Murine glomerular mesangial cell uptake of apoptotic cells is inefficient and involves serum-mediated but complement-independent mechanisms.

An increased number of apoptotic bodies have been detected in glomeruli of non-nephritic kidneys of C1q-deficient mice. In these mice an in vivo impaired uptake of apoptotic cells by peritoneal macrophages was also demonstrated. Here we investigated whether C1q plays a role in the in vitro clearance of apoptotic cells by glomerular mesangial cells. Phagocytosis was assessed using a novel flow cytometric assay that was validated by immunofluorescence studies. The uptake of apoptotic cells by mesangial cells, measured as percentage of mesangial cells ingesting apoptotic cells, was approximately 25%, 10% and 10% for a T cell lymphoma line (RMA), thymocytes and neutrophils, respectively. The uptake reached a plateau phase after 3 h, was specific for apoptotic cells and was mediated by serum but not by complement components C1q or C3. The phagocytosis of apoptotic cells was significantly inhibited by Arg-Gly-Asp-Ser (RGDS), a peptide capable of blocking the interaction of thrombospondin with CD36 or the vitronectin receptor. Pretreatment of the mesangial cells with dexamethasone (200 nm) but not with LPS increased the uptake markedly. These findings indicate that murine mesangial cells are capable of taking up syngeneic apoptotic cells, although much less efficiently than professional phagocytic cells. They also show that serum proteins other than complement components mediate the removal of apoptotic cells by murine mesangial cells in vitro.

C1-inhibitor deficiency and angioedema.

C1-inhibitor deficiency can be inherited or acquired; both conditions lead to recurrent angioedema that can be life threatening when the larynx is involved (hereditary angioedema, HAE; acquired angioedema, AAE). The genetic defect is due to the heterozygous deficiency of C1-Inh that is transmitted as an autosomal dominant trait. Mutations causing HAE have been found distributed over all exons and splice sites of C1-Inh structural gene: only a few of them have been found more than once. Depending on DNA defect, C1-Inh is not transcribed, or not translated or not secreted. Finally, in 15% of HAE patients, an antigenically normal, but non-functional C1-Inh is present in serum (HAE type II). C1-Inh deficiency can be acquired, due to an accelerated consumption. Such an accelerated consumption can depend on circulating autoantibodies that bind C1-Inh causing its inactivation and catabolism; or to associated diseases, usually lymphoproliferative diseases, that consume C1-Inh with different mechanisms. Effective therapies can prevent or revert angioedema symptoms in C1-Inh deficiency, the main problem of this condition remaining misdiagnosis. The common knowledge that angioedema is an allergic symptom frequently prevents a correct diagnostic approach: C1-Inh deficiency goes unrecognized and the disease can still be lethal. Correct prophylactic treatment is based on attenuated androgens in HAE and on antifibrinolytic agents in AAE. Life threatening laryngeal attacks and severe abdominal attacks are effectively reverted, in both conditions, with C1-Inh plasma concentrate. A special remark to this treatment should be made for autoantibody-mediated AAE where very high doses can be needed depending on the rate of C1-Inh consumption.

Frequent de novo mutations and exon deletions in the C1inhibitor gene of patients with angioedema.

BACKGROUND: Cases of angioedema with no family history but with functionally low levels of C1 inhibitor and recurrent attacks are often observed. Clinical and biochemical data do not distinguish these cases from proven inherited forms of hereditary angioedema. OBJECTIVE: We sought to test the hypothesis of de novo mutations in patients affected by angioedema without a family history of the disease. METHODS: Among 137 independent kindreds followed for hereditary angioedema, 45 (32.8%) patients with early onset of the disease were registered as sporadic cases. Nineteen patients with unaffected parents were screened for point mutations and microdeletions-insertions by using fluorescence-assisted mismatch analysis. The biologic paternity of these patients was verified by determining their alleles at 4 microsatellite loci. Gross deletions were detected with Southern blot analysis. RESULTS: C1 inhibitor plasma levels measured in both parents of 24 sporadic patients were normal in all but 3 patients. Among the 19 patients studied at the DNA level, 9 de novo single nucleotide substitutions and 6 de novo microdeletions were found. De novo exon deletions were detected in 3 additional patients with Southern blot analysis. CONCLUSIONS: De novo C1inhibitor mutations and exon deletions account for at least 25% of all unrelated cases of angioedema. This finding has implications relevant to the genetic epidemiology and genetic counseling of this disease. The observation that 5 of the 9 de novo point mutations reproduce previously reported changes underlines the presence of multiple hot spots, two of which contain a CpG dinucleotide.

A hierarchical role for classical pathway complement proteins in the clearance of apoptotic cells in vivo.

The strongest susceptibility genes for the development of systemic lupus erythematosus (SLE) in humans are null mutants of classical pathway complement proteins. There is a hierarchy of disease susceptibility and severity according to the position of the missing protein in the activation pathway, with the severest disease associated with C1q deficiency. Here we demonstrate, using novel in vivo models of apoptotic cell clearance during sterile peritonitis, a similar hierarchical role for classical pathway complement proteins in vivo in the clearance of apoptotic cells by macrophages. Our results constitute the first demonstration of an impairment in the phagocytosis of apoptotic cells by macrophages in vivo in a mammalian system. Apoptotic cells are thought to be a major source of the autoantigens of SLE, and impairment of their removal by complement may explain the link between hereditary complement deficiency and the development of SLE.

[Clinico-statistical considerations on the agreement between echographic and biopsy findings in hepatopathies of the diffuse type]. / Considerazioni clinico-statistiche sulla concordanza fra referto ecotomografico e bioptico nelle epatopatie di tipo diffuso.

A comparison between echographic and bioptic findings in diffuse liver disease is reported. The data obtained are compared with those quoted in the literature and found to be very similar. Finally echography is identified as the indispensable examination of choice.

[Clinical considerations on a case of Caroli disease]. / Considerazioni cliniche su un caso di malattia di Caroli.

A case of Caroli's disease is presented. Stress is laid on the importance of transcutaneous cholangiography in the diagnosis of this morbid form, and the usefulness of both echotomography and computed tomography. The latter permits visualisation of the intra- and extrahepatic bile ducts and indicates the extent of the disease. At the same time, it permits evaluation of any alterations of other organs. Attention is also drawn to the importance of careful diagnostic employment of these means of investigation. Emphasis is equally placed on the way complications can be prevented through medical and surgical management.