C3 Fragments (c3 + fragment)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Plasma protein profiles in early asthmatic responses to inhalation allergen challenge

ALLERGY, Issue 1 2009
T. Rhim
Although mediators, such as lipids, cytokines, and chemokines, are related to the appearance of an IPR, there has been no reliable indicator to predict conditions for the appearance of an IPR. In this study, we adopted a proteomic approach to investigate the pathogenesis at the level of the plasma proteins and to develop plasma markers to predict the appearance of an IPR following an inhalation challenge with Dermatophagoides pteronyssinus (D.p.). Sixteen mild asthmatics were recruited. Plasma was obtained before challenge and when a decline in forced expiratory volume in 1 s (FEV1) values greater than 20% from the phosphate-buffered saline value was achieved during D.p. allergen challenge (positive responders), or at 60 min after the highest concentration of D.p. allergen was inhaled (negative responders). After comparing normalized volumes of the spots in the two groups, differentially expressed spots were identified using intra-gel digestion and mass spectrometric analysis. Before D.p. antigen challenge, four spots of gamma fibrinogen and its isoforms were significantly decreased and two spots of complement C3 fragments were significantly increased in the positive responders compared to the negative responders. After D.p. antigen challenge, complement C3 fragment was persistently higher, while gamma fibrinogen was lower in the positive responders than in the negative responders. A validation study using Western blotting showed that gamma fibrinogen expression in the IPR-positive asthmatics was significantly decreased compared to the average of the IPR-negative asthmatic control group. These results indicate that alterations in the complement cascade and fibrinogen may predispose patients to the appearance of an immediate response to D.p. allergen challenge and may provide plasma markers to predict the appearance of an IPR. [source]

C-type lectin-independent interaction of complement opsonized HIV with monocyte-derived dendritic cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2005
Monika Pruenster
Abstract HIV directly activates the complement cascade and is, therefore, opsonized with C3-cleavage products in vivo. This cloud of C3 fragments on the viral surface may impair the interaction of the HIV envelope glycoproteins gp120/gp41 with C-type lectins expressed on immature dendritic cells (iDC). Therefore, we determined the accessibility of gp120 after opsonization and compared the interaction of DC with non-opsonized or complement-opsonized HIV. The recognition of native gp120 was drastically impaired when the virus was covered by complement. Independent of opsonization, similar amounts of HIV bound to DC. The interaction of iDC and the infection of DC-PBL co-cultures with non-opsonized virus was significantly reduced by mannan and antibodies which inhibit the ICAM-1-CR3 interaction. The binding of opsonized virus to iDC was reduced by an anti-CR3-antibody, which interferes with the binding of C3 fragments, but was not affected by mannan. Complement enhanced the HIV infection of DC and DC-PBL co-cultures significantly. Mannan did not inhibit the complement-dependent enhancement of infection. Thus, non-opsonized and opsonized HIV interacted with iDC, although the binding mechanisms seemed to differ. As HIV is opsonized in vivo, the C-type lectin-independent interaction of opsonized viruses with iDC has to be taken into account. [source]

Plasma protein profiles in early asthmatic responses to inhalation allergen challenge

ALLERGY, Issue 1 2009
T. Rhim
Although mediators, such as lipids, cytokines, and chemokines, are related to the appearance of an IPR, there has been no reliable indicator to predict conditions for the appearance of an IPR. In this study, we adopted a proteomic approach to investigate the pathogenesis at the level of the plasma proteins and to develop plasma markers to predict the appearance of an IPR following an inhalation challenge with Dermatophagoides pteronyssinus (D.p.). Sixteen mild asthmatics were recruited. Plasma was obtained before challenge and when a decline in forced expiratory volume in 1 s (FEV1) values greater than 20% from the phosphate-buffered saline value was achieved during D.p. allergen challenge (positive responders), or at 60 min after the highest concentration of D.p. allergen was inhaled (negative responders). After comparing normalized volumes of the spots in the two groups, differentially expressed spots were identified using intra-gel digestion and mass spectrometric analysis. Before D.p. antigen challenge, four spots of gamma fibrinogen and its isoforms were significantly decreased and two spots of complement C3 fragments were significantly increased in the positive responders compared to the negative responders. After D.p. antigen challenge, complement C3 fragment was persistently higher, while gamma fibrinogen was lower in the positive responders than in the negative responders. A validation study using Western blotting showed that gamma fibrinogen expression in the IPR-positive asthmatics was significantly decreased compared to the average of the IPR-negative asthmatic control group. These results indicate that alterations in the complement cascade and fibrinogen may predispose patients to the appearance of an immediate response to D.p. allergen challenge and may provide plasma markers to predict the appearance of an IPR. [source]

A new cleavage site for elastase within the complement component 3

APMIS, Issue 10 2010
ROLF CLAESSON
Claesson R, Kanasi E, Johansson A, Kalfas S. A new cleavage site for elastase within the complement component 3. APMIS 2010; 118: 765,68. The lysosomal enzyme elastase was earlier shown to cleave the complement molecule C3. During some preliminary experiments on the interactions of certain pathogenic bacteria with the innate defence mechanisms, we observed C3 cleavage, in the presence of elastase, to fragments not previously described. To elucidate this proteolytic reaction, the present study was conducted. Degradation of C3 in mixtures with elastase or cathepsin G was detected by an immunoblot procedure using anti-C3c and anti-C3d antibodies after separating the proteins by SDS-PAGE. Certain C3 fragments were analysed for amino acid sequence. The results revealed the existence of a cleavage site for elastase at the position alanine1350/lysine1351 of the C3 molecule, which has not been previously described. The fragment resulted from this cleavage has a size of about 39 kDa and it contains a part or the whole of C3d. This cleavage was distinct from the one previously described at position 987/988, which gives a 34 kDa C3d-containing fragment. [source]