Fandom

VroniPlag Wiki

Mag/Fragment 020 02

< Mag

31.288Seiten in
diesem Wiki
Seite hinzufügen
Diskussion0 Share

Störung durch Adblocker erkannt!


Wikia ist eine gebührenfreie Seite, die sich durch Werbung finanziert. Benutzer, die Adblocker einsetzen, haben eine modifizierte Ansicht der Seite.

Wikia ist nicht verfügbar, wenn du weitere Modifikationen in dem Adblocker-Programm gemacht hast. Wenn du sie entfernst, dann wird die Seite ohne Probleme geladen.


Typus
Verschleierung
Bearbeiter
PlagProf:-), Hindemith, Graf Isolan
Gesichtet
Yes.png
Untersuchte Arbeit:
Seite: 20, Zeilen: 2-32
Quelle: Wright 2005
Seite(n): 60-61, Zeilen: p. 60, col. 2, lines 30-32, 37-40,45-48, 51-50 - p. 61, col. 1: lines 1-16, figure 3
Surfactant proteins A and D bind to a variety of bacteria, viruses, allergens and apoptotic cells and thereby function as opsonins to enhance the uptake of these cells and particles. Binding of the collectins to pathogens occurs by various mechanisms. Some pathogens are aggregated by SP-A and/or SP-D and were phagocytized by immune cells like macrophages. SP-A and SP-D also have direct effects on immune cells and modulate the production of cytokines and inflammatory mediators.

Numerous studies have reported that SP-A mediates cellular functions through C1q receptors (Ferguson et al., 1999; Malholtra et al., 1994), including C1qR (also known as CD93) (Nepomuceno et al., 1997; Steinberger et al., 2002) and calreticulin (Malhotra et al., 1990; Malholtra et al., 1993). SP-A and SP-D are able to bind Calreticulin, which in turn binds to CD91. CD91 is a component of the binding complex (Gardai et al., 2003).

The binding of SP-A and/or SP-D to the signal-inhibitory regulatory protein-α (SIRP-α) modulates cellular functions in a similar way like the binding complex of surfactant proteins with the CD91–calreticulin complex. In the absence of a pathogen, SP-A binds through its lectin domain to SIRP-α, whereas in the presence of a foreign organism or cell debris, to which the lectin domain of SP-A binds, the free collagen-like region activates immune cells through CD91–calreticulin. Importantly, engagement of the different receptors elicits different responses. Upon binding of SP-A to SIRP-α, the inflammatory-mediator production is inhibited. By contrast, SP-A enhances inflammatory mediator like tumour-necrosis factor (TNF), CXCL12 and CCL2 production through its binding to the CD91-calreticulin complex. Therefore, SP-A and SP-D both are able to enhance and inhibit inflammatory-mediator production to modulate the regulation of immune cells.

Another receptor that binds surfactant protein A was identified by Chroneos and colleagues and termed SP-R210 (Chroneos et al., 1996). Blocking of this receptor with specific antibodies leads to a loss of SP-A mediated functions, including inhibition of lymphocyte proliferation (Borron et al., 1998), enhanced uptake of bacteria by macrophages (Weikert et al., 1997) and mycobacterial killing by a nitric-oxide-dependent pathway (Weikert et al., 2000). Nevertheless, the molecular identity of SP-R210 is still unclear.


Borron P, McCormack FX, Elhalwagi BM, Chroneos ZC, Lewis JF, Zhu S, Wright JR, Shepherd VL, Possmayer F, Inchley K, Fraher LJ. Surfactant protein A inhibits T cell proliferation via its collagen-like tail and a 210-kDa receptor. Am J Physiol. 1998 Oct; 275 (4 Pt 1): L679-86.

Borron PJ, Crouch EC, Lewis JF, Wright JR, Possmayer F, Fraher LJ. Recombinant rat surfactant-associated protein D inhibits human T lymphocyte proliferation and IL-2 production. J Immunol. 1998 Nov 1; 161 (9): 4599-603.

Chroneos ZC, Abdolrasulnia R, Whitsett JA, Rice WR, Shepherd VL. Purification of a cell-surface receptor for surfactant protein A. J Biol Chem. 1996 Jul 5; 271 (27): 16375-83.

Ferguson JS, Voelker DR, McCormack FX, Schlesinger LS. Surfactant protein D binds to Mycobacterium tuberculosis bacilli and lipoarabinomannan via carbohydrate-lectin interactions resulting in reduced phagocytosis of the bacteria by macrophages. J Immunol. 1999 Jul 1; 163 (1): 312-21.

Gardai SJ, Xiao YQ, Dickinson M, Nick JA, Voelker DR, Greene KE, Henson PM. By binding SIRPalpha or calreticulin/CD91, lung collectins act as dual function surveillance molecules to suppress or enhance inflammation. Cell. 2003 Oct 3; 115 (1): 13-23.

Malhotra R, Thiel S, Reid KB, Sim RB. Human leukocyte C1q receptor binds other soluble proteins with collagen domains. J Exp Med. 1990 Sep 1; 172 (3): 955-9.

Malhotra R, Willis AC, Jensenius JC, Jackson J, Sim RB. Structure and homology of human C1q receptor (collectin receptor). Immunology. 1993 Mar; 78 (3): 341-8.

Malhotra R, Haurum JS, Thiel S, Sim RB. Binding of human collectins (SP-A and MBP) to influenza virus. Biochem J. 1994 Dec 1; 304 (Pt2): 455-61.

Nepomuceno RR, Henschen-Edman AH, Burgess WH, Tenner AJ. cDNA cloning and primary structure analysis of C1qR(P), the human C1q/MBL/SPA receptor that mediates enhanced phagocytosis in vitro. Immunity. 1997 Feb; 6 (2): 119-29.

Steinberger P, Szekeres A, Wille S, Stockl J, Selenko N, Prager E, Staffler G, Madic O, Stockinger H, Knapp W. Identification of human CD93 as the phagocytic C1q receptor (C1qRp) by expression cloning. J Leukoc Biol. 2002 Jan; 71 (1): 133-40.

Weikert LF, Edwards K, Chroneos ZC, Hager C, Hoffman L, Shepherd VL. SP-A enhances uptake of bacillus Calmette-Guerin by macrophages through a specific SP-A receptor. Am J Physiol. 1997 May; 272 (5Pt1): L989-95.

Weikert LF, Lopez JP, Abdolrasulnia R, Chroneos ZC, Shepherd VL. Surfactant protein A enhances mycobacterial killing by rat macrophages through a nitric oxide-dependent pathway. Am J Physiol Lung Cell Mol Physiol. 2000 Aug; 279 (2): L216-23.

[page 60]

Numerous studies have reported that SP-A mediates cellular functions through C1q receptors37,38, including C1qR (also known as CD93)39,40 and calreticulin41,42. [...] However, recent studies have confirmed that calreticulin binds SP-A and SP-D and have shown that CD91 is a component of the binding complex43. [...] Gardai and co-workers43 recently reported that SP-A and SP-D also modulate cellular functions through signal-inhibitory regulatory protein-α (SIRP-α), as well as the CD91-calreticulin complex. [...] For example, in the absence of a pathogen, SP-A binds through its lectin domain to SIRP-α. In the presence of a foreign organism or cell debris, to which the lectin domain of SP-A binds, the free collagen-like region activates immune cells through CD91–calreticulin. Importantly, engagement of the different receptors elicits different responses. When SP-A binds SIRP-α, inflammatory-mediator production is inhibited. By contrast, SP-A enhances inflammatory mediator (for example, tumour-necrosis factor (TNF),

[page 61]

CXCL12 and CCL2) production through the CD91–calreticulin complex. This model provides at least a partial explanation for the apparently conflicting reports that SP-A and SP-D both enhance and inhibit inflammatory-mediator production and provides important information about mechanisms by which specific collectin responses might be mediated.

SP-R210 was identified more than eight years ago as an SP-A receptor45. SP-R210 was purified by SP-A affinity chromatography, and a SP-R210-specific antibody was shown to block SP-A-mediated functions, including inhibition of lymphocyte proliferation46, enhanced uptake of bacteria by macrophages47 and mycobacterial killing by a nitric-oxide-dependent pathway48. However, the molecular identity of SP-R210 has not yet been established.

[...]

Figure 3 Functions of SP-A and SP-D. Surfactant protein A (SP-A) and SP-D bind to a variety of bacteria, viruses, allergens and apoptotic cells and thereby function as opsonins to enhance the uptake of these cells and particles. Binding of the collectins to pathogens occurs by various mechanisms. Some pathogens are aggregated by SP-A and/or SP-D. SP-A and SP-D also have direct effects on immune cells and modulate the production of cytokines and inflammatory mediators.


37. Tenner, A. J. Membrane receptors for soluble defense collagens. Curr. Opin. Immunol. 11, 34–41 (1999).

38. Malhotra, R., Lu, J., Holmskov, U. & Sim, R. B. Collectins, collectin receptors and the lectin pathway of complement activation. Clin. Exp. Immunol. 97, 4–9 (1994).

39. Nepomuceno, R. R., Henschen-Edman, A. H., Burgess, W. H. & Tenner, A. J. cDNA cloning and primary structure analysis of C1aRp, the human C1q/MBL/SPA receptor that mediates enhanced phagocytosis in vitro. Immunity 6, 119–129 (1997).

40. Steinberger, P. et al. Identification of human CD93 as the phagocytic C1q receptor (C1qRp) by expression cloning. J. Leukoc. Biol. 71, 133–140 (2002).

41. Malhotra, R., Willis, A., Jensenius, J., Jackson, J. & Sim, R. Structure and homology of human C1q receptor (collectin receptor). Immunology 78, 341–348 (1993).

42. Malhotra, R., Thiel, S., Reid, K. B. & Sim, R. B. Human leukocyte C1q receptor binds other soluble proteins with collagen domains. J. Exp. Med. 172, 955–959 (1990).

43. Gardai, S. J. et al. By binding SIRPα or calreticulin/CD91, lung collectins act as dual function surveillance molecules to suppress or enhance inflammation. Cell 115, 13–23 (2003).
This is a compelling study showing that SP-A and SP-D bind two distinct receptors: SIRP-α and CD91–calreticulin.

45. Chroneos, Z. C., Abdolrasulnia, R., Whitsett, J. A., Rice, W. R. & Shepherd, V. L. Purification of a cell-surface receptor for surfactant protein A. J. Biol. Chem. 271, 16375–16383 (1996).
This paper was the first to report the characterization of an SP-A receptor.

46. Borron, P. et al. Surfactant protein A inhibits T cell proliferation via its collagen-like tail and a 210-kDa receptor. Am. J. Physiol. Lung Cell. Mol. Physiol. 275, L679–L686 (1998).

47. Weikert, L. F. et al. SP-A enhances uptake of bacillus Calmette-Guerin by macrophages through a specific SP-A receptor. Am. J. Physiol. Lung Cell. Mol. Physiol. 272, L989–L995 (1997).

48. Weikert, L. F., Lopez, J. P., Abdolrasulnia, R., Chroneos, Z. C. & Shepherd, V. L. Surfactant protein A enhances mycobacterial killing by rat macrophages through a nitric oxide-dependent pathway. Am. J. Physiol. Lung Cell. Mol. Physiol. 279, L216–L223 (2000).

Anmerkungen

Mag adopts Wright's literary review without indicating Wright as the source.

Note: there are two references "Borron et al. (1998)" in the bibliography.

Sichter
(SleepyHollow02), (Hindemith), (Graf Isolan) Schumann

Auch bei Fandom

Zufälliges Wiki