| 1. |
- Alyamani, Manar, et al.
(författare)
-
Alkaline sphingomyelinase (NPP7) impacts the homeostasis of intestinal T lymphocyte populations
- 2023
-
Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- Background and aim: Alkaline sphingomyelinase (NPP7) is expressed by intestinal epithelial cells and is crucial for the digestion of dietary sphingomyelin. NPP7 also inactivates proinflammatory mediators including platelet-activating factor and lysophosphatidylcholine. The aim of this study was to examine a potential role for NPP7 in the homeostasis of the intestinal immune system. Methods: We quantified the numbers of B-lymphocytes, plasma cells, T-lymphocytes including regulatory T-lymphocytes (Tregs), natural killer cells, dendritic cells, macrophages, and neutrophils, in the small and large intestines, the mesenteric lymph nodes and the spleens of heterozygous and homozygous NPP7 knockout (KO) and wildtype (WT) mice. Tissues were examined by immunohistochemistry and stainings quantified using computerized image analysis. Results: The numbers of both small and large intestinal CD3ε+, CD4+, and CD8α+ T-lymphocytes were significantly higher in NPP7 KO compared to WT mice (with a dose-response relationship in the large intestine), whereas Treg numbers were unchanged, and dendritic cell numbers reduced. In contrast, the numbers of CD3ε+ and CD4+ T-lymphocytes in mesenteric lymph nodes were significantly reduced in NPP7 KO mice, while no differences were observed in spleens. The numbers of B-lymphocytes, plasma cells, natural killer cells, macrophages, and neutrophils were similar between genotypes. Conclusion: NPP7 contributes to the regulation of dendritic cell and T-lymphocyte numbers in mesenteric lymph nodes and both the small and large intestines, thus playing a role in the homeostasis of gut immunity. Although it is likely that the downstream effects of NPP7 activity involve the sphingomyelin metabolites ceramide and spingosine-1-phosphate, the exact mechanisms behind this regulatory function of NPP7 need to be addressed in future studies.
|
|
| 2. |
- Andersson, David, et al.
(författare)
-
Ursolic acid and other pentacyclic triterpenoids stimulate intestinal alkaline sphingomyelinase in vitro
- 2006
-
Ingår i: European Journal of Lipid Science and Technology. - : Wiley. - 1438-7697 .- 1438-9312. ; 108:2, s. 103-108
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: Alkaline sphingomyelinase (alk-SMase) is an enzyme that hydrolyses sphingomyelin in a bile salt-dependent manner in the gastrointestinal tract, and has been proposed as an inhibitor of colon carcinogenesis. Ursolic acid (UA) is a plant-derived pentacyclic triterpenoid that has been shown to have anti-proliferative and apoptotic effects on HT29 human colon adenocarcinoma cells, with activation of alk-SMase as an early event. The aim of this study was to study the in vitro effects of UA and its analogues on the activity of purified rat intestinal alk-SMase. Methods: Rat intestinal alk-SMase activity was determined after incubation with UA in the presence and absence of taurocholate (TC). The effect was compared with boswellic acids, another group of pentacyclic triterpenoids. Results: UA enhanced the activity of rat intestinal alk-SMase in a dose-dependent manner, without a similar effect on bacterial neutral SMase. Four types of boswellic acid also increased the enzyme activity, with the effect of acetyl-keto-beta-boswellic acid being most potent. Activation of alk-SMase by TC; at a low concentration (0.4 mM), but not at a high concentration, was enhanced by UA. Conclusions: Ursolic acid and four types of boswellic acid, all pentacyclic triterpenoids, have a stimulatory effect on the activity of intestinal alk-SMase.
|
|
| 3. |
|
|
| 4. |
- Chen, Ying, et al.
(författare)
-
Enhanced colonic tumorigenesis in alkaline sphingomyelinase (NPP7) knockout mice.
- 2015
-
Ingår i: Molecular Cancer Therapeutics. - 1538-8514. ; 14:1, s. 259-267
-
Tidskriftsartikel (refereegranskat)abstract
- Intestinal alkaline sphingomyelinase (alk-SMase) generates ceramide and inactivates platelet-activating factor (PAF) and is previously suggested to have anticancer properties. The direct evidence is still lacking. We studied colonic tumorigenesis in alk-SMase knockout (KO) mice. Formation of aberrant crypt foci (ACF) was examined after azoxymethane (AOM) injection. Tumor was induced by AOM alone, a conventional AOM/dextran sulfate sodium (DSS) treatment, and an enhanced AOM/DSS method. beta-catenin was determined by immunohistochemistry, PAF levels by ELISA and sphingomyelin metabolites by mass spectrometry. Without treatment, spontaneous tumorigenesis was not identified but the intestinal mucosa appeared thicker in KO than in wild type (WT) littermates. AOM alone induced more ACF in KO mice but no tumors 28 weeks after injection. However, combination of AOM/DSS treatments induced colonic tumors and the incidence was significantly higher in KO than in WT mice. By the enhanced AOM/DSS method tumor number per mouse increased 4.5 times and tumor size 1.8 times in KO compared to WT mice. While all tumors were adenomas in WT mice, 32% were adenocarcinomas in KO mice. Compared to WT mice, cytosol expression of beta-catenin was significantly decreased and nuclear translocation in tumors was more pronounced in KO mice. Lipid analysis showed decreased ceramide in small intestine and increased sphingosine-1-phosphate in both small intestine and colon in nontreated KO mice. PAF levels in feces were significantly higher in the KO mice after AOM/DSS treatment. In conclusion lack of alk-SMase markedly increases AOM/DSS induced colonic tumorigenesis associated with decreased ceramide and increased sphingosine-1-phosphate and PAF levels.
|
|
| 5. |
|
|
| 6. |
- Cheng, Yajun, et al.
(författare)
-
Ezetimibe Inhibits Expression of Acid Sphingomyelinase in Liver and Intestine.
- 2009
-
Ingår i: Lipids. - : Wiley. - 0024-4201 .- 1558-9307. ; 44:10, s. 897-906
-
Tidskriftsartikel (refereegranskat)abstract
- Ezetimibe inhibits cholesterol absorption in the intestine. Sphingomyelin has strong interactions with cholesterol. We investigated the effects of ezetimibe on Sphingomyelinase (SMase) expression in intestine and liver. After feeding rats with ezetimibe (5 mg/kg per day) for 14 days, acid SMase activities in the liver and in the proximal part of small intestine were reduced by 34 and 25%, respectively. Alkaline SMase (alk-SMase) was increased in the proximal part of the small intestine. Administration of lower doses of ezetimibe reduced acid SMase only in the liver by 14% (P < 0.05). In cell culture studies, ezetimibe decreased acid SMase activity in Hep G2 and Caco-2 cells dose-dependently. The reductions were more rapid for Hep G2 cells than for Caco-2 cells. Western blot showed that acid SMase protein was decreased in both Hep G2 and Caco-2 cells by 100 muM ezetimibe. The SM content was increased in Hep G2 cells but not Caco-2 cells, and total cholesterol content was increased in both cell lines 24 h after stimulation with 100 muM ezetimibe. Mevastatin, the inhibitor of cholesterol synthesis, induced a mild increase in acid SMase activity in Hep G2 cells but not Caco-2 cells. Following the reduction of acid SMase, ezetimibe at high dose slightly increased alk-SMase activity. In conclusion, the study demonstrates an inhibitory effect of ezetimibe on acid SMase activity and expression in both liver and intestine.
|
|
| 7. |
- Cheng, Yajun, et al.
(författare)
-
Purification, characterization, and expression of rat intestinal alkaline sphingomyelinase.
- 2002
-
Ingår i: Journal of Lipid Research. - 1539-7262. ; 43:2, s. 316-324
-
Tidskriftsartikel (refereegranskat)abstract
- Intestinal alkaline sphingomyelinase (SMase) has physiological roles in the digestion of sphingomyelin (SM) and clinical implications in colonic carcinogenesis. In the present work, the enzyme from rat has been purified 1,589-fold with 11% recovery by elution of the intestine with bile salt, precipitation of the proteins by acetone, and several types of chromatographies. Its molecular mass was 58 kDa and optimal pH was 9 to 9.5. Under the optimal conditions, the V(max) was 930 micromol/h/mg and K(m) was about 1.25 mM. The enzyme could hydrolyze phosphatidylcholine at pH 7.4 in the presence of Ca2+; the rate was about 8% of that for SM. The activity against SM was dependent on bile salt. Taurine conjugated bile salts were much more effective than glycine conjugated ones, and the most effective bile salts were taurocholate and taurochenodeoxycholate. 3-[(3-Cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) and Triton X100 (TX100) had no stimulatory effects. Unlike neutral SMase, intestinal alkaline SMase was not Mg2+ dependent, not inhibited by EDTA, and not inhibited by glutathione. The enzyme was stable during incubation with temperatures up to 50 degree C and in pHs from 7 to 10. Trypsin and chymotrypsin had no effects on its activity, and 10 mM dithiothreitol reduced its activity by 25%. A specific antibody against the enzyme was developed, and Western blot showed that the enzyme was expressed in the intestine but not in other organs. In conclusion, we purified a potentially important SMase in the intestine with several properties different from neutral SMase.
|
|
| 8. |
- Duan, Rui-Dong, et al.
(författare)
-
Alkaliskt sfingomyelinas, en antiinflamatorisk faktor som kan motverka colit och colorektal cancer
- 2019
-
Ingår i: Gastrokuriren. - 1651-0453. ; 24:2, s. 26-27
-
Konferensbidrag (refereegranskat)abstract
- Alkaliskt sfingomyelinas, en antiinflammatorisk faktor som kan motverka colit och colorektal cancer Rui-Dong Duan, Erik Hertervig, Åke NilssonBakgrund: Borstbrämsenzymet alkaliskt sfingomyelinas (alk-SMas) som vi upptäckt, renat och klonat hydrolyserar sfingomyelin (SM) och den proinflammatoriska glycerofosfolipiden platelet activating factor (PAF). Metaboliter av SM är anticarcinogena och inaktivering av PAF är antiinflammatorisk. Alk-SMas nivån är sänkt vid coloncancer (CRC) (1), familjär colonpolypos och långvarig colit. Rektal administration av rekombinant alk-SMas lindrar experimentell colit och alk-SMas knockout (KO) möss är känsligare för induktion av colontumörer i en kombinerad colit/carcinogenmodell (2). Enzymet secerneras också i human galla och vi fann låga värden i ERCP galla från patienter med PSC och cholangiocarcinom. Alk-SMas KO möss utvecklar svårare dextransulfat colit än kontrollmöss (3). Metod: Vi analyserade PAF, enzymet autotaxin och dess metabolit lysofosfatidinsyra (LPA) i mucosan hos alk-SMas KO och kontrolldjur med colit inducerad med dextransulfat (3). Både PAF och LPA är trofiska och proinflammatoriska signalsubstanser. Fynden relaterades till colitens svårighetsgrad. Studien gav en mekanistisk bakgrund till alk-SMas anticarcinogena och antiinflammatoriska effekter. Vi kan därigenom bättre bedöma alk-SMas kliniska potential. Resultat: Vi fann att alk-SMas KO möss har högre PAF nivåer i mucosan under colitens induktionsfas och att nivån av autotaxin och LPA är högre i KO djuren när inflammationen etablerats (3). Bland våra tidigare fynd vill vi lyfta fram att alk-SMas uttryck kan nedregleras av fettrik kost, och ökas av lösliga fiber, 5-ASA och ursodeoxycholsyra. Slutsats: 1. Den anticarcinogena effekten av alk-SMas kan vara sekundär till den antiinflammatoriska effekten. 2. Reduktionen av på PAF och LPA nivåer är sannolikt viktigare för effekten än bildningen av sfingolipidmetaboliter. 3. Påverkan på alk-SMas nivån bidrar till kända effekter av kost och farmaka på inflammation och carcinogenes i colon. 4. Alk-SMas är proteasresistent och kan analyseras i faeces. 5 Alk SMase kan ges som slow release eller rektal beredning. Referenser: 1.Hertervig E, Nilsson A, Nyberg L, Duan RD. Alkaline sphingomyelinase activity is decreased in human colorectal carcinoma. Cancer. 1997; 79:448-53. 2. Chen Y, Zhang P, Xu SC, Yang L, Voss U, Ekblad E, Wu Y, Min Y, Hertervig E, Nilsson Å, Duan RD. Enhanced colonic tumorigenesis in alkaline sphingomyelinase (NPP7) knockout mice. Mol Cancer Ther. 2015; 14:259-67.3. Zhang P, Chen Y, Zhang T, Zhu J, Zhao L, Li J, Wang G, Li Y, Xu S, Nilsson Å, Duan RD. Deficiency of alkaline SMase enhances dextran sulfate-induced colitis in mice with upregulation of autotaxin. J Lipid Res. 2018; 59:1841-1850.
|
|
| 9. |
- Duan, Rui-Dong, et al.
(författare)
-
Changes of activity and isoforms of alkaline sphingomyelinase (nucleotide pyrophosphatase phosphodiesterase 7) in bile from patients undergoing endoscopic retrograde cholangiopancreatography.
- 2014
-
Ingår i: BMC Gastroenterology. - 1471-230X. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Alkaline sphingomyelinase (NPP7) is an ecto-enzyme expressed in intestinal mucosa, which hydrolyses sphingomyelin (SM) to ceramide and inactivates platelet activating factor. It is also expressed in human liver and released in the bile. The enzyme may have anti-tumour and anti-inflammatory effects in colon and its levels are decreased in patients with colon cancer and ulcerative colitis. Active NPP7 is translated from a transcript of 1.4 kb, whereas an inactive form from a 1.2 kb mRNA was found in colon and liver cancer cell lines. While the roles of NPP7 in colon cancer have been intensively studied, less is known about the function and implications of NPP7 in the bile. The present study examines the changes of NPP7 in bile of patients with various hepatobiliary diseases.
|
|
| 10. |
- Duan, Rui-Dong, et al.
(författare)
-
Effects of bile diversion in rats on intestinal sphingomyelinases and ceramidase.
- 2007
-
Ingår i: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier BV. - 1388-1981. ; 1771:2, s. 196-201
-
Tidskriftsartikel (refereegranskat)abstract
- Alkaline sphingomyelinase (Alk-SMase) and neutral ceramidase (N-CDase) in the intestinal microvillar membrane are responsible for dietary sphingomyelin digestion. The activities of the enzymes require the presence of bile salt, and the enzymes can be released into the gut lumen in active forms by bile salts and trypsin. It is unclear to what extent that the intestinal presence of bile salts is critical for the intraluminal activity of these enzymes. We compared the activities of Alk-SMase, N-CDase, and other types of SMases in control and permanently bile diverted rats. In the intestinal tract of control rats, the activity of Alk-SMase was profoundly higher than those of acid and neutral Wases. Bile diversion reduced Alk-SMase activity by 85% in the small intestinal content, and by 68% in the faeces, but did not significantly change the activity in the intestinal mucosa. Western blot showed a marked reduction of the enzyme in the intestinal lumen but not mucosa. N-CDase activities both in the intestinal mucosa and content were reduced by bile diversion. Bile diversion also decreased aminopeptidase N activity in the content and increased that in the mucosa, but had no effects on that of alkaline phosphatase. In conclusion, the presence of bile salts is important for maintaining high intraluminal levels of Alk-SMase and N-CDase, two key enzymes for hydrolysis of sphingomyelin in the gut. We speculate that the sphingomyelin hydrolysis in cholestatic conditions is impaired not only by reduced hydrolytic activity but also by deficient dissociation of the enzymes from the membrane.
|
|
