The Cholesterol-5,6-Epoxide Hydrolase: A Metabolic Checkpoint in Several Diseases

Cholesterol-5,6-epoxides (5,6-ECs) are oxysterols (OS) that have been linked to several pathologies including cancers and neurodegenerative diseases. 5,6-ECs can be produced from cholesterol by several mechanisms including reactive oxygen species, lipoperoxidation, and cytochrome P450 enzymes. 5,6-ECs exist as two different diastereoisomers: 5,6α-EC and 5,6β-EC with different metabolic fates. They can be produced as a mixture or as single products of epoxidation. The epoxide ring of 5,6α-EC and 5,6β-EC is very stable and 5,6-ECs are prone to hydration by the cholesterol-5,6-epoxide hydrolase (ChEH) to give cholestane-3β,5α,6β-triol, which can be further oxidized into oncosterone. 5,6α-EC is prone to chemical and enzymatic conjugation reactions leading to bioactive compounds such as dendrogenins, highlighting the existence of a new metabolic branch on the cholesterol pathway centered on 5,6α-EC. We will summarize in this chapter current knowledge on this pathway which is controlled by the ChEH.

27-Hydroxylation of oncosterone by CYP27A1 switches its activity from pro-tumor to anti-tumor

Oncosterone (6-oxo-cholestane-3β,5α-diol; OCDO) is an oncometabolite and a tumor promoter on estrogen receptor alpha-positive breast cancer (ER(+) BC) and triple-negative breast cancers (TN BC). OCDO is an oxysterol formed in three steps from cholesterol: 1) oxygen addition at the double bond to give α- or β- isomers of 5,6-epoxycholestanols (5,6-EC), 2) hydrolyses of the epoxide ring of 5,6-ECs to give cholestane-3β,5α,6β-triol (CT), and 3) oxidation of the C6 hydroxyl of CT to give OCDO. On the other hand, cholesterol can be hydroxylated by CYP27A1 at the ultimate methyl carbon of its side chain to give 27-hydroxycholesterol ((25R)-Cholest-5-ene-3beta,26-diol, 27HC), which is a tumor promoter for ER(+) BC. It is currently unknown whether OCDO and its precursors can be hydroxylated at position C27 by CYP27A1, as is the impact of such modification on the proliferation of ER(+) and TN BC cells. We investigated, herein, whether 27H-5,6-ECs ((25R)-5,6-epoxycholestan-3β,26-diol), 27H-CT ((25R)-cholestane-3β,5α,6β,26-tetrol) and 27H-OCDO ((25R)-cholestane-6-oxo-3β,5α,26-triol) exist as metabolites and can be produced by cells expressing CYP27A1. We report, for the first time, that these compounds exist as metabolites in humans. We give pharmacological and genetic evidence that CYP27A1 is responsible for their production. Importantly, we found that 27-hydroxy-OCDO (27H-OCDO) inhibits BC cell proliferation and blocks OCDO and 27-HC-induced proliferation in BC cells, showing that this metabolic conversion commutes the proliferative properties of OCDO into antiproliferative ones. These data suggest an unprecedented role of CYP27A1 in the control of breast carcinogenesis by inhibiting the tumor promoter activities of oncosterone and 27-HC.

Chemical synthesis and biochemical properties of cholestane-5α,6β-diol-3-sulfonate: A non-hydrolysable analogue of cholestane-5α,6β-diol-3β-sulfate

Cholestane-3β,5α,6β-triol (CT) is a primary metabolite of 5,6-epoxycholesterols (5,6-EC) that is catalyzed by the cholesterol-5,6-epoxide hydrolase (ChEH). CT is a well-known biomarker for Niemann-Pick disease type C (NP-C), a progressive inherited neurodegenerative disease. On the other hand, CT is known to be metabolized by the 11β-hydroxysteroid-dehydrogenase of type 2 (11β-HSD2) into a tumor promoter named oncosterone that stimulates the growth of breast cancer tumors. Sulfation is a major metabolic transformation leading to the production of sulfated oxysterols. The production of cholestane-5α,6β-diol-3β-O-sulfate (CDS) has been reported in breast cancer cells. However, no data related to CDS biological properties have been reported so far. These studies have been hampered because sulfate esters of sterols and steroids are rapidly hydrolyzed by steroid sulfatase to give free steroids and sterols. In order to get insight into the biological properties of CDS, we report herein the synthesis and the characterization of cholestane-5α,6β-diol-3β-sulfonate (CDSN), a non-hydrolysable analogue of CDS. We show that CDSN is a potent inhibitor of 11β-HSD2 that blocks oncosterone production on cell lysate. The inhibition of oncosterone biosynthesis of a whole cell assay was observed but results from the blockage by CDSN of the uptake of CT in MCF-7 cells. While CDSN inhibits MCF-7 cell proliferation, we found that it potentiates the cytotoxic activity of post-lanosterol cholesterol biosynthesis inhibitors such as tamoxifen and PBPE. This effect was associated with an increase of free sterols accumulation and the appearance of giant multilamellar bodies, a structural feature reminiscent of Type C Niemann-Pick disease cells and consistent with a possible inhibition by CDSN of NPC1. Altogether, our data showed that CDSN is biologically active and that it is a valuable tool to study the biological properties of CDS and more specifically its impact on immunity and viral infection.

Post-viral idiopathic purpura fulminans is associated with inherited thrombophilia and anti-cardiolipin antibodies

Introduction

Idiopathic purpura fulminans (IPF) is a rare and severe coagulation disorder, associated with transient anti-protein S (anti-PS) antibodies in the context of post-viral infection such as varicella. Anti-protein S antibodies are frequently found in the context of varicella, in contrast with the rarity of IPF. Other factors such as anti-phospholipid antibodies (APL) and inherited thrombophilia may be associated with severe vascular complication.

Method

This is an ancillary study of a French multicenter retrospective series and systematic review of literature. We analyzed patients who were tested for inherited thrombophilia, namely antithrombin, protein C, protein S deficiency; prothrombin gene G20210A polymorphism (FII:G20210A),Factor V R506Q polymorphism (FV:R506Q); and/or for APL (lupus anticoagulant (LA), anti-cardiolipin antibodies (ACL), or anti-beta 2-GPI antibodies (Aβ2GP1).

Results

Among the 25 patients tested for inherited thrombophilia, 7 (28%) had positive results. Three had FV R506Q, two FII:G20210A, one compound heterozygote FV:R506Q associated to FII:G20210A, and one protein C deficiency. APL testing was performed in 32 patients. It was positive in 19 patients (59%): 17 ACL (53%), 5 LA (16%), 4 Aβ2GP1 (13%). The risk of severe complications was not associated with presence of inherited thrombophilia or APL presence, with RR: 0.8 [95% CI: 0.37-1.71], p = 1 and RR: 0.7 [95% CI: 0.33-1.51], p = 0.39, respectively. We found a high prevalence of inherited thrombophilia or APL in a population of patients with IPF. However, we do not find an association with the occurrence of severe vascular complications or venous thromboembolism.

Targeting the liver X receptor with dendrogenin A differentiates tumour cells to secrete immunogenic exosome-enriched vesicles

Tumour cells are characterized by having lost their differentiation state. They constitutively secrete small extracellular vesicles (sEV) called exosomes when they come from late endosomes. Dendrogenin A (DDA) is an endogenous tumour suppressor cholesterol‐derived metabolite. It is a new class of ligand of the nuclear Liver X receptors (LXR) which regulate cholesterol homeostasis and immunity. We hypothesized that DDA, which induces tumour cell differentiation, inhibition of tumour growth and immune cell infiltration into tumours, could functionally modify sEV secreted by tumour cells. Here, we have shown that DDA differentiates tumour cells by acting on the LXRβ. This results in an increased production of sEV (DDA‐sEV) which includes exosomes. The DDA‐sEV secreted from DDA‐treated cells were characterized for their content and activity in comparison to sEV secreted from control cells (C‐sEV). DDA‐sEV were enriched, relatively to C‐sEV, in several proteins and lipids such as differentiation antigens, “eat‐me” signals, lipidated LC3 and the endosomal phospholipid bis(monoacylglycero)phosphate, which stimulates dendritic cell maturation and a Th1 T lymphocyte polarization. Moreover, DDA‐sEV inhibited the growth of tumours implanted into immunocompetent mice compared to control conditions. This study reveals a pharmacological control through a nuclear receptor of exosome‐enriched tumour sEV secretion, composition and immune function. Targeting the LXR may be a novel way to reprogram tumour cells and sEV to stimulate immunity against cancer.

Original implementation of low-temperature SPS for bioactive glass used as a bone biomaterial

Alkali borated bioactive glasses powders with compositions based on the SiO₂-Na₂O-CaO-P₂O₅-x B₂O₃ system (0 < x < 20 wt%); have been consolidated at low temperature using Spark Plasma Sintering (SPS). Through SPS technique under 50 MPa, it was possible to achieve fully dense and completely amorphous borated glasses at temperatures as low as 420 °C. By increasing the sintering temperature up to 430 °C, the dense samples crystallized which is mostly achieved at higher temperatures. This study reveals that the mechanical properties of these new borated biomaterials are suitable to be used as a promising candidate for repairing defects in non-load-bearing bones as well as for coating on the metallic surface implants to improve the bioactivity process bone/implant. The pressure had a weak effect on the crystallization and densification of the glass compared to the temperature during the powder consolidation by SPS. Moreover, by increasing the boron content, the compressive strength and the elastic modulus of the elaborated glasses decreased for being close to those of the natural.

Primary squamous cell carcinoma of the thyroid associated with papillary thyroid carcinoma and Hashimoto's thyroiditis

INTRODUCTION

We report the first case of squamous cell carcinoma (SCC) of the thyroid gland coexisting with papillary thyroid carcinoma (PTC) and Hashimoto's thyroiditis and discuss various theories concerning the histogenesis of SCC of the thyroid gland and the optimal treatment strategy.

CASE REPORT

A 54-year-old woman presented with an anterior neck mass measuring 4cm on clinical examination. Imaging showed a suspicious thyroid nodule invading the trachea. Total thyroidectomy with bilateral central lymph node resection was performed. Histological examination revealed tall cell variant of papillary thyroid carcinoma associated with SCC of the right lobe of the thyroid and Hashimoto's thyroiditis. Immunohistochemistry of the SCC showed positive staining for p53 and Ki67 and negative staining for thyroglobulin. The patient underwent adjuvant radioactive iodine therapy and radiotherapy. With postoperative follow-up of 24 months, the patient was in good health.

DISCUSSION

In conclusion, the most probable origin of SCC in this case was malignant transformation from Hashimoto's thyroiditis following a phase of metaplasia. This immunohistological profile is associated with a better prognosis. Optimal treatment consists of extensive surgical resection of tumour tissuefollowed by radiotherapy.

[Complicated sigmoid tumor: perforated amebiasis]

Amoeboma is an inflammatory mass of the colon. It can be an inaugural symptom and thus pose the problem of differential diagnosis with colon cancer. The purpose of this report is to describe the case of a 43-year-old patient who presented with acute abdomen. Physical examination revealed a perforated circumferential mass in the sigmoid colon. Based on a presumptive diagnosis of colonic cancer complicated by perforation, segmental colectomy was performed. Histological examination of the surgical specimen demonstrated colonic amoeboma. The patient was treated using metronidazole. Although rare, amoeboma must be considered in differential diagnosis of cancer of any colonic mass.

[Primary hydatid cyst of the pancreas: Diagnosis and surgical procedures. Report of three cases]

The pancreas is an uncommon site of a hydatid cyst, even in countries where echinococcal disease is endemic. We report three cases of primary hydatid cysts of the pancreas revealed by abdominal pain. The diagnosis was based on ultrasound and CT-scan, which showed a cystic mass in the tail of the pancreas in the two first cases. In the third case, the diagnosis was determined preoperatively and a pancreatic fistula was found in the head of the pancreas during peroperative cholangiography. The echinococcal immunological test (Elisa) was positive in all cases. Surgical treatment included resection of the prominent lump in two patients and a cystogastric anastomosis in the third. Based on these three cases and a study of the literature, the difficulties of diagnosing this rare disease and the surgical procedures are discussed.

[Unopened colostomy in colorectal surgery: a renewal interest?]

INTRODUCTION

Anastomotic leak or disruption is a grave complication of colorectal surgery. Protection of an at-risk anastomosis by an upstream open diverting colostomy (OC) reduces this gravity. An unopened upstream loop colostomy is a surgical alternative which may diminish the unpleasant consequences of an open colostomy while maintaining the option of diversion in case of need. The aim of this study is to report the results of this approach and to define its indications.

MATERIAL AND METHODS

[corrected] We report a retrospective series of 34 cases of unopened diverting loop colostomy to protect an at-risk colorectal anastomosis. Indications for this procedure were stool-laden bowel (59%), low serum albumin (11.5%), local inflammation (11.5%), and very low placed anastomosis (17.5%).

RESULTS

The loop colostomy was eventually opened after surgery in six cases because of anastomotic leakage diagnosed clinically and/or detected by water soluble contrast opacification which was performed routinely on the sixth post-operative day. In all six cases, there was no need for an urgent surgical intervention. In 28 cases, the anastomosis healed without complication and the exteriorized loop was returned to the abdominal cavity seven days after the initial surgery. This was a short, simple procedure with an average operating time of ten minutes. Average hospital stay after returning the unopened colostomy to the abdomen was two days.

CONCLUSION

Unopened loop colostomy offers the advantages of protection of a colorectal anastomosis without proper morbidity or mortality, shorter hospitalization, and improved psychological comfort for the patient. It's principal indication is to minimize the risks related to leakage from an at-risk colorectal anastomosis.

[Subcutaneous hydatid cyst. Case report of an exceptional location]

Primary subcutaneous cyst hydatid disease is an exceptional entity. We report a new case involving a 70-year-old woman hospitalized for a subcutaneous mass in the hypogastric area with no local inflammatory signs. Radiological examination was consistent with a partially calcified subcutaneous cyst in the hypogastric area. Complete surgical resection of the mass was performed with uneventful postoperative recovery. Histopathological examination of the surgical specimen demonstrated multivesicular hydatid cyst.

[A previously unreported late complication of Finney strictureplasty]

We report the case of a 23 year old woman, treated for Crohn's disease for 11 years. She was operated on for multiple obstructing jejuno-ileal strictures using strictureplasty technique. Nine stricturoplasties of Heineke-Mikulicz type and one Finney type were performed without immediate postoperative complication. The patient received Imurel(R) and remained in remission for 15 months. Peritonitis due to a perforation of the Finney strictureplasty required re-operation; an ileostomy was performed. Such a late complication of a strictureplasty has not previously been reported in the literature. Although this complication was severe, the indication for this procedure in the surgical management of Crohn's complications should not be modified.

[Subcutaneous rupture of hydatid cyst of liver: dealing with a rare observation]

Hydatid cyst of liver is a parasitosis of endemic proportions in Tunisia. The purpose of this report is to describe a case involving subcutaneous rupture of a hydatid cyst of liver in a 41-year-old patient. Diagnosis was established by ultrasonography and CT-scan. The patient underwent surgical treatment and recovered uneventfully. Subcutaneous rupture remains an uncommon complication. This is only the second case reported in the literature up to now.

[Gastric amyloidosis mimicking malignancy. A case report]

Amyloidosis is an abnormal extracellular deposition of insoluble proteins, which is associated with an involvement of the gastrointestinal tract in 50 to 70% of cases. In primary amyloidosis (light chain amyloidosis), localized gastric involvement is a rare finding which can mimic malignancy. We report the case of a 56-year-old man, admitted with upper digestive outlet obstruction. Linitis plastica with lymph node involvement was suspected by gastroscopy, barium meal and endoscopic ultrasonography but was not confirmed by gastric biopsies. The patient was treated with total gastrectomy with lymph node dissection. Pathological examination demonstrated gastric and lymph nodes amyloidosis and no malignant tumor was found. The patient died 9 months later from cardiac failure due to amyloidosis.

[Laparoscopic cholecystectomy in a patient with situs inversus]

Laparoscopic cholecystectomy is the standard approach to manage symptomatic gallbladder stones. However, only twelve patients with total situs invertus have been previously reported in the literature. We report a new case of a 58-year-old patient hospitalized for acute pain of the left hypochondrium with fever. The diagnosis of acute cholecystitis with situs inversus totalis was made following clinical examination and radiological investigations. Laparoscopic cholecystectomy was subsequently performed through a modification of the technique to adapt to the mirror image anatomy.

Fatal sepsis due to Escherichia coli after second-trimester amniocentesis

The case of a pregnant woman (16th week) needing an amniocentesis is reported. She rapidly developed a septic shock. Despite vaginal delivery, curettage and antibiotherapy, the patient deteriorated with the onset of an acute respiratory distress syndrome and a typical disseminated intravascular coagulation. Bacteriological data showed positive blood cultures to Escherichia coli. Amniotic liquid was positive to the same E. coli. Cultures obtained from instruments, disinfectant solutions and gel used during the procedure were negative. On the contrary, amniotic and fetal cultures were positive to E. coli and Clostridium perfringens. She died 2 days later. The incidence of septic shock following amniocentesis is very low but we report the first case of fatal sepsis and multiorgan failure, due to E. coli and C. perfringens. The mechanisms of infection are discussed: contamination from the instruments, systemic dissemination of bacteria coming from an asymptomatic intra-amniotic infection, and inoculation of the placenta with a needle passing through the bowel.

[Endoscopic hemostasis of hemorrhagic gastroduodenal ulcers]

The mortality rate for peptic ulcer bleeding has remained constant for several decades, despite advances in surgery and intensive care, and this has given rise to an interest in therapeutic hemostatic endoscopy. Thus, endoscopy in the treatment of peptic ulcer hemorrhage would be undertaken with the aim of obtaining an early and precise diagnosis of the hemorrhagic lesions, to arrest active bleeding and/or to prevent rebleeding. In the selection of patients justifying an endoscopic hemostatic treatment, intervene clinical criteria (age, concomitant pathologies, current medication, hemodynamic parameters), endoscopic criteria (active arterial bleeding, visible vessels). The most frequently employed methods are laser photocoagulation, thermal probe cauterization, electrocoagulation and sclerotherapy. None of these methods have gained supremacy. There is consensus that sclerotherapy should be the method of reference (simple and inexpensive). Endoscopic methods are capable of arresting bleeding and constitute an alternative method to surgery in cases of emergency. They should reduce recurrence of hemorrhages, but nevertheless have no influence on the prognostic parameters which are essentially clinical.