IgG4-Related Disease Manifesting as Hypocomplementemic Tubulointerstitial Nephritis: A Rare Case Report and Literature Review.

Immunoglobulin G4-related disease (IgG4-RD) is a chronic fibrosing inflammatory systemic disorder that has been recognized relatively recently in the medical literature. Little is known about the exact disease pathogenesis and epidemiology. IgG4-RD may be asymptomatic or may have minimal symptoms or involve multiple organs with overt symptoms. The different phenotypes of IgG4-RD can lead to delayed or incorrect diagnosis. We report the case of a 66-year-old male with coal worker's pneumoconiosis who presented with progressive kidney disease and was diagnosed with tubulointerstitial nephritis due to IgG4-RD. The patient was noted to have progressive kidney disease, skin involvement, worsening interstitial lung disease, complete vision loss in the left eye, and retroperitoneal fibrosis. Serologic workup revealed elevated inflammatory markers, IgG4 and IgG1 levels, and hypocomplementemia. A tissue biopsy helped us establish a definitive diagnosis of IgG4-RD and initiate treatment with glucocorticoids to prevent further progression of kidney disease and other end-organ damage.

Gene copy-number variations (CNVs) of complement C4 and C4A deficiency in genetic risk and pathogenesis of juvenile dermatomyositis.

OBJECTIVE: Complement-mediated vasculopathy of muscle and skin are clinical features of juvenile dermatomyositis (JDM). We assess gene copy-number variations (CNVs) for complement C4 and its isotypes, C4A and C4B, in genetic risks and pathogenesis of JDM. METHODS: The study population included 105 patients with JDM and 500 healthy European Americans. Gene copy-numbers (GCNs) for total C4, C4A, C4B and HLA-DRB1 genotypes were determined by Southern blots and qPCRs. Processed activation product C4d bound to erythrocytes (E-C4d) was measured by flow cytometry. Global gene-expression microarrays were performed in 19 patients with JDM and seven controls using PAXgene-blood RNA. Differential expression levels for selected genes were validated by qPCR. RESULTS: Significantly lower GCNs and differences in distribution of GCN groups for total C4 and C4A were observed in JDM versus controls. Lower GCN of C4A in JDM remained among HLA DR3-positive subjects (p=0.015). Homozygous or heterozygous C4A-deficiency was present in 40.0% of patients with JDM compared with 18.2% of controls (OR=3.00 (1.87 to 4.79), p=8.2×10(-6)). Patients with JDM had higher levels of E-C4d than controls (p=0.004). In JDM, C4A-deficient subjects had higher levels of E-C4d (p=0.0003) and higher frequency of elevated levels of multiple serum muscle enzymes at diagnosis (p=0.0025). Microarray profiling of blood RNA revealed upregulation of type I interferon-stimulated genes and lower abundance of transcripts for T-cell and chemokine function genes in JDM, but this was less prominent among C4A-deficient or DR3-positive patients. CONCLUSIONS: Complement C4A deficiency appears to be an important factor for the genetic risk and pathogenesis of JDM, particularly in patients with a DR3-positive background.

A role of oestrogen in aggravating SLE-like syndrome in C4-deficient mice.

BACKGROUND: As one of the epigenetic factors, oestrogen is considered to be a predisposing factor that is associated with a susceptibility to autoimmune disease development in women including systemic lupus erythematosus (SLE). Here, we proposed that oestrogen is also imparted in a post-lupus symptomatic enhancement as studied in the C4-deficient (C4-/-) mice model known to develop SLE-like symptoms. METHODS: Fifty-six C4 knockout mice were ovariectomised (OVX) to eliminate the effect of endogenous feminine hormones followed by 17-ß oestradiol (E2) administration in both dose- and time-dependent manners. Histopathological features of kidneys and spleens were studied by histological and immunofluorescent staining. The relative expression levels of IgG and IgM were measured densitometrically on their immunoreactive bands and the level of IgG-anti-double stranded (ds) DNA was measured by ELISA. RESULTS: E2-treated mice displayed a gradual increase in immune complex deposition (both IgG and IgM) in glomeruli and proximal convoluted tubules. An increased reactivity of autoantibodies against dsDNA correlated with increasing doses and longer exposure to E2 treatments. In addition, enlargement of the spleen (splenomegaly) was also observed in E2-treated mice. CONCLUSIONS: Our results support the hypothesis that oestrogen aggravates severity of the SLE-like symptoms in C4-deficient mice.

Comparison of immune manifestations between refractory cytopenia of childhood and aplastic anemia in children: A single-center retrospective study.

This retrospective single-center study assessed the incidence and clinical features of immune manifestations of refractory cytopenia of childhood (RCC) and childhood aplastic anemia (AA). We evaluated 72 children with RCC and 123 with AA between February 2008 and March 2013. RCC was associated with autoimmune disease in 4 children, including 1 case each with autoimmune hemolytic anemia, rheumatoid arthritis, systemic lupus erythematosus, and anaphylactoid purpura. No children with AA were diagnosed with autoimmune diseases. Immune abnormalities were common in both RCC and AA; the most significant reductions were in the relative numbers of CD3-CD56+ subsets found in RCC. Despite the many similar immunologic abnormalities in AA and RCC, the rate of autoimmune disease was significantly lower in childhood AA than RCC (p=0.008, χ2=6.976). The relative numbers of natural killer cells were significantly lower in RCC patients than AA patients. By month 6, there was no significant difference in autoimmune manifestations between RCC and AA in relation to the response to immunosuppressive therapy (p=0.907, χ2=0.014). The large overlap of analogous immunologic abnormalities indicates that RCC and childhood AA may share the same pathogenesis.

Classical pathway deficiencies - A short analytical review.

Deficiencies in the classical pathway of complement activation have some common features but show also great differences. Deficiencies of each of the components (C1q, C1s, C1r, C4 and C2) imply increased susceptibility to bacterial infections. They are also associated with increased risk to develop systemic lupus erythematosus where deficiency of C1q is strongly associated to the disease while C4 less and C2 much less. Deficiency of C1q affects only activation of the classical pathway while deficiency of C4 and C2 also prevent activation of the lectin pathway. Bypass mechanisms may result in complement activation also in absence of C2 but not in absence of C1q or C4. The genes for C2 and C4 isotypes are closely located within the MHC class III region on chromosome 6p and the genes for the 3 C1q chains are on chromosome 1p. Deficiencies of C1q and of C4 show genetic heterogeneity while deficiency of C2 in the great majority of cases is caused by a specific deletion. The production of C4 and C2 is mainly by the hepatocytes in the liver while C1q is produced by monocytic bone marrow derived cells. This has implications for the possibility to treat the deficiency and hematopoietic stem cell transplantation has been tried in C1q deficiency.

Clinical characteristics of IgA nephropathy associated with low complement 4 levels.

OBJECTIVE: C4 deficiency is the most commonly inherited immune disorder in human. The present study investigated the characteristics of the IgAN patients with low serum C4 levels. METHODS: We performed a prospective observational study. Clinical as well as histopathologic parameters were assessed. A Kaplan-Meier survival analysis was performed concerning the primary outcome defined as the serum creatinine increased 1.5-fold from baseline. The prognostic significances of clinical and histopathologic parameters were determined using Cox proportional hazards models. RESULTS: Five-hundred twelve biopsy proven IgAN cases were available for analysis with a median follow-up of 38.4 months. Ninety-nine cases (19.34%) presented with low C4 levels (LowC4 group) and the other 413 cases did not (NlowC4 group). At the time of renal biopsy, renal injury was lighter in the LowC4 group compared with the NlowC4 group. Renal C4 deposition was significantly decreased while IgM deposition was increased in the LowC4 group. A correlation analysis shows that lower C4 levels were associated with better renal presentations at biopsy. However, the risk of developing the primary outcome was significantly greater in those with low C4 levels. Specifically, during the follow-up period, the risk of developing primary outcome was nearly ten folds higher in those with low C4, compared to those without low C4. CONCLUSION: There is a high prevalence of low C4 levels in IgAN patients. These patients with low C4 levels exhibited better renal presentations at the time of renal biopsy, whereas might be associated with a poor prognosis.

Cutaneous vasculitis and glomerulonephritis associated with C4 deficiency.

Complete deficiency of the fourth component of complement (C4) is an extremely rare condition. However, it has been reported that partial C4 deficiency can occur in normal subjects, and is associated with several immune diseases. We report a 44-year-old woman who developed slight oedema and punctate purpura on her lower legs after a common cold. She was noted to have persistent microscopic haematuria and proteinuria, and her C4 level was undetectable. On histological examination of a skin biopsy specimen, leucocytoclastic vasculitis was seen, with granular deposition of IgG, IgM, C3 and C1q on the vessel walls in the upper dermis. A renal biopsy showed mild mesangial proliferative glomerulonephritis with slight damage to the capillary loops, and granular deposits of IgM and C4 mainly in the mesangium. The patient was systemically well and needed no medication. The C4 level remained low during the observation period, but neither genotyping nor allotyping analysis identified a C4 deficiency.

Complement C4 maintains peripheral B-cell tolerance in a myeloid cell dependent manner.

The factors that allow self-reactive B cells to escape negative selection and become activated remain poorly defined. Using a BCR knock-in mouse strain, we identify a pathway by which B-cell selection to nucleolar self-antigens is complement dependent. Deficiency in complement component C4 led to a breakdown in the elimination of autoreactive B-cell clones at the transitional stage, characterized by a relative increase in their response to a range of stimuli, entrance into follicles, and a greater propensity to form self-reactive GCs. Using mixed BM chimeras, we found that the myeloid compartment was sufficient to restore negative selection in the autoreactive mice. A model is proposed in which in the absence of complement C4, inappropriate clearance of apoptotic debris promotes chronic activation of myeloid cells, allowing the maturation and activation of self-reactive B-cell clones leading to increased spontaneous formation of GCs.

Impairment of CD4+CD25+ regulatory T cells in C4-deficient mice.

OBJECTIVE: To investigate the association between deficiencies of early components in the classical complement pathway and the development of SLE. METHODS: Forty inbred C57BL/6J mice and 40 knockout C4 complement gene (C4KO) mice, which included 10 mice in each age group (2, 4, 6, and 8 months) were used. The enumeration of CD4+CD25+ Tregs frequencies in bone marrow, spleen and peripheral blood from both normal and C4KO groups were performed by flow cytometry. The expression levels of Foxp3 and TGF-beta in the same tested tissues were measured using real time PCR. The antinuclear antibodies (ANA) were semi-quantitatively measured using ELISA. RESULTS: We report decreased frequencies of CD4+CD25+ Tregs and reduced expression levels of Foxp3 and TGF-beta, which efficiently program the development and function of Tregs, in lymphoid tissues and peripheral blood of C4KO mice. In this study, C4KO mice have higher titers of ANA than those of normal mice. Higher frequencies of mice positive for ANA are also found in older mice. CONCLUSIONS: The deficiency of the C4 gene induces the decreased numbers of Tregs that further increase the production of ANA resulting in the development of an autoimmune disorder. The outcomes of our study help us to understand the association between the deficiency of C4 in the classical complement pathway and development of autoimmune disorder via the role of Tregs.

Renal AA amyloidosis in a patient with hereditary complete complement C4 deficiency.

Hereditary complete C4 deficiency has until now been reported in 30 cases only. A disturbed clearance of immune- complexes probably predisposes these individuals to systemic lupus erythematosus, other immune- complex diseases and recurrent microbial infections. We present here a 20- year- old female with hereditary complete C4 deficiency. Renal biopsy demonstrated renal AA amyloidosis. This unique case further substantiates that deficiency of classical pathway components predisposes to the development of recurrent microbial infections and that the patients may develop AA amyloidosis. Furthermore, in clinical practice, the nephrotic syndrome occurring in a patient with hereditary complete complement C4 deficiency should lead to the suspicion of renal AA amyloidosis.

Stromal cell independent B cell development in vitro: generation and recovery of autoreactive clones.

We describe and characterize a stromal cell independent culture system that efficiently supports pro-B cell to IgM+ B cell development with near normal levels of IgH and Igkappa diversity. Pro-B cells present in non-adherent bone marrow cells proliferate in the presence of IL-7 and subsequent to the removal of IL-7 and addition of BAFF, differentiate normally into IgM+ B cells. B cell development in vitro closely follows the patterns of development in vivo with culture-derived (CD) B cells demonstrating characteristic patterns of surface antigen expression and gene activation. IgM+ CD B cells respond to TLR stimulation by proliferation and differentiation into antibody-secreting cells. Self-reactive IgM+ B cell development is blocked in 3H9 IgH knockin mice; however, cultures of 3H9 IgH knockin pro-B cells yields high frequencies of "forbidden", autoreactive IgM+ B cells. Furthermore, serum IgG autoantibody exceeded that present in autoimmune, C4(-/-) animals following the reconstitution of RAG1(-/-) mice with IgM+ CD cells derived from BL/6 mice.

Case report: diffuse plane xanthoma with low C4 and systemic inflammatory symptoms.

A normolipemic patient with diffuse plane xanthomas, IgG monoclonal gammopathy of unknown significance, low levels of C4, and systemic inflammatory symptoms is presented. Delay from disease onset to diagnosis is discussed.

Complement classical pathway components are all important in clearance of apoptotic and secondary necrotic cells.

Inherited deficiencies in components of the classical complement pathway are strong disease susceptibility factors for the development of systemic lupus erythematosus (SLE) and there is a hierarchy among deficiency states, the strongest association being with C1q deficiency. We investigated the relative importance of the different complement pathways regarding clearance of apoptotic cells. Phagocytosis of labelled apoptotic Jurkat cells by monocyte-derived macrophages in the presence of sera from individuals with complement deficiencies was studied, as well as C3 deposition on apoptotic cells using flow cytometry. Sera from individuals deficient in C1q, C4, C2 or C3 all showed decreased phagocytosis. Mannose binding lectin (MBL) and the alternative pathway did not influence phagocytosis. Notably, the components of the complement classical pathway, including C1q, were equally important in clearance of apoptotic cells. This indicates that deposition of C3 fragments is of major significance; we therefore studied C3 deposition on apoptotic cells. Experiments with MBL-deficient serum depleted of C1q or factor D confirmed the predominance of the classical pathway. At low dilution, sera deficient of C1q, C4 or C2 supported C3 fragment deposition demonstrating alternative pathway activation. In conclusion, we have found that complement-mediated opsonization and phagocytosis of apoptotic cells, particularly those undergoing secondary necrosis, are dependent mainly upon an intact classical pathway. The alternative pathway is less important, but may play a role in some conditions. C1q was not more important than other classical pathway components, suggesting a role in additional pathogenetic processes in SLE other than clearance of apoptotic cells.

Targeting classical complement pathway to treat complement mediated autoimmune diseases.

Mice deficient for classical complement pathway (CCP) factor C4 are resistant to antibody and complement mediated experimental autoimmune myasthenia gravis (EAMG). Anti-C1q antibody administration before or following acetylcholine receptor immunization suppresses EAMG development by reducing lymph node cell IL-6 production and neuromuscular junction IgG, C3 and C5b-C9 deposition. This effect is achieved by treating mice with 10 microg of anti-C1q antibody, twice weekly for 4 weeks. Treatment with a higher amount of anti-C1q antibody gives rise to increased serum anti-acetylcholine receptor antibody, immune complex and C3 levels, facilitates kidney C3 and IgG deposits and thus reduces the treatment efficacy. C4 KO and anti-C1q antibody treated mice display normal immune system functions and intact antibody production capacity. Furthermore, CCP inhibition preserves alternative complement pathway activation, which is required for host defense against microorganisms. Therefore, CCP inhibition might constitute a specific treatment approach for not only myasthenia gravis but also other complement mediated autoimmune diseases.

T cells and in situ cryoglobulin deposition in the pathogenesis of lupus nephritis.

We discuss a 53-year-old woman with systemic lupus erythematosus who presented with vasculitis, hypocomplementemia and nephritis. Although her serum complement 4 (C4) levels were zero, she had four copies of C4 gene. Renal biopsy revealed membranoproliferative glomerulonephritis and the presence of cryoglobulins, detected by electron microscopy, and significant numbers of T cells in the interstitium. Cryoglobulins were considered responsible for the complete consumption of C4 in the serum the levels of which improved gradually after treatment. T cells in the kidney were found to express CD44 and phosphorylated ezrin/radixin/moiesin which explain why they homed to the kidney inappropriately. The contribution of cryoglobulins and T cells in the expression of kidney pathology is discussed.

Clinicopathologic profile of normocomplementemic and hypocomplementemic urticarial vasculitis: a study from South India.

BACKGROUND: This study aims to study the clinical and histopathological characteristics of hypocomplementemic and normocomplementemic urticarial vasculitis (HUVS and NUV) among dermatology clinic attendees in a tertiary care hospital in South India. PATIENTS AND METHODS: A prospective study was conducted in the dermatology department from February 2003 to May 2004. Seventy-five patients met the inclusion criteria for UV. Sixty-eight patients in whom complement levels were available were classified into either NUV or HUVS groups. Clinical features, laboratory parameters and histological features were compared, and the significance of differences was established using Pearson's Chi-squared test. RESULTS: There was a female preponderance among patients with HUVS. Wheals > 24 h were seen in 90% of patients, and in 54.4% of patients, the wheals were partially blanching or non-blanching. Angioedema was more prevalent in patients with NUV than HUVS (44.4% vs. 21.4%). Systemic involvement was seen in 64.3% of patients with HUVS and 44.4% of patients with NUV. Fever, ANA positivity and systemic lupus erythematosus (SLE) were significantly associated with HUVS. In most cases of UV, a provoking factor could not be identified. Neutrophilic small vessel vasculitis was seen in 42.9% of patients with HUVS and 16.6% patients with NUV. Direct immunofluorescence test showing immunoreactants at the dermo-epidermal junction were present in 60% of patients with HUVS and 33.3% patients with NUV. CONCLUSION: The clinical features of Indian patients with UV were similar to those reported from the West. Fever, ANA positivity and SLE were significantly associated with HUVS.

Kidney transplantation in patients suffering from hereditary complete complement C4 deficiency.

Hereditary complete C4 deficiency (C4def) is a very rare condition that predisposes to immune complex disease and end-stage renal failure. Whether such patients should undergo renal transplantation is debated. The clinical outcome of five transplantations in three C4def patients is described. The first patient lost one allograft after 6 years because of chronic allograft rejection. Back on dialysis, he suffered from meningitis caused by Neisseria menigitidis and Aspergillus. One year after a second transplantation under alemtuzumab induction, he developed fulminant Kaposi's sarcoma and died. His sister is now 6 years post-transplantation without complications. The third patient lost his first graft after 3 years because of chronic allograft nephropathy and recurrence of glomerulonephritis. He has now been living with a second graft for over 9 years. He suffered from pneumonia, a generalized varicella infection and Hemophilis parainfluenzae bronchitis. Patients with complete C4def are at increased risk for infection after kidney transplantation. Under certain precautions and with judicious use of immunosuppression, good long-term results are achievable.

Predicting adverse outcomes in primary Sjogren's syndrome: identification of prognostic factors.

OBJECTIVE: To identify features present at diagnosis that were prospectively associated with adverse outcomes in a large cohort of patients with primary Sjögren's syndrome (SS). METHODS: Two hundred and sixty-six patients diagnosed with primary SS in our department between 1984 and 2002 were consecutively included and followed up. Outcomes measured were vasculitis, B-cell lymphoma and death. Cox regression analysis was used to evaluate the effect of variables at diagnosis on outcomes. RESULTS: Twenty-five (9%) patients developed vasculitis. Multivariate analysis identified parotid scintigraphy grades III or IV (HR 3.55, P = 0.05) and C4 levels <0.11 g/l (HR 8.26, P < 0.001) as variables predicting the development of vasculitis. Nine (3%) patients developed B-cell lymphoma. Multivariate analysis identified C3 levels <0.82 g/l (HR 7.54, P = 0.016) as a predictive factor of lymphoma development. Twenty-five (9%) patients died during follow-up. Systemic involvement (HR 4.51, P = 0.022), vasculitis (HR 4.58, P = 0.042), C4 levels <0.11 g/l (HR 5.47, P = 0.027) and cryoglobulins (HR 4.58, P = 0.013) were independently associated with death. The presence of at least two of the above-mentioned predictive factors (parotid scintigraphy, vasculitis, hypocomplementaemia and cryoglobulinaemia) was associated with a lower survival in comparison with patients with no factor (log rank and Breslow tests <0.001). CONCLUSION: The main prognostic factors for an adverse outcome identified in our cohort of patients with primary SS were vasculitis, severe involvement in parotid scintigraphy, hypocomplementaemia and/or cryoglobulins at diagnosis. Patients with at least two of these factors need a closer follow-up.

[Hypocomplementemic urticarial vasculitis syndrome. Successful therapy with intravenous immunoglobulins]. / Hypokomplementämisches Urtikaria-Vaskulitis-Syndrom. Erfolgreiche Therapie mit intravenösen Immunglobulinen.

Autoimmune diseases can initially present as chronic urticaria. We describe the course of a patient with hypocomplementemic urticarial vasculitis syndrome (HUVS) as well as his successful treatment with high-dose intravenous immunoglobulins (IVIG). HUVS was diagnosed clinically and confirmed by histology and laboratory studies. After only one cycle with IVIG (2 g/kg) all HUVS symptoms were significantly decreased.

Cellular prion protein modulates the intracellular calcium response to hydrogen peroxide.

The physiological function of the cellular prion protein (PrP(C)) is still under intense investigation. It has been suggested that PrP(C) has a protective role in neuronal cells, particularly against environmental stress caused by reactive oxygen species (ROS). Here we analysed the acute effect of a major ROS, hydrogen peroxide (H(2)O(2)), on intracellular calcium homeostasis in cultured cerebellar granule cells and immortalized hippocampal neuronal cells. Both neuronal cell culture models showed that the rise in intracellular calcium following application of H(2)O(2) was strongly dependent on the presence of PrP(C). Moreover, the N-terminal octapeptide repeats of PrP(C) were required for this effect, because neuronal cells expressing a PrP(C) lacking the N-terminus resembled the PrP(C)-deficient phenotype. Neurones deficient of fyn kinase, or pharmacological inhibition of fyn, also abrogated the calcium response to H(2)O(2) treatment, indicating that fyn activation is a critical step within the PrP(C) signalling cascade. Finally, we identified a possible role of this PrP(C) signalling pathway in the neuroprotective response of PrP(C) to oxidative stress. In conclusion, we put forward the hypothesis that PrP(C) functions as a sensor for H(2)O(2), thereby activating a protective signalling cascade involving fyn kinase that leads to calcium release from intracellular stores.