Contribution of intestinal triglyceride-rich lipoproteins to residual atherosclerotic cardiovascular disease risk in individuals with type 2 diabetes on statin therapy.

AIMS/HYPOTHESIS: This study explored the hypothesis that significant abnormalities in the metabolism of intestinally derived lipoproteins are present in individuals with type 2 diabetes on statin therapy. These abnormalities may contribute to residual CVD risk. METHODS: To investigate the kinetics of ApoB-48- and ApoB-100-containing lipoproteins, we performed a secondary analysis of 11 overweight/obese individuals with type 2 diabetes who were treated with lifestyle counselling and on a stable dose of metformin who were from an earlier clinical study, and compared these with 11 control participants frequency-matched for age, BMI and sex. Participants in both groups were on a similar statin regimen during the study. Stable isotope tracers were used to determine the kinetics of the following in response to a standard fat-rich meal: (1) apolipoprotein (Apo)B-48 in chylomicrons and VLDL; (2) ApoB-100 in VLDL, intermediate-density lipoprotein (IDL) and LDL; and (3) triglyceride (TG) in VLDL. RESULTS: The fasting lipid profile did not differ significantly between the two groups. Compared with control participants, in individuals with type 2 diabetes, chylomicron TG and ApoB-48 levels exhibited an approximately twofold higher response to the fat-rich meal, and a twofold higher increment was observed in ApoB-48 particles in the VLDL1 and VLDL2 density ranges (all p < 0.05). Again comparing control participants with individuals with type 2 diabetes, in the latter, total ApoB-48 production was 25% higher (556 ± 57 vs 446 ± 57 mg/day; p < 0.001), conversion (fractional transfer rate) of chylomicrons to VLDL was around 40% lower (35 ± 25 vs 82 ± 58 pools/day; p=0.034) and direct clearance of chylomicrons was 5.6-fold higher (5.6 ± 2.2 vs 1.0 ± 1.8 pools/day; p < 0.001). During the postprandial period, ApoB-48 particles accounted for a higher proportion of total VLDL in individuals with type 2 diabetes (44%) compared with control participants (25%), and these ApoB-48 VLDL particles exhibited a fivefold longer residence time in the circulation (p < 0.01). No between-group differences were seen in the kinetics of ApoB-100 and TG in VLDL, or in LDL ApoB-100 production, pool size and clearance rate. As compared with control participants, the IDL ApoB-100 pool in individuals with type 2 diabetes was higher due to increased conversion from VLDL2. CONCLUSIONS/INTERPRETATION: Abnormalities in the metabolism of intestinally derived ApoB-48-containing lipoproteins in individuals with type 2 diabetes on statins may help to explain the residual risk of CVD and may be suitable targets for interventions. TRIAL REGISTRATION: ClinicalTrials.gov NCT02948777.

Alerta monitoramento do horizonte tecnológico: MIPOMERSEN (KYNAMRO®) para Hipercolesterolemia Familiar Homozigótica / Technological horizon monitoring alert: IMIPOMERSEN (KYNAMRO®) for Homozygous Familial Hypercholesterolemia

DESCRIÇÃO DA TECNOLOGIA: Mipomersen3 é um medicamento cujo alvo é o RNA mensageiro para a apolipoproteina B-100, integrante do colesterol LDL ("colesterol ruim"). É indicado com tratamento adjuvante à dieta e à maior dose tolerada de outros medicamentos anticolesterol, como estatinas. REGISTRO DO MEDICAMENTO NO MUNDO: O mipomersen não possui registro no Brasil para esta ou outra indicação. Nos Estados Unidos, o medicamento foi registrado em 2006 como "droga órfã". Em 2008 foi aceito o desfecho substituto "níveis de LDL" para aprovação acelerada. Em 2013 foi aprovado com indicação de uso restrito e condicionado a um programa REMS (avaliação de risco e estratégias de mitigação) frente ao risco de hepatoxicidade e destacada a necessidade da empresa conduzir estudos de segurança pósmarketing. O medicamento foi registrado em 2014, no México, Argentina, Coréia do Sul e Peru1. A Comissão Europeia (EMA) negou a autorização de comercialização do medicamento na Europa em 2012 e reiterou a negativa em 2013. PESQUISA CLÍNICA: Para coletar informações de eficácia e segurança do mipomersen, bases de dados na internet foram consultadas a fim de localizar pesquisas com o medicamento (ensaios clínicos de fase 1d, 2e e 3f) em pacientes com HFHo concluídas e em andamento. Estudos em andamento: Não foram encontrados registros na plataforma oficial de registro de ensaios clínicos no mundo, o ClinicalTrials.gov de estudos em andamento. Estudos concluídos: Dois estudos concluídos, sendo um fase 2 e um fase 3, foram localizados no ClinicalTrials.gov. Estudos concluídos: Dois estudos concluídos, sendo um fase 2 e um fase 3, foram localizados no ClinicalTrials.gov. O estudo clínico fase 2 (NCT00280995), randomizado, aberto e com doses escalonadas do medicamento, foi realizado a fim de demonstrar a eficácia e segurança do mipomersen em doses variadas e a um curto prazo no tratamento de pacientes com HFHo. O estudo foi concluído em 2007 e não foram encontrados resultados publicados. O estudo fase 3 RADICHOL-1 (NCT00607373) foi elaborado a fim de demonstrar a eficácia e segurança do mipomersen 200mg/semana, quando adicionado a hipolipemiantes em pacientes com HFHo. Dos 51 pacientes que iniciaram o ensaio clínico, 45 completaram o tratamento de 26 semanas. Dentre as razões para o abandono do mipomersen, tem-se: reações no local da injeção (n=2); erupção cutânea (n=1); aumento da alanina aminotransferase (ALT) (n=1); não-aderência ao tratamento (n=1); e consentimento revogado (n=1). O desfecho primário analisado mediu a porcentagem de alteração na concentração do colesterol LDL. Os desfechos secundários de eficácia analisaram a porcentagem de alteração na concentração de apolipoproteína B, colesterol total e colesterol não-HDL. A segurança e tolerabilidade do mipomersen foram avaliadas por meio da incidência e gravidade dos eventos adversos e suspensão do tratamento.

Apolipoprotein B100 autoimmunity and atherosclerosis - disease mechanisms and therapeutic potential.

PURPOSE OF REVIEW: Adaptive immune responses have been shown to play an important role in the atherosclerotic disease process and both pathogenic and protective immunity has been identified. Apolipoprotein (apo) B100 appears to be a key antigen and novel therapies modulating immune responses against apo B100 have shown promising results in experimental models. This review will discuss recent developments in the mechanistic understanding of apo B100 autoimmunity and approaches taken to use this knowledge for development of novel therapies. RECENT FINDINGS: It has recently been shown that not only apo B100 modified by oxidation but also nonmodified apo B100 is targeted by autoimmune responses. This implies that a corresponding set of regulatory T cells with the same antigen specificity must exist and that these cells under normal circumstances are able to prevent autoimmunity against LDL. Recent studies also suggest that the atheroprotective effect of apo B100 peptide immunization acts by re-enforcing the activity of such cells. SUMMARY: These novel findings suggest that aggravation of plaque inflammation may occur as a result of a local loss of tolerance against LDL in the plaque due to insufficient activity of regulatory T cells. Restoration of lost tolerance represents an interesting novel approach for treatment of cardiovascular disease.

CD8+ T cells mediate the athero-protective effect of immunization with an ApoB-100 peptide.

Immunization of hypercholesterolemic mice with selected apoB-100 peptide antigens reduces atherosclerosis but the precise immune mediators of athero-protection remain unclear. In this study we show that immunization of apoE (-/-) mice with p210, a 20 amino acid apoB-100 related peptide, reduced aortic atherosclerosis compared with PBS or adjuvant/carrier controls. Immunization with p210 activated CD8(+) T cells, reduced dendritic cells (DC) at the site of immunization and within the plaque with an associated reduction in plaque macrophage immunoreactivity. Adoptive transfer of CD8(+) T cells from p210 immunized mice recapitulated the athero-protective effect of p210 immunization in naïve, non-immunized mice. CD8(+) T cells from p210 immunized mice developed a preferentially higher cytolytic response against p210-loaded dendritic cells in vitro. Although p210 immunization profoundly modulated DCs and cellular immune responses, it did not alter the efficacy of subsequent T cell dependent or independent immune response to other irrelevant antigens. Our data define, for the first time, a role for CD8(+) T cells in mediating the athero-protective effects of apoB-100 related peptide immunization in apoE (-/-) mice.

Immunotherapy with tolerogenic apolipoprotein B-100-loaded dendritic cells attenuates atherosclerosis in hypercholesterolemic mice.

BACKGROUND: Atherosclerosis is a chronic inflammatory disease characterized by a massive intimal accumulation of low-density lipoprotein that triggers chronic vascular inflammation with an autoimmune response to low-density lipoprotein components. METHODS AND RESULTS: To dampen the inflammatory component of atherosclerosis, we injected hypercholesterolemic huB100(tg) × Ldlr(-/-) mice (mice transgenic for human apolipoprotein B100 [ApoB100] and deficient for the low-density lipoprotein receptor) intravenously with dendritic cells (DCs) that had been pulsed with the low-density lipoprotein protein ApoB100 in combination with the immunosuppressive cytokine interleukin-10. DCs treated with ApoB100 and interleukin-10 reduced proliferation of effector T cells, inhibited production of interferon-γ, and increased de novo generation of regulatory T cells in vitro. Spleen cells from mice treated with DCs plus ApoB100 plus interleukin-10 showed diminished proliferative responses to ApoB100 and significantly dampened T-helper 1 and 2 immunity to ApoB100. Spleen CD4(+) T cells from these mice suppressed activation of ApoB100-reactive T cells in a manner characteristic of regulatory T cells, and mRNA analysis of lymphoid organs showed induction of transcripts characteristic of these cells. Treatment of huB100(tg) × Ldlr(-/-) mice with ApoB100-pulsed tolerogenic DCs led to a significant (70%) reduction of atherosclerotic lesions in the aorta, with decreased CD4(+) T-cell infiltration and signs of reduced systemic inflammation. CONCLUSIONS: Tolerogenic DCs pulsed with ApoB100 reduced the autoimmune response against low-density lipoprotein and may represent a novel possibility for treatment or prevention of atherosclerosis.