Eosinophil-expressed galectin-3 regulates cell trafficking and migration

Expression of inducible nitric oxide synthase, nitrotyrosine, eosinophilic peroxidase, eotaxin-3, and galectin-3 in patients with gastroesophageal reflux disease, eosinophilic esophagitis, and in healthy controls: a semiquantitative image analysis of 3,3'-diaminobenzidine-stained esophageal biopsies

Eosinophilic esophagitis (EoE) and gastroesophageal reflux disease (GERD) share many histopathological features; therefore, markers for differentiation are of diagnostic interest and may add to the understanding of the underlying mechanisms. The nitrergic system is upregulated in GERD and probably also in EoE. Esophageal biopsies of patients with EoE (n = 20), GERD (n = 20), and healthy volunteers (HVs) (n = 15) were exposed to antibodies against inducible nitric oxide synthase (iNOS), nitrotyrosine, eosinophilic peroxidase, eotaxin-3, and galectin-3. The stained object glasses were randomized, digitized, and blindly analyzed regarding the expression of DAB (3,3'-diaminobenzidine) by a protocol developed in QuPath software. A statistically significant overexpression of iNOS was observed in patients with any of the two inflammatory diseases compared with that in HVs. Eotaxin-3 could differentiate HVs versus inflammatory states. Gastroesophageal reflux patients displayed the highest levels of nitrotyrosine. Neither iNOS nor nitrotyrosine alone were able to differentiate between the two diseases. For that purpose, eosinophil peroxidase was a better candidate, as the mean levels increased stepwise from HVs via GERD to EoE. iNOS and nitrotyrosine are significantly overexpressed in patients with EoE and GERD compared with healthy controls, but only eosinophil peroxidase could differentiate the two types of esophagitis. The implications of the finding of the highest levels of nitrotyrosine among gastroesophageal reflux patients are discussed.

The effects of a galectin-3 inhibitor on bladder pain syndrome in mice with cyclophosphamide-induced cystitis

AIMS

To explore the effect of blocking galectin-3 in the bladder pain syndrome associated with interstitial cystitis.

METHODS

A galectin-3 inhibitor was used to treat mice with cyclophosphamide-induced cystitis. The expression of galectin-3 in bladder tissues and urine was examined by immunohistochemistry and enzyme-linked immunosorbent assay (ELISA), respectively. Suprapubic-pelvic pain, bladder voiding, bladder pain-like nociceptive behavior, and referred hyperalgesia were assessed. The weights of the bladders were also measured, and inflammatory cell infiltration and inflammatory cytokine levels were examined by histopathological evaluation. The inflammatory cytokines interleukin 1β (IL-1β), nerve growth factor (NGF), IL-6, and tumor necrosis factor α (TNF-α) were measured by ELISA.

RESULTS

Increases in galectin-3 levels, inflammation, bladder weight, and bladder pain-related symptoms were observed in bladders with cyclophosphamide-induced cystitis. Administration of the galectin-3 inhibitor significantly mitigated bladder pain-related symptoms and inflammatory response. In response to the 500 μM dose of the galectin-3 inhibitor, nociceptive behaviors, nociceptive score, and bladder-to-body weight ratios were reduced by 65.1%, 65.3%, and 40.3%, respectively, while 500 μM Gal-3 inhibitor increased pelvic pain threshold by 86.7%. Moreover, galectin-3 inhibitor treatment inhibited the inflammation. Compared to untreated CYP-induced mice, there were significant changes in the levels of IL-1β (41.72 ± 2.05 vs. 18.91 ± 2.26 pg/mg tissues), NGF (9.64 ± 0.38 vs. 1.88 ± 0.05 pg/mg tissues), IL-6 (42.67 + 1.51 vs. 21.26 + 2.78 pg/mg tissues, and TNF-α (22.02 ± 1.08 vs. 10.70 ± 0.80 pg/mg tissues) in response to the highest dose of the Gal-3 inhibitor subgroup (500 μM), and 500 μM Gal-3 inhibitor reduced mast cell infiltration ratios by 71.8%.

CONCLUSIONS

The galectin-3 inhibitor relieved pelvic pain, urinary symptoms, and bladder inflammation in mice with cyclophosphamide-induced cystitis. Thus, galectin-3 inhibitors may be novel agents in interstitial cystitis treatment.

Galectin-3, a damage-associated molecular pattern, in tears of patients with vernal keratoconjunctivitis

PURPOSE

Galectin-3 is a damage-associated molecular pattern (DAMPs), released from damaged or dying cells. In this study, we investigated the concentration and source of galectin-3 in the tears of patients with vernal keratoconjunctivitis (VKC) and evaluated whether the concentration of galectin-3 in tears represents a biomarker of corneal epithelial damage.

STUDY DESIGN

Clinical and experimental.

METHODS

We measured the concentration of galectin-3 in tear samples from 26 patients with VKC and 6 healthy controls by enzyme-linked immunosorbent assay (ELISA). The expression of galectin-3 in cultured human corneal epithelial cells (HCEs) stimulated with or without tryptase or chymase was investigated by polymerase chain reaction (PCR), ELISA, and Western blotting. We also estimated the concentration of galectin-3 in the supernatants of cultured HCEs induced to necrosis. Finally, we investigated whether recombinant galectin-3 induced the expression of various genes related to cell migration or the cell cycle in HCEs by using microarray analysis.

RESULTS

High concentrations of galectin-3 were detected in the tears of patients with VKC. The concentration showed significant correlation with the severity of corneal epithelial damage. Stimulation of cultured HCEs with various concentrations of tryptase or chymase had no effect on the expression of galectin-3. However, high concentrations of galectin-3 were detected in the supernatants of necrotic HCEs. Recombinant human galectin-3 induced various cell migration- and cell cycle-related genes.

CONCLUSION

The concentrations of galectin-3 in the tears of patients with VKC may represent a biomarker of the severity of corneal epithelial damage.

Galectin-3 is a key hepatoprotective molecule against the deleterious effect of cisplatin

AIMS

Evaluate the role of galectin-3 in the liver using an acute model of cisplatin-induced toxicity.

MATERIAL AND METHODS

Modified citrus pectin (MCP) treatment was used to inhibit galectin-3. Rats were distributed into four groups: SHAM, CIS, MCP and MCP + CIS. On days 1-7, animals were treated by oral gavage with 100 mg/kg/day of MCP (MCP and MCP + CIS groups). On days 8, 9 and 10, animals received intraperitoneal injection of 10 mg/kg/day of cisplatin (CIS and MCP + CIS groups) or saline (SHAM and MCP groups).

KEY FINDINGS

Cisplatin administration caused a marked increase in hepatic leukocyte influx and liver degeneration, and promoted reactive oxygen species production and STAT3 activation in hepatocytes. Plasma levels of cytokines (IL-6, IL-10), and hepatic toxicity biomarkers (hepatic arginase 1, α-glutathione S-transferase, sorbitol dehydrogenase) were also elevated. Decreased galectin-3 levels in the livers of animals in the MCP + CIS group were also associated with increased hepatic levels of malondialdehyde and mitochondrial respiratory complex I. Animals in the MCP + CIS group also exhibited increased plasma levels of IL-1β, TNF-α, and aspartate transaminase 1. Furthermore, MCP therapy efficiently antagonized hepatic galectin-9 in liver, but not galectin-1, the latter of which was increased.

SIGNIFICANCE

Reduction of the endogenous levels of galectin-3 in hepatocytes favors the process of cell death and increases oxidative stress in the acute model of cisplatin-induced toxicity.

Blood and adipose-resident eosinophils are defined by distinct transcriptional profiles

Eosinophils are granular leukocytes of the innate immune system that play important functions in host defense. Inappropriate activation of eosinophils can occur in pathologies such as asthma and esophagitis. However, eosinophils also reside within adipose tissue, where they play homeostatic roles and are important in the activation of thermogenic beige fat. Here we performed bulk RNA sequencing in mouse adipose tissue-resident eosinophils isolated from both subcutaneous and gonadal depots, for the first time, and compared gene expression to blood eosinophils. We found a predominantly conserved transcriptional landscape in eosinophils between adipose depots that is distinct from blood eosinophils in circulation. Through exploration of differentially expressed transcription factors and transcription factors with binding sites enriched in adipose-resident eosinophil genes, we identified KLF, CEBP, and Fos/Jun family members that may drive functional specialization of eosinophils in adipose tissue. These findings increase our understanding of tissue-specific eosinophil heterogeneity, with implications for targeting eosinophil function to treat metabolic disorders such as obesity.

Effects of galectin-3 protein on UVA-induced damage in retinal pigment epithelial cells

Several inflammatory molecules have been suggested as biomarkers of age-related macular degeneration (AMD). Galectin-3 (Gal-3), which has been shown to have a protective role in corneal injury by promoting epithelial cells adhesion and migration to the extracellular matrix, is also highly expressed in the retinal pigment epithelium (RPE) of patients with AMD. This study evaluated the role of Gal-3 in an in vitro model of UVA-induced RPE damage, as a proof-of-concept. ARPE-19 cells (human RPE cell line), were incubated with Gal-3 at 0.5-2.5 µg/mL concentrations prior to UVA irradiation for 15, 30, and 45 min, which resulted in accumulated doses of 2.5, 5, and 7.5 J/cm², respectively. After 24 h incubation, MTT and LDH assays, immunofluorescence, and ELISA were performed. UVA irradiation for 15, 30, and 45 min proved to reduce viability in 83%, 46%, and 11%, respectively. Based on the latter results, we chose the intermediate dose (5-J/cm²) for further analysis. Pretreatment with Gal-3 at concentrations > 1.5 µg/mL showed to increase the viability of UVA-irradiated cells (~ 75%) compared to untreated cells (64%). Increased levels of cleaved caspase 3, a marker of cell death, were detected in the ARPE cells after UVA irradiation with or without addition of exogenous Gal-3. The inhibitory effect of Gal-3 on UVA-induced cell damage was characterized by decreased ROS levels and increased p38 activation, as detected by fluorescence analysis. In conclusion, our study suggests a photoprotective effect of Gal-3 on RPE by reducing oxidative stress and increasing p38 activation.

Glycan-Lectin Interactions in Cancer and Viral Infections and How to Disrupt Them

Glycan-lectin interactions play an essential role in different cellular processes. One of their main functions is involvement in the immune response to pathogens or inflammation. However, cancer cells and viruses have adapted to avail themselves of these interactions. By displaying specific glycosylation structures, they are able to bind to lectins, thus promoting pathogenesis. While glycan-lectin interactions promote tumor progression, metastasis, and/or chemoresistance in cancer, in viral infections they are important for viral entry, release, and/or immune escape. For several years now, a growing number of investigations have been devoted to clarifying the role of glycan-lectin interactions in cancer and viral infections. Various overviews have already summarized and highlighted their findings. In this review, we consider the interactions of the lectins MGL, DC-SIGN, selectins, and galectins in both cancer and viral infections together. A possible transfer of ways to target and disrupt them might lead to new therapeutic approaches in different pathological backgrounds.

Galectins in allergic inflammatory diseases

Allergic inflammatory diseases are a global public health concern affecting millions of people. Although there are several potential hypotheses, details regarding their molecular mechanisms are still ambiguous. Recently, a group of β-galactoside-binding proteins, galectins, have been revealed as important factors in altering allergic chronic inflammatory diseases. In this review, we describe the molecular and cellular basis of how galectins modulate inflammatory reactions. We also provide an overview of clinical features related to galectins. Finally, we discuss the potential issues that might lead to misrepresentation of the exact biological functions of galectins.

Trichinella spiralis co-infection exacerbates Plasmodium berghei malaria-induced hepatopathy

Background

Although Plasmodium parasites and intestinal helminths share common endemic areas, the mechanisms of these co-infections on the host immune response remain not fully understood. Liver involvement in severe Plasmodium falciparum infections is a significant cause of morbidity and mortality. However, the effect of pre-existing Trichinella spiralis infection on the immune response and liver immune-pathogenesis in P. berghei ANKA (PbANKA)-infected mice needs to be elucidated.

Methods

Outbred Kunming mice were infected with T. spiralis and 9 days later were challenged with P. berghei ANKA (PbANKA), and the investigation occurred at 13 days after co-infection.

Results

Compared with PbANKA-mono-infected mice, T. spiralis + PbANKA-co-infected mice had similar survival rate but lower PbANKA parasitaemia; however, there were more severe hepatosplenomegaly, increased liver and spleen indexes, and increased liver pathology observed by hematoxylin and eosin staining; higher expression levels of galectin (Gal)-1, Gal-3, CD68⁺ macrophages, and elastase-positive neutrophils measured by immunohistochemical staining; upregulated mRNA expression levels of Gal-1, Gal-3, cytokines (interferon-gamma (IFNγ) and interleukin (IL)-6), and M1 macrophage polarization marker (inducible nitric oxide synthase (iNOS)) in the liver, and increased expression levels of Gal-1, IFNγ, IL-6, eosinophil cationic protein, eosinophil protein X, and M1 (IL-1β and iNOS) and M2 (Ym1) macrophage polarization markers in the spleen of co-infected mice detected by using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). In vitro study showed that compared with PbANKA-mono-infected mice, there were significantly increased expression levels of Gal-1, Gal-3, IL-6, IL-1β, and iNOS in the peritoneal macrophage isolated from co-infected mice detected by using qRT-PCR. Correlation analysis revealed significant positive correlations between Gal-3 and IL-1β in the peritoneal macrophages isolated from PbANKA-mono-infected mice, between Gal-3 and IFNγ in the spleen of co-infected mice, and between Gal-1 and Ym1 in the peritoneal macrophages isolated from co-infected mice.

Conclusions

Our data indicate that pre-existing infection of T. spiralis may suppress P. berghei parasitaemia and aggravate malaria-induced liver pathology through stimulating Gal-1 and Gal-3 expression, activating macrophages, neutrophils, and eosinophils, and promoting mediator release and cytokine production.

Genetic determinants of circulating galectin-3 levels in patients with coronary artery disease

Background

Galectin‐3 plays a crucial role in the regulation of inflammation. The aim of this study was to elucidate the association between LGALS3 genotypes, galectin‐3 levels, and inflammatory marker levels in patients with coronary artery disease (CAD).

Results

A total of 474 patients with CAD were enrolled. Significant correlations were discerned between galectin‐3 levels and leukocyte counts, C‐reactive protein, soluble intercellular adhesion molecule‐1, and matrix metalloproteinase 9 levels (all p < .05). The LGALS3 rs2274273, rs4644, rs4652 genotypes, and haplotypes CAC, CCC, and ACT exhibited a significant association with galectin‐3 levels (for genotypes, p = 1.05 × 10⁻²⁵, 3.54 × 10⁻²⁵, and 2.74 × 10⁻⁷, respectively). Multivariate analysis showed LGALS3 rs2274273 and rs4644 genotypes contributing to 20.8% variation of galectin‐3 levels. However, there was no association between LGALS3 genotypes and other inflammatory marker levels.

Conclusions

Our data showed strong genetic determinants of galectin‐3 levels in patients with CAD. The galectin‐3 levels, but not LGALS3 genotypes, were associated with multiple inflammatory marker levels. Further study may be necessary to elucidate the molecular mechanism of galectin‐3 in the pathogenesis of chronic inflammatory disorders.

Eosinophil function in adipose tissue is regulated by Krüppel-like factor 3 (KLF3)

The conversion of white adipocytes to thermogenic beige adipocytes represents a potential mechanism to treat obesity and related metabolic disorders. However, the mechanisms involved in converting white to beige adipose tissue remain incompletely understood. Here we show profound beiging in a genetic mouse model lacking the transcriptional repressor Krüppel-like factor 3 (KLF3). Bone marrow transplants from these animals confer the beige phenotype on wild type recipients. Analysis of the cellular and molecular changes reveal an accumulation of eosinophils in adipose tissue. We examine the transcriptomic profile of adipose-resident eosinophils and posit that KLF3 regulates adipose tissue function via transcriptional control of secreted molecules linked to beiging. Furthermore, we provide evidence that eosinophils may directly act on adipocytes to drive beiging and highlight the critical role of these little-understood immune cells in thermogenesis.

Immune cells are important regulators of adipose tissue function, including adaptive thermogenesis. Here the authors show that mice with Krüppel-like factor 3 (KLF3) deficiency in bone marrow-derived cells have increased adipose tissue beiging which may at least in part be due to altered eosinophil paracrine signaling.

Effect Of Dual sEH/COX-2 Inhibition on Allergen-Induced Airway Inflammation

Arachidonic acid metabolites resulting from the cyclooxygenase (COX), lipoxygenase, and cytochrome P450 oxidase enzymatic pathways play pro- and anti-inflammatory roles in allergic airway inflammation (AAI) and asthma. Expression of COX-2 and soluble epoxide hydrolase (sEH) are elevated in allergic airways and their enzymatic products (e.g., prostaglandins and diols of epoxyeicosatrienoic acids, respectively) have been shown to participate in the pathogenesis of AAI. Here, we evaluated the outcome of inhibiting the COX-2 and sEH enzymatic pathways with a novel dual inhibitor, PTUPB, in A. alternata-induced AAI. Allergen-challenged mice were administered with 10 or 30 mg/kg of PTUPB, celecoxib (selective COX-2 inhibitor), t-TUCB (selective sEH inhibitor) or vehicle daily by gavage and evaluated for various features of AAI. PTUPB and t-TUCB at 30 mg/kg, but not celecoxib, inhibited eosinophilic infiltration and significantly increased levels of anti-inflammatory EETs in the lung tissue of allergen-challenged mice. t-TUCB significantly inhibited allergen-induced IL-4 and IL-13, while a less pronounced reduction was noted with PTUPB and celecoxib. Additionally, t-TUCB markedly inhibited eotaxin-2, an eosinophil-specific chemokine, which was only marginally reduced by PTUPB and remained elevated in celecoxib-treated mice. PTUPB or t-TUCB administration reversed allergen-induced reduction in levels of various lipid mediators in the lungs, with only a minimal effect noted with celecoxib. Despite the anti-inflammatory effects, PTUPB or t-TUCB did not reduce allergen-induced airway hyperresponsiveness (AHR). However, development of structural changes in the allergic airways, such as mucus hypersecretion and smooth muscle hypertrophy, was significantly inhibited by both inhibitors. Celecoxib, on the other hand, inhibited only airway smooth muscle hypertrophy, but not mucus hypersecretion. In conclusion, dual inhibition of COX-2 and sEH offers no additional advantage relative to sEH inhibition alone in attenuating various features associated with A. alternata-induced AAI, while COX-2 inhibition exerts only moderate or no effect on several of these features. Dual sEH/COX-2 inhibition may be useful in treating conditions where eosinophilic inflammation co-exists with pain-associated inflammation.

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.

Galectin-3 in M2 Macrophages Plays a Protective Role in Resolution of Neuropathology in Brain Parasitic Infection by Regulating Neutrophil Turnover

Macrophages/microglia with M2-activation phenotype are thought to play important anti-inflammatory and tissue reparative functions in the brain, yet the molecular bases of their functions in the CNS remain to be clearly defined. In a preclinical model of neurocysticercosis using brain infection with a parasite Mesocestoides corti, we previously reported the presence of large numbers of M2 cells in the CNS. In this study using female mice, we report that M2 macrophages in the parasite-infected brain display abundant galectin-3 expression. Disease severity was increased in Galectin-3^-/- mice correlating with increased neurological defects, augmented cell death and, importantly, massive accumulation of neutrophils and M2 macrophages in the CNS of these mice. Because neutrophil clearance by efferocytosis is an important function of M2 macrophages, we investigated a possible role of galectin-3 in this process. Indeed, galectin-3-deficient M2 macrophages exhibited a defect in efferocytic clearance of neutrophils in vitro Furthermore, adoptive transfer of M2 macrophages from galectin-3-sufficient WT mice reduced neutrophilia in the CNS and ameliorated disease severity in parasite-infected Galectin-3^-/- mice. Together, these results demonstrate, for the first time, a novel role of galectin-3 in M2 macrophage function in neutrophil turnover and resolution of inflammatory pathology in the CNS. This likely will have implications in neurocysticercosis and neuroinflammatory diseases.SIGNIFICANCE STATEMENT Macrophages/microglia with M1-activation phenotype are thought to promote CNS pathology, whereas M2-anti-inflammatory phenotype promote CNS repair. However, the mechanisms regulating M2 cell-protective functions in the CNS microenvironment are undefined. The current study reports that helminth infection of the brain induces an increased expression of galectin-3 in M2 macrophages accumulated in the CNS. Using multiple experimental models in vivo and in vitro, they show that galectin-3 in M2 macrophages functions to clear neutrophils accumulated in the CNS. Importantly, galectin-3 in M2 macrophages plays a central role in the containment of neuropathology and disease severity. These results provide a direct mechanistic evidence of the protective function of M2 macrophages in the CNS.

Expression of Galectins-1 and Galectin-3 in Stomach and Colorectal Cancer with Tissue Eosinophilia

We analyzed the expression of galectin-1 and galectin-3 in tumor tissue in stomach and colorectal cancer with and without tissue eosinophilia. Low expression of galectin-3 was detected in all patients with malignant gastrointestinal tumors irrespective of the presence of eosinophilia. Low expression of galectin-1 was detected only in patients with gastrointestinal cancer associated with eosinophilia. Association of galectin-1 expression with eosinophilic infiltration of the tumor tissue in stomach and colorectal cancer was detected.

Dual role of YM1+ M2 macrophages in allergic lung inflammation

Alternatively activated (M2 or YM1+) macrophages have been associated with the development of asthma but their contribution to disease initiation and progression remains unclear. To assess the therapeutic potential of modulating these M2 macrophages, we have studied inhibition of M2 polarisation during and after development of allergic lung inflammation by treating with cynaropicrin, a galectin-3 pathway inhibitor. Mice that were treated with this inhibitor of M2 polarisation during induction of allergic inflammation developed less severe eosinophilic lung inflammation and less collagen deposition around airways, while the airway α-smooth muscle actin layer was unaffected. When we treated with cynaropicrin after induction of inflammation, eosinophilic lung inflammation and collagen deposition were also inhibited though to a lesser extent. Unexpectedly, both during and after induction of allergic inflammation, inhibition of M2 polarisation resulted in a shift towards neutrophilic inflammation. Moreover, airway hyperresponsiveness was worse in mice treated with cynaropicrin as compared to allergic mice without inhibitor. These results show that M2 macrophages are associated with remodeling and development of eosinophilic lung inflammation, but prevent development of neutrophilic lung inflammation and worsening of airway hyperresponsiveness. This study suggests that macrophages contribute to determining development of eosinophilic or neutrophilic lung inflammation in asthma.

The effects of galectin-3 depletion apheresis on induced skin inflammation in a porcine model

Galectin-3 (Gal-3), a β-galactoside-binding lectin that is expressed in mammalian cells, is known to modulate several biological functions such as cell-cell adhesion, macrophage activation, angiogenesis, metastasis, and fibrosis. The goal of this study was to evaluate the ability of Gal-3 depletion apheresis using an adsorption column with immobilized anti-Gal-3-antibody to reduce inflammation induced by Complete Freund's Adjuvant injection in a skin inflammation porcine model. Here, we report that plasma perfusion by apheresis through a Gal-3 binding immuno-affinity column reduces plasma Gal-3 levels to below limits of quantitative detection, and results in significant decrease in skin inflammation, including degree and duration of inflammatory lesions. Human plasma was tested ex vivo and found to be efficiently depleted using the anti-Gal-3 affinity column. This study demonstrates the potential of Gal-3 depletion apheresis as a therapeutic method for inflammation-mediated disease, supporting continued research in this area for clinical application.

Galectin-3: role in ocular allergy and potential as a predictive biomarker

Aims

To evaluate galectin-3 (Gal-3), a β-galactoside binding protein, as a possible biomarker in ocular allergy and further investigated the role of endogenous Gal-3 in a murine model of ovalbumin (OVA)-induced allergic conjunctivitis (AC).

Methods

Conjunctival impression cytology specimens from control and patients with severe vernal keratoconjunctivitis, treated or untreated, were used to evaluate Gal-3 expression by immunocytochemistry. To investigate the mechanism of action of Gal-3, OVA-immunised BALB/c male wild-type (WT) and Gal-3 null (Gal-3-/-) mice were challenged with eye drops containing OVA on days 14–16 with a subset of animals pretreated with 0.03% tacrolimus (TC) or dexamethasone (Dex).

Results

Patients with AC and OVA-sensitised WT mice exhibited increased levels of Gal-3 in the conjunctiva compared with control, an effect reverted by the action of Dex and TC therapy. Twenty-four hours after the final OVA challenge, total and anti-OVA IgE levels increased significantly in the blood of OVA-sensitised WT and Gal-3-/- mice compared with controls, supporting the efficacy of the AC model. The lack of endogenous Gal-3 exacerbated the local inflammatory response, increasing the influx of eosinophils and mast cell activation. Additionally, OVA-sensitised Gal-3-/- animals exhibited increased CD4+ expression in the eyes as well as eotaxin, IL-4, IL-13 and interferon-γ levels in the tear fluid compared with WT animals.

Conclusion

Gal-3 contributes to the pathogenesis of ocular allergy and represents a relevant therapeutic target.

Can we define migraine patients with blood high-sensitivity C-reactive protein and galectin-3 levels in the emergency department?

INTRODUCTION

Migraine, the most widespread cause of headache in young adults, is a frequent reason for presentation to emergency departments. The aim of this study was to determine the diagnostic value of serum galectin-3 and high-sensitivity C-reactive protein (hsCRP) levels in migraine patients.

MATERIAL AND METHODS

Serum galectin-3 and hsCRP levels were measured using enzyme-linked immunosorbent assay in 70 migraine patients and 70 healthy control subjects.

RESULTS

The mean values of hsCRP and galectin-3 levels were significantly higher in the migraine group than those in the control group (1.67 ±0.49, 1.12 ±0.38 mg/l, p < 0.001; and 3.76 ±1.45, 2.05 ±0.29 ng/ml, p < 0.001, respectively). When the diagnostic values of the biomarkers were assessed in the migraine attack and control groups, the sensitivity and specificity of the test for hsCRP at the cut-off point of 1.32 mg/l were 70% and 73% (AUC = 0.805, 95% CI: 0.74-0.88, p < 0.001), and for galectin-3 at the cut-off point of 2.4 ng/ml, 89% and 90% (AUC = 0.97, 95% CI: 0.95-0.99, p < 0.001), respectively.

CONCLUSIONS

This study showed the presence of a relation between high serum levels of hsCRP and galectin-3 in migraine patients. However, well-controlled, carefully executed longitudinal studies are required to confirm these findings.

Evaluation of galectin-1 and galectin-3 as prospective biomarkers in keratoconus

Aims

To evaluate the expression of β-galactoside-binding proteins galectin (Gal)-1 and Gal-3 in patients with keratoconus (KC) and postcorneal collagen cross-linking (CXL) treatment in vitro.

Methods

Tear fluid, cornea samples and conjunctival impression cytology specimens from control and KC patients were used to evaluate Gal-1 and Gal-3 expressions. Primary keratocytes were isolated by collagenase digestion from surgically removed corneas of five normal or KC human corneal buttons and cultured in Dulbecco’s modified eagle medium/Ham’s F12 medium supplemented with 2% fetal bovine serum. These cells were evaluated under two experimental conditions: control and submitted to the application of ultraviolet A light and riboflavin 0.1% (CXL) for 30 min.

Results

Patients with KC displayed increased levels of Gal-1 and Gal-3 in conjunctival epithelial cells compared with control. Furthermore, KC corneas were associated with intense expression of Gal-1 in the stroma, released by keratocytes. Ultrastructural analysis of keratocytes showed a marked increase of endogenous Gal-3 levels, but not Gal-1, in KC. In vitro, CXL induced significant release of Gal-1 in keratocyte supernatants (116±18 ng/mL, P<0.05) and decreased inflammatory biomarkers as interleukin (IL)-6, IL-8, matrix metalloproteinase (MMP)-2 and MMP-9. Gal-3 levels were not detected in the keratocyte supernatants.

Conclusion

Gal-1 and Gal-3 represent new interesting KC biomarkers as revealed by their different expression patterns in KC and control corneal samples. CXL has an immunosuppressive effect on keratocytes by reducing the release of cytokines and MMPs and increased expression of anti-inflammatory protein Gal-1.

Regulation of Eosinophil Recruitment and Activation by Galectins in Allergic Asthma

Eosinophils are differentiated granulocytes that are recruited from the bone marrow to sites of inflammation via the vascular system. Allergic asthma is characterized by the presence of large numbers of eosinophils in the lungs and airways. Due to their capacity to rapidly release inflammatory mediators such as cytokines, chemokines, growth factors, and cytotoxic granule proteins upon stimulation, eosinophils play a critical role in pro-inflammatory processes in allergen-exposed lungs. Identifying key players and understanding the molecular mechanisms directing eosinophil trafficking and recruitment to inflamed airways is a key to developing therapeutic strategies to limit their influx. Recent studies have brought to light the important role of glycans and glycan binding proteins in regulating recruitment of eosinophils. In addition to the role of previously identified eosinophil- and endothelial-expressed adhesion molecules in mediating eosinophil trafficking and recruitment to the inflamed airways, studies have also indicated a role for galectins (galectin-3) in this process. Galectins are mammalian lectins expressed by various cell types including eosinophils. Intracellularly, they can regulate biological processes such as cell motility. Extracellularly, galectins interact with β-galactosides in cell surface-expressed glycans to regulate cellular responses like production of inflammatory mediators, cell adhesion, migration, and apoptosis. Eosinophils express galectins intracellularly or on the cell surface where they interact with cell surface glycoconjugate receptors. Depending on the type (galectin-1, -3, etc.) and location (extracellular or intracellular, endogenous or exogenously delivered), galectins differentially regulate eosinophil recruitment, activation, and apoptosis and thus exert a pro- or anti-inflammatory outcome. Here, we have reviewed information pertaining to galectins (galectin-1, -3 -9, and -10) that are expressed by eosinophils themselves and/or other cells that play a role in eosinophil recruitment and function in the context of allergic asthma and their potential use as disease biomarkers or therapeutic targets for immunomodulation.

Galectin-3: A Positive Regulator of Leukocyte Recruitment in the Inflamed Microcirculation

In vivo and ex vivo imaging were used to investigate the function of galectin-3 (Gal-3) during the process of leukocyte recruitment to the inflamed microcirculation. The cremasteric microcirculation of wild-type (C57BL/6), Gal-3^-/-, and CX₃CR1^gfp/+ mice were assessed by intravital microscopy after PBS, IL-1β, TNF-α, or recombinant Gal-3 treatment. These cellular responses were investigated further using flow-chamber assays, confocal microscopy, flow cytometry, PCR analysis, and proteome array. We show that mechanisms mediating leukocyte slow rolling and emigration are impaired in Gal-3^-/- mice, which could be because of impaired expression of cell adhesion molecules and an altered cell surface glycoproteome. Local (intrascrotal) administration of recombinant Gal-3 to wild-type mice resulted in a dose-dependent reduction in rolling velocity associated with increased numbers of adherent and emigrated leukocytes, ∼50% of which were Ly6G⁺ neutrophils. Intrascrotal administration of Gal-3 to CX₃CR1^gfp/+ mice confirmed that approximately equal numbers of monocytes are also recruited in response to this lectin. Exogenous Gal-3 treatment was accompanied by increased proinflammatory cytokines and chemokines within the local tissue. In conclusion, this study unveils novel biology for both exogenous and endogenous Gal-3 in promoting leukocyte recruitment during acute inflammation.

Regulation of eosinophilia and allergic airway inflammation by the glycan-binding protein galectin-1

Galectin-1 (Gal-1), a glycan-binding protein with broad antiinflammatory activities, functions as a proresolving mediator in autoimmune and chronic inflammatory disorders. However, its role in allergic airway inflammation has not yet been elucidated. We evaluated the effects of Gal-1 on eosinophil function and its role in a mouse model of allergic asthma. Allergen exposure resulted in airway recruitment of Gal-1-expressing inflammatory cells, including eosinophils, as well as increased Gal-1 in extracellular spaces in the lungs. In vitro, extracellular Gal-1 exerted divergent effects on eosinophils that were N-glycan- and dose-dependent. At concentrations ≤0.25 µM, Gal-1 increased eosinophil adhesion to vascular cell adhesion molecule-1, caused redistribution of integrin CD49d to the periphery and cell clustering, but inhibited ERK(1/2) activation and eotaxin-1-induced migration. Exposure to concentrations ≥1 µM resulted in ERK(1/2)-dependent apoptosis and disruption of the F-actin cytoskeleton. At lower concentrations, Gal-1 did not alter expression of adhesion molecules (CD49d, CD18, CD11a, CD11b, L-selectin) or of the chemokine receptor CCR3, but decreased CD49d and CCR3 was observed in eosinophils treated with higher concentrations of this lectin. In vivo, allergen-challenged Gal-1-deficient mice exhibited increased recruitment of eosinophils and CD3(+) T lymphocytes in the airways as well as elevated peripheral blood and bone marrow eosinophils relative to corresponding WT mice. Further, these mice had an increased propensity to develop airway hyperresponsiveness and displayed significantly elevated levels of TNF-α in lung tissue. This study suggests that Gal-1 can limit eosinophil recruitment to allergic airways and suppresses airway inflammation by inhibiting cell migration and promoting eosinophil apoptosis.

The role of eosinophils and basophils in allergic diseases considering genetic findings

PURPOSE OF REVIEW

Basophils and eosinophils represent less than 1 and 5% of white blood cells, respectively. Their role in asthma and allergic inflammation remains incompletely defined. The present review addresses recent advances regarding the role of these two cell populations in allergic inflammation and asthma regarding both biological and genetic point of view.

RECENT FINDINGS

Regarding eosinophils, the role of interleukin(IL)-25, IL-33 and thymic stromal lymphoprotein (TSLP) have been evidenced, and activation states of eosinophil β1 and β2 integrins have been found to correlate with the measurement of eosinophil recruitment and pulmonary function in asthma. New insights into the biology of basophils concern their role as regulators of Th2 cell response through IL-4 expression or the differentiation of monocytes to macrophages, and their population heterogeneity in human. The transcription factor PU.1 was reported to be involved in controlling transcription of specific genes both in eosinophils and basophils. Candidate genetic studies on eosinophils have explored genes involved in the intracellular calcium influx and apoptosis. At the genome-wide level, studies identified genetic variants belonging to IL1RL1, TSLP and IL-33, and four loci with pleiotropic effects on eosinophil and basophil counts [GATA2 (3q21), MHC (6p21), HBS1L-MYB (6q23), and ERG (21q22)].

SUMMARY

Recent findings from biological and genetic studies on eosinophils and basophils highlight the role of epithelial cell-derived cytokines such as TSLP and IL-33 in asthma and allergic diseases.