OBJECTIVES: To explore the role of C1q, the promoter of the classical pathway of the complement system, in regulating postpartum depressive-like behaviors in mice and the therapeutic mechanism of C1q-neutralizing antibodies. METHODS: Female C57BL/6 mouse models of postpartum depression established by hormone-simulated pregnancy (HSP) were evaluated for depression-like behaviors, and peripheral blood levels and hippocampal expressions of C1q were detected using ELISA and Western blotting. Immunofluorescence staining was used for detecting co-labeling of C1q and microglia, and the differentially expressed mRNAs in the hippocampus of HSP mice were analyzed using RNA sequencing. The Edinburgh Postnatal Depression Scale was used to screen patients with postpartum depression, from whom peripheral blood mononuclear cells were extracted for detecting C1q expression levels with Western blotting. The HSP mice were subjected to stereotactic injection of C1q-neutralizing antibody or a control IgG in the hippocampus, and the changes in depressive-like behaviors and hippocampal expression of C3 were examined. RESULTS: The HSP mice exhibited obvious depressive behaviors, demonstrated by significantly decreased preference for sugar water and increased forced swimming and tail suspension time. The mouse models showed significantly increased peripheral blood C1q level and hippocampal expression level of C1q, accompanied by an increase in Iba1 and C1q co-labeling in the hippocampus. The expression level of C1q in peripheral monocytes was also significantly increased in patients with postpartum depression. In HSP mice, stereotactic injection of C1q-neutralizing antibody, but not the control IgG, obviously alleviated depressive-like behaviors, shown by significantly increased preference for sugar water and decreased forced swimming and tail suspension time, resulting also in decreased expression of C3 in the hippocampus and lowered serum levels of IL-6 and TNF-α. CONCLUSIONS C1q-neutralizing antibodies improve postpartum depressive-like behaviors in mice possibly by regulating the C1q/C3 signaling pathway.
Animals ; Female ; Depression, Postpartum ; Complement C1q/metabolism* ; Antibodies, Neutralizing/pharmacology* ; Mice, Inbred C57BL ; Mice ; Hippocampus/metabolism* ; Pregnancy ; Disease Models, Animal

Hereditary angioedema (HAE) is a rare,unpredictable,autosomal dominant disorder characterized by recurrent swelling in subcutaneous and submucosal tissue.In recent years,the pathophysiology and pathogenesis of HAE have been continuously studied and elucidated.In addition to the genes encoding complement 1 esterase inhibitors,new pathogenic variants have been identified in the genes encoding coagulation factor Ⅻ,plasminogen,angiopoietin-1,kininogen,heparan sulfate 3-O-sulfotransferase 6,and myoferlin in HAE.Moreover,different pathogenic variants have different mechanisms in causing HAE.In addition,the pathogenic genes of some patients remain unknown.This review summarizes the recent progress in the classification,epidemiology,pathophysiology,and pathogenesis of HAE,aiming to provide ideas for further fundamental research,clinical diagnosis,and drug development of HAE.
Humans ; Angioedemas, Hereditary/diagnosis* ; Angiopoietin-1/metabolism* ; Plasminogen/metabolism* ; Kininogens/metabolism* ; Complement C1 Inhibitor Protein/metabolism*

Inflammation underlies a wide variety of physiological and pathological processes, and plays a pivotal role in controlling pathogen infection. C1q/tumor necrosis factor (TNF) related proteins (CTRPs), a newly discovered adipokine family with conservative structure and wide distribution, has attracted increasing attention. The CTRP family consists of more than 15 members which fall into the characteristic C1q domain. Increasing studies have demonstrated that CTRPs are involved in the onset and development of inflammation and metabolism as well as related diseases, including myocardial infarction, sepsis and tumors. Here, we first clarified the characteristic domains of CTRPs, and then elucidated their roles in inflammatory-related diseases. Taken together, the information presented here provides new perspectives for therapeutic strategies to improve inflammatory and metabolic abnormalities.
Humans ; Complement C1q/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Inflammation/metabolism* ; Myocardial Infarction

Objective: To assess the correlation of glomerular C1q or IgA deposition with clinical and pathological features of primary membranous nephropathy (PMN) in children. Methods: The clinical and pathological manifestations including (phospholipase A2 receptor, PLA2R) and IgG subclasses staining in renal biopsies, serum anti-PLA2R antibody and therapeutic response of 33 children diagnosed with PMN in Peking University First Hospital from December 2012 to December 2020 were retrospectively summarized and analyzed. According to results of PLA2R test and findings renal pathological, the patients were divided into PLA2R-related group and non-PLA2R-related group, typical MN group and atypical MN group, C1q deposit group and non-C1q deposit group, as well as IgA deposit group and non-IgA deposit group respectively. T-test, Mann-Whitney U test and Fisher's exact probability test were used for comparison between the groups. Results: Among the 33 children with PMN, there were 20 males and 13 females, of that the age of onset was 11 (8, 13) years, and 32 patients had nephrotic level proteinuria. Renal biopsies were performed at 4.6 (2.1, 11.6) months after onset, and 28 patients (85%) received glucocorticoid or immunosuppressive therapy prior to renal biopsy. There were 20 cases (61%) with PLA2R-related MN and 13 cases (39%) with non-PLA2R-related MN. Compared with the non-PLA2R-related group, the PLA2R-related group had an older age of onset (12 (10, 13) vs. 7 (3, 12) years, Z=-2.52, P=0.011), a lower preceding infection rate (45% (9/20) vs. 11/13, P=0.032) and lower spontaneous remission rate (0 vs. 4/13, P=0.017). Renal PLA2R positivity was significantly associated with predominant or co-deposition of IgG4 (13/17 vs. 5/15, P=0.031) and low albumin levels at renal biopsy ((25±6) vs. (29±7) g/L, t=2.14, P=0.041). There were 12 patients with typical PMN and 21 patients with atypical PMN, and no significant difference in clinical and pathological manifestations was found between these 2 groups (all P>0.05). There were 10 cases (32.3%) with glomerular C1q deposition, and their disease course before renal biopsy was significantly shorter than those without C1q deposition (1.8 (0.8, 5.9) vs. 6.0 (2.5, 22.3) months, Z=-2.27, P=0.023). Twelve cases (36.4%) had glomerular IgA deposition, and their course of disease,clinical and pathological manifestations were not significantly different from those without IgA deposition (all P>0.05). Conclusion: Glomerular C1q or IgA deposition may not affect the clinical manifestations, glomerular PLA2R and IgG subclasses staining pattern, or the response to treatment of PMN in children.
Autoantibodies ; Child ; Complement C1q/metabolism* ; Female ; Glomerulonephritis, Membranous/drug therapy* ; Humans ; Immunoglobulin A/immunology* ; Immunoglobulin G ; Kidney Glomerulus ; Male ; Retrospective Studies

OBJECTIVE: To analyze the change of serum C1q in the course of multiple myeloma (MM) and its correlation with clinical characteristics. METHODS: A total of 138 newly diagnosed MM patients in Zhongnan Hospital of Wuhan University from June 2016 to December 2019 were selected as research objects, during the same period 50 age-matched anemia patients, 50 lymphoma patients, 50 leukemia patients, and 50 myelodysplastic syndrome (MDS) patients were selected as control groups. All the patients met WHO disease classification, and were definitely diagnosed by pathology or bone marrow smear/biopsy. The changes of C1q between MM patients and control group, as well as in different therapeutic responses of MM patients before and after treatment were compared, also the difference of clinical characteristics among MM patients with different C1q level, so as to analyze risk factors which led to C1q decline. RESULTS: The average value of C1q in MM patients was (128.18±51.24) mg/L, which was significantly lower than control group (P<0.01). The levels of white blood cell, platelet (PLT), hemoglobin (Hb), serum calcium, albumin, lactate dehydrogenase (LDH) in newly diagnosed high C1q group were significantly higher than those in low C1q group (P<0.05). Logistic analysis showed that the levels of PLT, Hb, albumin, and LDH in newly diagnosed high C1q group were higher than those in low C1q group (r=0.248, r=0.394, r=0.405, r=0.295). After treatment, the levels of C1q in MM patients with complete remission and very good partial remission were significantly higher than before treatment (P<0.05), while those with partial remission and stable disease also increased but not significantly (P>0.05). CONCLUSION The C1q level in MM patients is significantly lower than that in patients with other hematologic system diseases, and it increases with the remission of the disease after treatment.
Albumins ; Bone Marrow ; Complement C1q ; Humans ; Multiple Myeloma ; Risk Factors

The C1q family is one of the subcomponents of the C1 complex that recognizes immune complexes and initiates the classical pathway of the complement system. In addition, as a pattern recognition receptor (PRR), the C1q family binds to a wide variety of ligands. As a member of the C1q family, the secretory C1q includes several subtypes. The main subtypes are cerebellin (Cbln) and C1q-like protein (C1ql). In the nervous system, secretory C1q is involved in the formation and regulation of various types of synapses, thus secretory C1q is closely related to diseases of the central nervous system. In this article, we review the role of secretory C1q in synapse formation and regulation, and its relationship with some diseases of the central nervous system.
Antigen-Antibody Complex ; Central Nervous System ; Complement C1q ; physiology ; Humans ; Synapses ; physiology

Ehlers-Danlos syndrome (EDS) VIII is an autosomal dominant inherited connective tissue disorder characterized by intractable periodontal inflammation, absence of gingiva, pretibial plaques, skin hyperextensibility, joint hypermobility, and tissue fragility with onset in the childhood or adolescence. In a recent report, heterozygous variants of the C1R or C1S related to the classical complement pathway were identified in families with history of EDS VIII. The current report describes a Korean 34-year-old female carrying a novel missense variant of C1R c.925T>G (p.Cys309Gly) and exhibiting early severe periodontitis, skin fragility, and joint hypermobility. The patient also had frontal, parietal, and temporal white matter brain lesions without definite vascular abnormalities on brain magnetic resonance imaging, which have not been surveyed meticulously in EDS VIII. Considering the genetic alteration of classic complement pathways in this condition, it is necessary to carefully observe multisystemic inflammation processes such as changes in brain white matter.
Adolescent ; Adult ; Brain ; Complement C1r ; Complement Pathway, Classical ; Complement System Proteins ; Connective Tissue ; Ehlers-Danlos Syndrome ; Female ; Gingiva ; Humans ; Inflammation ; Joint Instability ; Magnetic Resonance Imaging ; Periodontitis ; Rabeprazole ; Skin ; White Matter

Hereditary angioedema is a disease of congenital deficiency or functional defect in the C1 esterase inhibitor (C1-INH) consequent to mutation in the SERPING1 gene, which encodes C1-INH. This disease manifests as recurrent, non-pitting, non-pruritic subcutaneous, or submucosal edema as well as an erythematous rash in some cases. These symptoms result from the uncontrolled localized production of bradykinin. The most commonly affected sites are the extremities, face, gastrointestinal tract, and respiratory system. When the respiratory system is affected by hereditary angioedema, swelling of the airway can restrict breathing and lead to life-threatening obstruction. Herein, we report a case of a 24-year-old woman with type 2 hereditary angioedema who presented with recurrent episodic abdominal pain and swelling of the extremities. She had no family history of angioedema. Although her C4 level was markedly decreased (3.40 mg/dL; normal range: 10-40 mg/dL), she presented with a very high C1-INH level (81.0 mg/dL; normal range: 21.0-39.0 mg/dL) and abnormally low C1-INH activity (less than 25%; normal range: 70%-130%). The SERPING1 gene mutation was confirmed in this patient. She was treated with prophylactic tranexamic acid, as needed, and subsequently reported fewer and less severe episodes. To our knowledge, this is the first reported case of type 2 hereditary angioedema in Korea that was consequent to SERPING1 mutation and involved a significantly elevated level of C1-INH as well as a low level of C1-INH activity.
Abdominal Pain ; Angioedema ; Angioedemas, Hereditary* ; Bradykinin ; Complement C1 Inhibitor Protein ; Edema ; Exanthema ; Extremities ; Female ; Gastrointestinal Tract ; Humans ; Korea ; Reference Values ; Respiration ; Respiratory System ; Tranexamic Acid ; Young Adult

C1q nephropathy is a rare type of glomerulonephritis manifested as the deposition of C1q in the glomerular mesangium during immunofluorescent staining. Systemic lupus erythematosus and type I membranoproliferative glomerulonephropathy need to be excluded in the diagnosis of C1q nephropathy. C1q nephropathy has various manifestations under a light microscope, mainly including minimal change disease, focal segmental glomerulosclerosis, and proliferative glomerulonephritis. This disease is mainly manifested as persistent proteinuria or nephrotic syndrome and occurs more frequently in boys. Currently, glucocorticoids are mainly used for the treatment of this disease. Patients with C1q nephropathy show a good response to immunosuppressant treatment, but have a high rate of glucocorticoid resistance. Therefore, in this case, methylprednisolone pulse therapy or a combination with immunosuppressant treatment helps to achieve a good prognosis.
Complement C1q ; metabolism ; Diagnosis, Differential ; Glomerulonephritis ; diagnosis ; drug therapy ; etiology ; Glucocorticoids ; therapeutic use ; Humans ; Prognosis

C1q nephropathy is a rare glomerular disease, defined by characteristic mesangial C1q immune deposition seen in immunofluorescence microscopy with no serological evidence of systemic lupus erythematosus. C1q nephropathy can be diagnosed with a subsequent biopsy, as with IgA nephropathy. There are some cases with an initial diagnosis of hematuria and proteinuria with minimal disease changes, focal segmental glomerulonephritis, and mesangial proliferative glomerulonephritis, but lacking C1q nephropathy, in which C1q deposition on immunofluorescence subsequently develops. We report a case that was diagnosed as diffuse mesangial proliferative glomerulonephritis, but a subsequent biopsy showed C1q nephropathy, with C1q deposition in both immunohistochemistry and electron microscopy (EM). We treated the C1q nephropathy with methylprednisolone and confirmed the disappearance of C1q depositions by both immunohistochemistry and EM in a follow-up biopsy.
Biopsy ; Complement C1q ; Diagnosis ; Fluorescent Antibody Technique ; Follow-Up Studies ; Glomerulonephritis ; Glomerulonephritis, IGA ; Hematuria ; Immunohistochemistry ; Lupus Erythematosus, Systemic ; Methylprednisolone ; Microscopy, Electron ; Microscopy, Fluorescence ; Proteinuria