Recent advances and opportunities in research on lupus: environmental influences and mechanisms of disease

HTLV-1, Immune Response and Autoimmunity

Human T-lymphotropic virus type-1 (HTLV-1) infection is associated with adult T-cell leukemia/lymphoma (ATL). Tropical spastic paraparesis/HTLV-1-associated myelopathy (PET/HAM) is involved in the development of autoimmune diseases including Rheumatoid Arthritis (RA), Systemic Lupus Erythematosus (SLE), and Sjögren's Syndrome (SS). The development of HTLV-1-driven autoimmunity is hypothesized to rely on molecular mimicry, because virus-like particles can trigger an inflammatory response. However, HTLV-1 modifies the behavior of CD4⁺ T cells on infection and alters their cytokine production. A previous study showed that in patients infected with HTLV-1, the activity of regulatory CD4⁺ T cells and their consequent expression of inflammatory and anti-inflammatory cytokines are altered. In this review, we discuss the mechanisms underlying changes in cytokine release leading to the loss of tolerance and development of autoimmunity.

Pathogenesis and prevention of rheumatic disease: focus on preclinical RA and SLE

Established and emerging data demonstrate that a 'preclinical' period of disease precedes the onset of clinical rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), as well as other autoimmune rheumatic diseases (ARDs).This preclinical stage of development of disease is characterized by abnormalities in disease-related biomarkers before the onset of the clinically apparent signs and symptoms. Numerous genetic and environmental risk factors for ARDs have also been identified, and many of these factors are likely to act before the clinical appearance of tissue injury to initiate and/or propagate autoimmunity and autoimmune disease. Thus, biomarkers representative of these autoimmune processes could potentially be used in conjunction with other clinical parameters during the preclinical period of ARDs to predict the future development of clinically apparent disease. This Review focuses on the preclinical stages of RA and SLE, as our current understanding of these diseases can be used to present an overall model of the development of ARDs that might ultimately be used to develop screening programmes and preventive strategies. Important considerations for the future development of such approaches, in particular, the issues that require additional research and how they might be addressed, are also discussed.

In utero azathioprine exposure and increased utilization of special educational services in children born to mothers with systemic lupus erythematosus

OBJECTIVE

Azathioprine (AZA) is recognized among immunosuppressive medications as relatively safe during pregnancy for women with systemic lupus erythematosus (SLE) requiring aggressive treatment. This pilot study aimed to determine whether SLE therapy during pregnancy was associated with developmental delays in offspring.

METHODS

This cohort study included SLE patients with at least one live birth postdiagnosis. Medical histories were obtained via interviews and chart review. Multiple logistic regression was used to examine associations between SLE therapy during pregnancy and maternal report of special educational (SE) requirements (as proxy for developmental delays) among offspring. Propensity scoring (incorporating corticosteroid use, lupus flare, and lupus nephritis) was used to account for disease severity.

RESULTS

Of 60 eligible offspring from 38 mothers, 15 required SE services, the most common indication for which was speech delay. Seven (54%) of the 13 children with in utero AZA exposure utilized SE services versus 8 (17%) of 47 nonexposed children (P < 0.01). After adjustment for pregnancy duration, small for gestational age, propensity score, maternal education level, and antiphospholipid antibody syndrome, AZA was significantly associated with SE utilization occurring from age 2 years onward (odds ratio 6.6, 95% confidence interval 1.0-43.3), and bordered on significance for utilization at any age or age <2 years.

CONCLUSION

AZA exposure during SLE pregnancy was independently associated with increased SE utilization in offspring, after controlling for confounders. Further research is indicated to fully characterize developmental outcomes among offspring with in utero AZA exposure. Vigilance and early interventions for suspected developmental delays among exposed offspring may be warranted.

The role of environmental factors in the pathogenesis of non-organ-specific autoimmune diseases

The immune system must be able to discriminate between self and non-self. However, mechanisms of doing so sometimes fail, causing the activation and clonal expansion of autoreactive lymphocytes and the development of autoimmune conditions. Although some autoimmune diseases have heritable components, these components are not sufficient to develop an autoimmune condition. A variety of environmental factors have been described as possible triggers of autoimmune diseases, including drugs, infectious agents, smoking, vaccination and adjuvants. The aim of this chapter is to review the most common environmental factors associated with autoimmune diseases.

Sex-specific environmental influences on the development of autoimmune diseases

Sex differences in autoimmune diseases are evolutionarily tied to the fact that the female immune system is confronted with intense alterations during menstrual cycles, pregnancy and childbirth. These events may be associated with breaches in the mucosal epithelial layers that are shielding us from environmental factors. Associations between environmental agents and autoimmune diseases have been described extensively in prior studies. Little evidence, however, exists for sex-specific environmental effects on autoimmune diseases. In this review, we summarize studies involving this often-neglected aspect. We give examples of environmental factors that may influence the sex bias in autoimmunity. We conclude that most studies do not give insight into sex-specific environmental effects due to the influence of gender-selective social, occupational or other exposures. Prospective studies are needed in order to determine true sex-biased environmental influences. Finally, humanized murine models might aid in better understanding the mechanisms involved in sex-specific environmental effects on autoimmune diseases.

Decreased microRNA-142-3p/5p expression causes CD4+ T cell activation and B cell hyperstimulation in systemic lupus erythematosus

OBJECTIVE

To examine the role of microRNA-142-3p/5p (miR-142-3p/5p) in the development of autoimmunity in patients with systemic lupus erythematosus (SLE).

METHODS

MicroRNA-142-3p/5p expression levels were determined by real-time quantitative polymerase chain reaction, and potential target genes were verified using luciferase reporter gene assays. The effects of miR-142-3p/5p on T cell function were assessed by transfection with miR-142-3p/5p inhibitors or mimics. Histone modifications and methylation levels within a putative regulatory region of the miR-142 locus were detected by chromatin immunoprecipitation assay and bisulfite sequencing, respectively.

RESULTS

We confirmed that miR-142-3p and miR-142-5p were significantly down-regulated in SLE CD4+ T cells compared with healthy controls and observed that miR-142-3p/5p levels were inversely correlated with the putative SLE-related targets signaling lymphocytic activation molecule-associated protein (SAP), CD84, and interleukin-10 (IL-10). We demonstrated that miR-142-3p and miR-142-5p directly inhibit SAP, CD84, and IL-10 translation, and that reduced miR-142-3p/5p expression in CD4+ T cells can significantly increase protein levels of these target genes. Furthermore, inhibiting miR-142-3p/5p in healthy donor CD4+ T cells caused T cell overactivation and B cell hyperstimulation, whereas overexpression of miR-142-3p/5p in SLE CD4+ T cells had the opposite effect. We also observed that the decrease in miR-142 expression in SLE CD4+ T cells correlated with changes to histone modifications and DNA methylation levels upstream of the miR-142 precursor sequence.

CONCLUSION

The results of this study indicate that reduced expression of miR-142-3p/5p in the CD4+ T cells of patients with SLE causes T cell activity and B cell hyperstimulation.