Atypical hemolytic uremic syndrome (aHUS), a rare form of thrombotic microangiopathy, is distinguished from the typical form by the absence of a preceding verotoxin-producing Escherichia coli infection. Notably, aHUS occurs in association with genetic or acquired disorders causing dysregulation of the alternative complement pathway. Patients with aHUS may show the presence of anti-complement factor H (CFH) autoantibodies. This acquired form of aHUS (anti-CFH-aHUS) primarily affects children aged 9–13 years. We report a case of a 13-year-old Lao girl with clinical features of aHUS (most likely anti-CFH-aHUS). The initial presentation of the patient met the classical clinical triad of thrombotic microangiopathy (microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury) without preceding diarrheal illness. Low serum levels of complement 3 and normal levels of complement 4 indicated abnormal activation of the alternative complement pathway. Plasma infusion and high-dose corticosteroid therapy resulted in improvement of the renal function and hematological profile, although the patient subsequently died of infectious complications. This is the first case report that describes aHUS (possibly anti-CFH-aHUS) in Laos.
Adolescent ; Anemia, Hemolytic ; Atypical Hemolytic Uremic Syndrome ; Autoantibodies ; Child ; Complement C3 ; Complement C4 ; Complement Factor H ; Complement Pathway, Alternative ; Female ; Humans ; Immunosuppression ; Kidney ; Laos ; Plasma ; Shiga-Toxigenic Escherichia coli ; Thrombocytopenia ; Thrombotic Microangiopathies

Neisseria gonorrhoeae (NG), as a pathogen of gonorrhea, is strictly limited to growth on the human host. In case of gonococcal infection, the body may recruit such inflammatory cells as neutrophils to resist the invasion of NG or initiate its adaptive immune response by antigen presentation to eliminate the pathogen. However, a series of immune escape mechanisms of NG make it difficult to clear up the infection. In the innate immune system, NG can not only secrete thermonuclease to degrade neutrophile granulocytes, inhibit respiratory burst to resist killing by neutrophils, activate NLRP3 to prompt the pyronecrosis of inflammatory cells, but also regulate the differentiation of macrophages to reduce the inflammatory response, combine with factor H to evade complement-mediated killing. NG infection can hardly give rise to effective adaptive immune response and immune memory, but can promote TGF-β production to inhibit Th1/Th2-mediated adaptive immune response, bind to CEACAM1 on the B cell surface to promote apoptosis in B cells, and combine with CEACAM1 on the T cell surface to inhibit helper T cell proliferation, which makes it difficult for B cells to produce high-affinity specific antibodies. With the increasing drug-resistance of NG, immunological studies may play a significant role in the development of novel therapies and effective vaccines against the infection.
Adaptive Immunity ; Antibodies ; immunology ; Antigens, CD ; immunology ; Cell Adhesion Molecules ; immunology ; Complement Factor H ; immunology ; Gonorrhea ; immunology ; Humans ; Immune Evasion ; immunology ; Immunity, Innate ; immunology ; Neisseria gonorrhoeae ; immunology

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a rare disease that is often associated with genetic defects. Mutations of complement factor H (CFH) are the most common genetic defects that cause aHUS and often result in end-stage renal disease. Since CFH is mainly produced in the liver, liver transplantation (LT) has been performed in patients with defective CFH. METHODS: The clinical courses of four kidney allograft recipients who lost their native kidney functions due to aHUS associated with a CFH mutation were reviewed. RESULTS: Subject A underwent kidney transplantation (KT) twice, aHUS recurred and the allograft kidney failed within a few years. Subject B received a KT and soon experienced a recurrence of aHUS coinciding with infection. Her allograft kidney function has worsened, and she remains on plasma infusion therapy. Subject C underwent LT followed by KT. She is doing well without plasma infusion therapy after combined LT-KT for 3 years. Subject D received KT following LT and is now recurrence-free from aHUS. CONCLUSION: In patients with aHUS associated with a CFH mutation, KT without LT was complicated with a recurrence of aHUS, which might lead to allograft loss. Conversely, LT was successful in preventing the recurrence of aHUS and thus might be another option for a recurrence-free life for aHUS patients associated with CFH mutation.
Allografts ; Atypical Hemolytic Uremic Syndrome ; Complement Factor H ; Complement System Proteins ; Humans ; Kidney Failure, Chronic ; Kidney Transplantation ; Kidney ; Liver Transplantation ; Liver ; Plasma ; Rare Diseases ; Recurrence

The complement system is part of the innate immune response and as such defends against invading pathogens, removes immune complexes and damaged self-cells, aids organ regeneration, confers neuroprotection, and engages with the adaptive immune response via T and B cells. Complement activation can either benefit or harm the host organism; thus, the complement system must maintain a balance between activation on foreign or modified self surfaces and inhibition on intact host cells. Complement regulators are essential for maintaining this balance and are classified as soluble regulators, such as factor H, and membrane-bound regulators. Defective complement regulators can damage the host cell and result in the accumulation of immunological debris. Moreover, defective regulators are associated with several autoimmune diseases such as atypical hemolytic uremic syndrome, dense deposit disease, age-related macular degeneration, and systemic lupus erythematosus. Therefore, understanding the molecular mechanisms by which the complement system is regulated is important for the development of novel therapies for complement-associated diseases.
Adaptive Immunity ; Antigen-Antibody Complex ; Autoimmune Diseases ; Autoimmunity ; B-Lymphocytes ; Complement Activation ; Complement Factor H ; Complement System Proteins* ; Glomerulonephritis, Membranoproliferative ; Hemolytic-Uremic Syndrome ; Immunity, Innate ; Lupus Erythematosus, Systemic ; Macular Degeneration ; Physiology* ; Regeneration

No abstract available.
Complement Factor H*

OBJECTIVETo investigate the clinical characteristics, renal pathology, treatment and prognosis of children with atypical hemolytic uremic syndrome associated with H factor antibody.

METHODFour children less than 18 yr of age admitted from Nov. 2010 to May 2011 in Peking University First Hospital were included. They all met the criteria for atypical hemolytic uremic syndrome and with positive serum anti factor H antibody. They aged from 5 to 11 yr. Data on clinical manifestations, renal pathology, treatment and prognosis were analyzed.

RESULTAll of the 4 cases had gastrointestinal symptoms such as vomiting, abdominal pain, or abdominal distension. None of them had diarrhea. Two children had hypertension. One child had episodes of convulsion. One child had history of atypical hemolytic uremic syndrome. All of them had low serum complement C3. Three of them had low serum factor H (38.0, 88.4, 209.4 mg/L). All of them had serum antibody to factor H (1: 7 068, 1: 1 110, 1: 174, and 1: 869). Three of them received renal biopsy, all of them showed thrombotic microangiopathy. All of them were treated with steroid combined with mycophenolate mofetil. Two children received plasma exchange. They were followed up for 8 to 29 months. The renal function became normal and proteinuria relieved in all of them. The serum factor H concentration increased to 405.8, 155.8 and 438.4 mg/L, respectively. The titer of anti factor H antibody decreased to 1: 119, 1: 170, 1: 123, and 1: 674, respectively.

CONCLUSIONGastrointestinal symptom is common in children with atypical hemolytic uremic syndrome associated with H factor antibody. Hypocomplementemia was observed in all of them. Steroid combined with mycophenolate mofetil seemed to be effective for them. The monitoring of serum factor H and antibody to factor H may help diagnosis and treatment.

Atypical Hemolytic Uremic Syndrome ; Autoantibodies ; blood ; immunology ; Child ; Child, Preschool ; Complement Factor H ; immunology ; Creatinine ; blood ; Female ; Hemolytic-Uremic Syndrome ; drug therapy ; immunology ; pathology ; Humans ; Kidney ; pathology ; physiopathology ; Kidney Function Tests ; Male ; Mycophenolic Acid ; administration & dosage ; analogs & derivatives ; therapeutic use ; Plasma Exchange ; Prednisolone ; administration & dosage ; therapeutic use ; Prognosis ; Retrospective Studies

We experienced a living donor liver transplantation for a 26-month-old girl with complement factor H deficiency. Complement factor H is a plasma protein that regulates the activity of the complement pathway. Complement overactivity induced by complement factor H deficiency is associated with atypical hemolytic uremic syndrome. Liver transplantation can be the proper treatment for this condition. During the liver transplantation of these patients, prevention of the complement overactivation is necessary. Minimizing complement activation, through the use of modalities such as plasma exchange before the surgery and transfusion of fresh frozen plasma throughout the entire perioperative period, may be the key for successful liver transplantation in these patients.
Child, Preschool ; Complement Activation ; Complement Factor H* ; Complement System Proteins ; Female ; Hemolytic-Uremic Syndrome* ; Humans ; Liver Transplantation* ; Living Donors* ; Perioperative Period ; Plasma ; Plasma Exchange

OBJECTIVEA R1210C mutation of complement factor H (CFH) gene has been associated with age-related macular degeneration (AMD) in Caucasian population. This study was to verify above association in Han Chinese population.

METHODSThe mutation was detected by direct sequencing in 258 patients with wet AMD and 426 matched controls.

RESULTSThe R1210C mutation has not been identified in either sample.

CONCLUSIONThe R1210C mutation in CFH gene is not associated with AMD in Han Chinese population.

Aged ; Aged, 80 and over ; Complement Factor H ; genetics ; Female ; Humans ; Macular Degeneration ; genetics ; Male ; Middle Aged ; Mutation

Autoantibodies ; Child ; Complement Factor H ; immunology ; Female ; Hemolytic-Uremic Syndrome ; immunology ; Humans

OBJECTIVETo study the characteristics of clinicopathology and prognosis of 3 pediatric cases diagnosed as C3 glomerulopathy, and to improve the understanding of C3 glomerulopathy in children.

METHODThe medical record, plasma complement C3, Factor H (FH) and its autoantibody, and therapeutic response of the 3 cases were analyzed, and their prognosis were followed up.

RESULTOf the 3 cases, 2 were male and 1 was female, the age of onset was 9 years, 12 years, 5 years 4 months, the duration from onset to renal biopsy was 3 months, 7 months and 20 days, and the follow-up period were 2.6 years, 8 months and 1.5 years respectively.

CLINICAL MANIFESTATIONSAll the 3 cases showed microscopic hematuria, with or without gross hematuria and proteinuria. Two showed persistently decreased plasma complement C3, in the other one C3 was in normal lower limit, all presented with decreased FH concertration, in 1 case anti-FH antibody was positive. Their clinical diagnosis was post-streptococcal glomerulonephritis, nephrotic syndrome (NS) nephritis type, and mesangial proliferative glomerulonephritis respectively.

PATHOLOGICAL FINDINGSAll showed evident deposition of C3 on glomerular basement membrance (GBM) and mesangial region by immunofluorescence (IF) and electron dense deposit in GBM, mesangial region or para-mesangial region by Electron microscopic (EM) examination Treatment and prognosis: The case with NS showed no response to steroid, so steroid was gradually stopped after renal biopsy and replaced by angiotensin converting enzyme inhibitors (ACEI) and angiotensin receptor antagonist (ARB). The other two cases were treated with ACEI and renal protective treatment. Of the 3 cases, one gradually showed elevated serum creatinine (Scr) and decreased creatinine clearance rate (Ccr), the other two were normal, but slightly increased indications for early kidney injury.

CONCLUSIONC3 glomerulopathy is characterized by evident C3 deposition under IF. Its clinical and pathological manifestations vary a lot. The decreased plasma C3 and FH suggest that the abnormal regulation of complement system play an importment role in its pathogenesis.

Angiotensin Receptor Antagonists ; therapeutic use ; Angiotensin-Converting Enzyme Inhibitors ; therapeutic use ; Child ; Child, Preschool ; Complement C3 ; metabolism ; Complement Factor H ; deficiency ; metabolism ; Female ; Fluorescent Antibody Technique ; Glomerulonephritis ; complications ; drug therapy ; metabolism ; pathology ; Hematuria ; etiology ; pathology ; Humans ; Kidney Glomerulus ; metabolism ; pathology ; Male ; Nephrotic Syndrome ; etiology ; pathology ; Proteinuria ; etiology ; pathology