocilia and epithelium, but low levels in the connective tissue. In the immature epididymis tail, only low levels of galectin-3 staining were found in the epithelium, whereas the mature epididymis tail showed high levels of galectin-3 in the principal cells, moderate levels in the basal cells and low levels in connective tissue. These findings suggest that galectin-3 expression plays a role in the maturation and activation of sperm in bulls.

Regulation of tumor progression by extracellular galectin-3

The relationship between a tumor cell and its microenvironment is bi-directional. The proteins expressed by the tumor cells alter the signatures on the seemingly normal stromal cells within the microenvironment, while the tumor cell signatures reflect the changes that occur as these cells interact with the host microenvironment. Galectin-3 is a carbohydrate-binding protein that is over-expressed in a variety of tumors and immune cells in response to various stimuli. Ever since its discovery, it has been associated with cell and extracellular matrix interactions. However, in the last decade, an extensive accumulation of data has changed the perspective of this multifunctional protein. The unique structure of this protein, consisting of a carbohydrate-binding domain and a matrix metalloproteinase cleavable domain, enables it to interact with a plethora of ligands in a carbohydrate-dependent or independent manner. It is now becoming evident that galectin-3 is involved with a variety of extracellular functions like cell adhesion, migration, invasion, angiogenesis, immune functions, apoptosis and endocytosis. Galectin-3 is a substrate for matrix metalloproteinases and its cleavage plays an important role in tumor progression and can be used as a surrogate diagnostic marker for in vivo MMP activity.

Disrupted galectin-3 causes non-alcoholic fatty liver disease in male mice

Galectin-3, a beta-galactoside-binding animal lectin, is a multifunctional protein. Previous studies have suggested that galectin-3 may play an important role in inflammatory responses. Non-alcoholic fatty liver disease (NAFLD) is increasingly recognized as a liver condition that may progress to end-stage liver disease and based on the known functions of galectin-3, it was hypothesized that galectin-3 might play a role in the development of NAFLD. Thus, this study investigated the role of galectin-3 in NAFLD by comparing galectin-3 knockout (gal3(-/-)) mice and wild-type (gal3(+/+)) mice. The livers of gal3(-/-) male mice at 6 months of age histologically displayed mild to severe fatty change. The liver weight per body weight ratio, serum alanine aminotransferase levels, liver triglyceride levels, and liver lipid peroxide in gal3(-/-) mice were significantly increased compared with those in gal3(+/+) mice. Furthermore, the hepatic protein levels of advanced glycation end-products (AGE), receptor for AGE (RAGE), and peroxisome proliferator-activated receptor gamma (PPARgamma) were increased in gal3(-/-) mice relative to gal3(+/+) mice. In conclusion, this study suggests that the absence of gal3 can cause clinico-pathological features in male mice similar to those of NAFLD.

Proteomic Analysis on the Alteration of Protein Expression in the Placental Villous Tissue of Early Pregnancy Loss

Early pregnancy loss is the most common complication of human reproduction. Given the complexities of early development, it is likely that many mechanisms are involved. Knowledge of differences in protein expression in parallel profiling is essential to understand the comprehensive pathophysiological mechanism underlying early pregnancy loss. To identify proteins with different expression profiles related to early pregnancy loss, we applied a proteomic approach and performed two-dimensional gel electrophoresis (2-DE) on six placental villous tissues from patients with early pregnancy loss and six from normal pregnant women, followed by comparison of the silver-stained 2-DE profiles. It was found that 13 proteins were downregulated and 5 proteins were upregulated significantly (P < 0.05) in early pregnancy loss as determined by spot volume. Among them, 10 downregulated and 2 upregulated spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Anomalies of these proteins, including three principal antioxidant enzymes (copper/zinc-superoxide dismutase, peroxiredoxin 3, and thioredoxin-like 1 protein), S100 calcium binding protein, galectin-1, chorionic somatomammotropin hormone 1, transthyretin, fas inhibitory molecule, eukaryotic translation elongation factor, RNA-binding protein, ubiquitin-conjugating enzyme E2N, and proteasome beta-subunit, indicate widespread failure in cell regulations and processes such as antioxidative defense, differentiation, cell proliferation, metabolism, apoptosis, transcription, and proteolysis in early pregnancy loss. This study has identified several proteins that are associated with placentation and early development, shedding a new insight into the proteins that may be potentially involved in the pathophysiological mechanisms underlying early pregnancy loss.

Galectin-1: a small protein with major functions

Galectins are a family of carbohydrate-binding proteins with an affinity for beta-galactosides. Galectin-1 (Gal-1) is differentially expressed by various normal and pathological tissues and appears to be functionally polyvalent, with a wide range of biological activity. The intracellular and extracellular activity of Gal-1 has been described. Evidence points to Gal-1 and its ligands as one of the master regulators of such immune responses as T-cell homeostasis and survival, T-cell immune disorders, inflammation and allergies as well as host-pathogen interactions. Gal-1 expression or overexpression in tumors and/or the tissue surrounding them must be considered as a sign of the malignant tumor progression that is often related to the long-range dissemination of tumoral cells (metastasis), to their dissemination into the surrounding normal tissue, and to tumor immune-escape. Gal-1 in its oxidized form plays a number of important roles in the regeneration of the central nervous system after injury. The targeted overexpression (or delivery) of Gal-1 should be considered as a method of choice for the treatment of some kinds of inflammation-related diseases, neurodegenerative pathologies and muscular dystrophies. In contrast, the targeted inhibition of Gal-1 expression is what should be developed for therapeutic applications against cancer progression. Gal-1 is thus a promising molecular target for the development of new and original therapeutic tools.

Expression of lysosome-associated membrane protein 1 (Lamp-1) and galectins in human keratinocytes is regulated by differentiation

Lysosomes and their components are suspected to be involved in epidermal differentiation. In this study, lysosomal enzyme activities, expression of the lysosome-associated membrane protein 1 (Lamp-1) and expression of the epidermal galectins-1, -3 and -7 were investigated in human keratinocytes cultured at different cell densities (subconfluence, confluence and postconfluence) in order to induce differentiation. Detected by Western blot and immunofluorescence, Lamp-1 expression is transiently upregulated at culture confluence, but reduced at postconfluence. Northern blot analyses performed on subconfluent, confluent and post-confluent cultures of keratinocytes show that Lamp-1 mRNA expression is also upregulated at culture confluence, but downregulated at postconfluence. Measurements of lysosomal enzyme activities indicate a transient upregulation at culture confluence, whereas cathepsins B, C and L are particularly downregulated at postconfluence. Cell density and differentiation of epidermal cells also differentially regulates galectin expression in autocrine cultures. As the expression of galectin-1 mRNA is high in subconfluent cells, it is assumed to be associated with their proliferative state. On the other hand, as the mRNA levels for galectins-3 and -7 are notably upregulated at culture confluence (galectin-7) or at postconfluence (galectin-3), their expression is thought to be related to the differentiated state of keratinocytes. However, we collected evidence by confocal microscopy that galectin-3 and Lamp-1 do not colocalize in vitro in keratinocytes. Altogether, our results suggest that the upregulated Lamp-1 expression at confluence could be involved in keratinocyte differentiation, but apparently not through interaction with galectin-3.

Galectin-3: an open-ended story

Galectins, an ancient lectin family, are characterized by specific binding of beta-galactosides through evolutionary conserved sequence elements of carbohydrate-recognition domain (CRD). A structurally unique member of the family is galectin-3; in addition to the CRD it contains a proline- and glycine-rich N-terminal domain (ND) through which is able to form oligomers. Galectin-3 is widely spread among different types of cells and tissues, found intracellularly in nucleus and cytoplasm or secreted via non-classical pathway outside of cell, thus being found on the cell surface or in the extracellular space. Through specific interactions with a variety of intra- and extracellular proteins galectin-3 affects numerous biological processes and seems to be involved in different physiological and pathophysiological conditions, such as development, immune reactions, and neoplastic transformation and metastasis. The review attempts to summarize the existing information on structural, biochemical and intriguing functional properties of galectin-3.

The galectin-3 gene promoter binding proteins in the liver of rats 48-h post-treatment with CCl4

The present study was undertaken to characterize structure-function relationships of the rat galectin-3 gene promoter especially focusing on the promoter binding proteins included in livers injured with CCl4. Transcription start site determination identified a 66-nucleotide-long exon 1 of this gene. Transient expression analysis using a reporter luciferase gene assigned a region between -161 and -15 to the proximal promoter within the 1-kb region flanking the 5'-end of exon 1. The rat galectin-3 gene promoter possesses a Runx2 binding site and inverted repeats of Sp1 binding motifs in separate regions downstream from -117 as structures resembling those of the mouse galectin-3 gene promoter. The -161/-118 region bound two different proteins. One is a novel protein, a rat version of Purbeta that binds to a guanine nucleotide pair at -145 and -144 to modulate constitutive galectin-3 gene transcription. Southwestern blot analysis using the -161/-118 ligand revealed a signal of a 50-kDa protein in liver nuclear extracts from rats 48-h post-treatment with CCl4, but not in those from Ac2F cells and normal rat livers. The inducible nature of this protein suggested its distinctive role in galectin-3 induction in a liver injured with CCl4. E-box and peroxisome proliferator response element-like motifs reside on separate DNA strands from -140 to -135. Contribution of this segment to the regulation of galectin-3 gene transcription under pathological conditions was suggested, since a DNA ligand with the two motifs simultaneously mutagenized at -136 and -137 was not bound by the 50-kDa protein.

Galectin-3 surface expression on human adult chondrocytes: a potential substrate for collagenase-3

BACKGROUND

Galectin-3 is a lectin detected in mature and early hypertrophic chondrocytes; osteoarthritic (OA) chondrocytes can re-express hypertrophic markers.

OBJECTIVE

To investigate the synthesis and subcellular localisation of galectin-3 in adult chondrocytes as well as the possibility of cleavage of galectin-3 by collagenase-1 and -3.

METHODS

Galectin-3 was assessed by immunohistochemistry and real time polymerase chain reaction (PCR) in normal and OA cartilage. Its localisation was investigated by subcellular fractionation, immunocytology, and flow cytometry. Proteolysis of galectin-3 by collagenase-1 and -3 was determined by in vitro assay.

RESULTS

Galectin-3 expression was increased 2.4-fold as measured by reverse transcriptase (RT)-PCR (p<0.05, n = 5) and threefold by immunohistochemistry (p<0.003 n = 6) in OA cartilage compared with normal cartilage. In adult chondrocytes, galectin-3 was found in the cytosol and membrane enriched fractions. Both immunocytology and flow cytometry confirmed the presence of galectin-3 at the surface of chondrocytes. A strong correlation was found between integrin-beta1 and galectin-3 expression at the surface of chondrocytes. Moreover, collagenase-3 cleaved galectin-3 with a higher activity than collagenase-1. The proteolysed sites generated were identical to those produced by gelatinases A and B.

CONCLUSION

Galectin-3 may play a part in OA, having two roles, one intracellular and not yet identified, and another at the cell surface, possibly related to the interaction of chondrocytes and the cartilage matrix.

Global gene expression analysis comparing bovine blastocysts flushed on day 7 or produced in vitro

In vitro produced (IVP) bovine embryos have darker cytoplasm, reduced buoyant density, fragile zonae pellucidae, chromosomal abnormalities, higher pregnancy failure rates, and altered gene expression compared to embryos produced in vivo. Characterization of early deviations in gene expression would enable us to better understand the biology of early embryo development and improve in vitro culture systems. Here we compared gene expression between Day 7 blastocysts generated in TCM199 with 5% FBS and Day 7 in vivo derived blastocysts and using suppression-subtractive hybridization (SSH). Pools of 25 embryos for both driver and tester were used in the RNA extraction process. The subtracted products were cloned and subjected to differential hybridization screening analysis. cDNAs were isolated, single-pass sequenced, and subjected to BLAST search. Of 32 in vivo ESTs (expressed sequence tags) that provided sequence information, 30 matched homologous sequences in GenBank. Of 32 in vitro ESTs, 22 provided specific matches while the remaining ten represented novel transcripts. Two in vivo ESTs, galectin-1 and fibronectin, and one in vitro EST, filamin A, were further characterized using real-time quantitative PCR. To further examine the reproducibility of the SSH data, three different pools of embryos with each pool containing ten embryos produced from each of the following production systems, namely, in vivo, IVP in TCM199 with 5% FBS and CR1aa with 5% FBS were used for real-time reverse transcription-polymerase chain reaction (RT-PCR) confirmation studies. Significant increases in the expression level of galectin-1 and fibronectin were observed in the in vivo derived blastocysts compared to blastocysts produced in TCM199 with 5% FBS and CR1aa cultures. No significant difference in filamin A expression was found between blastocysts produced in vivo and those derived from either of the in vitro production systems. We conclude that these techniques are useful to characterize the transcriptome of the early preattachment embryo and observed deviations in mRNA expression may partially explain the differences in quality between in vivo and IVP embryos.

Galectin-3 expression in normal, hyperplastic, and neoplastic endometrial tissues

This study evaluated the expression of galectin-3 in 101 curettage specimens from normal, hyperplastic, and neoplastic endometrial tissues using immunohistochemistry. The histologic diagnoses were as follows: normal proliferative (n = 8) and secretory (n = 4) phase, simple hyperplasia (SH, n = 16), complex hyperplasia without atypia (CH, n = 11), atypical hyperplasia (AH, n = 13), endometrioid adenocarcinoma (EC, n = 35), serous papillary carcinoma (SPC, n = 10), and clear cell carcinoma (CC, n = 4). Immunostaining was scored with regard to the approximate percentage of positive tumor cells and relative staining intensity. The scores of immunostaining increased significantly from NE, SH, CH, and AH to the adenocarcinomas (ANOVA, p < 0.0001). Subsequently, three significantly different levels of galectin-3 expression were found (Newman-Keuls multiple comparison test). These consisted of (a) NE, SH, and CH, (b) AH and EC, and (c) SPC and CC. Galectin-3 expression increased with tumor grade (ANOVA, p = 0.0026). The scores of FIGO stages I to III did not differ significantly (ANOVA, p = 0.1687). Enhanced nuclear galectin-3 expression was noted in carcinomas, immunostaining of stromal cells decreased in the latter. This study shows that galectin-3 expression increases from normal and hyperplastic to atypical hyperplastic and cancerous states of endometrial tissues, and provides further evidence of a relationship between AH and EC.

Participation of pigment epithelium in ocular immune privilege. 3. Epithelia cultured from iris, ciliary body, and retina suppress T-cell activation by partially non-overlapping mechanisms

PURPOSE

The ocular microenvironment is immunosuppressive and anti-inflammatory. Since various ocular pigmented epithelia contribute to this microenvironment, we studied the relative capacities of pigment epithelial (PE) cells cultured from the iris, ciliary body, and retina of mouse eyes to suppress T-cell activation in vitro.

METHODS

Pigment epithelium was cultured from iris, ciliary body, and retina for 14 days, then assayed for the capacity, directly or across transwell membranes, to suppress mixed lymphocyte reactions and anti-CD3 stimulation of T cells. Potential molecules responsible for suppression were examined by attempting to block suppression with appropriate reagents, and by using mice with pertinent mutant or disrupted genes.

RESULTS

We found that PE cells from all three ocular tissue sources profoundly suppressed T-cell activation in vitro. While iris PE suppressed poorly when separated from T cells by a transwell membrane (implying that cell contact is necessary), retina PE suppressed fully even in the presence of such a membrane (implying that soluble factors were responsible). Ciliary body PE used both soluble factors as well as cell contact to achieve suppression. Suppression could not be ascribed to TGFbeta, IFNgamma, TNFalpha, CD48, or ICAM-1, or to interactions between CD40 and CD154, or CD95 and CD95 ligand. Galectin-1, a galactoside-binding protein, was found to be expressed on all cultured PE cells, but only retinal pigment epithelium (RPE) from galectin-1 KO mice showed reduced capacity to inhibit T-cell activation.

CONCLUSIONS

Cultured pigment epithelia from iris, ciliary body, and retina comparably suppress T-cell activation in vitro, but by partially different mechanisms. Although RPE cells suppress in part through expression of galectin-1, the molecular mediators of suppression by iris and ciliary body PE remain to be identified.

Expression of galectin-1 and galectin-3 in human fetal thyroid gland

High levels of expression of galectin-1 and galectin-3, the beta-galactoside-binding proteins, have been recently described in malignant thyroid tumors but not in adenomas nor in normal thyroid tissue. However, there are no data about the expression of these galectins during fetal thyroid development. In this study we analyzed immunohistochemically the presence of galectin-1 and galectin-3 in human fetal thyroid glands (16-37 weeks of gestation). Weak to moderate cytoplasmic staining for galectin-1 was observed in follicular cells of all fetal thyroids. Galectin-3 could not be detected in thyroid follicular cells of any fetal thyroid investigated. Both galectins were detected in stromal tissue, but staining for galectin-1 was more intense. The absence of galectin-3 in thyroid cells during fetal development suggests that galectin-3 is expressed de novo during malignant transformation of thyroid epithelium, and that galectin-1 could be considered an oncofetal antigen. The results obtained indicated potential roles for galectin-1 and galectin-3 during the investigated period of human fetal thyroid gland development. Both galectins might participate in developmental processes regarding stromal fetal thyroid tissue organization, whereas galectin-1 might have a function in thyroid epithelium maturation.

Nuclear localization of Galectin-3 in transformed thyroid cells: a role in transcriptional regulation

The differential proteomic approach (2D gel analysis coupled to MALDI-MS analysis) of nuclear proteins can provide an extremely useful tool to understand control of cell proliferation and differentiation. In order to identify possible markers of dedifferentiation between normal and cancerous thyroid cells, we used a differential proteomics approach by comparing nuclear extracts from the normal rat thyroid cell line FRTL-5 and the completely undifferentiated Ki-mol cell line, obtained by transformation with the Ki-ras oncogene. Galectin-3 (Gal-3) was identified as highly expressed, in the nuclear compartment, only in the transformed cell line. By using different human cancer cell lines, we showed that Gal-3 is maximally expressed in nuclei of papillary cancer cells. We focused on the functional relationship existing between Gal-3 and the thyroid-specific transcription factor TTF-1, whose expression is maintained in papillary cancer where it can contribute to the proliferating status. By using gel-retardation and transient tranfection assays, we demonstrate that Gal-3 upregulates the TTF-1 transcriptional activity. GST-pulldown experiments demonstrate the occurrence of interaction between Gal-3 and TTF-1 homeodomain. Since several lines of evidence suggest a role for Gal-3 in controlling proliferation and tumor progression in thyroid cancer, the stimulatory activity played by Gal-3 over TTF-1 would account for a possible molecular mechanism through which the galectin controls proliferation in thyroid cells.

Developmental aspects of galectin-3 expression in the lens

In order to investigate the temporal and spatial expression pattern of the lectin galectin-3 during lens development we performed immunohistochemical studies using monoclonal and polyclonal antibodies against galectin-3 on paraffin sections of human, mouse and rat eyes. Galectin-3 has been shown to be involved in various biological functions related to cell adhesion, proliferation, apoptosis and differentiation in other tissues. In the human lens, galectin-3 shows a selective expression pattern during lens development. It is present in all cells of the early lens vesicle and at later stages it is strongly expressed during the elongation phase in differentiating primary lens fibres. From about 7 weeks onwards the anterior lens epithelium fails to express galectin-3. Adult lenses, however, exhibit immunoreactivity in the anterior epithelial cells and in the early differentiating secondary fibres of the lens' outer cortex prior to the onset of degradation of the nuclei. In contrast to the observed expression pattern in prenatal human lenses, mouse and rat lenses exhibited immunoreactivity for galectin-3 during postnatal and adult stages only. At these stages, the expression pattern closely resembles that seen in the corresponding human lenses. The spatiotemporal pattern of galectin-3 distribution during lens development favours a role of this lectin in adhesion processes and in the regulation of programmed organelle elimination during lens cell differentiation.