A simple and rapid microenzyme-linked immunosorbent assay for antibodies to poly(ADP-ribose) in systemic lupus erythematosus

Overview on poly(ADP-ribose) immuno-biomedicine and future prospects

Poly(ADP-ribose), identified in 1966 independently by three groups Strassbourg, Kyoto and Tokyo, is synthesized by poly(ADP-ribose) polymerases (PARP) from NAD(+) as a substrate in the presence of Mg(2+). The structure was unique in that it has ribose-ribose linkage. In the early-1970s, however, its function in vivo/in vitro was still controversial and the antibody against it was desired to help clear its significance. Thereupon, the author tried to produce antibody against poly(ADP-ribose) in rabbits and succeeded in it for the first time in the world. Eventually, this success has led to the following two groundbreaking papers in Nature: "Naturally-occurring antibody against poly(ADP-ribose) in patients with autoimmune disease SLE", and "Induction of anti-poly(ADP-ribose) antibody by immunization with synthetic double-stranded RNA, poly(A)·poly(U)".On the way to the publication of the first paper, a reviewer gave me a friendly comment that there is "heteroclitic" fashion as a mechanism of the production of natural antibody. This comment was really a God-send for me, and became a train of power for publication of another paper, as described above. Accordingly, I thought this, I would say, episode is worth describing herein. Because of its importance in biomedical phenomena, a certain number of articles related to "heteroclitic" have become to be introduced in this review, although they were not always directly related to immuno-biological works on poly(ADP-ribose). Also, I tried to speculate on the future prospects of poly(ADP-ribose), product of PARP, as an immuno-regulatory molecule, including either induced or naturally-occurring antibodies, in view of "heteroclitic".

Induction and natural occurrence of serum nucleosomal DNA in autoimmune MRL/lpr/lpr mice: its relation to apoptosis in the thymus

Long-term administration of low doses (5 micrograms) of recombinant nucleobindin (rNuc), which is an MRL/lpr/lpr (MRL/l) mouse-derived DNA-binding protein, induces autoimmunity in both young lupus-prone MRL/+/+ (MRL/n) and normal BALB/c mice. In relation to this autoimmunity, using agarose gel electrophoresis we found an approximately 160 bp mono-nucleosomal DNA (nsDNA) in the sera of 6-week-old normal mice 15 h after i.p. injection of 50 micrograms rNuc. Co-injection of rNuc (50 micrograms) and anti-CD3 monoclonal antibody (mAb, 50 micrograms) further accelerated the appearance of nsDNA in the serum together with DNA fragmentation (apoptosis) in the thymus, which had not been so clearly induced by either double amounts of rNuc or anti-CD3 mAb alone. Acceleration of the appearance of nsDNA in the serum by co-injection was also found in age-matched MRL/n and MRL/l mice, indicating the close association of apoptosis in the thymus with the appearance of nsDNA in the serum. Furthermore, we have detected naturally occurring tri-, di- and mono-nsDNAs from immune complexes (IC) of the sera of 20 approximately 22-week-old MRL/l mice, which indicates that apoptosis in the lymphoid tissues, including the thymus, is the source of serum nsDNA that may trigger or continue production of anti-nuclear antibodies. Evidence that clearance of nsDNA from the circulation is retarded in the presence of rNuc in BALB/c mice may give rationale to the induction of autoimmunity in normal mice by long-term administration of even low doses (5 micrograms) of rNuc after all.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of autoantibodies in normal mice by injection of nucleobindin and natural occurrence of antibodies against nucleobindin in autoimmune MRL/lpr/lpr mice

Our previous works have shown that nucleobindin (Nuc) or recombinant (r) Nuc not only augments anti-DNA antibody production in vitro but also accelerates autoimmune response in vivo in MRL/+/+ (MRL/n) mice which are the substrain of autoimmune MRL/lpr/lpr (MRL/l) mice. To investigate whether rNuc can induce autoimmune response similarly in naive mice, we carried out intraperitoneal (i.p.) injection of rNuc (5 micrograms) without adjuvant into 8-week-old female BALB/c mice and continued injection twice a week for 12 weeks. About 5 weeks after the first injection, all the mice began to show IgG hypergammaglobulinemia (HG) followed by elevation of a number of autoantibodies of the IgG class such as anti-double-stranded (ds) DNA, anti-U1 ribonuclear protein (RNP), anti-ssB(La) and anti-Fc antibodies (RF), but not by anti-Sm antibodies. However, the IgG anti-dsDNA antibody response and histopathological changes in the kidney of these BALB/c mice were not so noticeable as those in MRL/n mice induced by rNuc in our previous experiment. In contrast, the IgG anti-rNuc antibody response of normal BALB/c mice induced by rNuc was stronger than that of MRL/n mice induced by rNuc. Since the titers of each autoantibody of BALB/c mice induced by rNuc were not always associated with the level of IgG HG, and either IgG HG or IgG autoantibodies could not be induced by control administration of extracts (5 micrograms) of Escherichia coli with or without harboring plasmid alone, polyclonal B cell activation (PBA) appeared not to be the mechanism of this autoimmunity.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphadenopathy induced by the cooperation between lprcg and gld genes is of lpr but not of gld phenotype

Mice homozygous for the lpr (lymphoproliferation), lprcg or gld (generalized lymphoproliferative disease) mutation develop strikingly similar lymphadenopathy with expansion of B220+ CD4- CD8- double-negative (DN) T cells and autoimmunity. To elucidate the roles of bone marrow (BM) and lymph node (LN) in lymphoproliferation, BM and LN were transplanted simultaneously into normal or +/+ mice in various genotype combinations. In lpr/lpr or lprcg/lprcg BM recipients grafted lpr/lpr and lprcg/lprcg LN swelled but +/+ and gld/gld LN atrophied. In gld/gld BM recipients all of LN swelled regardless of genotype. Thus, lpr and lprcg are phenotypically different from gld in the interaction of BM-derived DN T cells and +/+ LN. Compared with lpr the lprcg gene differs in its ability to complement with gld in induction of lymphadenopathy. To determine whether lymphoproliferation induced by the cooperation between lprcg and gld is of lpr or gld phenotype, LN of various genotypes were implanted into double heterozygous lprcg/+, gld/+ mice. Grafted lpr/lpr and lprcg/lprcg LN swelled but +/+ and gld/gld LN atrophied, indicating that it is of lpr phenotype. Moreover, grafted lprcg/+ LN swelled but lpr/+ LN atrophied, indicating that, in the heterozygous state, lprcg is phenotypically different from lpr as it allows for LN accumulation of DN T cells induced by lprcg-gld cooperation.

Characterization of lymphoproliferation induced by interactions between lprcg and gld genes

The lprcg gene is the novel mutation at the lpr locus characterized by its complementary to the gld gene in induction of lymphoproliferation in the mouse. Because of the potential usefulness of mice with this mutation in studies on the interrelationship between lpr and gld, we were urged to characterize the lymphoproliferative disease developing in (CBA/K1Jms-lprcg/lprcg x C3H/HeJ-gld/gld) F1 hybrid (lprcg-gld) mice. Despite the milder lymphadenopathy in the lprcg-gld mice, the expanding lymph node cells showed the same surface marker pattern as that in C3H/HeJ-lpr/lpr, C3H/HeJ-gld/gld, and CBA/K1Jms-lprcg/lprcg mice, characterized by the positivity for Thy-1, B220, Ly-6, and Ly-24, and the negativity for L3T4, Lyt-2 (hence designated double-negative cells), and sIg. Furthermore, these cells proved to be of a T-cell lineage based on the rearrangement of the TCR beta-chain gene, the same as the already known double-negative cells. Noticeably, in lprcg-gld mice, serum IgG and autoantibodies of the IgG class were not elevated at an early age but were slightly elevated at an advanced age despite early elevation of the serum IgM and IgM autoantibodies. These results suggest that the lymphoproliferative mice carrying lprcg and gld genes in a heterozygous state will serve as a new tool for inquiring into the interrelationship among lpr, gld, and lprcg.

Role of bone marrow cells in autoantibody production and lymphoproliferation in the novel mutant strain of mice, CBA/KlJms-lprcg/lprcg

The novel mutant gene, lprcg, is allelic with lpr, but complements the gld gene in induction of lymphoproliferation. Mice with this autosomal recessive mutation, CBA/KlJms-lprcg/lprcg (CBA-lprcg), served in this study to analyze the abnormalities of bone marrow (BM) stem cells responsible for autoantibody production and lymphoproliferation by BM transfer experiments. Transferred CBA-lprcg BM cells might have differentiated into so-called double-negative, anomalous lymphoid cells and caused production of autoantibodies such as anti-DNA antibodies in the environment of normal CBA/KlJms-(+)/+ (CBA-(+)) mice. Macroscopic graft-vs.-host-like disease as reported in lpr----non-lpr BM transfer was not observed in these recipients. In this BM chimera, however, lymphoproliferation did not ensue and the host's lymph nodes became atrophic. The lymphoproliferation required the coexistence of lprcg BM cells and lprcg lymph nodes in CBA-(+) mice. The results indicate that the functions of the lprcg gene are expressed at both BM and lymph node levels. Thus, this mutant strain of mice should provide an excellent model for analyzing aberrant lymphocyte differentiation from the BM cells leading to autoimmunity and lymphoproliferative disorder.

A new allele of the lpr locus, lprcg, that complements the gld gene in induction of lymphadenopathy in the mouse

Several mice with generalized lymphadenopathy were found in the CBA/KlJms (CBA) colony maintained at our institute. A new mutant strain of mice that develop massive lymphoid hyperplasia at 100% incidence within 5 mo after birth was established by crossing these diseased mice. Genetic studies on lymphadenopathy were conducted in F1, F2, and backcross populations from crosses between mutant CBA (CBA-m) and various inbred strains of mice. The results supported the control of lymphadenopathy by a single autosomal recessive gene. Since C3H/He-gld/gld (C3H-gld), MRL/MpJ-lpr/lpr (MRL-lpr), and C3H/HeJ-lpr/lpr (C3H-lpr) mice develop the same type of lymphoid hyperplasia, allelism of the mutant gene with gld or lpr was tested by investigating lymphadenopathy in F1 and backcross populations from crosses between CBA-m and C3H-gld, MRL-lpr, or C3H-lpr mice. The gene was confirmed to be allelic with lpr but not with gld. Interestingly, however, the mutant gene interacted with gld to induce less severe lymphadenopathy. Thus, the mutant gene was named lprcg, an lpr gene complementing gld in induction of lymphoproliferation. The genetic conclusion was supported by the same profile of surface markers of lymphoid cells with gld/gld, lpr/lpr, lprcg/lprcg, lprcg/lpr, and +/gld +/lprcg genotypes, as well as by massive lymph node hyperplasia and high titers of autoantibodies in the first four genotypes, but slight hyperplasia and insignificant autoantibody production in the last. The discovery of lprcg provided strong genetic evidence for the parallels between anomalous phenotypes of gld and lpr, and CBA/KlJms-lprcg/lprcg mice will contribute to elucidation of the mechanism of induction of the same abnormal differentiation and functions of lymphocytes by gld and lpr.

Serological and histological characterization of the new mutant strain of lpr mice, CBA/KlJms-lprcg/lprcg

CBA/KlJms-lprcg/lprcg mice with a novel mutation producing systemic lymphoproliferation were investigated for their serological and histological characteristics. The mutant mice showed elevated levels of serum immunoglobulin, C1q-binding immune complexes and antibodies to nuclear antigens such as dsDNA and ssDNA and poly(ADP-ribose). In contrast, histopathological lesions, e.g. glomerulonephritis, vasculitis or interstitial pneumonitis, were not revealed by histological and immunofluorescent examinations, except for lymphocytic infiltration in various organs. These results suggest that this mutant mouse strain may provide a new animal model for autoimmunity. However, further investigations are required to clarify whether this strain is unique as compared with other well-known lupus-prone strains of mice with respect to serological and histological abnormalities and become to be a new model of systemic autoimmune disease.

A dot-blot method for screening polyclonal and monoclonal antisera to poly(ADP-ribose)

ADP-ribosylation reactions play a key role at several points in cellular regulation and repair of DNA damage. The use of polyclonal or monoclonal antisera to poly(ADP-ribose) as probes to localize the site(s) of action of the polymer offers a promising tool for these studies. We report here a simple, sensitive method for detection and titration of these antisera to poly(ADP-ribose) using nitrocellulose membrane (NC) as a support for a dot-blot analysis. We take advantage of the fact that a highly labeled poly(ADP-ribose) preparation can be obtained by incubation of a 0.3 M KCl extract prepared from calf thymus nuclei with 32P-NAD. Such a preparation of labeled antigen is used as a reagent to detect the positive antibody spots on the NC with negligible background. Subsequent titration of the antisera and their semi-quantitative evaluation are also feasible using the dot-blot method. The sensitivity of the assay is only limited by the specific activity that can be achieved for the labeled polymer prepared as the antigen probe. The advantage of this method is that it eliminates the need to prepare pure, highly radiolabeled polymer as well as the fact that several samples can be handled on the membrane simultaneously. We demonstrate application of this technique for screening sera from patients with systemic lupus erythematosus (SLE) for anti-poly(ADP-ribose) antibodies. Further, we also extend the use of these sera for immunoquantitation of ADP-ribosylated proteins in six human tumor cells in tissue culture.

Anticalmodulin autoantibody in liver diseases: a new antibody against a cytoskeleton-related protein

An ELISA has been developed for detection of auto-antibodies against calmodulin. There was a significantly increased frequency (63.1%) of autoantibodies against calmodulin in 103 patients with chronic liver diseases as compared to that (30%) of patients with systemic lupus erythematosus and to that (6.9%) of normal subjects (p less than 0.01). IgG autoantibodies against calmodulin were detected in the patients with acute hepatitis (37.9%), chronic liver disease (45.6%) and also in the patients with systemic lupus erythematosus (30%). IgM autoantibodies against calmodulin were frequently found in patients with liver cirrhosis (52.2%), primary biliary cirrhosis (50%) and autoimmune chronic active hepatitis (38.7%), but rarely in patients with acute hepatitis (13.8%), chronic persistent hepatitis (9.5%) and systemic lupus erythematosus (0%). IgA autoantibodies against calmodulin were frequently found in liver cirrhosis (33.3%), primary biliary cirrhosis (42.9%) and autoimmune chronic active hepatitis (53.6%), but rarely in chronic persistent hepatitis (15.8%), chronic active hepatitis (14.3%) and systemic lupus erythematosus (0%). The occurrences of autoantibodies against calmodulin correlated neither with those of antismooth muscle antibody, antinuclear antibody and antimitochondrial antibody, nor with serum IgG concentrations. Autoantibodies against calmodulin did not cross-react with troponin, myosin light chain, calf thymus DNA and actin. The titer of autoantibodies against calmodulin was decreased by absorption of serum with calmodulin and the liver plasma membrane fraction. The immunoblotting experiment revealed the binding of autoantibodies against calmodulin to calmodulin. IgG fraction from a patient with autoimmune chronic active hepatitis inhibited the activation of phosphodiesterase by calmodulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Specificity of naturally occurring antibodies to poly(ADP-ribose) in patients with systemic lupus erythematosus: determination by an enzyme linked immunosorbent assay

Serum autoantibodies to poly(ADP-ribose), single-stranded (ss) DNA and double-stranded (ds) DNA in 145 patients with systemic lupus erythematosus (SLE) were measured by an enzyme-linked immunosorbent assay (ELISA). The specificities of the antibodies for poly(ADP-ribose) or for ssDNA in 14 serum samples from different patients, who had relatively high antibody titers to either or both these antigens, were tested by competitive ELISA with poly(ADP-ribose) and ssDNA as inhibitors. The IgG class anti-poly(ADP-ribose) antibodies of 4 serum samples (cases 9, 11, 13 and 14) preferred poly(ADP-ribose) and those of 2 samples (cases 2 and 4) cross-reacted preferentially with ssDNA, while the IgG class anti-ssDNA antibodies of 2 serum samples (cases 9 and 11) significantly cross-reacted with poly(ADP-ribose). Hence, the nature of the antibodies to poly(ADP-ribose) in SLE patients seemed to be different from that of the anti-poly(ADP-ribose) antibodies in autoimmune MRL/Mp-lpr/lpr (MRL/l) mice, which seem to be subpopulations of anti-ssDNA antibodies and react equally well with poly(ADP-ribose) and ssDNA.

Binding of cis- and trans-diamminedichloroplatinum(II) to deoxyribonucleic acid exposes nucleosides as measured immunochemically with anti-nucleoside antibodies

We report the use of anti-nucleoside antibodies to probe for local denaturation of calf thymus DNA upon binding of the antitumor drug cis-diamminedichloroplatinum(II), cis-DDP, and the biologically inactive analogues trans-diamminedichloroplatinum(II), trans-DDP, and chloro(diethylenetriamine)platinum(II) chloride, [Pt(dien)Cl]Cl. These antibodies specifically recognize each of the four DNA nucleosides. They bind well to denatured DNA, but not to native DNA in which the bases are less accessible owing to Watson-Crick duplex structure. At relatively high levels of modification (D/N approximately 0.1), cis-DDP causes significant disruption of DNA base pairing as reflected by the increased binding of anti-cytidine, anti-adenosine, and anti-thymidine antibodies. At lower levels of platinum adduct formation, however, all four anti-nucleoside antibodies bind more to DNA modified with trans-DDP. This result indicates that adducts formed by trans-DDP disrupt the DNA structure to a greater extent than those formed by cis-DDP at low D/N ratios. Modification of DNA by the monofunctional complex [Pt(dien)Cl]Cl does not affect its recognition by anti-nucleoside antibodies, demonstrating that base pair disruption is a consequence of bifunctional binding. The relative anti-nucleoside antibody recognition of cis-DDP-modified DNA is anti-cytosine greater than anti-adenosine approximately anti-thymidine much greater than anti-guanosine, consistent with the major adduct being an intrastrand d(GpG) cross-link. These results reveal that base pair disruption in a naturally occurring DNA modified by either cis-DDP or trans-DDP is sufficient to be detected by protein (antibody) binding. The relevance of these findings to current ideas about the molecular mechanism of action of cis-DDP is discussed.