Association of Apo(a)isoform size with dyslipoproteinemia in male venous thrombosis patients

Targeted proteomics using stable isotope labeled protein fragments enables precise and robust determination of total apolipoprotein(a) in human plasma

Lipoprotein(a), also known as Lp(a), is an LDL-like particle composed of apolipoprotein(a) (apo(a)) bound covalently to apolipoprotein B100. Plasma concentrations of Lp(a) are highly heritable and vary widely between individuals. Elevated plasma concentration of Lp(a) is considered as an independent, causal risk factor of cardiovascular disease (CVD). Targeted mass spectrometry (LC-SRM/MS) combined with stable isotope-labeled recombinant proteins provides robust and precise quantification of proteins in the blood, making LC-SRM/MS assays appealing for monitoring plasma proteins for clinical implications. This study presents a novel quantitative approach, based on proteotypic peptides, to determine the absolute concentration of apo(a) from two microliters of plasma and qualified according to guideline requirements for targeted proteomics assays. After optimization, assay parameters such as linearity, lower limits of quantification (LLOQ), intra-assay variability (CV: 4.7%) and inter-assay repeatability (CV: 7.8%) were determined and the LC-SRM/MS results were benchmarked against a commercially available immunoassay. In summary, the measurements of an apo(a) single copy specific peptide and a kringle 4 specific peptide allow for the determination of molar concentration and relative size of apo(a) in individuals.

Associations of Serum Lipids and Deep Venous Thrombosis Risk After Total Knee Arthroplasty in Patients With Primary Knee Osteoarthritis

Deep venous thrombosis (DVT) of the lower extremities is a common complication after total knee arthroplasty (TKA). This study aimed to investigate the potential associations between serum lipids and the risk of DVT after TKA in patients with primary knee osteoarthritis (OA). A total of 431 patients who received TKA caused by primary knee OA were randomly enrolled. According to the results of the color Doppler ultrasound of bilateral lower extremities deep veins on the third day postoperatively, patients were divided into DVT and non-DVT groups. Comparisons of preoperative serum levels of triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDL-C), apolipoprotein A1, and apolipoprotein B were then performed by the Student’s t test, χ2 test, and multivariate logistic regression analysis. For females, DVT patients had a higher serum LDL-C level at baseline ( P = .043) compared with non-DVT patients. A higher LDL-C value was significantly associated with an elevated DVT risk following TKA in female patients ( P = .037). In female patients with primary knee OA, preoperative serum LDL-C level may have an association with DVT risk after TKA. The relatively small male sample size may limit the accuracy of the findings.

Predictive value of HDL cholesterol for cancer-associated venous thromboembolism during chemotherapy

BACKGROUND

Dyslipidemia is a well-known risk factor for the development of atherothrombosis; however, its involvement in venous thromboembolism (VTE) is still debated. Low levels of HDL cholesterol (HDL-C) have been found to be associated with VTE, which is a common complication of cancer and its treatment. VTE incidence is increased in cancer patients, especially those undergoing chemotherapy.

OBJECTIVE

We sought to investigate the value of pretreatment HDL-C in the risk prediction of future VTE in a population of ambulatory cancer patients undergoing chemotherapy.

PATIENTS AND METHODS

Blood lipid composition was retrospectively evaluated in 592 consecutive patients with primary (n = 373) or relapsing/recurrent (n = 219) solid cancers at the start of a new chemotherapy regimen (12% neoadjuvant, 31% adjuvant, 57% metastatic).

RESULTS

VTE occurred during chemotherapy in 38 patients (median time-to-event: 3 months). Mean HDL-C levels were lower in patients who developed VTE during chemotherapy (41 mg dL(-1) ; standard deviation [SD] 13 mg dL(-1) ) than in those who did not (48 mg dL(-1) ; SD 14 mg dL(-1) ). Cox proportional hazard survival analysis showed that HDL-C levels ≤ 43 mg dL(-1) were able to significantly predict a first VTE episode, with a hazard ratio of 2.87 (95% confidence interval 1.45-5.68). Moreover, patients with HDL-C levels ≤ 43 mg dL(-1) had worse 1-year VTE-free survival (86%) than those with HDL-C levels > 43 mg dL(-1) (96%; log rank test, 3.14).

CONCLUSIONS

Patients with low HDL-C levels have a three-fold higher risk of developing a first VTE episode during chemotherapy. Baseline analysis of HDL-C levels might be of clinical value in predicting VTE in cancer outpatients treated with anticancer drugs.