Hypercholesterolemia Due to Lipoprotein X: Case Report and Thematic Review

Use of therapeutic plasma exchange to remove lipoprotein X in a patient with vanishing bile duct syndrome presenting with cholestasis, pseudohyponatremia, and hypercholesterolemia: A case report and review of literature

INTRODUCTION

Lipoprotein X (Lp-X) is an abnormal lipoprotein found in multiple disease conditions, including liver dysfunction and cholestasis. High Lp-X concentrations can interfere with some laboratory testing that may result in spurious results. The detection of Lp-X can be challenging, and there is currently a lack of consensus regarding the management of Lp-X other than treating the underlying disease.

CASE PRESENTATION

A 42-year-old female with Hodgkin's lymphoma treated with dexamethasone, high dose cytarabine and cisplatin and vanishing bile duct syndrome confirmed by liver biopsy presented with cholestasis, pseudohyponatremia (sodium, 113 mmol/L; reference range 136-146 mmL/L; serum osmolality, 303 mOsm/kg), and hypercholesterolemia (> 2800 mg/dL, reference range < 200 mg/dL). Lp-X was confirmed by lipoprotein electrophoresis (EP). Although she did not manifest any specific signs or symptoms, therapeutic plasma exchange (TPE) was initiated based on laboratory findings of extreme hypercholesterolemia, spuriously abnormal serum sodium, and HDL values, and the potential for short- and long-term sequelae such as hyperviscosity syndrome, xanthoma, and neuropathy. During the hospitalization, she was treated with four 1.0 plasma volume TPE over 6 days using 5% albumin for replacement fluid. After the first TPE, total cholesterol (TC) decreased to 383 mg/dL and sodium was measured at 131 mmol/L. The patient was transitioned into outpatient maintenance TPE to eliminate the potential of Lp-X reappearance while the underlying disease was treated. Serial follow-up laboratory testing with lipoprotein EP showed the disappearance of Lp-X after nine TPEs over a 10-week period.

LITERATURE REVIEW

There are seven and four case reports of Lp-X treated with TPE and lipoprotein apheresis (LA), respectively. While all previous case reports showed a reduction in TC levels, none had monitored the disappearance of Lp-X after completing a course of therapeutic apheresis.

CONCLUSION

Clinicians should have a heightened suspicion for the presence of abnormal Lp-X in patients with cholestasis, hypercholesterolemia, and pseudohyponatremia. Once Lp-X is confirmed by lipoprotein EP, TPE should be initiated to reduce TC level and remove abnormal Lp-X. Most LA techniques are not expected to be beneficial since Lp-X lacks apolipoprotein B. Therefore, we suggest that inpatient course of TPE be performed every other day until serum sodium, TC and HDL levels become normalized. Outpatient maintenance TPE may also be considered to keep Lp-X levels low while the underlying disease is treated. Serum sodium, TC, and HDL levels should be monitored while on maintenance TPE.

Severe Hypercholesterolemia Mediated by Lipoprotein X in an Immunosuppressed Patient: A Case Report

Cholestatic liver diseases may be associated with increased plasmatic cholesterol due to an abnormal lipoprotein - lipoprotein X (LpX). Correcting the underlying cause of cholestasis is the critical treatment of LpX-associated hypercholesterolemia without any proven benefit from conventional lipid-lowering agents. In some situations, plasma exchange may apply to prevent associated complications, such as hyperviscosity syndrome. The authors present the case of a 44-year-old man with orbital inflammatory pseudotumor on prednisolone, admitted due to hepatocellular and cholestatic lesion and severe hypercholesterolemia. Laboratory investigation established that hepatitis E virus was responsible for liver injury and showed that LpX mediated the severe hypercholesterolemia. Reduction of the immunosuppressive load contributed to virus clearance. The consequent resolution of cholestasis and cholesterol removal by plasmapheresis allowed lipid profile normalization. The authors report the first case of LpX-associated hypercholesterolemia in a patient with hepatitis E-induced cholestasis and revisit the role of the liver in lipid metabolism.

Lipoprotein-X: A Case of Falsely Elevated LDL Hypercholesterolemia

Lipoprotein-X is an extremely rare cause of severe hyperlipidemia. We present a case of a 26-year-old man with primary sclerosing cholangitis who developed lipoprotein X-induced pseudohyponatremia with severe hyponatremia. In this case report, we also discuss the diagnostic approach and the treatment for lipoprotein X. (Level of Difficulty: Advanced.).

Hypercholesterolemia After COVID-19: Time to Include Lipoprotein X Among the Differential Diagnoses

Background

Lipoprotein X (LpX) is an abnormal lipoprotein composed of phospholipids, free cholesterol, and albumin. Its overaccumulation is an infrequent cause of hyperlipidemia, which oftentimes presents in patients with cholestatic liver disease. The aim is to present the first 2 cases of patients with post-COVID cholangiopathy and LpX overaccumulation.

Case Report

We present 2 female patients (ie, a 34-year-old [patient 1] and a 56-year-old [patient 2]), who had complicated courses of COVID-19, requiring prolonged mechanical ventilation (>4 weeks). One month after discharge, patient 1 presented with abdominal pain. Patient 2 had gangrenous cholecystitis and later developed recurrent elevation of alkaline phosphatase and bilirubin. Both patients were diagnosed with cholestatic liver disease. During outpatient follow-up both patients were found to have elevated plasma low-density lipoprotein cholesterol (LDL-C) in routine lipid panels (723 mg/dL and 1389 mg/dL, respectively). Both patients underwent various treatments for elevated LDL-C before referral to endocrinology. Patients were diagnosed with LpX overaccumulation from post-COVID-19 cholangiopathy. In both patients, LDL-C fluctuations seen in routine lipid panels (affected by LpX levels) were tightly correlated with changes in alkaline phosphate and bilirubin.

Discussion

Our patients represent the first report of LpX overaccumulation in patients with post-COVID-19 cholangiopathy. Whether LpX accumulation is only the result of liver dysfunction, or COVID-19 infection plays a direct role in elevated LpX levels is still unknown.

Conclusion

In patients with complicated courses of COVID-19, LpX overaccumulation should be considered when a routine lipid panel shows significant LDL-C elevations. Awareness among health care providers regarding LpX is important to avoid unnecessary workup and treatment.

Hypercholesterolemia due to lipoprotein-X manifesting as pseudohyponatremia in a patient with cholestasis

Pseudohyponatremia is an often misdiagnosed condition that needs to be managed by addressing the underlying cause. Treatment of hyponatremic patients with intravenous fluids without ruling out pseudohyponatremia may aggravate a patient's hyponatremia and result in adverse outcomes. In a patient whose sodium is deteriorating, it is critical to diagnose pseudohyponatremia early in the course and acquire necessary consultations, even if the patient is asymptomatic. We discuss a case of a man in his 20s with a history of liver transplantation who presented with unexplained dangerously low sodium while being asymptomatic. The case illustrates an uncommon cause of pseudohyponatremia due to lipoprotein-X hypercholesterolemia in a patient with cholestatic liver disease.

Lipoprotein-X and Lipoprotein-Z Induced Hyperviscosity Syndrome in the Setting of Cholestatic Liver Failure

We describe a case referred for worsening hypercholesterolemia in the setting of atorvastatin and fenofibrate-induced liver injury. The patient reported neurological complaints attributed to hyperviscosity syndrome (induced by lipoprotein-X and lipoprotein-Z). Hepatic recovery was associated with reduction of whole blood viscosity and amelioration of neurological symptoms. (Level of Difficulty: Advanced.).

A Simple Fluorescent Cholesterol Labeling Method to Cryoprotect and Detect Plasma Lipoprotein-X

Simple Summary

Lipoprotein-X is an abnormal toxic particle in blood that is highly enriched in cholesterol. Lipoprotein-X forms in patients lacking an enzyme in blood called lecithin-cholesterol-acyl-transferase. With time, lipoprotein-X causes kidney disease in these patients, resulting in death at 40–50 years of age. Lipoprotein-X also forms, at very high levels, in the blood of patients with several different types of liver disease. Such high levels of lipoprotein-X cause additional painful and debilitating problems in these patients that can also be fatal. Currently, difficult and time-consuming tests only available in research laboratories can identify lipoprotein-X in blood. Unfortunately, lipoprotein-X in patient blood samples is unstable outside the body, and so with time becomes undetectable, even more so if it is frozen for evaluation at a later time. We have developed a simple method to label blood-derived lipoprotein-X so that it can be easily detected, and this method also stabilizes lipoprotein-X particles when frozen, enabling its detection after thawing. This methodology can easily be developed into a simple clinical test to identify both types of diseases where lipoprotein-X particles form in the blood and can be used to monitor how well treatments are able to reduce toxic lipoprotein-X in people with these diseases.

Abstract

Lipoprotein-X (LpX) are abnormal nephrotoxic lipoprotein particles enriched in free cholesterol and phospholipids. LpX with distinctive lipid compositions are formed in patients afflicted with either familial LCAT deficiency (FLD) or biliary cholestasis. LpX is difficult to detect by standard lipid stains due to the absence of a neutral lipid core and because it is unstable upon storage, particularly when frozen. We have recently reported that free cholesterol-specific filipin staining after agarose gel electrophoresis sensitively detects LpX in fresh human plasma. Herein, we describe an even more simplified qualitative method to detect LpX in both fresh and frozen–thawed human FLD or cholestatic plasma. Fluorescent cholesterol complexed to fatty-acid-free BSA was used to label LpX and was added together with trehalose in order to cryopreserve plasma LpX. The fluorescent cholesterol bound to LpX was observed with high sensitivity after separation from other lipoproteins by agarose gel electrophoresis. This methodology can be readily developed into a simple assay for the clinical diagnosis of FLD and biliary liver disease and to monitor the efficacy of treatments intended to reduce plasma LpX in these disease states.

Verrucous plane xanthomas secondary to lipoprotein X dyslipidemia in the context of cholestatic fulminant hepatitis: A case report

Cutaneous xanthomas are the result of dermal deposition of lipid, mostly caused by disorders of lipid metabolism. Less commonly, they occur in the setting of cholestatic liver disease, leading to accumulation of lipoprotein X, a rare form of dyslipidemia that does not respond well to conventional treatments. We describe an atypical presentation of sudden diffuse xanthomas secondary to lipoprotein X dyslipidemia in the context of cholestatic fulminant hepatitis caused by trimethoprim-sulfamethoxazole hypersensitivity. Histopathology was also atypical and showed an unusual verrucous appearance consisting of overlying epidermal hyperplasia with hyperkeratosis. Our patient had significant improvement, after normalization of her lipid panel under cholestyramine and 13 sessions of apheresis, with topical corticosteroids offering some relief. This rare case shows the importance of recognizing atypical presentations of xanthomas, particularly when they do not respond to conventional dyslipidemia treatments.

Alagille Syndrome: A Focused Review on Clinical Features, Genetics, and Treatment

Alagille syndrome (ALGS) is an autosomal dominant disorder caused by pathogenic variants in JAG1 or NOTCH2, which encode fundamental components of the Notch signaling pathway. Clinical features span multiple organ systems including hepatic, cardiac, vascular, renal, skeletal, craniofacial, and ocular, and occur with variable phenotypic penetrance. Genotype-phenotype correlation studies have not yet shown associations between mutation type and clinical manifestations or severity, and it has been hypothesized that modifier genes may modulate the effects of JAG1 and NOTCH2 pathogenic variants. Medical management is supportive, focusing on clinical manifestations of disease, with liver transplant indicated for severe pruritus, liver synthetic dysfunction, portal hypertension, bone fractures, and/or growth failure. New therapeutic approaches are under investigation, including ileal bile acid transporter (IBAT) inhibitors and other approaches that may involve targeted interventions to augment the Notch signaling pathway in involved tissues.

Clinical laboratory characteristics of patients with obstructive jaundice accompanied by dyslipidemia

BACKGROUND

Abnormal lipid metabolism manifests as hypercholesterolemia in patients with obstructive jaundice due to lipoprotein X (LpX). Our aim was to explore the clinical laboratory characteristics of patients with obstructive jaundice accompanied by dyslipidemia in a large number of samples.

METHODS

A total of 665 patients with obstructive jaundice were included and categorized into two groups (with/without dyslipidemia) based on the ratio of the sum of HDL-c and LDL-c to total cholesterol [(HDL-c + LDL-c)/TC] with a cut-off value of 0.695. Laboratory liver, kidney, and blood lipid parameters were determined. Cholesterol composition assessment was performed by ultracentrifugation and high-performance liquid chromatography (UC-HPLC), and serum protein profiles were analyzed by capillary electrophoresis.

RESULTS

Liver function in patients with obstructive jaundice accompanied by dyslipidemia was more aggravated than that in patients with simple obstructive jaundice (P < 0.05). The (HDL-c + LDL-c)/TC ratio was negatively correlated with bilirubin levels (P < 0.05). In addition, the difference in ApoB/LDL-c ratios was statistically significant between the obstructive jaundice accompanied by dyslipidemia group and healthy control group (P < 0.05). The LDL-c concentration determined by the UC-HPLC method was more than five times that determined by the enzymatic method (P < 0.05). Bisalbuminemia was found in 43 of 60 patients with obstructive jaundice accompanied by hypercholesterolemia.

CONCLUSIONS

In patients with obstructive jaundice, the decreased (HDL-c + LDL-c)/TC ratio may be a novel marker to identify dyslipidemia secondary to LpX. The decreased ratio was associated with poor liver function and indicated disease progression.

Transiently Elevated TC and sdLDL-C Levels and Falsely Low LDL-C Levels in Patients with Extrahepatic Cholangiocarcinoma

Purpose

Most patients diagnosed with extrahepatic cholangiocarcinoma (ECCA) exhibit cholestasis caused by obstruction of the bile duct. Cholestasis is associated with lipid disorders, but studies focused on the changing lipid parameters in patients with ECCA are lacking. Here, we observed lipid profiles in patients with ECCA and investigated whether the removal of biliary obstruction could correct dyslipidemia.

Patients and Methods

We consecutively included patients admitted to the hepatobiliary surgery department at the Affiliated Hospital of Xuzhou Medical University. The patients were divided into an ECCA group or a non-ECCA group based on the disease assessment. Patients with histological confirmation of ECCA were included in the ECCA group. Blood samples were collected on admission as well as five days after treatment. An automatic biochemistry analyzer was used to test liver function and serum lipid levels. Serum lipoprotein electrophoresis was performed using barbitone sodium buffer and Sudan black B.

Results

A total of 180 patients met inclusion criteria and were enrolled for this study. Of these, 76 patients were diagnosed with ECCA; all other patients were enrolled in the non-ECCA group. Total cholesterol (TC) and small and dense low-density lipoprotein cholesterol (sdLDL-C) levels were significantly elevated in the ECCA group. LDL-C levels were found to be slightly lower in the ECCA group. In the ECCA group, serum samples were detained in sample wells and lipoproteins failed to be separated. TC and sdLDL-C levels significantly decreased after cholestasis relief in the ECCA group. Lipoprotein electrophoresis revealed that patients with ECCA showed normal lipoprotein patterns after treatment.

Conclusion

Patients with ECCA exhibited transiently elevated TC and sdLDL-C levels and falsely low LDL-C results. TC, sdLDL-C, and LDL-C levels could be restored to normal levels after biliary obstruction removal and cholestasis relief.

Monocyte phenotyping and management of lipoprotein X syndrome

BACKGROUND

Accumulation of lipoprotein X (LpX) in blood can cause severe hypercholesterolemia and cutaneous xanthomas. Monocytes sensitively sense lipid changes in circulation and contribute to inflammation. However, how monocytes respond to LpX is undefined.

OBJECTIVE

We examined the phenotype of monocytes from a patient, who had LpX, severe hypercholesterolemia, and extensive cutaneous xanthomas, and effects of semiselective plasmapheresis therapy (SPPT).

METHOD

Fluorescence-activated cell sorting and adhesion assays were used to examine monocyte phenotype and ex vivo oxidized low-density lipoprotein uptake and adhesion in the patient before and after treatment with SPPT. Effects of plasma from the patient on the phenotype and adhesion of monocytes from a healthy participant were determined.

RESULTS

SPPT improved hypercholesterolemia and cutaneous xanthomas. Before treatment, the patient had lower frequency of nonclassical monocytes but higher frequency of intermediate monocytes than the control participant. Before treatment, monocytes from the patient with LpX showed more intracellular lipid accumulation, alterations in several cell surface markers and intracellular cytokines, as well as enhanced oxidized low-density lipoprotein uptake and reduced adhesion compared with control. After SPPT, the phenotypes of monocytes from the patient with LpX were similar to control monocytes. Incubation with plasma from the patient before treatment as compared with plasma from the control participant or the patient after treatment increased CD11c expression and adhesion of monocytes from a healthy participant.

CONCLUSION

LpX-induced hypercholesterolemia increased lipid accumulation and altered the phenotype of monocytes, which may contribute to cutaneous xanthoma development. Removal of LpX by SPPT reduced lipid accumulation and improved monocyte phenotype, likely contributing to xanthoma resolution.