Intravenous immunoglobulin and atherosclerosis

Role of inflammation and immune response in atherosclerosis: Mechanisms, modulations, and therapeutic targets

Cardiovascular diseases (CVDs) have emerged as the leading cause of mortality globally, with atherosclerosis being a prominent focus of investigation among medical researchers worldwide. Atherosclerosis is characterized as a disease of the large and medium-sized arteries that is multifocal, accumulative, and immunoinflammatory in nature, resulting from the deposition of lipids. Accumulating evidence suggests that inflammatory responses and immunoregulation play a vital role in the occurrence and development of atherosclerosis. While existing treatments for atherosclerosis can assist in symptom management and slowing disease progression, a complete cure remains elusive. Consequently, there is significant interest in research and development of potential new drugs for this condition. Therefore, this review aims to consolidate the current understanding of the pathogenesis of atherosclerosis with an emphasis on inflammation, immune response and infection. Besides, it examines the effects and mechanisms of immunological modulations in atherosclerosis, and the potential therapeutic targets and drugs for intervening in the inflammatory responses and immunoregulation associated with atherosclerosis. Additionally, novel drug options for treating atherosclerosis are explored within the context of this review.

Atherosclerosis: Beyond the lipid storage hypothesis. The role of autoimmunity

Atherosclerosis has long been considered as a lipid storage disease. Recent data suggest that autoimmune mechanisms seem to be involved in the pathophysiology of atherosclerosis. The presence of activated endothelial vascular cells, neutrophils, macrophages, T and to a lesser extent B cells in atherosclerotic plaques, together with the proinflammatory cytokine burden suggest mobilization of both innate and adaptive immune pathways in atherosclerosis pathobiology. The development of antibodies to oxidized low-density lipoprotein (ox-LDL), the experimental induction of atherosclerosis either via the transfer of T cells or immunization with autoantigens such as β2 glycoprotein Ι (β2-GPI) and heat shock proteins (HSP) further support the autoimmune nature of atherosclerosis. However, classical immunosuppressive and immune-modulatory drugs, successfully used in the therapy of autoimmune rheumatic diseases have shown limited benefits so far in the treatment of atherosclerosis.

Atherosclerosis and autoimmunity: a growing relationship

Atherosclerosis is regarded as one of the leading causes of mortality and morbidity in the world. Nowadays, it seems that atherosclerosis cannot be defined merely through the Framingham traditional risk factors and that autoimmunity settings exert a remarkable role in its mechanobiology. Individuals with autoimmune disorders show enhanced occurrence of cardiovascular complications and subclinical atherosclerosis. The mechanisms underlying the atherosclerosis in disorders like rheumatoid arthritis, systemic lupus erythematosus, antiphospholipid syndrome, systemic sclerosis and Sjögren's syndrome, seem to be the classical risk factors. However, chronic inflammatory processes and abnormal immune function may also be involved in atherosclerosis development. Autoantigens, autoantibodies, infectious agents and pro-inflammatory mediators exert a role in that process. Being armed with the mechanisms underlying autoimmunity in the etiopathogenesis of atherosclerosis in rheumatic autoimmune disorders and the shared etiologic pathway may result in substantial developing therapeutics for these patients.

Relationship of serum immunoglobulin levels to blood pressure and hypertension in an adult population

Evidence suggests long-term chronic inflammation, as the pathological basis of formation and development, plays an important part in atherosclerosis. Immunoglobulins (Igs) provided key information on the humoral immune status. However, few studies have evaluated the correlation between Igs and hypertension and blood pressure (BP) in a general population. We designed a cross-sectional study to evaluate whether serum Ig levels are related to BP and the prevalence of hypertension. About 12,373 participants in Tianjin, China were recruited for this study. Hypertension was diagnosed according to the criteria of the JNC 7 and serum levels of Igs were determined by the immunonephelometric technique. Multiple logistic regression analysis and analysis of covariance were used to assess relationships between serum Ig concentrations and the prevalence of hypertension and BP. The overall prevalence of hypertension was 35.5%. The means (standard deviation) of immunoglobulins [immunoglobulin G (IgG), immunoglobulin E (IgE), immunoglobulin M (IgM), and immunoglobulin A (IgA)] were 1206.0 (249.0) mg/dL, 93.8 (235.4) IU/mL, 105.3 (56.8) mg/dL, and 236.7 (98.1) mg/dL, respectively. The multivariable-adjusted odds ratios (95% confidence interval) of hypertension for the highest immunoglobulins (IgG, IgE, IgM, and IgA) quintile, when compared to the lowest quintile were 1.10 (0.96-1.26), 1.04 (0.91-1.19), 0.83 (0.72-0.96), and 1.32 (1.15-1.51), respectively. Decreased IgM and increased IgG and IgA were related to a higher prevalence of hypertension. IgM was negatively correlated with BP, while IgG and IgA were positively correlated with BP.

[Low-grade systemic inflammation and the development of metabolic diseases: from the molecular evidence to the clinical practice]

BACKGROUND

Systemic inflammation is characterised by high circulating levels of inflammatory cytokines and increased macrophage infiltration in peripheral tissues. Most importantly, this inflammatory state does not involve damage or loss of function of the infiltrated tissue, which is a distinctive feature of the low-grade systemic inflammation. The term "meta-inflammation" has also been used to refer to the low-grade systemic inflammation due to its strong relationship with the development of cardio-metabolic diseases in obesity.

OBJECTIVE

A review is presented on the recent clinical and experimental evidence concerning the role of adipose tissue inflammation as a key mediator of low-grade systemic inflammation. Furthermore, the main molecular mechanisms involved in the inflammatory polarization of macrophages with the ability to infiltrate both the adipose tissue and the vascular endothelium via activation of toll-like receptors by metabolic damage-associated molecular patterns, such as advanced glycation-end products and oxidized lipoproteins, is discussed. Finally, a review is made of the pathogenic mechanisms through which the low-grade systemic inflammation contributes to develop insulin resistance, dyslipidaemia, atherogenesis, type 2 diabetes, and hypertension in obese individuals.

CONCLUSIONS

A better understanding of the molecular mechanisms of low-grade systemic inflammation in promoting cardio-metabolic diseases is necessary, in order to further design novel anti-inflammatory therapies that take into consideration clinical data, as well as the circulating levels of cytokines, immune cells, and metabolic damage-associated molecular patterns in each patient.

Evidence for the use of intravenous immunoglobulins--a review of the literature

Intravenous immunoglobulins (IVIg) were first introduced in the middle of the twentieth century for the treatment of primary immunodeficiencies. In 1981, Paul Imbach noticed an improvement of immune-mediated thrombocytopenia, in patients receiving IVIg for immunodeficiencies. This opened a new era for the treatment of autoimmune conditions with IVIg. Since then, IVIg has become an important treatment option in a wide spectrum of diseases, including autoimmune and acute inflammatory conditions, most of them off-label (not included in the US Food and Drug Administration recommendation). A panel of immunologists and internists with experience in IVIg therapy reviewed the medical literature for published data concerning treatment with IVIg. The quality of evidence was assessed, and a summary of the available relevant literature in each disease was given. To our knowledge, this is the first all-inclusive comprehensive review, developed to assist the clinician when considering the use of IVIg in autoimmune diseases, immune deficiencies, and other conditions.

IgG regulates the CD1 expression profile and lipid antigen-presenting function in human dendritic cells via FcgammaRIIa

Dendritic cells (DCs) process and present bacterial and endogenous lipid antigens in complex with CD1 molecules to T cells and invariant natural killer T (NKT) cells. However, different types of DCs, such as blood myeloid DCs and skin Langerhans cells, exhibit distinct patterns of CD1a, CD1b, CD1c, and CD1d expression. The regulation of such differences is incompletely understood. Here, we initially observed that monocyte-derived DCs cultured in an immunoglobulin-rich milieu expressed CD1d but not CD1a, CD1b, and CD1c, whereas DCs cultured in the presence of low levels of immunoglobulins had an opposite CD1 profile. Based on this, we tested the possibility that immunoglobulins play a central role in determining these differences. IgG depletion and intravenous immunoglobulin (IVIg) add-in experiments strongly supported a role for IgG in directing the CD1 expression profile. Blocking experiments indicated that this effect was mediated by FcgammaRIIa (CD32a), and quantitative polymerase chain reaction data demonstrated that regulation of the CD1 profile occurred at the gene expression level. Finally, the ability of DCs to activate CD1-restricted NKT cells and T cells was determined by this regulatory effect of IgG. Our data demonstrate an important role for FcgammaRIIa in regulating the CD1 antigen presentation machinery of human DCs.