Genetic susceptibility to systemic lupus erythematosus

Follow-up of clinical activity and accumulated organic damage in a cohort of patients with systemic lupus erythematosus from the Yucatán Peninsula, Mexico (1995-2016)

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune with variable severity, common in Hispanic and African-American individuals.

OBJECTIVE

To know the clinical activity and the accumulated damage, as well as the prevalence and incidence, in a dynamic cohort of patients with SLE from the Yucatan Peninsula (1995-2016).

PATIENTS AND METHODS

A cohort of 200 patients with SLE, medical service beneficiaries of the ISSSTE Regional Hospital of Mérida, Yucatán, was analysed for 22 years. Disease activity and accumulated damage were evaluated using the MEX-SLEDAI scale and the SLICC-ACR-DI, respectively, and its correlation with clinical and demographic variables.

RESULTS

185 female and 15 male patients were analysed. Average accumulated damage and activity indices during follow-up were 4.63 and 1.10, respectively. The activity index was significantly lower in females compared to males (4.36 vs 7.43), and the accumulated damage did not present a difference by sex. The manifestations associated with greater activity were the mucocutaneous and articular ones, and the organs with the greatest accumulated damage were the musculoskeletal, neurological and gonadal. A relationship between the indices was found with the evolution time, remissions/reactivations, and persistent activity. Mortality was related to persistent activity due to systemic vascular complications and kidney and liver failure. The annual incidence and prevalence of SLE calculated was 2.86% and 48.43% in Yucatán Peninsula.

CONCLUSIONS

The patients presented persistent activity, with mild to moderate reactivations, and accumulated damage more aggressive in men. The clinical activity decreases and increases the accumulated damage at a longer evolution time, with less kidney disease and greater survival, which suggests a more benign course in the population of the Yucatan Peninsula.

Delivery of AntagomiR-7 through polymer nanoparticles for assisting B Cell to alleviate systemic lupus erythematosus

An autoimmune condition known as systemic lupus erythematosus (SLE) is characterized by B cell hyperresponsiveness and persistent generation of pathogenic autoantibodies that cause damage to various organs and tissues. The treatments available today are either ineffective or have adverse effects. The dysregulation of B cell activation is crucial for the emergence of SLE. MiR-7 explicitly targeted PTEN mRNA in B cells. Treatment with antagomiR-7 reduced B cell hyperresponsiveness and prevented the onset of lupus. As a result, inhibiting miR-7 may be used therapeutically to treat SLE. We developed a SA (sialic acid)-poly (D, L-lactide-co-glycolide) (SA-PLGA) nano delivery system to deliver antagomiR-7 into splenic B cells since the stability and targeted delivery of miRNA remain significant challenges in vivo. Results show that SA-PLGA nanoparticles (SA-PLGA@antagomiR-7) loaded with antagomiR-7 display good biocompatibility and shield antagomiR-7 from degradation, extending the miRNA's duration in circulation in vivo. Additionally, in MRL/Ipr lupus mice, SA-PLGA@antagomiR-7 is successfully delivered to the splenic B cells and preferentially enriched in the diseased spleen in MRL/Ipr lupus mice. The SA-PLGA@antagomiR-7 NPs therapy effectively decreases immunological abnormalities, normalizes splenic B cell subtypes, and suppresses B cell activation. The antagomiR-7 NPs exhibit excellent therapeutic efficiency and high biosafety collectively, which may result in a more effective treatment for SLE.

Copy Number Variation and Frequency of rs179008 in TLR7 Gene Associated with Systemic Lupus Erythematosus in Two Mexican Populations

Systemic Lupus Erythematosus (SLE) is an autoimmune disease in which genetic factors play a role in the susceptibility to develop it. Genes related to the synthesis of interferons such as TLR7 and genetics factors such as single nucleotide polymorphisms (SNPs) or copies number variation (CNV) in the gene have been involved with the development of the disease. The genetic differences between the populations contribute to the complexity of LES. Mexico has a mestizo population with a genetic load of at least three origins: Amerindian, Caucasian, and African. The mestizo of Yucatán is the only group whose contribution Amerindian is mainly Mayan, geographically distant from other Mexican Amerindians. We analyzed the CNV and the frequency of SNP rs179008 of the TLR7 as genetic risk factors in developing the disease in patients from Yucatán and Central Mexico. Results show that 14% of the cases of the Yucatecan population showed significantly >2 CNV and a higher risk of developing the disease (OR: 34.364), concerning 4% of those coming from Central Mexico (OR: 10.855). T allele and the A/T and T/T risk genotypes of rs179008 were more frequent in patients of Central Mexico than in those of Yucatán (50% vs. 30%, 93% vs. 30%, 4% vs. 1%), and association with susceptibility to develop SLE was observed (OR: 1.5 vs. 0.58, 9.54 vs. 0.66, 12 vs. 0.14). Data support the genetic differences between and within Mexican mestizo populations and the role of the TLR7 in the pathogenesis of SLE.

Serological and molecular analysis of parvovirus B19 infection in Mayan women with systemic lupus erythematosus in Mexico

Background:

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that mainly affects women, characterized by the production of autoantibodies. Its causal agent is unknown, but the combination of environmental, hormonal and genetic factors may favor the development of the disease. Parvovirus B19 has been associated with the development of SLE, since it induces the production of anti-single stranded DNA antibodies. It is unknown whether PV-B19 infection is an environmental factor that trigger or reactivate SLE in the Mexican Mayan population.

Aim:

A preliminary serological and molecular study of PV-B19 infection in Mayan women with established SLE was done.

Methods:

IgG and IgM anti PV-B19 were evaluated in 66 SLE patients and 66 control subjects, all women of Mayan origin. Viral DNA and viral load were analyzed by qPCR.

Results:

Insignificant levels of IgM were observed in 14.3% (4/28) of the patients and 11.4% (4/35) of control subjects. IgG was detected in 82.1% (23/28) of the patients and 82.9% (29/35) of control subjects, but were significantly higher in patients. Viral DNA was found in 86.0% (57/66) of the patients and 81.0% (54/66) of control subjects. Viral load, quantified in 28/66 patients and 31/66 controls which were positive for IgM and IgG, was significantly higher in controls.

Conclusion:

The high prevalence of PV-B19 in Yucatan, and the presence of IgM, IgG, and viral load in Mayan women with established SLE suggest that PV-B19 infection could be an environmental factor to trigger or reactivate SLE.

Angiotensin type 1 receptor A1166C polymorphism and systemic lupus erythematosus: correlation with cellular immunity and oxidative stress markers

Angiotensin II, one of the rennin–angiotensin system components, is important in the cardiovascular hemodynamic and plays an important role in the development of cardiovascular disease in systemic lupus erythematosus (SLE) patients. The angiotensin II, through interaction with angiotensin II type 1 receptor (AGTR1), promotes proliferation, inflammation and fibrosis. The single nucleotide polymorphism of the AGTR1 (dbSNP: rs5186) gene can be associated with development and progression of SLE disease. The aims of this study were to compare the frequency of AGTR1 rs5186 in SLE patients with healthy individuals and to evaluate possible association between AGTR1 A1166C gene polymorphism and serum level of lipids, neopterin and malondialdehyde in SLE patients from a population of West Iran. One hundred SLE patients and 98 healthy subjects were studied. The AGTR1 A1166C polymorphism was detected by polymerase chain reaction– restriction fragment length polymorphism method and the serum lipid profile was obtained by enzymatic method. Neopterin and malondialdehyde were detected using high-performance liquid chromatography. We did not detect significant association between AGTR1 A1166C polymorphism and the risk of SLE. The levels of triglyceride (225 ± 118 mg/dl), neopterin (30 ± 24 nmol/l) and malondialdehyde (25 ± 9.6 nmol/l) in SLE patients were significantly higher than those in control subjects (139 ± 56 mg/dl, p = 0.03, 6.4 ± 2, p = 0.03, 9.4 ± 2.5 nmol/l, p = 0.01, respectively). Individuals with AGTR1 AC + CC genotype had higher levels of total cholesterol and malondialdehyde compared with those with AGTR1 AA genotype. SLE patients with either AGTR1 AA or AGTR1AC + CC genotype had significantly higher malondialdehyde or neopterin levels compared with the corresponding control subjects. In conclusion, although the present study did not find any association between AGTR1 A1166C polymorphism and the risk of SLE, the presence of this polymorphism was associated with higher levels of malondialdehyde and higher concentration of neopterin in patients.

Absent in Melanoma 2 proteins in SLE

Type I interferons (IFN-α/β)-inducible PYRIN and HIN domain-containing protein family includes Absent in Melanoma 2 (murine Aim2 and human AIM2), murine p202, and human PYRIN-only protein 3 (POP3). The generation of Aim2-deficient mice indicated that the Aim2 protein is essential for inflammasome activation, resulting in the secretion of interleukin-1β (IL-1β) and IL-18 and cell death by pyroptosis. Further, Aim2-deficiency also increased constitutive expression of the IFN-β and expression of the p202 protein. Notably, an increased expression of p202 protein in female mice associated with the development of systemic lupus erythematosus (SLE). SLE in patients is characterized by a constitutive increase in serum levels of IFN-α and an increase in the expression IFN-stimulated genes. Recent studies indicate that p202 and POP3 proteins inhibit activation of the Aim2/AIM2 inflammasome and promote IFN-β expression. Therefore, we discuss the role of Aim2/AIM2 proteins in the suppression of type I IFNs production and lupus susceptibility.

Gene Expression Studies in Systemic Lupus Erythematosus

In a single assay, gene microarrays generate tens of thousands of measurements for the relative levels of messenger RNA expression, and thus hold promise to uncover the regulation of transcriptional responses behind clinical phenotypes of various diseases. Systemic lupus erythematosus (SLE) offers a unique opportunity to study gene expression both systemically and organ specific, as the tissues involved and specifically peripheral blood cells are readily accessible for molecular analysis. In the current review we highlight the current knowledge related to gene microarray in SLE. We approached the following questions: 1) Can gene microarray technology be used to translate molecular profiles into meaningful and applicable clinical information? 2) Does the assessment of differential gene expression provide specific signatures that may contribute to diagnostic and prognostic markers of SLE? 3) Can clinicians be helped in monitoring disease activity by identification of drug response gene profile? 4) Does evaluation of differential gene expression provide clues to detect previously unrecognized genes associated with the disease? It is evident that though not all questions can be currently answered appropriately, gene expression studies in SLE have important implications and will not only be beneficial for SLE patients, but will also lead to a better understanding of other autoimmune inflammatory diseases, thereby leading to novel diagnostic and therapeutic strategies in autoimmunity.

Expression of TLR-7, MyD88, NF-kB, and INF-α in B Lymphocytes of Mayan Women with Systemic Lupus Erythematosus in Mexico

Background

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease involving multiple organs. It is currently accepted that several genetic, environmental, and hormonal factors are contributing to its development. Innate immunity may have a great influence in autoimmunity through Toll-like receptors. TLR-7 recognizing single-strand RNA has been involved in SLE. Its activation induces intracellular signal with attraction of MyD88 and NF-kBp65, leading to IFN-α synthesis which correlate with disease activity.

Objective

To assess the expression of TLR-7, MyD88, and NF-kBp65 in B lymphocytes of Mayan women with SLE.

Methods

One hundred patients with SLE and 100 healthy controls, all of them Mayan women, were included. TLR-7 was analyzed on B and T lymphocytes, and MyD88 and NF-kB only in B lymphocytes. Serum INF-α level was evaluated by ELISA.

Results

Significant expression (p < 0.0001) of TLR-7 in B and T lymphocytes and serum IFN-α increased (p = 0.034) was observed in patients. MyD88 and NF-kBp65 were also increased in B lymphocytes of patients. TLR-7 and NF-kBp65 expression correlated, but no correlation with INF-α and disease activity was detected.

Conclusion

Data support the role of TLR-7 and signal proteins in the pathogenesis of SLE in the Mayan population of Yucatán.

Large-scale phenotyping of noise-induced hearing loss in 100 strains of mice

A cornerstone technique in the study of hearing is the Auditory Brainstem Response (ABR), an electrophysiologic technique that can be used as a quantitative measure of hearing function. Previous studies have published databases of baseline ABR thresholds for mouse strains, providing a valuable resource for the study of baseline hearing function and genetic mapping of hearing traits in mice. In this study, we further expand upon the existing literature by characterizing the baseline ABR characteristics of 100 inbred mouse strains, 47 of which are newly characterized for hearing function. We identify several distinct patterns of baseline hearing deficits and provide potential avenues for further investigation. Additionally, we characterize the sensitivity of the same 100 strains to noise exposure using permanent thresholds shifts, identifying several distinct patterns of noise-sensitivity. The resulting data provides a new resource for studying hearing loss and noise-sensitivity in mice.

Clinical characteristics of male and female Korean patients with systemic lupus erythematosus: a comparative study

BACKGROUND/AIMS

To compare the clinical characteristics and outcomes of systemic lupus erythematosus between male and female Korean patients.

METHODS

A retrospective analysis was performed at a single tertiary hospital from August 1994 to May 2010. Male patients were matched with two to three female patients based on age and disease duration. Organ damage was assessed using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology damage index (SLICC/ACR DI).

RESULTS

Fifty-three male patients were compared with 150 female patients. Renal disorders were found more frequently in male patients at disease onset (p < 0.001); the adjusted odds ratio (OR) demonstrated a significant sex preponderance for renal manifestations (OR, 3.26; 95% confidence interval [CI], 1.62 to 6.57). Diffuse proliferative lupus nephritis and end-stage renal disease requiring dialysis during the disease course were more prevalent in male patients (p = 0.025 and p < 0.001, respectively). The risk for requiring long-term dialysis was significantly higher in male than in female patients (OR, 4.02; 95% CI, 1.07 to 15.06), as was the mean SLICC/ACR DI (1.55 ± 1.35 vs. 1.02 ± 1.57, respectively; p = 0.028).

CONCLUSIONS

Our data demonstrate that Korean patients with lupus have characteristics similar to those of cohorts reported previously. Male patients had significantly higher incidences of renal manifestations and organ damage.

Copy Number Variation of TLR-7 Gene and its Association with the Development of Systemic Lupus Erythematosus in Female Patients from Yucatan Mexico

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by the production of autoantibodies against self-antigens, which occurs most often in women between 15 and 40 years of age. The innate immunity is involved in the pathogenesis of SLE through TLR- 7. Genetic factors such as copy number variation (CNV) of target genes may contribute to disease development, but this possible risk has not yet been studied in SLE patients from Yucatan, Mexico. The CNV of TLR-7 gene was determined by quantitative polymerase chain reaction assay using TaqMan probes in 80 SLE women and 150 control subjects. The results showed that 10% of SLE patients exhibited more than two copies of TLR-7 gene, whereas no mRNA overexpression was detected. These data suggested that increased CNV of the TLR-7 gene in Yucatan SLE women can be a risk factor for this disease.

Serum DNase I activity in systemic lupus erythematosus: correlation with immunoserological markers, the disease activity and organ involvement

BACKGROUND

Decreased activity of serum desoxyribonuclease I (DNase I) in systemic lupus erythematosus (SLE) has been reported, but its role as a biomarker in SLE is still unelucidated.

METHODS

Seventy-seven SLE patients (aged 39.6 ± 13.1 years) were studied for serum DNase I activity, levels of antinuclear (ANA), anti-dsDNA [high-avidity ELISA, conventional ELISA and indirect immunofluorescence (IIF)], anti-nucleosome, anti-histone antibodies, complement components C3 and C4. SLE disease activity was evaluated by disease activity index (SLEDAI-2K). Thirty-five patients were serologically and clinically followed for 3-12 months (mean 5.6 ± 2.8). Thirty-seven healthy blood donors were the control group.

RESULTS

DNase I activity in SLE patients was lower than in healthy controls (p<0.01). DNase I activity was in positive correlation with SLEDAI-2K (p<0.01), levels of ANA, anti-dsDNA, anti-nucleosome and anti-histone antibodies (p<0.01) and in negative correlation with C3 concentration (p<0.05). The highest correlation was found between DNase I activity and anti-dsDNA concentrations determined by high-avidity ELISA (r=0.624), followed by IIF (r=0.541) and conventional ELISA (r=0.405). In the follow-up study, DNase I activity also correlated with SLEDAI-2K (p<0.01). SLE patients with low DNase I activity more frequently had SLE-specific cutaneous lesions (p<0.05).

CONCLUSIONS

Monitoring of DNase I activity simultaneously with SLEDAI-2K might be a useful tool in the follow-up of SLE. An increase of DNase I activity characterized relapse in most SLE patients, although it did not reach the levels of healthy individuals. A decrease of DNase I activity in SLE flare-ups might be a functional biomarker of a subset of patients with specific dysfunction of apoptotic chromatin degradation.

CCR5-Delta32: implications in SLE development

Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease with strong genetic and environmental components. Previous studies have shown increased levels of several chemokines in active SLE. C-C chemokine receptor type 5 (CCR5) is involved in the recruitment of inflammatory cells into tissues, and mechanisms modulating CCR5 expression and function may interfere in SLE development, influencing the clinical course of the disease. The aim of this study was to evaluate the possible association between the CCR5∆32 base-pair deletion polymorphism and SLE disease in a group of Portuguese patients. A total of 219 patients with SLE and 205 healthy individuals were studied. The frequency of CCR5/∆32 heterozygotes was lower in patients with SLE than in controls (8% vs. 15% OR = 0.5162; P = 0.0319), suggesting a protective association between CCR5∆32 allele and SLE. These results highlight the protective role of Th1 cells that express CCR5 in SLE pathogenesis.

Association of Asian ethnicity with disease activity in SLE: an observational study from the Monash Lupus Clinic

OBJECTIVE

Systemic lupus erythematosus (SLE), an autoimmune condition with diverse clinical manifestations, is reported to have different expression in populations of different ancestry. Most previous studies compared patients of different ethnic groups from geographically distinct cohorts. In our study, we aimed to characterize disease manifestations in patients of different ethnic groups from a single centre, and studied patterns of disease activity over time.

METHODS

Demographics, baseline disease characteristics and autoantibody profiles, and disease activity (SLEDAI) measured at each visit, were captured from all consenting patients prospectively followed between 2007 and 2011 in an urban teaching hospital lupus clinic. Ethnicity was self-reported.

RESULTS

Asian ethnicity was significantly associated with more clinically severe SLE. Time-adjusted mean SLEDAI (p = 0.01) and maximum SLEDAI (p = 0.0018) were significantly higher in Asian patients. Asians were more likely to have renal disease (OR 2.9, 95% CI 1.4-5.98; p = 0.004) and persistently active disease (PAD) (OR 2.14, 95% CI 1.05-4.38, p = 0.04). Asian lupus patients also had a significantly higher proportion of autoantibody positivity to anti-dsDNA, anti-RNP, anti-Sm, anti-Ro and anti-La, as well as increased likelihood of hypocomplementaemia and immunosuppressant use.

CONCLUSION

In this single-cohort study, Asian ethnicity was found to be associated with increased SLE disease activity. This suggests significant inter-ethnic genetic contributions to the regulation of autoimmune responses and disease severity in SLE.

FYB gene polymorphisms are associated with susceptibility for systemic lupus erythemathosus (SLE)

Systemic Lupus Erythematosus (SLE) is a multifactorial autoimmune disease affecting different organs or systems. Several genes have been associated with SLE susceptibility so far. A previous study has reported, in SLE patients, a differential expression of Fyn Binding Protein gene (FYB), encoding for a protein participating in the T cells signaling cascade and in the interleukin-2A expression modulation. This study investigates the association of 10 FYB SNPs with differential susceptibility to SLE in 143 SLE patients and 184 controls from Southern Brazil. Significant differences were observed when comparing allele and genotype frequencies distribution in patients and controls: the T allele for rs6863066 C>T SNP and C for rs358501 T>C SNP were significantly more frequent in SLE patients than in controls (p=0.0002 and p=0.008) and associated with an increased risk for SLE (OR=1.93 and OR=1.69). The frequencies of rs6863066 C/T and T/T and rs358501 C/C genotypes were significantly higher in patients than in controls (p=0.001, p=0.006 and p=0.008). A significant association was also found for the rs6863066-rs358501 T-T and T-C haplotypes (OR=2.06, p=0.002 and OR=2.93, p=0.001). When considering clinical and laboratorial manifestations, an association was found between rs2161612 G allele and G/G genotype and hematological alterations (p=0.008) and rs379707 A/C genotype and anti-dsDNA (p=0.01). In conclusion, our findings indicate an association between polymorphisms located in FYB gene and SLE, suggesting their possible involvement in disease susceptibility and clinical manifestations.

Somatic mutagenesis in autoimmunity

Our laboratory investigates systemic autoimmune disease in the context of mouse models of systemic lupus erythematosus (SLE). SLE is associated with high titers of serum autoantibodies of the IgG class that are predominantly directed against nuclear antigens, with pathological manifestations that are considered by many to be characteristic of an immune-complex mediated disease. In this review, we focus on the known and potential roles of somatic mutagenesis in SLE. We will argue that anti-nuclear antibodies (ANA) arise predominantly from nonautoreactive B cells that are transformed into autoreactive cells by the process of somatic hypermutation (SHM), which is normally associated with affinity maturation during the germinal center reaction. We will also discuss the role of SHM in creating antigenic peptides in the V region of the B cell receptor (BCR) and its potential to open an avenue of unregulated T cell help to autoreactive B cells. Finally, we will end this review with new experimental evidence suggesting that spontaneous somatic mutagenesis of genes that regulate B cell survival and activation is a rate-limiting causative factor in the development of ANA.

Quorum sensing contributes to activated IgM-secreting B cell homeostasis

Maintenance of plasma IgM levels is critical for immune system function and homeostasis in humans and mice. However, the mechanisms that control homeostasis of the activated IgM-secreting B cells are unknown. After adoptive transfer into immune-deficient hosts, B lymphocytes expand poorly, but fully reconstitute the pool of natural IgM-secreting cells and circulating IgM levels. By using sequential cell transfers and B cell populations from several mutant mice, we were able to identify novel mechanisms regulating the size of the IgM-secreting B cell pool. Contrary to previous mechanisms described regulating homeostasis, which involve competition for the same niche by cells having overlapping survival requirements, homeostasis of the innate IgM-secreting B cell pool is also achieved when B cell populations are able to monitor the number of activated B cells by detecting their secreted products. Notably, B cell populations are able to assess the density of activated B cells by sensing their secreted IgG. This process involves the FcγRIIB, a low-affinity IgG receptor that is expressed on B cells and acts as a negative regulator of B cell activation, and its intracellular effector the inositol phosphatase SHIP. As a result of the engagement of this inhibitory pathway, the number of activated IgM-secreting B cells is kept under control. We hypothesize that malfunction of this quorum-sensing mechanism may lead to uncontrolled B cell activation and autoimmunity.

An intronic variant associated with systemic lupus erythematosus changes the binding affinity of Yinyang1 to downregulate WDFY4

Two recent genome-wide association studies of East Asian populations revealed three genetic variants in WDFY4/LRRC18 associated with systemic lupus erythematosus (SLE). To identify the gene contributing to this disease susceptibility, we examined the mRNA expression of WDFY4 and LRRC18 in patients with SLE and healthy controls. WDFY4 was significantly downregulated in SLE patients as compared with controls. We used allelic expression and dual-luciferase assays to identify the functional variant. Transcriptional activity was lower for the rs877819A than -G allele. Electrophoretic mobility shift and supershift assays revealed that the transcription factor Yinyang1 (YY1) binds to rs877819, with lower affinity to the A allele, which explained the reduced transcriptional activity. This effect was further confirmed by YY1 small interfering RNA knockdown, overexpression and chromatin immunoprecipitation experiments. rs877819 in WDFY4 might be the functional site associated with SLE by reduced binding of YY1 and downregulating WDFY4 expression.

Interferon-inducible Ifi200-family genes as modifiers of lupus susceptibility

Both genetic and environmental factors contribute to the development and progression of systemic lupus erythematosus (SLE), a complex autoimmune disease. The disease exhibits a strong gender bias and develops predominantly in females. Additionally, most SLE patients exhibit increased serum levels of interferon-α (IFN-α) and the "IFN signature". Studies using the mouse models of lupus have identified several lupus susceptibility loci, including the New Zealand Black (NZB)-derived autoimmunity 2 (Nba2) interval on the chromosome 1. The interval, which is syntenic to the human chromosome 1q region, harbors the FcγR family, SLAM/CD2-family, and the IFN-inducible Ifi200-family genes (encoding for the p200-family proteins). Studies involving the B6.Nba2 congenic mice revealed that the development of antinuclear autoantibodies (ANAs) depends on the age, gender, and activation of type I IFN-signaling. Interestingly, recent studies involving the generation of Nba2 subcongenic mouse lines and generation of mice deficient for the Fcgr2b or Aim2 gene within the interval have provided evidence that epistatic interactions among the Nba2 genes contribute to increased lupus susceptibility. Given that the expression of some of the p200-family proteins is differentially regulated by sex hormones and these proteins differentially regulate cytosolic DNA-induced production of type I IFN and proinflammatory cytokines (IL-1β and IL-18), the major known contributors of SLE-associated inflammation, we discuss the recent advancements in our understanding of the role of p200-family proteins in lupus susceptibility modification. An improved understanding of the role of p200-family proteins in the development of autoimmunity is likely to identify new approaches to treat SLE patients.

Role of MHC-linked susceptibility genes in the pathogenesis of human and murine lupus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies against nuclear antigens and a systemic inflammation that can damage a broad spectrum of organs. SLE patients suffer from a wide variety of symptoms, which can affect virtually almost any tissue. As lupus is difficult to diagnose, the worldwide prevalence of SLE can only be roughly estimated to range from 10 and 200 cases per 100,000 individuals with dramatic differences depending on gender, ethnicity, and location. Although the treatment of this disease has been significantly ameliorated by new therapies, improved conventional drug therapy options, and a trained expert eye, the underlying pathogenesis of lupus still remain widely unknown. The complex etiology reflects the complex genetic background of the disease, which is also not well understood yet. However, in the past few years advances in lupus genetics have been made, notably with the publication of genome-wide association studies (GWAS) in humans and the identification of susceptibility genes and loci in mice. This paper reviews the role of MHC-linked susceptibility genes in the pathogenesis of systemic lupus erythematosus.

Lack of B and T lymphocyte attenuator exacerbates autoimmune disorders and induces Fas-independent liver injury in MRL-lpr/lpr mice

MRL/Mp-Fas (lpr) (MRL-lpr) mice develop a systemic autoimmune disease and are considered to be a good model for systemic lupus erythematosus in humans. We have recently shown that mice lacking B and T lymphocyte attenuator (BTLA), an inhibitory co-receptor expressed mainly on lymphocytes, on a 129SvEv background spontaneously develop lymphocytic infiltration in multiple organs and an autoimmune hepatitis (AIH)-like disease. In this study, we investigated the role of BTLA in the pathogenesis of autoimmune diseases in MRL-lpr mice. We found that BTLA-deficient (BTLA(-/-)) MRL-lpr/lpr mice developed severe lymphocytic infiltration in salivary glands, lungs, pancreas, kidneys and joints as compared with BTLA-sufficient (BTLA(+/+)) MRL-lpr/lpr mice. In addition, although AIH-like disease was not found in BTLA(+/+) MRL-lpr/lpr mice, AIH-like disease was exacerbated in BTLA(-/-) MRL-lpr/lpr mice as compared with that in BTLA(-/-) 129SvEv mice. These results suggest that BTLA plays a protective role in autoimmune diseases in MRL-lpr mice and that AIH-like disease develops in BTLA(-/-) mice even in the absence of Fas-dependent signaling.

Recent advances using FcRn overexpression in transgenic animals to overcome impediments of standard antibody technologies to improve the generation of specific antibodies

This review illustrates the salutary effects of neonatal Fc receptor (FcRn) overexpression in significantly improving humoral immune responses in the generation of antibodies for immunotherapy and diagnostics. These include: (1) improved IgG protection; (2) augmented antigen-specific humoral immune response with larger numbers of antigen specific B cells, thus offering a wider spectrum of clones; (3) generation of antibodies against weakly immunogenic antigens; (4) significant improvements in the number and substantial developments in the diversity of hybridomas. FcRn transgenesis thus confers a number of practical benefits, including faster antibody production, higher antibody yields and improved generation of hybridomas for monoclonal antibody production. Notably, these efficiencies in polyclonal antibody production were also demonstrated in FcRn transgenic rabbits. Overall, FcRn transgenic animals yield more antibodies and provide a route to the generation of antibodies against antigens of low immunogenicity that are difficult to obtain using currently available methods.

T cell-specific overexpression of interleukin-27 receptor α subunit (WSX-1) prevents spontaneous skin inflammation in MRL/lpr mice

BACKGROUND

Interleukin (IL)-27 and WSX-1, the receptor α-specific subunit, have been shown to play important roles in initiating Th1 responses and in inducing immune modulation, and the immunosuppressive effect of IL-27 appears to be exerted via suppression of IL-10 and IL-17, which may participate in the pathogenesis of human systemic lupus erythematosus (SLE).

OBJECTIVES

To examine the significance of IL-27/WSX-1 signalling in spontaneous skin inflammation of MRL/lpr mice, a model for SLE.

METHODS

The severity and development of skin lesions, dermal inflammatory cells and epidermal-dermal depositions in the skin lesions of MRL/lpr mice with CD2-promoted WSX-1 overexpression (WSX-1 Tg mice) and those with globally disrupted WSX-1 (WSX-1 KO mice) were examined and compared with those of MRL/lpr mice.

RESULTS

By 4 months of age, both WSX-1 KO mice and control MRL/lpr mice developed predominantly similar skin inflammation, while WSX-1 Tg mice hardly did so, demonstrating that intensifying IL-27/WSX-1 signalling on T cells prevents the spontaneous skin inflammation. WSX-1 KO mice showed Th2-type skin inflammation as evidenced by the Th2-prone dermal infiltrating cells and an absence of cutaneous Th1-type IgG deposition. Interestingly, there were significant IL-17+ dermal infiltrating cells in both WSX-1 KO and control MRL/lpr mice, which might potentially contribute to the formation of skin inflammation in these mice.

CONCLUSIONS

These data indicate that IL-27/WSX-1 signalling may play a protective role in the development of SLE-like skin inflammation, and modulating IL-27/WSX-1 signalling might be an interesting therapeutic strategy in the treatment of SLE.

Galectin-1-induced down-regulation of T lymphocyte activation protects (NZB x NZW) F1 mice from lupus-like disease

Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by a hyperactive immune system, including activation of autoreactive T and B cells. These studies demonstrate that administration of recombinant galectin-1, a β-galactose binding protein, to SLE-prone (NZB × NZW) F1 mice reduced lymphocyte activation, inhibited serum anti-double-stranded DNA(dsDNA) IgG antibody production, decreased the incidence of proteinuria, and increased survival rate. In addition, recombinant galectin-1'-treated mice had a higher frequency of Foxp3 expression, which suggested an increase in the percentage of peripheral regulatory T cells. Consistent with the finding that there were fewer activated T lymphocytes, ex vivo T cells from mice treated with recombinant galectin-1 exhibited less proliferation in response to TCR stimulation. Furthermore, these cells were less efficient at lipid raft clustering in response to TCR/CD28 engagement, consistent with published reports that galectin-1 can reorganize the synaptic contact to interfere with TCR signaling and activation to prevent T cell activation. Aged galectin-1-deficient mice had higher serum levels of antibodies against dsDNA, elucidating a role for endogenous galectin-1 in decreasing susceptibility to autoimmunity. Together, the findings highlight galectin-1 as a novel potential therapeutic immune modulator for treatment of lupus-like disease.

Complement-4 deficiency in a child with systemic lupus erythematosus presenting with standard treatment-resistant severe skin lesion

The complement system is of great importance in systemic lupus erythematosus. Complete genetically determined deficiencies are with few exceptions reported for the various complement proteins, and most of the deficiency states are rare. Deficiencies of the factors in the classical pathway are also associated with development SLE and SLE-like disorders. Most of the patients with lupus present skin involvement. Approximately, 75-95% of patients with cutaneous lupus erythematosus respond to antimalarial therapy and/or topical glucocorticosteroids. Immunosuppressive agents are usually considered a second-line approach in patients with resistant disease. In this study, we present the clinical features and determine the molecular basis responsible for the complete C4A and C4B deficiencies in a lupus patient presented subacute cutaneous lupus erythematosus and resistance to treatment.

Association of increased serum IL-33 levels with clinical and laboratory characteristics of systemic lupus erythematosus in Chinese population

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by abnormal production of autoantibodies and proinflammatory cytokines. Although interleukin-33 (IL-33), a novel number of the IL-1 family, has been reported to have proinflammatory effects, the association of IL-33 with SLE has remained unknown. The aim of this study was to examine whether the serum IL-33 level is associated with SLE. A total of 70 patients with SLE were recruited. Sera from these patients were obtained at their visit and were compared to sera from 40 healthy controls or 28 patients with rheumatoid arthritis (RA) for IL-33 level. Furthermore, blood samples from patients with SLE were determined for various SLE-related laboratory variables, including blood routine, complements, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) and some autoantibodies. Serum IL-33 level was significantly increased in patients with SLE, compared with healthy controls, but was lower than that with RA. In patients with SLE, most clinical and laboratory characteristics did not correlate with serum IL-33 levels, with exceptions of thrombocytopenia, erythrocytopenia, anti-SSB antibody, ESR, CRP and IgA. By Spearman's correlation coefficient, patients with SLE showed close correlation of IL-33 with ESR, CRP and IgA, and by multivariate logistic regressions, patients with SLE showed significantly independent association of IL-33 with thrombocytopenia, erythrocytopenia and anti-SSB antibody. Our results suggest that IL-33 may play a role in acute phase of SLE, but it was not associated with course of the disease. Moreover, IL-33 may exert biologic effects on erythrocytes and platelets or their precursors in SLE.

Down-regulated expression of IKZF1 mRNA in peripheral blood mononuclear cells from patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease with complex genetic inheritance. IKZF1 was established as a new susceptibility gene for SLE in a recent genome-wide association study (GWAS) in Chinese Han population. In order to examine whether expression levels of IKZF1 contribute to the pathogenesis of SLE, we estimated IKZF1 mRNA expression levels in peripheral blood mononuclear cells (PBMCs) via fluorescent quantitative reverse transcription polymerase chain reaction (RT-PCR) in 60 patients with SLE and 60 controls. We also explored whether the IKZF1 mRNA expression levels are associated with the variant of the SNP rs4917014 and the SLE Disease Activity Index (SLEDAI). The expression levels of IKZF1 mRNA in patients with SLE were significantly decreased compared with those in healthy controls (P<0.001). No significant differences were found between IKZF1 mRNA expression levels and SLEDAI scores, SNP rs4917014. Our results suggest that decreased expression of IKZF1 mRNA may be correlated with the pathogenesis of SLE.

Dendritic cells in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) persists as a chronic inflammatory autoimmune disease and is characterized by the production of autoantibodies and immune complexes that affect multiple organs. The underlying mechanism that triggers and sustains disease are complex and involve certain susceptibility genes and environmental factors. There have been several immune mediators linked to SLE including cytokines and chemokines that have been reviewed elsewhere [ 1-3 ]. A number of articles have reviewed the role of B cells and T cells in SLE [ 4-10 ]. Here, we focus on the role of dendritic cells (DC) and innate immune factors that may regulate autoreactive B cells.

Role of endogenous retroviruses in murine SLE

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by B cell hyperactivity leading to the production of various autoantibodies and subsequent development of glomerulonephritis, i.e. lupus nephritis. Among the principal targets of the autoantibodies produced in murine SLE are nucleic acid-protein complexes and the envelope glycoprotein gp70 of endogenous retroviruses. Recent studies have revealed that the innate receptor TLR7 plays a pivotal role in the development of a wide variety of autoimmune responses against DNA- and RNA-containing nuclear antigens, while TLR9 rather plays a protective role. In addition, the regulation of autoimmune responses against endogenous retroviral gp70 by TLR7 suggests the implication of endogenous retroviruses in this autoimmune response. Moreover, the demonstration that TLR7 is involved in the acute phase expression of serum gp70 uncovers an additional pathogenic role of TLR7 in murine lupus nephritis by promoting the expression of nephritogenic gp70 autoantigen. Clearly, the eventual identification of endogenous retroviruses implicated in murine SLE and of mouse genes regulating their production could provide a clue for the potential role of endogenous retroviruses in human SLE.

Toxicology of autoimmune diseases

Susceptibility to most autoimmune diseases is dependent on polygenic inheritance, environmental factors, and poorly defined stochastic events. One of the significant challenges facing autoimmune disease research is in identifying the specific events that trigger loss of tolerance and autoimmunity. Although many intrinsic factors, including age, sex, and genetics, contribute to autoimmunity, extrinsic factors such as drugs, chemicals, microbes, or other environmental factors can also act as important initiators. This review explores how certain extrinsic factors, namely, drugs and chemicals, can promote the development of autoimmunity, focusing on a few better characterized agents that, in most instances, have been shown to produce autoimmune manifestations in human populations. Mechanisms of autoimmune disease induction are discussed in terms of research obtained using specific animal models. Although a number of different pathways have been delineated for drug/chemical-induced autoimmunity, some similarities do exist, and a working model is proposed.

MicroRNA-21 and microRNA-148a contribute to DNA hypomethylation in lupus CD4+ T cells by directly and indirectly targeting DNA methyltransferase 1

Systemic lupus erythematosus is a complex autoimmune disease caused by genetic and epigenetic alterations. DNA methylation abnormalities play an important role in systemic lupus erythematosus disease processes. MicroRNAs (miRNAs) have been implicated as fine-tuning regulators controlling diverse biological processes at the level of posttranscriptional repression. Dysregulation of miRNAs has been described in various disease states, including human lupus. Whereas previous studies have shown miRNAs can regulate DNA methylation by targeting the DNA methylation machinery, the role of miRNAs in aberrant CD4+ T cell DNA hypomethylation of lupus is unclear. In this study, by using high-throughput microRNA profiling, we identified that two miRNAs (miR-21 and miR-148a) overexpressed in CD4+ T cells from both patients with lupus and lupus-prone MRL/lpr mice, which promote cell hypomethylation by repressing DNA methyltransferase 1 (DNMT1) expression. This in turn leads to the overexpression of autoimmune-associated methylation-sensitive genes, such as CD70 and LFA-1, via promoter demethylation. Further experiments revealed that miR-21 indirectly downregulated DNMT1 expression by targeting an important autoimmune gene, RASGRP1, which mediated the Ras-MAPK pathway upstream of DNMT1; miR-148a directly downregulated DNMT1 expression by targeting the protein coding region of its transcript. Additionally, inhibition of miR-21 and miR-148a expression in CD4+ T cells from patients with lupus could increase DNMT1 expression and attenuate DNA hypomethylation. Together, our data demonstrated a critical functional link between miRNAs and the aberrant DNA hypomethylation in lupus CD4+ T cells and could help to develop new therapeutic approaches.

Association of the MCP-1 −2518 A/G Polymorphism and No Association of Its Receptor CCR2 −64 V/I Polymorphism with Lupus Nephritis

Objective.

To evaluate whether the A/G polymorphism at position −2518 in the regulatory region of the monocyte chemoattractant protein-1 (MCP-1) or the V/I polymorphism at position −64 of the receptor, CCR2, are associated with lupus nephritis (LN) or any clinical characteristics of the disease or with renal survival in a patient population.

Methods.

We selected 197 patients with lupus nephritis and 220 matched healthy controls for study. MCP-1 and CCR2 genotyping was performed by polymerase chain reaction. Clinical and laboratory data were compiled from patients’ charts over followup that ranged from 6 months to 10 years.

Results.

The G/G genotype of MCP-1 was more common in LN patients (p = 0.019), while the A allele was associated with healthy controls (p = 0.007) as was the V allele of CCR2 (p = 0.046) compared to LN patients. Clinical index measures [SLE Disease Activity Index (SLEDAI)], immunological markers, renal histology, renal function at enrollment, and renal survival were not influenced by these polymorphisms. A less aggressive renal disease, measured by renal SLEDAI index, was associated with the V allele of the CCR2 gene polymorphism.

Conclusion.

These findings support that MCP-1 −2518 G/G is associated with LN but there was no association of this genotype with renal function or renal survival. When studying CCR2 −64 V/I polymorphism we showed a positive association of the V allele with healthy controls but no association of the genotype with LN patients.

Spontaneous lupus-like syndrome in HLA-DQ2 transgenic mice with a mixed genetic background

To investigate the role of HLA-DQ2 in the pathogenesis of associated immune disorders, we generated transgenic mice that expressed HLA-DQ2 in the absence of endogenous murine class II molecules (AE(0)DQ2). These AE(0)DQ2 mice with a mixed genetic background spontaneously developed skin lesions on their ears, whereas control AE(0)DQ6 genotype control mice (also with a mixed genetic background) did not. The skin lesions were characterized by deep subepidermal blistering with hydropic degeneration and lymphoid infiltration in the subepidermal area as determined by histopathology. Immunofluorescence analysis revealed thick band-like granular deposition of IgG, IgM, and a thin band of IgA deposition along the basement membrane. AE(0)DQ2 mice also developed significant and progressive hematuria and proteinuria as compared with the AE(0)DQ6 mice (p < 0.05). Histopathology showed immune complex deposits in the glomeruli of AE(0)DQ2 mice. Immunofluorescence analysis showed progressive mesangial and capillary wall deposition of IgA, IgM, IgG and C1q in the kidney. With electron microscopy, the deposits showed a 'fingerprint' substructure; and tubuloreticular structures were identified within endothelial cells. Conversely, these changes were not observed in AE(0)DQ6 mice. Serum anti-double stranded (ds)DNA IgM and IgG levels were also significantly elevated among AE(0)DQ2 mice compared with AE(0)DQ6 mice (p < 0.001). In conclusion, AE(0)DQ2 mice spontaneously develop an autoimmune lupus-like syndrome and are useful model for this disease. It remains to be determined whether genetic admixture played a role in the development of this systemic lupus erythematosus-like syndrome in HLA-DQ2 transgenic mice. Lupus (2010) 19, 815-829.

Emerging roles of TLR7 and TLR9 in murine SLE

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by B cell hyperactivity leading to the production of various autoantibodies and subsequent development of glomerulonephritis, i.e. lupus nephritis. Among the principal targets of autoantibodies produced in murine SLE are nucleic acid-protein complexes, such as chromatin and ribonucleoproteins, and the envelope glycoprotein gp70 of endogenous retroviruses. The preferential production of these autoantibodies is apparently promoted by the presence of genetic abnormalities leading to defects in the elimination of apoptotic cells and to an enhanced expression of endogenous retroviruses. Moreover, recent studies revealed that the innate receptors TLR7 and TLR9 are critically involved in the activation of dendritic cells and autoreactive B cells through the recognition of endogenous DNA- or RNA-containing antigens and subsequent development of autoimmune responses against nuclear autoantigens. Furthermore, the regulation of autoimmune responses against endogenous retroviral gp70 by TLR7 suggested the implication of endogenous retroviruses in this autoimmune response. Clearly, further elucidation of the precise molecular role of TLR7 and TLR9 in the development of autoimmune responses will help to develop novel therapeutic strategies and targets for SLE.

The MHC haplotype H2b converts two pure nonlupus mouse strains to producers of antinuclear antibodies

Studies of mouse lupus models have linked the MHC H2(b) haplotype with the earlier appearance of antinuclear autoantibodies and the worsening of nephritis. However, it is unknown whether H2(b) by itself, in the context of pure nonlupus strains, is "silent" or sufficient with regard to loss of tolerance to chromatin (nucleosomes). In this study we show that, beginning approximately 6-9 mo of age, H2(b)-congenic BALB/c (denoted BALB.B) mice, unlike BALB/c (H2(d)) and H2(k)-congenic BALB/c (denoted BALB.K) mice, develop strikingly increased serum levels of anti-chromatin Ab dominated by the IgG2a subclass, along with minor increase of Abs to DNA and moderately increased total serum IgG2a. The BALB.B mice did not have glomerulonephritis or an increased mortality rate. H2(b)-congenic C3H/He mice (designated C3.SW mice), unlike C3H/He (H2(k)) mice, showed low but measurable serum levels of chromatin-reactive IgG2a Abs and minor but significant hypergammaglobulinemia. By immunofluorescence, IgG2a of sera from both H2(b)-congenic strains stained HEp-2 cell nuclei, confirming the presence of antinuclear autoantibodies. Thus, in the context of two pure nonlupus genomes, the MHC H2(b) haplotype in homozygous form is sufficient to induce loss of tolerance to chromatin.

Molecular basis of complete complement C4 deficiency in two North-African families with systemic lupus erythematosus

Complete deficiency of complement C4 is among the strongest genetic risk factors for human systemic lupus erythematosus (SLE). C4 is a constituent of the RP-C4-CYP21-TNX (RCCX) module in the human leukocyte antigen (HLA) that exhibits inter-individual copy-number and gene-size variations. Here, we studied two North-African families with complete C4 deficiency and SLE. The first included a Moroccan male SLE patient (1P) and a sibling, who were both homozygous for HLA-A*02 B*17 DRB1*07. The second had an Algerian female SLE patient (2P) homozygous for HLA-A*01 B*17 DRB1*13. Early SLE disease onset, the presence of photosensitive rashes, anti-Ro/SSA, renal disease and high titers of antinuclear antibodies were the common features of complete C4 deficiency. Southern blot analyses showed that 1P had monomodular RCCX with a long C4A, whereas 2P had bimodular RCCX with one long C4A and one short C4B. Genomic DNA fragments for these mutant genes were amplified and sequenced. A C>T transition that created the R540X nonsense mutation in C4A was found in 1P. An identical 4-bp insertion that generated the Y1537X nonsense mutation was discovered in both C4A and C4B of 2P. The high concordance of SLE and C4 deficiency among patients with non-DR3 and non-DR2 haplotypes underscores the importance of C4 proteins in the protection against SLE.

The lupus-susceptibility gene kallikrein downmodulates antibody-mediated glomerulonephritis

Sle3 is a NZM2410/NZW-derived lupus-susceptibility interval on murine chromosome 7, which is associated with spontaneous lupus nephritis (SLN), and also anti-GBM-induced glomerulonephritis (GN). The tissue kallikrein gene cluster is located within the Sle3 interval and constitutes potential candidate genes for this locus. We have recently reported that renal kallikrein expression was upregulated by anti-GBM antibody challenge in a strain-specific manner and that it was significantly underexpressed in the anti-GBM-sensitive strains, including B6.Sle3. Further sequencing and functional studies reported earlier provided evidence that kallikreins could constitute disease genes in lupus. In this report, we have used an adenoviral vector to deliver the klk1 gene to B6.Sle3 congenics to directly test if kallikreins might have a protective effect against anti-GBM-induced nephritis. Our data show that klk1 gene delivery ameliorated anti-GBM-induced nephritis in B6.Sle3 congenics. Taken together with earlier studies, these findings indicate that kallikreins play an important protective role in autoantibody-initiated GN and could constitute potential candidate genes for anti-GBM-induced GN and SLN.

Copy number variation in the human genome and its implication in autoimmunity

The causes of autoimmune disease remain poorly defined. However, it is known that genetic factors contribute to disease susceptibility. Hitherto, studies have focused upon single nucleotide polymorphisms as both tools for mapping and as probable causal variants. Recent studies, using genome-wide analytical techniques, have revealed that, in the genome, segments of DNA ranging in size from kilobases to megabases can vary in copy number. These changes of DNA copy number represent an important element of genomic polymorphism in humans and in other species and may therefore make a substantial contribution to phenotypic variation and population differentiation. Furthermore, copy number variation (CNV) in genomic regions harbouring dosage-sensitive genes may cause or predispose to a variety of human genetic diseases. Several recent studies have reported an association between CNV and autoimmunity in humans such as systemic lupus, psoriasis, Crohn's disease, rheumatoid arthritis and type 1 diabetes. The use of novel analytical techniques facilitates the study of complex human genomic structures such as CNV, and allows new susceptibility loci for autoimmunity to be found that are not readily mappable by single nucleotide polymorphism-based association analyses alone.

Autoimmune disease during pregnancy and the microchimerism legacy of pregnancy

Pregnancy has both short-term effects and long-term consequences on the maternal immune system. For women who have an autoimmune disease and subsequently become pregnant, pregnancy can induce amelioration of the mother's disease, such as in rheumatoid arthritis, while exacerbating or having no effect on other autoimmune diseases like systemic lupus erythematosus. That pregnancy also leaves a long-term legacy has recently become apparent by the discovery that bi-directional cell trafficking results in persistence of fetal cells in the mother and of maternal cells in her offspring for decades after birth. The long-term persistence of a small number of cells (or DNA) from a genetically disparate individual is referred to as microchimerism. While microchimerism is common in healthy individuals and is likely to have health benefits, microchimerism has been implicated in some autoimmune diseases such as systemic sclerosis. In this paper, we will first discuss short-term effects of pregnancy on women with autoimmune disease. Pregnancy-associated changes will be reviewed for selected autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus and autoimmune thyroid disease. The pregnancy-induced amelioration of rheumatoid arthritis presents a window of opportunity for insights into both immunological mechanisms of fetal-maternal tolerance and pathogenic mechanisms in autoimmunity. A mechanistic hypothesis for the pregnancy-induced amelioration of rheumatoid arthritis will be described. We will then discuss the legacy of maternal-fetal cell transfer from the perspective of autoimmune diseases. Fetal and maternal microchimerism will be reviewed with a focus on systemic sclerosis (scleroderma), autoimmune thyroid disease, neonatal lupus and type I diabetes mellitus.