Complexity, cost, and content - three important factors for translation of clinical protein mass spectrometry tests, and the case for apolipoprotein C-III proteoform testing.

Complexity, cost, and content are three important factors that can impede translation of clinical protein mass spectrometry (MS) tests at a larger scale. Complexity stems from the many components/steps involved in bottom-up protein MS workflows, making them significantly more complicated than enzymatic immunoassays (EIA) that currently dominate clinical testing. This complexity inevitably leads to increased costs, which is detrimental in the price-competitive clinical marketplace. To successfully compete, new clinical protein MS tests need to offer something new and unique that EIAs cannot - a new content of proteoform detection. The preferred method for proteoform profiling is intact protein MS analysis, in which all proteins are measured as intact species thus allowing discovery of new proteoforms. To illustrate the importance of intact proteoform testing with MS and its potential clinical implications, we discuss here recent findings from multiple studies on the distribution of apolipoprotein C-III proteoforms and their correlations with key clinical measures of dyslipidemia. Such studies are only made possible with assays that are low in cost, avoid unnecessary complexity, and are unique in providing the content of proteoforms.

Apolipoprotein C3 induces inflammation and organ damage by alternative inflammasome activation.

NLRP3-inflammasome-driven inflammation is involved in the pathogenesis of a variety of diseases. Identification of endogenous inflammasome activators is essential for the development of new anti-inflammatory treatment strategies. Here, we identified that apolipoprotein C3 (ApoC3) activates the NLRP3 inflammasome in human monocytes by inducing an alternative NLRP3 inflammasome via caspase-8 and dimerization of Toll-like receptors 2 and 4. Alternative inflammasome activation in human monocytes is mediated by the Toll-like receptor adapter protein SCIMP. This triggers Lyn/Syk-dependent calcium entry and the production of reactive oxygen species, leading to activation of caspase-8. In humanized mouse models, ApoC3 activated human monocytes in vivo to impede endothelial regeneration and promote kidney injury in an NLRP3- and caspase-8-dependent manner. These data provide new insights into the regulation of the NLRP3 inflammasome and the pathophysiological role of triglyceride-rich lipoproteins containing ApoC3. Targeting ApoC3 might prevent organ damage and provide an anti-inflammatory treatment for vascular and kidney diseases.

Emerging Evidence that ApoC-III Inhibitors Provide Novel Options to Reduce the Residual CVD.

PURPOSE OF REVIEW: Apolipoprotein C-III (apoC-III) is known to inhibit lipoprotein lipase (LPL) and function as an important regulator of triglyceride metabolism. In addition, apoC-III has also more recently been identified as an important risk factor for cardiovascular disease. This review summarizes the mechanisms by which apoC-III induces hypertriglyceridemia and promotes atherogenesis, as well as the findings from recent clinical trials using novel strategies for lowering apoC-III. RECENT FINDINGS: Genetic studies have identified subjects with heterozygote loss-of-function (LOF) mutations in APOC3, the gene coding for apoC-III. Clinical characterization of these individuals shows that the LOF variants associate with a low-risk lipoprotein profile, in particular reduced plasma triglycerides. Recent results also show that complete deficiency of apoC-III is not a lethal mutation and is associated with very rapid lipolysis of plasma triglyceride-rich lipoproteins (TRL). Ongoing trials based on emerging gene-silencing technologies show that intervention markedly lowers apoC-III levels and, consequently, plasma triglyceride. Unexpectedly, the evidence points to apoC-III not only inhibiting LPL activity but also suppressing removal of TRLs by LPL-independent pathways. Available data clearly show that apoC-III is an important cardiovascular risk factor and that lifelong deficiency of apoC-III is cardioprotective. Novel therapies have been developed, and results from recent clinical trials indicate that effective reduction of plasma triglycerides by inhibition of apoC-III might be a promising strategy in management of severe hypertriglyceridemia and, more generally, a novel approach to CHD prevention in those with elevated plasma triglyceride.

Predictive Models for the Risk of Dyslipidemia in Adolescents with Essential Arterial Hypertension.

Predictive models of comorbidity, dyslipidemic disorders and essential arterial hypertension, in Russian adolescents aged 12 to 18 years (mean 15.48±1.53) were formulated with consideration for biochemical (lipid profiles) and genetic parameters (carrier state of gene polymorphic variants of apolipoprotein genes ApoA1 (-75G/A and +83C/T), ApoB (Ins/Del), ApoC3 (S1/S2), and ApoE (ε2/ε3/ε4). Significant prognostic risk factors for the mentioned comorbid pathologies were lipid metabolism parameters HDL-Ch, LDL-Ch, VLDL-Ch and carrier state of the +83T allele of the ApoA1 gene and Del allele of the ApoB gene. The obtained mathematical model is characterized by high predictive accuracy: the percentage of correct classification or the rate of correct assignment of each participant to the proper group was 96.33%.

An immunohistochemical study of human platelets using a rabbit antibody against H18-K24 of apolipoprotein CIII (HATKTAK).

H18-K24 of human apolipopotein CIII (Apo CIII) (HATKTAK) is an activator of the macromolecular activators of phagocytosis from platelets (MAPPs). Using a rabbit antibody against HATKTAK, we performed an immunohistochemical study of human platelets. Indirect ELISA showed that this antibody reacts with Apo CIII-derived peptides with a C-terminal of HATKTAK, but not with Apo CIII. Immunoelectron microscopy revealed that reaction of anti-HATKTAK antibody occurred in the pseudopods of activated platelets. In blood coagula produced from the peripheral blood and formalin-fixed after various incubation periods, reaction of this antibody with platelets appeared rapidly with a peak at 3 to 6 h of incubation, and then diminished gradually. Leukocytes in the blood coagula were stained strongly positive. In tissue sections, fresh thrombi and hemorrhages with slight fibrin formation revealed a positive response of platelets to anti-HATKTAK antibody, whereas older ones with leukocytic infiltration, fibrin formation and organization did not. In addition to platelets, endothelial cells and leukocytes were stained positive by anti-HATKTAK antibody. All of the positive reactions by anti-HATKTAK antibody disappeared or diminished by co-incubation with HATKTAK. In conclusion, the anti-HATKTAK antibody reveals platelets during the early phase of activation.