Common lupus anti-DNA antibody idiotypes in chronic liver diseases

Liver injury correlates with biomarkers of autoimmunity and disease activity and represents an organ system involvement in patients with systemic lupus erythematosus

Liver disease (LD), defined as ≥ 2-fold elevation of aspartate aminotransferase (AST) or alanine aminotransferase (ALT), was examined in a longitudinal study of systemic lupus erythematosus (SLE) patients. Among 435 patients, 90 (20.7%) had LD with a greater prevalence in males (15/39; 38.5%) than females (75/396; 18.9%; p = 0.01). SLE disease activity index (SLEDAI) was greater in LD patients (7.8 ± 0.7) relative to those without (5.8 ± 0.3; p = 0.0025). Anti-smooth muscle antibodies, anti-DNA antibodies, hypocomplementemia, proteinuria, leucopenia, thrombocytopenia, and anti-phospholipid syndrome were increased in LD. An absence of LD was noted in patients receiving rapamycin relative to azathioprine, cyclosporine A, or cyclophosphamide. An absence of LD was also noted in patients treated with N-acetylcysteine. LFTs were normalized and SLEDAI was diminished with increased prednisone use in 76/90 LD patients over 12.1 ± 2.6 months. Thus, LD is attributed to autoimmunity and disease activity, it responds to prednisone, and it is potentially preventable by rapamycin or N-acetylcysteine treatment.

Tracing environmental markers of autoimmunity: introducing the infectome

We recently introduced the concept of the infectome as a means of studying all infectious factors which contribute to the development of autoimmune disease. It forms the infectious part of the exposome, which collates all environmental factors contributing to the development of disease and studies the sum total of burden which leads to the loss of adaptive mechanisms in the body. These studies complement genome-wide association studies, which establish the genetic predisposition to disease. The infectome is a component which spans the whole life and may begin at the earliest stages right up to the time when the first symptoms manifest, and may thus contribute to the understanding of the pathogenesis of autoimmunity at the prodromal/asymptomatic stages. We provide practical examples and research tools as to how we can investigate disease-specific infectomes, using laboratory approaches employed from projects studying the “immunome” and “microbiome”. It is envisioned that an understanding of the infectome and the environmental factors that affect it will allow for earlier patient-specific intervention by clinicians, through the possible treatment of infectious agents as well as other compounding factors, and hence slowing or preventing disease development.

16/6-idiotype expressing antibodies induce brain inflammation and cognitive impairment in mice: the mosaic of central nervous system involvement in lupus

BACKGROUND

The 16/6-idiotype (16/6-Id) of the human anti-DNA antibody was found to induce experimental lupus in naïve mice, manifested by production of autoantibodies, leukopenia and elevated inflammatory markers, as well as kidney and brain involvement. We assessed behavior and brain pathology of naive mice injected intra-cerebra-ventricularly (ICV) with the 16/6-Id antibody.

METHODS

C3H female mice were injected ICV to the right hemisphere with the human 16/6-Id antibody or commercial human IgG antibodies (control). The mice were tested for depression by the forced swimming test (FST), locomotor and explorative activity by the staircase test, and cognitive functions were examined by the novel object recognition and Y-maze tests. Brain slices were stained for inflammatory processes.

RESULTS

16/6-Id injected mice were cognitively impaired as shown by significant differences in the preference for a new object in the novel object recognition test compared to controls (P = 0.012). Similarly, the preference for spatial novelty in the Y-maze test was significantly higher in the control group compared to the 16/6-Id-injected mice (42% vs. 9%, respectively, P = 0.065). Depression-like behavior and locomotor activity were not significantly different between the16/6-Id-injected and the control mice. Immunohistochemistry analysis revealed an increase in astrocytes and microglial activation in the hippocampus and amygdala, in the 16/6-Id injected group compared to the control.

CONCLUSIONS

Passive transfer of 16/6-Id antibodies directly into mice brain resulted in cognitive impairments and histological evidence for brain inflammation. These findings shed additional light on the diverse mosaic pathophysiology of neuropsychiatric lupus.See related Commentary article: http://www.biomedcentral.com/1741-7015/11/91.

Infectome: a platform to trace infectious triggers of autoimmunity

The "exposome" is a term recently used to describe all environmental factors, both exogenous and endogenous, which we are exposed to in a lifetime. It represents an important tool in the study of autoimmunity, complementing classical immunological research tools and cutting-edge genome wide association studies (GWAS). Recently, environmental wide association studies (EWAS) investigated the effect of environment in the development of diseases. Environmental triggers are largely subdivided into infectious and non-infectious agents. In this review, we introduce the concept of the "infectome", which is the part of the exposome referring to the collection of an individual's exposures to infectious agents. The infectome directly relates to geoepidemiological, serological and molecular evidence of the co-occurrence of several infectious agents associated with autoimmune diseases that may provide hints for the triggering factors responsible for the pathogenesis of autoimmunity. We discuss the implications that the investigation of the infectome may have for the understanding of microbial/host interactions in autoimmune diseases with long, pre-clinical phases. It may also contribute to the concept of the human body as a superorganism where the microbiome is part of the whole organism, as can be seen with mitochondria which existed as microbes prior to becoming organelles in eukaryotic cells of multicellular organisms over time. A similar argument can now be made in regard to normal intestinal flora, living in symbiosis within the host. We also provide practical examples as to how we can characterise and measure the totality of a disease-specific infectome, based on the experimental approaches employed from the "immunome" and "microbiome" projects.

Autoimmune cholangiopathy associated with systemic lupus erythematosus

We report a 39-year-old female who presented over 11 years with autoimmune cholangiopathy associated with kaleidoscopic manifestations of systemic lupus erythematosus (SLE), including, arthritis, skin changes, pleuritis, diffuse proliferative glomerulonephritis, lymphadenopathy, splenomegaly, hyperglobulinemia, and major depression. While antimitochondrial antibodies (AMA) were absent, antinuclear (ANA) and anti-DNA antibodies were detected in high titres associated with hypocomplementemia. The patient also had vitamin B12 deficiency and antiphospholipid antibodies. The patient required steroids and repeated courses of cyclophosphamide for the management of lupus nephritis, and ursodeoxycholic acid (ursolite) administration resulted in amelioration of cholestatic laboratory abnormalities. This unusual case report and review of literature illustrate that immune liver disease may be an important clinical manifestation of SLE, especially autoimmune cholangiopathy.

Antibody convergence along a common idiotypic axis in immunodeficiency virus and hepatitis C virus infections

The anti-idiotypic antibody 1F7 selectively binds antibodies against human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) gag, pol, and env proteins. We tested anti-hepatitis C virus (HCV) antibodies to investigate selection of the 1F7 idiotype on antibodies against other chronic pathogens. Twelve of 15 HCV-seropositive individuals co-infected with HIV had detectable antibodies against recombinant HCV core, 4 against HCV NS4 protein, and 3 against HCV NS3 protein. All four HCV-seropositive, non-HIV-infected individuals had antibodies against HCV core and NS4, while 3 had antibodies against NS3. The 1F7 idiotype was frequently present on antibodies against each of the HCV antigens in the HIV co-infected and non-HIV-infected groups. Antibodies against HCV, including antibodies recognizing the putative principal neutralizing determinant of HCV E2 protein, displayed skewed kappa/lambda light chain usage consistent with clonal dominance. These observations extend the association between expression of the 1F7 idiotype and abnormal B cell clonal dominance in HIV and SIV infection to HCV infection and suggest that early establishment of an oligoclonal antibody response against HCV may freeze the B cell repertoire, impair adaptation to emergent HCV variants, and favor escape from neutralizing antibodies. We also demonstrated that expression of the 1F7 idiotype extends beyond antibodies against multiple antigens of AIDS-causing retroviruses to include antibodies against multiple antigens of an unrelated chronic hepatitis virus. Thus, distinct pathogens establishing chronic infection in the face of strong humoral immune responses select antibodies along a common idiotypic axis of the immune network.

The effect of cyclosporin A on early and late stages of experimental lupus

OBJECTIVE

To investigate the effect of cyclosporin A (CSA) on the development of lupus in an experimental model.

METHODS

Lupus was induced in naive mice following injection of a human anti-double-stranded DNA (anti-dsDNA) monoclonal antibody carrying the 16/6 idiotype (Id). CSA was injected into the mice at an early stage of the disease (2 months after immunization) and at a late stage (4 months after immunization).

RESULTS

CSA was found to have a suppressive effect on autoantibody production, as well as on the appearance of other disease manifestations, in the mice with lupus. The effects of the drug were more prominent when the mice were treated at an early stage. This was reflected by a dramatic decrease, to normal levels, in autoantibodies to dsDNA, histones, cardiolipin, Sm, RNP, SS-A/Ro, SS-B/La, and anti-DNA 16/6 Id. Similar effects on the erythrocyte sedimentation rate, white blood cell count, and urinary protein levels were noted. These data were supported by electron microscopy analysis showing a lack of immunoglobulin deposition in the kidneys of mice in which treatment was started early.

CONCLUSION

This study demonstrates that, similar to findings in other autoimmune conditions (e.g., insulin-dependent diabetes mellitus), administration of CSA at an early stage in systemic lupus erythematosus may be more beneficial than if the drug is given at a later stage.

Modulation of SLE induction in naive mice by specific T cells with suppressor activity to pathogenic anti-DNA idiotype

T cells (CD8+) with specific suppressor activity against anti-dsDNA antibody (16/6 Id+) were generated in vitro. The cells were established from BALB/c-enriched T cells exposed in vitro to silica beads coated with the pathogenic anti-DNA idiotype, 16/6. The idiotype specificity of the suppressor cells was demonstrated by (a) specific induction of a decrease in proliferative response of T helper cell lines specific for the pathogenic idiotype (16/6 Id), when exposed to the idiotype, with no effect on T cell lines with other specificities, e.g., against human IgM or synthetic polypeptide. (b) Effectively suppressing in vitro antibody production of anti-16/6 antibody, employing 16/6-primed B cells and specific helper T cell line. The 16/6 Id-specific Ts cells were found to be MHC restricted. Weekly intravenous injections of 10(7) 16/6 Id-specific Ts cells given to BALB/c mice at different stages of experimental SLE disease prevented the clinical, serological, and pathological manifestations. This effect was characterized by decreased titers of autoantibodies (e.g., anti-DNA, anti-Sm antibodies) in the sera, by abolishment of the proteinuria, leukopenia, and the increased ESR, followed by decreased immunoglobulin deposition in the kidneys. Treating the mice with control IgM-specific T cells did not affect the above parameters. These studies demonstrate the ability to generate Ts cells specific for pathogenic idiotypes. The method might be employed therapeutically to modulate the course of autoimmune conditions.

Induction of systemic lupus erythematosus in naive mice with T-cell lines specific for human anti-DNA antibody SA-1 (16/6 Id+) and for mouse tuberculosis antibody TB/68 (16/6 Id+)

Previously we have shown the ability to induce experimental systemic lupus erythematosus (SLE) in naive mice with pathogenic antibodies carrying the 16/6 idiotype (Id) and with the T-cell line specific for the 16/6 Id. In the present study we established and characterized a series of T-cell clones that react against diverse autoantibodies carrying the 16/6 Id and show that they are capable of inducing a SLE-like disease in mice. The T-cell clones were generated from BALB/c mice immunized with the human mAb anti-DNA antibody (SA-1) and the mouse monoclonal anti-tuberculous Ab (TB/68), both carrying the 16/6 Id. The T-cell clones proliferated only in the presence of either human or mouse mAb carrying the 16/6 Id. All the T-cell clones were found to be of the helper type (L3T4) and were H-2 restricted in their function. The injection of the clones to BALB/c mice resulted in serological findings (e.g., anti-DNA, anti-Sm), clinical manifestations (e.g., proteinuria, low white blood cell counts, increased erythrocyte sedimentation rate), and renal insult typical of SLE disease. Our data support the role attributed to pathogenic idiotypes in SLE on the one hand and that played by cellular immunity on the other. The mechanism by which Id-specific T-helper cells may induce SLE is currently not clear. The immunogenicity of the T-cell receptor (anti-16/6) and the cells themselves acting as effector/helper cells, thus leading to damage, may play a role in initiating a chain of events that ends in the production of a panoply of autoantibodies, some of which may also have a regulatory function.

The effect of the immunomodulator agent AS101 on interleukin-2 production in systemic lupus erythematosus (SLE) induced in mice by a pathogenic anti-DNA antibody

The role of the synthetic immunomodulator AS101 on the production of interleukin-2 (IL-2) by spleen cells of mice with SLE was investigated. BALB/c female mice, in which SLE was induced by immunization with the pathogenic idiotype of anti-DNA antibody 16/6 Id were treated with AS101 for 7 weeks 2 and 4 months after induction of the disease. The ability of the splenocytes of the mice with SLE to produce IL-2 was restored after administration of AS101. This effect was particularly impressive when the 7-week AS101 treatment was initiated 4 months after immunization. Despite its beneficial effect on IL-2 production, AS101 exerted no influence on the titres of autoantibodies in the sera of the mice. It also had no effect on clinical parameters of SLE, such as the increased sedimentation rate, proteinuria and low white blood cell counts. Our data indicate that defective IL-2 production in SLE is probably secondary to other disease processes and is not necessarily associated with the production of autoantibodies in this disorder.

DNA antibody idiotypes: an analysis of their clinical connections and origins

Approximately thirty common DNA antibody idiotypes have been described on hybridoma derived or affinity purified DNA-binding antibodies. There are associations between some idiotypes and the clinical manifestations of systemic lupus erythematosus although none are sufficiently firm to be clinically useful in identifying subsets of SLE or in assessing disease activity in individual patients. The expression of these idiotypes is not confined to DNA antibodies in SLE. They may be found in the serum from patients with a range of autoimmune rheumatic disorders, infectious disease and blood dyscrasias. In most cases the antigen binding specificity of the antibody bearing the idiotype is unknown. The precise relationship between the various idiotypes is becoming better understood with increasing availability of genetic and structural data. DNA antibody idiotype manipulation may provide a potential new therapeutic modality in SLE.

The importance of the pathogenic 16/6 idiotype in the induction of SLE in naive mice

We have previously demonstrated the pathogenicity of the common anti-DNA idiotype designated 16/6 Id. Immunization of naive mice with the 16/6 Id induced SLE-like disease characterized by serological (e.g. anti-dsDNA and anti-Sm auto-antibodies), clinical (increased ESR, leucopenia and proteinuria), and pathological (16/6 Id deposition in kidneys) parameters. To elucidate further the role of the 16/6 Id in SLE induction the following studies were carried out: BALB/c mice were immunized with SA-1, a human anti-DNA monoclonal antibody carrying the 16/6 Id; TB-68, a mouse monoclonal anti-tuberculosis (TB) glycolipid, which binds dsDNA and carries the 16/6 Id; TB-72, a mouse monoclonal anti-TB glycolipid that binds DNA and does not harbour the 16/6 Id; and 4B4, a human anti-Sm antibody that carries the 16/6 Id. SLE was induced in BALB/c mice only when immunized with SA-1, TB-68, and 4B4, namely antibodies with diverse binding capacities albeit having the 16/6 Id. Our studies further support previous evidence on the pathogenic role attributed to the 16/6 Id in SLE, and suggest that SLE is most probably an idiotype-induced disease.

Autoantibodies to histones and their subfractions in chronic liver diseases

Sera of 78 patients with different chronic liver diseases were examined for the presence of anti-histone activity using an enzyme-linked immunosorbent assay. Eighteen patients had primary biliary cirrhosis (PBC), 20 had chronic active hepatitis, and 40 had cirrhosis. Anti-histone antibodies were detected in 34 patients (43.6%), distributed among all liver disease entities studied. When antibodies of specific isotypes (IgG, IgM, and IgA) were measured, even higher frequencies were noted--50% for IgG and 53.8% for IgA. Antibodies to histone subfractions H1, H2a, H2b, H3, and H4 were also observed in all liver disorders investigated (in 22-32% of patients)--H1 and H3 being the prominent fractions involved. Of the various disease entities examined PBC was the one disclosing the highest frequency of anti-histone antibodies.

Autoimmune diseases other than lupus share common anti-DNA idiotypes

We examined the sera of 170 patients with various autoimmune diseases other than systemic lupus erythematosus (SLE) for the presence of an anti-DNA antibody idiotype termed 16/6 and known to occur with high frequency in sera of patients with SLE. The idiotype was found in 6/15 sera from patients with polymyositis (49%), 3/18 with multiple sclerosis (17%), 3/18 with primary Sjögren's syndrome (18%), 9/40 with autoimmune thyroid diseases (23%), 2/35 with myasthenia gravis (6%), and 3/42 patients with rheumatoid arthritis (7%). The idiotype was not detected among 12 patients with scleroderma or 77 normal controls. The presence of the 16/6 idiotype was associated with the presence of another anti-DNA idiotype termed 134-Id. Serum samples were also tested for activity against DNA, various synthetic polynucleotides, and cardiolipin. The serum activity against these antigens was found to be polyspecific, though overlap in reaction against the various polynucleotides was not absolute. The 16/6 idiotype is thought to be coded by a germline gene. The presence of this idiotype in various autoimmune diseases points to a pathophysiologic link between the diseases.