Flow cytometric assessment of effects of fluvastatin on low-density lipoprotein receptor activity in stimulated T-lymphocytes from patients with heterozygous familial hypercholesterolemia

Multiparametric platform for profiling lipid trafficking in human leukocytes

Systematic insight into cellular dysfunction can improve understanding of disease etiology, risk assessment, and patient stratification. We present a multiparametric high-content imaging platform enabling quantification of low-density lipoprotein (LDL) uptake and lipid storage in cytoplasmic droplets of primary leukocyte subpopulations. We validate this platform with samples from 65 individuals with variable blood LDL-cholesterol (LDL-c) levels, including familial hypercholesterolemia (FH) and non-FH subjects. We integrate lipid storage data into another readout parameter, lipid mobilization, measuring the efficiency with which cells deplete lipid reservoirs. Lipid mobilization correlates positively with LDL uptake and negatively with hypercholesterolemia and age, improving differentiation of individuals with normal and elevated LDL-c. Moreover, combination of cell-based readouts with a polygenic risk score for LDL-c explains hypercholesterolemia better than the genetic risk score alone. This platform provides functional insights into cellular lipid trafficking and has broad possible applications in dissecting the cellular basis of metabolic disorders.

Apolipoprotein B binding domains: evidence that they are cell-penetrating peptides that efficiently deliver antigenic peptide for cross-presentation of cytotoxic T cells

Low-density lipoproteins (LDLs) are a good source of cholesterol, which is important in cellular homeostasis and production of steroids. Apolipoprotein B-100 (ApoB-100), the sole protein component of LDL, is known to bind to cell surface LDL receptor (LDLR) or cell surface-bound proteoglycans and to be internalized into cells. We found that APCs, consisting of macrophages and dendritic cells, upregulate LDLR on culture in vitro without obvious stimulation. In contrast, T cell populations only upregulate LDLR on activation. Thus, we strategized that tagging immunogens to ApoB-100 might be a useful means to target Ag to APCs. We generated fusion proteins consisting of receptor binding sites in ApoB-100, coupled to OVA peptide (ApoB-OVA), as Ag delivery vehicles and demonstrated that this novel delivery method successfully cross-presented OVA peptides in eliciting CTL responses. Surprisingly, internalization of ApoB-OVA peptide occurred via cell surface proteoglycans rather than LDLRs, consistent with evidence that structural elements of ApoB-100 indicate it to have cell-penetrating peptide properties. Finally, we used this strategy to assess therapeutic vaccination in a tumor setting. OVA-expressing EL-4 tumors grew progressively in mice immunized with ApoB-100 alone but regressed in mice immunized with ApoB-OVA fusion protein, coinciding with development of OVA-specific CTLs. Thus, to our knowledge, this is the first article to describe the cell-penetrating properties of a conserved human origin cell penetrating peptide that may be harnessed as a novel vaccination strategy as well as a therapeutics delivery device.

Effect of atorvastatin and clopidogrel on cellular immune function

Lipid lowering therapy by statins and antiaggregation have become the basis of any anti-atherosclerotic prophylaxis either as primary or secondary prophylaxis. As several recent papers indicated immunosuppressive properties of statins we investigated changes in lymphocyte subpopulations, apoptosis markers, and cellular immune response towards mitogens after a short-term therapy with atorvastatin and clopidogrel. Nine healthy volunteers (four male, five female, age ranging from 26 to 43 years) were treated with 20 mg atorvastatin for 4 weeks and for 2 additional weeks with 20 mg atorvastatin and 75 mg clopidogrel after oral consent was given. Lymphocyte subpopulations were counted by flow cytometry. To assess cellular in vitro immune function, lymphocyte transformation tests with four mitogens (PHA, ConA, PWM, and OKT3) were performed. Absolute leucocyte counts remained unchanged as well as the granulocyte, monocyte, lymphocyte, and lymphocyte subpopulation counts. There were no detectable changes in markers of cell activation (HLA-DR, CD25, CD69, and CD86) or apoptosis (CD95, annexin). Cellular in vitro responses towards four mitogens did not show significant changes after atorvastatin nor after atorvastatin plus clopidogrel treatment.In conclusion, our data show that atorvastatin is not an immunosuppressive drug under therapeutical conditions.