M Tonon

Infections and autoimmunity: the multifaceted relationship

Multiple factors are thought to contribute to the development of immune response to self, including differences in genotypes, hormonal milieu, and environmental factors. This review focuses on the pivotal role of infection in the induction of autoimmune disorders. Although the development of autoimmune phenomena linked to infections is a common finding, the onset of autoimmune diseases is a rare event, arising from a combination of genetic susceptibility and environmental factors. There are several mechanisms through which pathogens can initiate or perpetuate autoimmunity. Some of them are antigen‐specific, including molecular mimicry, expression of modified, cryptic, or new antigenic determinants, and superantigens. Others are nonspecific and collectively known as “bystander activation.” They include enhanced processing and presentation of self‐antigens, immune cell activation, cytokine release, and cell apoptosis/necrosis. Infections may also trigger organ‐specific autoimmune diseases, but studies carried out until now have provided conflicting and inconclusive results regarding the role of viral and bacterial agents. Infections and autoimmune diseases have multifaceted and multidirectional relationships. It has been suggested recently that infections cannot only induce or precipitate autoimmune diseases, but they may also protect from autoimmunity or even abrogate an ongoing autoimmune process depending on the interaction between microorganisms and host. Therefore, we should look at microorganisms, not only as causes of infections but also as potential agents able to modulate the immune system. On the other hand, numerous evidences have emerged regarding the higher susceptibility of autoimmune patients to infections, possibly as a result of immunosuppressive therapy and treatment with biologic agents.

Infections as triggers and complications of systemic lupus erythematosus

A growing body of experimental and clinical evidence supports the pivotal role of infections in the induction or exacerbation of systemic lupus erythematosus (SLE). Infections can be responsible for aberrant immune response leading to a loss of tolerance towards native proteins. Molecular mimicry, especially between Sm or Ro autoantigens and EBV Nuclear Antigen-1 response, as well as the over-expression of type 1 INF genes are among the major contributors to SLE development. On the other hand infections are very common in SLE patients, where they are responsible for 30-50% of morbidity and mortality. Several factors, either genetic, including complement deficiencies or mannose-binding lectin deficiency or acquired such as severe disease manifestations or immunosuppressant use, predispose SLE patients to infections. All types of infections, including bacterial, viral and opportunistic infections, have been reported and the most frequently involved sites of infections are the same as those observed in the general population, including respiratory, skin, and urinary tract infections. Some preventive measures could be adopted in order to reduce the rate of infections in SLE patients: i.e. screening for Mycobacterium tuberculosis and for some chronic viral infections before immunosuppressive treatment; adequate prophylaxes or drug adjustments when indicated, and pneumococcal and influenza vaccinations in patients with stable disease.

Preventive strategies in systemic lupus erythematosus

Despite the improvement of systemic lupus erythematosus (SLE) survival observed in the last decades, the long-term prognosis of these patients remains poor mainly due to complications of the disease and/or of its treatment. Therefore, in order to improve SLE prognosis, we should try to avoid long-term complications by adopting, early in the disease course, some strategies directed to prevent infections, atherosclerosis and cancer. Moreover, since it has been shown that autoantibodies appear before clinical manifestations in SLE, the question of whether or not asymptomatic individuals with a reliable positive serology should be treated arises. Other than advising these individuals to avoid sun exposure, drugs implicated in drug-induced lupus and cigarette smoking, the use of vitamin D and hydroxychloroquine could be considered. Finally, early SLE diagnosis has led to a modification of disease clinical spectrum at disease onset with an increased frequency of mild disease manifestations over severe ones. Thus great effort should be made in order to identify early in the disease course risk factors for the development of severe SLE manifestations. Finally patients with mild disease carrying factors predictive of severe manifestations should be treated more aggressively than we have done up to now.

Pentraxins, Anti-pentraxin Antibodies, and Atherosclerosis

Atherosclerosis is a disease of the vascular wall, which predominantly affects large and medium-sized arteries. It represents a leading cause of morbidity and mortality in the Western world. In the last few decades, it has been clearly shown that immune system plays a relevant role in atherogenesis. The effectors of both innate and adaptive immunity, including immune cells, cell or soluble receptors, cytokines, chemokines, complement components or coagulation systems, and autoantibodies are able to modulate atherosclerosis. Among proteins belonging to innate immunity, the highly conserved pentraxin family, which encompass C-reactive protein (CRP), serum amyloid P (SAP), and the long pentraxin 3 (PTX3) seems to be directly involved in the induction and progression of atherosclerosis. By immunohistochemical staining, pentraxins were found within the atherosclerotic plaques where they could play a key role interacting with atherogenic-modified lipoproteins, favoring the formation of foam cells, and exerting a proinflammatory action. Pentraxin serum levels have been shown to be associated with clinical and subclinical atherosclerosis in general population. Antibodies against pentraxins have been demonstrated in patients with autoimmune diseases, but their role in atherogenesis is still controversial.

oxLDL/beta2GPI complex and anti-oxLDL/beta2GPI in SLE: prevalence and correlates.

High levels of oxidized low-density liprotein/beta2 glycoprotein 1 (oxLDL/β2GPI) complexes and anti-complex IgG as well as IgM have been reported in SLE. We analysed this complex and Ab against the complex in SLE patients and evaluated their relationship with clinical and serological findings, traditional risk factors for atherosclerosis, and subclinical atherosclerosis. The prevalence and the levels of the complex and of anti-complex Ab were significantly higher in systemic lupus erythematosus (SLE) patients than in normal healthy donors (NHD). The titers of oxLDL/β2GPI were significantly higher in patients with renal involvement and previous thromboembolic episodes and were correlated with the number of risk factors for atherosclerosis, whereas they were significantly lower in patients with neurological involvement. Both IgG and IgM anti-complex Ab were associated with antiphospholipid (APL). In conclusion, the oxLDL/β2GPI complex as well as Ab against the complex are prevalent in SLE where they seem to be involved in organ damage.

Oxldl/β2gpi Complex And Anti-oxldl/β2gpi In Sle: Prevalence And Correlates

High levels of oxidized low-density liprotein/beta2 glycoprotein 1 (oxLDL/β2GPI) complexes and anti-complex IgG as well as IgM have been reported in SLE. We analysed this complex and Ab against the complex in SLE patients and evaluated their relationship with clinical and serological findings, traditional risk factors for atherosclerosis, and subclinical atherosclerosis. The prevalence and the levels of the complex and of anti-complex Ab were significantly higher in systemic lupus erythematosus (SLE) patients than in normal healthy donors (NHD). The titers of oxLDL/β2GPI were significantly higher in patients with renal involvement and previous thromboembolic episodes and were correlated with the number of risk factors for atherosclerosis, whereas they were significantly lower in patients with neurological involvement. Both IgG and IgM anti-complex Ab were associated with antiphospholipid (APL). In conclusion, the oxLDL/β2GPI complex as well as Ab against the complex are prevalent in SLE where they seem to be involved in organ damage.

Oxldl/β2gpi Complex And Anti-oxldl/β2gpi In Sle: Prevalence And Correlates: Brief research report

High levels of oxidized low-density liprotein/beta2 glycoprotein 1 (oxLDL/β2GPI) complexes and anti-complex IgG as well as IgM have been reported in SLE. We analysed this complex and Ab against the complex in SLE patients and evaluated their relationship with clinical and serological findings, traditional risk factors for atherosclerosis, and subclinical atherosclerosis. The prevalence and the levels of the complex and of anti-complex Ab were significantly higher in systemic lupus erythematosus (SLE) patients than in normal healthy donors (NHD). The titers of oxLDL/β2GPI were significantly higher in patients with renal involvement and previous thromboembolic episodes and were correlated with the number of risk factors for atherosclerosis, whereas they were significantly lower in patients with neurological involvement. Both IgG and IgM anti-complex Ab were associated with antiphospholipid (APL). In conclusion, the oxLDL/β2GPI complex as well as Ab against the complex are prevalent in SLE where they seem to be involved in organ damage.