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Abstract

Galectin-1 is an important mediator that regulates the T-cell-mediated immune response. It has many other biological functions such as cell growth, immunomodulation, and wound healing. The aim of this study was to reveal the role of galectin-1 on liver morphology, cell proliferation, apoptosis, inflammatory and anti-inflammatory mediators, oxidative stress, and antioxidant system in colitis-mediated hepatotoxicity induced by dextran sulfate sodium (DSS). In the present study, adult mice were divided into four groups: The control group intraperitoneally injected with phosphate buffer saline (I), the group which was orally administered with DSS (II), the control group which was injected with galectin-1 (III), and the group which was given DSS and galectin-1 (IV). DSS administration caused degenerative changes and diffuse necrotic damage, an increase in caspase-3 and cyclooxygenase-2 expression, the levels of lipid peroxidation and tumor necrosis factor-alpha, lactate dehydrogenase, and myeloperoxidase activities, and a decrease in cell proliferation, interleukin-10 levels, and antioxidant system parameters in liver tissues. Treatment of DSS group with galectin-1 reversed these effects and prevented liver damage. This study showed that galectin-1 has proliferative, antiapoptotic, anti-inflammatory, and antioxidant effects against DSS-induced liver injury in mice. It is expected considering all results of this study that galectin-1 may be useful as a protective agent against liver toxicity.

Keywords

Dextran sulfate sodium galectin-1 hepatotoxicity mouse ulcerative colitis

Introduction

Ulcerative colitis is an inflammatory disease that occurs in the colon. However, its extraintestinal and systemic manifestations may also appear in the patients.^1,2 It has been reported that the individuals suffering from inflammatory bowel diseases frequently have hepatic disorders such as fatty liver, hepatic steatosis, liver abscess, granulomatous hepatitis, and hepatic amyloidosis.³ Sulfasalazine, aminosalicylic acid, and steroids are not only the common compounds used in the studies of ulcerative colitis treatment, but their use as immunosuppressive agent is also quite common. However, these treatment methods are not effective for full recovery from the disease. In addition, they have serious side effects, leading to liver toxicity, hepatitis, diabetes, and pancreatitis.⁴ Therefore, there is a need to develop new and effective treatment methods for ulcerative colitis.

Investigation of ulcerative colitis pathogenesis and effective therapeutic approaches involves the use of chemically induced experimental colitis models. One of the most common agents employed for the induction of experimental colitis in animal models is dextran sulfate sodium (DSS). It is a polyanionic dextran derivative formed by the esterification of dextran with chlorosulfonic acid. DSS is known to be involved in the inhibition of blood coagulation, platelet aggregation, B lymphocyte activation, and humoral immunity, as well as precipitating low density lipoprotein (LDL) and very low density lipoprotein (VLDL).^5,6

Galectin-1 is a member of β-galactoside-binding protein family called galectins; also known as S-type lectins rich in sulfhydryl groups. This lectin is a monomer or noncovalent dimer encoded by the LSGALS1 gene on the chromosome 22q12.^7,8 Galectin-1 is an important mediator which is specifically synthesized in T cells, activated macrophages, and endothelial cells and expressed in various normal and pathological tissues.⁹ It has been found that galectin-1 has anti-inflammatory and immunosuppressive effects in some disease models such as hepatitis, pancreatitis, arthritis, and 2,4,6-trinitrobenzene sulfonic acid-induced colitis.^10

–13 Moreover, it was reported to have strong immunomodulatory effects due to its ability to inhibit T cell functions.¹⁰

In spite of deep literature search, there are no studies investigating the effects of galectin-1 on DSS-induced liver injury. The aim of this study was to show the possible role of galectin-1 on cell proliferation, apoptosis, inflammatory and anti-inflammatory mediators, oxidative stress, and antioxidant system in ulcerative colitis-mediated hepatotoxicity induced by DSS. Thus, the effect of galectin-1, which is recommended for therapeutic and prophylactic purposes in inflammatory diseases, against liver toxicity was investigated.

Materials and methods

Experimental design

Animal Care and Use Committee of Istanbul University approved the experimental protocol of this study with the number 2012/95. In this study, male C57BL/6 mice were used. The animals were fed with standard diet and tap water ad libitum but fasted for overnight prior to sacrificing. The mice were randomly divided into four groups.

Group I (control, n = 8): Mice were injected intraperitoneally with phosphate buffer saline (PBS, pH 7.4) once daily for 7 days.

Group II (DSS, n = 8): Animals were given 3% DSS (molecular weight 36,000–50,000) orally in tap water from the third day of the experiment and injected PBS once daily for 7 days.

Group III (galectin-1, n = 8): Mice were injected intraperitoneally with a dose of 1 mg/kg recombinant human galectin-1 (Novoprotein Scientific Inc., USA) dissolved in PBS once daily for 7 days.

Group IV (DSS + galectin-1, n = 8): Animals were injected with recombinant human galectin-1 in PBS for 7 days and fed orally 3% DSS for 5 days, starting on the third day of galectin-1 treatment.

The animals were killed under anesthesia on the 8th day of the experiment. The liver tissues were removed from the mice for analyses.

Histological assessment of liver injury

Samples from the liver were fixed in Bouin’s solution and embedded in paraffin for light microscopic examination. Sections of 5 µm thick were stained with Masson’s trichrome (Masson) and hematoxylin and eosin. The histological damage score of each liver section was determined by considering light microscopic criteria such as vacuolization in hepatocytes, hypertrophy, hepatocytes with pyknotic nuclei and intense eosinophilic cytoplasm, mononuclear cell infiltration, necrosis, hyperemia, sinusoidal dilatation, and ruptured endothelium of veins. Each histological criterion was scored from 0 (undamaged) to 3 (severe injury). The total score was obtained from the total of all histological criterions examined, and the maximum histological score was accepted as 24 for 1 individual.

Detection of cell proliferation index

In this study, streptavidin–biotin–peroxidase method was used for immunohistochemical detection. Liver samples were fixed in 10% phosphate-buffered formalin and embedded in paraffin. The proliferating cells in liver sections were detected with an anti-Ki-67 antibody (Abcam 16667, 1:100 in PBS, Cambridge, United Kingdom). Quantitative analysis of Ki-67 positive hepatic cells was made by using an Olympus (Tokyo, Japan) BX53 light microscope and approximately 1000 cells in different areas were counted. The proliferation index was calculated as multiplied by 100 the ratio of Ki-67 positive cell number to total cell number.

Western blot analysis

Liver tissues were taken for protein expression analysis. They were immediately transferred into liquid nitrogen after specimen collection and then stored in −86°C freezer until the beginning of analysis. Tissues were homogenized in Magna Lyser (Roche Diagnostics GmbH, Germany) at 7000 r/min by adding radioimmunoprecipitation assay buffer (RIPA), ethylenediaminetetraacetic acid (EDTA), and protease inhibitor. The samples were further homogenized for 15 min at 1500 g. The amount of protein in the supernatants was examined by using the Bradford method with bovine serum albumin (BSA) as standard. The proteins were run on 4–12% Bis-Tris gel with MES buffer, the electrophoretically separated proteins were transferred to nitrocellulose membrane using the iBlot transfer system (Invitrogen, USA). Thereafter, the membrane was blocked with 5% BSA in tris-buffered saline (TBST) (50 mM Tris-HCl, 150 mM NaCl, pH 7.5, and 0.1% Tween-20) at room temperature for 1 h. Subsequently, it was soaked in primary and secondary antibodies. All antibodies were diluted with 1% BSA dissolved in TBST buffer. The dilution rate was determined as 1:2000 for cyclooxygenase-2 (COX-2) antibody (Novus NB100-689, USA) and 1:1000 for active caspase-3 antibody (Novus NB100-56113). Membranes were incubated for one night at 4°C with primary antibodies and then secondary antibody at room temperature for 90 min. Normalization of the proteins was made using glyceraldehyde-3-phosphate dehydrogenase bands.

Detection of cytokine concentrations

The tumor necrosis factor-alpha (TNF-α) and interleukin-10 (IL-10) concentrations in the liver tissues were quantified by enzyme-linked immunosorbent assay (ELISA). The liver tissues of mice were homogenized with 10% ice-cold PBS (0.01 M, pH: 7.2). The obtained homogenates were six times subjected to ultrasonication for 10 s to lysis the cell membranes. The homogenates were centrifuged at 5000g at 4°C for 5 min, and the clear supernatants were used in the cytokine and protein measurements. TNF-α levels were detected by the mouse-specific TNF-α Sandwich ELISA Kit (USCN, Cloud-Clone Corp. SEA133Mu, USA). IL-10 concentrations were measured using Mouse IL-10 Sandwich ELISA Kit (USCN, Cloud-Clone Corp. SEA056Mu) following the manufacturer’s recommendations. Protein levels of the supernatants were assayed by Lowry’s method for ELISA analyses.

Biochemical analyses

For biochemical analyses, liver samples were washed in 0.9% ice-cold saline and homogenized in 0.9% saline (weight/volume (w/v)) with a glass homogenizer to make up to 10% homogenate (w/v). The homogenates were centrifuged and the clear supernatants were used for enzymes activity, glutathione (GSH), lipid peroxidation (LPO), sialic acid (SA) levels, and protein analysis.

The methods of Beutler, Ledwozy, Lorentz, Aebi, Mylroie, Wroblewski, and Wei were employed for estimation of liver GSH, LPO, SA levels, catalase (CAT), superoxide dismutase (SOD), lactate dehydrogenase (LDH), and myeloperoxidase (MPO) activities, respectively.^14

–20 The protein content in the supernatant was estimated by the Lowry method using BSA as a standard.²¹

Statistical analyses

All data were evaluated using the SPSS 15.0 for Windows (IBM Corporation) statistical program. Histological damage score, immunohistochemical, and Western blot results were analyzed by nonparametric Kruskal–Wallis test and Mann–Whitney U test. ELISA and biochemical analysis data are analyzed by one-way analysis of variance (ANOVA), followed by the Duncan’s/Newman–Keuls multiple comparison test and unpaired student t test.

Results

Galectin-1 exhibits a protective effect against hepatic damage by decreasing degenerative changes

Light microscopic photographs of liver sections of all groups are shown in Figure 1(a). Normal histological appearance was observed in control subjects according to microscopic examination of liver tissues. In the DSS-given group, vacuolization in hepatocytes, hypertrophic cells around the central veins, a large number of hepatocytes with pyknotic nuclei and intense eosinophilic cytoplasm, extensive necrotic areas, and mononuclear cell infiltration were common findings. Hyperemia, sinusoidal dilatation, and ruptured endothelium of veins were also observed in the mice of this group. In the control group given galectin-1, a normal histological appearance was similar to that of individuals in the control group, except for mononuclear cell infiltration and hyperemia in some areas. Galectin-1 treatment to the DSS group significantly reduced degenerative changes such as mononuclear cell infiltration, necrosis, and sinusoidal dilatation. In addition, hypertrophic cells, hepatocytes with pyknotic nuclei, hyperaemia, and ruptured endothelium of veins were not observed in this group.

Figure 1.

(a) Light micrographs of liver tissues of control (A), DSS (B) and (C), galectin-1 (D), and DSS + galectin-1 (E) groups. Necrotic area (◂), hepatocytes with pyknotic nuclei and intense eosinophilic cytoplasm (➡), mononuclear cell infiltration (⇒), hypertrophic cells (➞), and hyperemia (H). Masson, original magnification ×200. (b) The histological damage score in the liver tissues. The data were given as mean ± SE per group. ^a p < 0.01 versus the control group, ^b p < 0.001 versus the DSS group. (c) Ki-67 immunoreactive proliferating cells in liver of the mice (➞). Control group (A), DSS group (B), galectin-1 group (C), and DSS + galectin-1 group (D). Original magnification ×400. (d) Cell proliferation index for all groups. ^a p < 0.001 versus the control group, ^b p < 0.001 versus the DSS group. All data were given as mean ± SE per group. DSS: dextran sulfate sodium; SE: standard error.

The histological damage score is presented in Figure 1(b). This score was highest in the liver tissues of DSS-given mice. In the DSS group, the damage score showed a statistically significant increase compared to the control group (p < 0.01). There was no significant difference in the histological score between the galectin-1 group and the control group. Although histological damage score increased significantly in the DSS + galectin-1 group compared to the control group (p < 0.01), there was a significant decrease in the damage score compared to the DSS group (p < 0.001).

Galectin-1 stimulates cell proliferation which was suppressed by DSS in liver

The cell proliferation index showed a statistically significant decrease in the DSS group compared to the control group (p < 0.001). A decreased cell proliferation was also observed in the galectin-1 injected group compared to the control group, but this decrease was not statistically significant. In the DSS + galectin-1 group, there was a nonsignificant decrease in the number of Ki-67 positive cells in comparison to the control group. However, a significant increase was detected in the DSS + galectin-1 group when compared to the DSS group (p < 0.001; Figure 1(c) and (d)).

Galectin-1 reduces the expression of caspase-3 by suppressing DSS-induced apoptosis

Figure 2(a) represents Western blot bands of active caspase-3 and Figure 2(b) shows graphic of caspase-3 expression. The caspase-3 expressions in both the DSS group (p < 0.05) and the galectin-1 group (p < 0.05) were significantly increased compared to the control group. However, in the DSS + galectin-1 group, caspase-3 levels were significantly decreased compared to control (p < 0.05), DSS (p < 0.01), and galectin-1 (p < 0.01) groups.

Figure 2.

(a)Western blot bands of caspase-3, COX-2, and GAPDH for all groups. (b) Active caspase-3 expressions in liver tissues. ^a p < 0.05 versus the control group, ^b p < 0.01 versus the DSS group, ^c p < 0.01 versus the galectin-1 group. (c) The expression of COX-2 in liver tissues for all groups. ^a p < 0.01 versus the control group, ^b p < 0.001 versus the DSS group, ^c p < 0.01 versus the galectin-1 group. All data were given as mean ± SE per group. COX-2: cyclooxygenase-2; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; DSS: dextran sulfate sodium; SE: standard error.

Galectin-1 prevents hepatic inflammation by inhibiting inflammatory mediators

Figure 2(a) and (c) shows COX-2 expression levels analyzed by western blot. The COX-2 expression was significantly increased in the DSS colitis group compared to the control group (p < 0.01). There was a statistically insignificant increase in the COX-2 expression of galectin-1 group compared to the control group. However, in the galectin-1-treated DSS group, COX-2 levels were significantly lower than that of the control (p < 0.01), DSS (p < 0.001), and galectin-1 (p < 0.01) groups.

According to the statistical results, TNF-α concentration of DSS-given group was significantly increased (p < 0.05), while the IL-10 level was significantly decreased (p < 0.01) when compared to the control group. In the galectin-1-given group, IL-10 levels significantly decreased in comparison to the control group (p < 0.05). However, galectin-1 treatment of the DSS group significantly reduced TNF-α levels compared to both the control group (p < 0.05) and the DSS group (p < 0.001). Moreover, galectin-1 pretreatment in the DSS group increased the IL-10 concentration significantly compared to the DSS group (p ≤ 0.05) but decreased compared to the control individuals (p < 0.05; Figure 3(a) and (b)).

Figure 3.

(a) TNF-α concentration in the liver of all groups.^a p < 0.05 versus the control group, ^b p < 0.001 versus the DSS group. (b) IL-10 levels in liver tissue per group. ^a p < 0.01 versus the control group, ^b p < 0.05 versus the control group, ^c p ≤ 0.05 versus the DSS group. All data were given as mean ± SE per group. TNF-α: tumor necrosis factor-alpha; IL-10: interleukin-10; DSS: dextran sulfate sodium; SE: standard error.

Effects of galectin-1 on oxidative stress, LPO, and antioxidant system

According to Table 1, GSH levels were significantly decreased in the DSS group as compared to the control group (p < 0.05). Administration of galectin-1 significantly increased the liver GSH levels in the DSS group (p < 0.0001). Liver LPO and SA levels were found to be significantly increased in the DSS group compared with the control group, respectively (p < 0.05, p < 0.0001). Administration of galectin-1 caused a decrease in liver LPO and SA levels in the DSS group (p < 0.0001, p < 0. 001; Table 1).

Table 1.

Liver GSH, LPO, and SA levels in control and experimental groups.^a

Group	GSH (nmol GSH/mg protein)	LPO (nmol MDA/mg protein)	SA (nmol/mg protein)
Control	0.91 ± 0.36	0.33 ± 0.01	0.29 ± 0.09
Galectin-1	0.85 ± 0.04	0.26 ± 0.10	0.52 ± 0.10
DSS	0.35 ± 0.08^b	0.76 ± 0.20^b	0.53 ± 0.03^d
DSS + galectin-1	1.11 ± 0.09^c	0.24 ± 0.06^c	0.42 ± 0.02^e

GSH: glutathione; LPO: lipid peroxidation; SA: sialic acid; DSS: dextran sulfate sodium; SD: standard deviation.

^a Mean ± SD.

^b p < 0.05 versus the control group.

^c p < 0.0001 versus the DSS group.

^d p < 0.0001 versus the control group.

^e p < 0.001 versus the DSS group.

Liver CAT and SOD activities were significantly decreased in the DSS group when compared with the control group, respectively (p < 0.05, p < 0.0001). The activities of the enzymes were increased in the DSS + galectin-1 group when compared with the DSS group (p < 0.0001; Table 2).

Table 2.

Liver CAT, SOD, LDH, and MPO activities in all groups.^a

Group	CAT (U/mg protein)	SOD (U/g protein)	LDH (U/mg protein)	MPO (U/g tissue)
Control	8.38 ± 1.24	8.38 ± 1.24	148.43 ± 18.29	10.42 ± 1.29
Galectin-1	12.62 ± 1.30	12.62 ± 1.30	71.05 ± 10.93	7.32 ± 1.44
DSS	2.69 ± 0.39^b	2.69 ± 0.39^d	235.75 ± 30.17^d	15.50 ± 1.05^d
DSS + galectin-1	15.68 ± 2.11^c	15.68 ± 2.11^c	117.10 ± 2.51^c	5.91 ± 1.54^c

CAT: catalase; SOD: superoxide dismutase; LDH: lactate dehydrogenase; MPO: myeloperoxidase; DSS: dextran sulfate sodium; SD: standard deviation.

^a Mean ± SD.

^b p < 0.05 versus the control group.

^c p < 0.0001 versus the DSS group.

^d p < 0.0001 versus the control group.

LDH and MPO activities were significantly increased in the DSS group compared to the control group (p < 0.0001). The activities of the enzymes were decreased in the DSS + galectin-1 group compared with the DSS group (p < 0.0001; Table 2).

Discussion

Hepatobiliary dysfunction is found in approximately 5–10% of people with inflammatory bowel disease,²² with also secondary liver injury observed thereafter.²³ In addition, steatosis is frequently reported in liver biopsies of patients with ulcerative colitis. The structural damages of the mucosal barrier in the ulcerative colitis may result in translocation of the intestinal flora into the liver through the portal vein; this, in fact, causes liver inflammation and secondary liver injury. Single or multiple pyogenic liver abscesses are often identified as the first indication of inflammatory bowel disease.^2,24 Pathological changes are observed in colon, liver, kidney, skin, and lymphoid organs in the DSS-induced colitis model. Trivedi and Jena²² identified hepatic fibrosis and fatty infiltration in the liver, as well as bacterial translocation to liver in the DSS-induced chronic colitis model. In another study, significant findings such as hepatocyte destructions, increased lipid accumulation, and pathological damage score in liver were also observed in BALB/c mice given 4% DSS for 14 days.²³ Hakansson et al.²⁵ reported that three cycles of 4% DSS administration to rats caused steatosis, hemorrhage, cell infiltration, and loss of parenchyma in the liver. In the present study, 5-day DSS administration to mice gave rise to mononuclear cell infiltration, hyperemia, hypertrophy, and necrosis in hepatocytes, as well as a significant increase of histological damage score in the liver.

The most important function of endogenous galectin-1 is known to be control of cellular processes associated with the regulation of immune responses. There are some findings suggesting that galectin-1 inhibits the development of acute and chronic inflammation in some disease models associated with inflammation.^{10

–13,26,27} Injection of phospholipase A2 (PLA-2) with or without galectin-1 in rats inhibited PLA-2-induced paw edema by reducing leukocyte infiltration and mast cell degranulation. Also, it showed a protective effect against acute inflammation.²⁶ In the present study, pretreatment with galectin-1 exhibited a protective effect against hepatic damage by decreasing degenerative changes such as mononuclear cell infiltration and necrosis in the DSS-induced ulcerative colitis-mediated hepatic inflammation.

It is known that an increased rate of apoptosis in inflamed colon mucosa of animals with ulcerative colitis is an important indicator of the rate of damage in the tissue. In addition to this, short-term DSS administration causes decreased cell proliferation, increased apoptotic cell death, and degenerated epithelial barrier in colon mucosa and thus tissue damage occurs.²⁸ When the duration of DSS administration was increased by 7-, 14-, and 21-day cycles, an increased rate of apoptosis in the liver of DSS-treated mice was observed via terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. In our study, the significant increase in caspase-3 expression of the DSS group is consistent with the findings of previous studies. After DSS administration, a significant decrease in cell proliferation index of liver tissue was also consistent with DSS-induced cell cycle arrest findings of previous papers.^28,29 The effect of galectin-1 on cell proliferation change depends on cell type and dose.^30,31 Maeda et al.³² reported that galectin-1 stimulated cell proliferation in hepatic stellate cells and exhibited mitogenic effects on these cells. Galectin-1 has been reported to precipitate apoptosis of T lymphocytes by the activation of caspase via releasing cytochrome C from mitochondria.³³ However, apoptosis was induced in hepatic stellate cells in galectin-1 knockout mice with liver fibrosis, whereas cell proliferation was reported to be suppressed.³⁴ In line with the findings of investigators, we found that the reduced proliferation rate in the liver of DSS group increased with galectin-1 administration. However, galectin-1 reduced the expression of caspase-3 by suppressing DSS-induced apoptosis.

Degradation of the balance between pro-inflammatory cytokines and anti-inflammatory cytokine levels is an important mechanism in the pathogenesis of inflammation-induced tissue damage. The expression level of TNF-α increases during the acute phase inflammation process and caused tissue damage by stimulating the release of various inflammatory mediators and the production of reactive oxygen species (ROS).³⁵ One of the molecules inducible by cytokines is COX-2, which is involved in prostaglandin biosynthesis. It is known that the expression of COX-2 in colon mucosa increases in inflammatory processes, especially in intestinal diseases such as colitis.³⁶ Pro-inflammatory cytokine levels such as IL-1, IL-2, IL-6, IL-8, interferon-2, and TNF-α were increased in colon biopsies of ulcerative colitis patients. However, it has been reported that the anti-inflammatory cytokine levels such as IL-4 and IL-10 decreased.^35,37 It was estimated that pro-inflammatory cytokine levels such as TNF-α, interleukin-1 beta, and IL-6 were approximately doubled in plasma samples of rats with acute colitis induced by 5% DSS for 5 days.³⁸ In this study, it was observed that TNF-α levels and COX-2 expression in liver tissues of mice with acute colitis induced by DSS significantly increased, but IL-10 levels significantly decreased. There are a limited number of studies examining the effects of galectin-1 on inflammatory mediators in the liver. Concanavalin A (ConA)-induced hepatitis is a T cell-dependent liver injury model. Galectin-1 administered intravenously at a dose of 40 µg for 30 min prior to ConA administration reduces the number of T cells in the liver. It also protects mice against ConA-induced liver damage by inhibiting the expression/release of T-helper cell type 1 (Th1)-derived cytokines such as TNF-α and interferon-gamma.¹¹ In parallel to the above study, galectin-1 injection to DSS-given mice significantly decreased TNF-α concentration and increased IL-10 levels, and vice versa in the DSS group in this present study. Additionally, it was found that increased liver expression of COX-2 during the initiation of the DSS-induced inflammation process was significantly suppressed by galectin-1 administration. These results suggest that galectin-1 is effective on altering the expression levels of inflammatory mediators on liver tissue and inhibits hepatic inflammation.

Studies have been shown that DSS administration gives rise to inflammatory cell infiltration and oxidative damage in the mucosa because of MPO release from neutrophils and macrophages, and ROS from activated polymorphonuclear leukocytes.³⁹ Decreased levels of antioxidant system parameters and increased oxidative stress indicators were found in DSS-induced colitis models and inflammatory bowel disease.⁴⁰ So far, several studies have shown that GSH concentrations and antioxidant enzyme activities are reduced in liver tissue during DSS administration. Additionally, hepatic LPO and MPO activities are stimulated.^38,41,42 The present study was in accordance with the findings of other investigations, revealing a decrease in GSH levels, SOD and CAT activities, and the increase in activity of MPO and concentration of malondialdehyde (MDA) in the liver tissues of DSS-given mice. These findings have been pointed out that the antioxidant defense system is suppressed, while oxidative damage and LPO occur during inflammatory processes in the liver. In addition to the fact that high LDH activity is a general marker of cell and tissue damages in the liver of DSS administrated mice, it is also an important indicator of colitis-mediated hepatotoxicity. In a study conducted by Arda-Pirincci and Aykol (unpublished data), it was shown for the first time that galectin-1 inhibited LPO in DSS-induced mouse ulcerative colitis model. Moreover, galectin-1 protected the tissue from oxidative stress by stimulating the antioxidant defense system. In the present study, in parallel with the biochemical findings of our previous study, it was found that galectin-1 exhibits antioxidant effects by decreasing MDA levels and MPO activity and by increasing GSH concentration and antioxidant enzyme activities against oxidative damage derived from DSS in the liver tissue. In addition, suppression of LDH activity with galectin-1 treatment in the liver is important evidence suggesting that this lectin is protective against hepatotoxicity. SA is an N-acetylated derivative of neuraminic acids and a monosaccharide containing nine-carbon. Increased SA levels have been reported during inflammatory disease, diabetes mellitus, bacterial infections, rheumatoid arthritis, malignant disease, and chronic liver disease.^43,44 In the present study, increased liver SA level was detected in the DSS group. Galectin-1 treatment resulted to decrease in the liver SA levels in the DSS group.

In conclusion, we can suggest that galectin-1 has antiapoptotic, anti-inflammatory, antioxidant, and cytoprotective activities in DSS-induced colitis-mediated hepatotoxicity and thus prevents liver injury. The results obtained from the present study suggest that galectin-1 is not only convenient for use in ulcerative colitis as a protective agent but also very efficient in overcoming liver toxicity. Accordingly, it can be used as a new agent in preventing and treating secondary liver injury triggered by inflammatory bowel diseases.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by the Scientific Research Project Coordination Unit of Istanbul University (project number: 52327).

ORCID iD

P Arda-Pirincci

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Galectin-1 exhibits a protective effect against hepatotoxicity induced by dextran sulfate sodium in mice