Project description:Systemic lupus erythematosus is progressive, immune complex-mediated autoimmune disease targeting numerous organs. A central feature of the disease is the development of antibodies against nuclear components, including DNA. Antibodies against double-stranded DNA are so characteristic of this disease that their detection constitutes one of the criteria for diagnosis. We examined the formation of immune complexes on the surface of autoantigen microarrays incubated in the sera of 39 inactive and 22 active lupus patients and of 31 control subjects. Three different kinds of nucleic acids, dsDNA, ssDNA and RNA were used as antigens, along with chromatin (nucleosomal extract) and several other reference molecules. The composition with respect to IgG, IgM and complement components C3 and C4 was determined. We find that while IgM and C4 are physiological components of immune complexes formed from nucleic acids, both IgG and C3 are extremely characteristic of lupus patients. Complement C4 deposition changes were not consistent: these increased on ssDNA and RNA, decreased on chromatin and did not change significantly on dsDNA. The presence of IgG and C3 in the immune complexes formed from different nucleic acids was characteristic for both active and inactive lupus patients. Receiver-operating curve statistics indicate that C3 deposition measurements can improve the efficiency of identification of inactive lupus patients. These observations reveal the complexity of immune profile changes accompanying SLE. C3, IgM, C4 and IgG binding in 92 human serum samples were examined using custom-made protein arrays
Project description:Systemic lupus erythematosus is progressive, immune complex-mediated autoimmune disease targeting numerous organs. A central feature of the disease is the development of antibodies against nuclear components, including DNA. Antibodies against double-stranded DNA are so characteristic of this disease that their detection constitutes one of the criteria for diagnosis. We examined the formation of immune complexes on the surface of autoantigen microarrays incubated in the sera of 39 inactive and 22 active lupus patients and of 31 control subjects. Three different kinds of nucleic acids, dsDNA, ssDNA and RNA were used as antigens, along with chromatin (nucleosomal extract) and several other reference molecules. The composition with respect to IgG, IgM and complement components C3 and C4 was determined. We find that while IgM and C4 are physiological components of immune complexes formed from nucleic acids, both IgG and C3 are extremely characteristic of lupus patients. Complement C4 deposition changes were not consistent: these increased on ssDNA and RNA, decreased on chromatin and did not change significantly on dsDNA. The presence of IgG and C3 in the immune complexes formed from different nucleic acids was characteristic for both active and inactive lupus patients. Receiver-operating curve statistics indicate that C3 deposition measurements can improve the efficiency of identification of inactive lupus patients. These observations reveal the complexity of immune profile changes accompanying SLE.
Project description:Systemic lupus erythematosus is a chronic autoimmune disease with multifactorial ethiopathogenesis. The complement system is involved in both the early and late stages of disease development and organ damage. To better understand autoantibody mediated complement consumption the GAPAID consortium examined ex vivo immune complex formation on autoantigen arrays. We recruited patients with SLE (n=211), with other systemic autoimmune diseases (n=65) and non-autoimmune control subjects (n=149) in two rheumatology tertiary care centers. Standard clinical and laboratory data were collected from all subjects and serum complement levels were determined in SLE patients. The genotype of SNP rs1143679 in the ITGAM gene was also determined. On-chip formation of immune complexes was examined using a functional immunoassay on autoantigen microarray. The amount of antigen-bound IgM, IgG and complement C4 and C3 was quantified on autoantigens comprising nucleic acids, proteins and lipids. Our results show that the relatively high complement consumption of nucleic acids is further increased upon binding of IgM and IgG. This is true even when serum complement levels are decreased due to complement consumption in SLE patients. A negative correlation between serum complement levels and ex vivo complement deposition on nucleic acid autoantigens is demonstrated. On the contrary, most protein and lipid autoantigens show positive correlation with C4 and C3 levels. Genetic analysis reveals that the non-synonymous variant rs1143679 in complement receptor type 3 is associated with an increased production of anti-dsDNA IgG antibodies. Notwithstanding, homozygous carriers of the previously reported susceptible allele (AA) have lower levels of dsDNA specific IgM among SLE patients. Regarding organ involvement we find that besides anti-C1q IgG, low levels of dsDNA specific IgM and low complement C4 binding to C1q are also associated with renal injury. In summary, nucleic acids maintain a skewed complement deposition balance when bound by IgG and IgM, depleting the early classical complement pathway from other physiological processes. Dysfunction of the receptor responsible for complement-mediated apoptotic debris removal promotes the development of autoantibodies targeting nucleic acids. These observations provide serological and genetic evidence for complement-mediated clearance deficiency of apoptotic debris in lupus.
Project description:Systemic lupus erythematosus is a chronic autoimmune disease with multifactorial ethiopathogenesis. The complement system is involved in both the early and late stages of disease development and organ damage. To better understand autoantibody mediated complement consumption the GAPAID consortium examined ex vivo immune complex formation on autoantigen arrays. We recruited patients with SLE (n=211), with other systemic autoimmune diseases (n=65) and non-autoimmune control subjects (n=149) in two rheumatology tertiary care centers. Standard clinical and laboratory data were collected from all subjects and serum complement levels were determined in SLE patients. The genotype of SNP rs1143679 in the ITGAM gene was also determined. On-chip formation of immune complexes was examined using a functional immunoassay on autoantigen microarray. The amount of antigen-bound IgM, IgG and complement C4 and C3 was quantified on autoantigens comprising nucleic acids, proteins and lipids. Our results show that the relatively high complement consumption of nucleic acids is further increased upon binding of IgM and IgG. This is true even when serum complement levels are decreased due to complement consumption in SLE patients. A negative correlation between serum complement levels and ex vivo complement deposition on nucleic acid autoantigens is demonstrated. On the contrary, most protein and lipid autoantigens show positive correlation with C4 and C3 levels. Genetic analysis reveals that the non-synonymous variant rs1143679 in complement receptor type 3 is associated with an increased production of anti-dsDNA IgG antibodies. Notwithstanding, homozygous carriers of the previously reported susceptible allele (AA) have lower levels of dsDNA specific IgM among SLE patients. Regarding organ involvement we find that besides anti-C1q IgG, low levels of dsDNA specific IgM and low complement C4 binding to C1q are also associated with renal injury. In summary, nucleic acids maintain a skewed complement deposition balance when bound by IgG and IgM, depleting the early classical complement pathway from other physiological processes. Dysfunction of the receptor responsible for complement-mediated apoptotic debris removal promotes the development of autoantibodies targeting nucleic acids. These observations provide serological and genetic evidence for complement-mediated clearance deficiency of apoptotic debris in lupus.
Project description:Systemic lupus erythematosus is a chronic autoimmune disease with multifactorial ethiopathogenesis. The complement system is involved in both the early and late stages of disease development and organ damage. To better understand autoantibody mediated complement consumption the GAPAID consortium examined ex vivo immune complex formation on autoantigen arrays. We recruited patients with SLE (n=211), with other systemic autoimmune diseases (n=65) and non-autoimmune control subjects (n=149) in two rheumatology tertiary care centers. Standard clinical and laboratory data were collected from all subjects and serum complement levels were determined in SLE patients. The genotype of SNP rs1143679 in the ITGAM gene was also determined. On-chip formation of immune complexes was examined using a functional immunoassay on autoantigen microarray. The amount of antigen-bound IgM, IgG and complement C4 and C3 was quantified on autoantigens comprising nucleic acids, proteins and lipids. Our results show that the relatively high complement consumption of nucleic acids is further increased upon binding of IgM and IgG. This is true even when serum complement levels are decreased due to complement consumption in SLE patients. A negative correlation between serum complement levels and ex vivo complement deposition on nucleic acid autoantigens is demonstrated. On the contrary, most protein and lipid autoantigens show positive correlation with C4 and C3 levels. Genetic analysis reveals that the non-synonymous variant rs1143679 in complement receptor type 3 is associated with an increased production of anti-dsDNA IgG antibodies. Notwithstanding, homozygous carriers of the previously reported susceptible allele (AA) have lower levels of dsDNA specific IgM among SLE patients. Regarding organ involvement we find that besides anti-C1q IgG, low levels of dsDNA specific IgM and low complement C4 binding to C1q are also associated with renal injury. In summary, nucleic acids maintain a skewed complement deposition balance when bound by IgG and IgM, depleting the early classical complement pathway from other physiological processes. Dysfunction of the receptor responsible for complement-mediated apoptotic debris removal promotes the development of autoantibodies targeting nucleic acids. These observations provide serological and genetic evidence for complement-mediated clearance deficiency of apoptotic debris in lupus.
Project description:Systemic lupus erythematosus is a chronic autoimmune disease with multifactorial ethiopathogenesis. The complement system is involved in both the early and late stages of disease development and organ damage. To better understand autoantibody mediated complement consumption the GAPAID consortium examined ex vivo immune complex formation on autoantigen arrays. We recruited patients with SLE (n=211), with other systemic autoimmune diseases (n=65) and non-autoimmune control subjects (n=149) in two rheumatology tertiary care centers. Standard clinical and laboratory data were collected from all subjects and serum complement levels were determined in SLE patients. The genotype of SNP rs1143679 in the ITGAM gene was also determined. On-chip formation of immune complexes was examined using a functional immunoassay on autoantigen microarray. The amount of antigen-bound IgM, IgG and complement C4 and C3 was quantified on autoantigens comprising nucleic acids, proteins and lipids. Our results show that the relatively high complement consumption of nucleic acids is further increased upon binding of IgM and IgG. This is true even when serum complement levels are decreased due to complement consumption in SLE patients. A negative correlation between serum complement levels and ex vivo complement deposition on nucleic acid autoantigens is demonstrated. On the contrary, most protein and lipid autoantigens show positive correlation with C4 and C3 levels. Genetic analysis reveals that the non-synonymous variant rs1143679 in complement receptor type 3 is associated with an increased production of anti-dsDNA IgG antibodies. Notwithstanding, homozygous carriers of the previously reported susceptible allele (AA) have lower levels of dsDNA specific IgM among SLE patients. Regarding organ involvement we find that besides anti-C1q IgG, low levels of dsDNA specific IgM and low complement C4 binding to C1q are also associated with renal injury. In summary, nucleic acids maintain a skewed complement deposition balance when bound by IgG and IgM, depleting the early classical complement pathway from other physiological processes. Dysfunction of the receptor responsible for complement-mediated apoptotic debris removal promotes the development of autoantibodies targeting nucleic acids. These observations provide serological and genetic evidence for complement-mediated clearance deficiency of apoptotic debris in lupus.
Project description:Humoral immune responses are traditionally characterized by determining the presence and quality of antibodies specific for certain antigens. Arraying of large numbers of antigens allows the parallel measurement of antibodies, generating patterns called antibody profiles. Functional characterization of these antibodies could help draw an even more informative map of an immune response. To generate functional antibody profiles we simultaneously tested not only IgM, IgG and IgA binding to but also complement activation by a panel of endogenous and exogenous antigens printed as microarrays, using normal and autoimmune human sera. We show that complement activation by a particular antigen in a given individual cannot be predicted by the measurement of antigen specific antibodies, in spite of a general correlation between the amount of antigen-bound antibody and the deposited C3 fragments. This is due to both differences in the isotypes that dominate in the recognition of an antigen and individual variations for a given isotype, resulting in altered complement activation potential. Thus, antigen specific C3 deposition can be used as an additional parameter in immune response monitoring. This is exemplified by comparing the coordinates of antigens, used for the diagnosis of systemic lupus erythematosus, of normal and autoimmune serum samples in a two-dimensional space derived from C3 deposition and antibody binding. Since cleavage fragments of C3 mediate important immunological processes we propose that measurement of their deposition on antigen microarrays, in addition to antibody profiling, can provide useful functional signature about the tested serum. Keywords: IgM immuneprofile, antigen array IgM, IgG, IgA and C3 binding in 30 human serum samples were examined using custom-made protein arrays
Project description:Humoral immune responses are traditionally characterized by determining the presence and quality of antibodies specific for certain antigens. Arraying of large numbers of antigens allows the parallel measurement of antibodies, generating patterns called antibody profiles. Functional characterization of these antibodies could help draw an even more informative map of an immune response. To generate functional antibody profiles we simultaneously tested not only IgM, IgG and IgA binding to but also complement activation by a panel of endogenous and exogenous antigens printed as microarrays, using normal and autoimmune human sera. We show that complement activation by a particular antigen in a given individual cannot be predicted by the measurement of antigen specific antibodies, in spite of a general correlation between the amount of antigen-bound antibody and the deposited C3 fragments. This is due to both differences in the isotypes that dominate in the recognition of an antigen and individual variations for a given isotype, resulting in altered complement activation potential. Thus, antigen specific C3 deposition can be used as an additional parameter in immune response monitoring. This is exemplified by comparing the coordinates of antigens, used for the diagnosis of systemic lupus erythematosus, of normal and autoimmune serum samples in a two-dimensional space derived from C3 deposition and antibody binding. Since cleavage fragments of C3 mediate important immunological processes we propose that measurement of their deposition on antigen microarrays, in addition to antibody profiling, can provide useful functional signature about the tested serum. Keywords: IgM immuneprofile, antigen array
Project description:Up to 75% of systematic lupus erythematosus (SLE) patients experience neuropsychiatric (NP) symptoms, called neuropsychiatric SLE (NPSLE), yet the underlying mechanisms remain elusive. Complement cascades mediate synaptic pruning by microglia during early postnatal brain development. The process in NPSLE remains unclear. Here, we show that complement-coordinated elimination of synaptic terminals participated in NPSLE in MRL/lpr mice, a lupus-prone murine model. We elucidated that lupus mice developed increased anxiety-like behaviors and persistent phagocytic microglia reactivation before overt peripheral lupus pathology. Microglial engulfment of synapses explained behavioral disorders. We further determined that neuronal Nr4a1 signaling was essential for attracting C1q synaptic deposition then apposition of phagocytic microglia, ensuing synaptic loss and neurological disease. Minocycline-deactivated microglia, antibody-blocked C1q, or neuronal Nr4a1 restore protected lupus mice from synapse loss and NP manifestations. Our findings revealed an active role of neurons in coordinating microglia-mediated synaptic loss and highlight neuronal Nr4a1 and C1q as critical components amenable to pharmacological intervention.