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Trichinella spiralis Paramyosin Binds Human Complement C1q and Inhibits Classical Complement Activation.

Sun R, Zhao X, Wang Z, Yang J, Zhao L, Zhan B, Zhu X - PLoS Negl Trop Dis (2015)

Bottom Line: Trichinella spiralis expresses paramyosin (Ts-Pmy) as a defense mechanism.The binding of recombinant and natural Ts-Pmy to human C1q were determined by ELISA, Far Western blotting and immunoprecipitation, respectively.Binding of recombinant Ts-Pmy (rTs-Pmy) to C1q inhibited C1q binding to IgM and consequently inhibited C3 deposition.

View Article: PubMed Central - PubMed

Affiliation: Department of Parasitology, School of Basic Medical Sciences, Capital Medical University, Beijing, PR China.

ABSTRACT

Background: Trichinella spiralis expresses paramyosin (Ts-Pmy) as a defense mechanism. Ts-Pmy is a functional protein with binding activity to human complement C8 and C9 and thus plays a role in evading the attack of the host's immune system. In the present study, the binding activity of Ts-Pmy to human complement C1q and its ability to inhibit classical complement activation were investigated.

Methods and findings: The binding of recombinant and natural Ts-Pmy to human C1q were determined by ELISA, Far Western blotting and immunoprecipitation, respectively. Binding of recombinant Ts-Pmy (rTs-Pmy) to C1q inhibited C1q binding to IgM and consequently inhibited C3 deposition. The lysis of antibody-sensitized erythrocytes (EAs) elicited by the classical complement pathway was also inhibited in the presence of rTs-Pmy. In addition to inhibiting classical complement activation, rTs-Pmy also suppressed C1q binding to THP-1-derived macrophages, thereby reducing C1q-induced macrophages migration.

Conclusion: Our results suggest that T. spiralis paramyosin plays an important role in immune evasion by interfering with complement activation through binding to C1q in addition to C8 and C9.

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Related in: MedlinePlus

The binding of C1q to THP-1-derived macrophages was inhibited by rTs-Pmy.(A) After fixing with 4% paraformaldehyde and blocking with goat serum, M2 type macrophage cells were incubated with C1q, C1q plus rTs-Pmy or PBS alone for 1 h at 37°C, and then detected with an anti-C1q mAb or anti-Ts-Pmy mAb 9G3. Dylight 488 was used as a secondary antibody (green). The nuclei were stained with DAPI (blue). The imagine magnitude is 400 X with one cell 1000 X at the bottom right corner. (B) The fluorescence intensity was measured with high content analysis. The results shown are means ± SD and are representative of three independent experiments. ***p<0.001.
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pntd.0004310.g006: The binding of C1q to THP-1-derived macrophages was inhibited by rTs-Pmy.(A) After fixing with 4% paraformaldehyde and blocking with goat serum, M2 type macrophage cells were incubated with C1q, C1q plus rTs-Pmy or PBS alone for 1 h at 37°C, and then detected with an anti-C1q mAb or anti-Ts-Pmy mAb 9G3. Dylight 488 was used as a secondary antibody (green). The nuclei were stained with DAPI (blue). The imagine magnitude is 400 X with one cell 1000 X at the bottom right corner. (B) The fluorescence intensity was measured with high content analysis. The results shown are means ± SD and are representative of three independent experiments. ***p<0.001.

Mentions: To assess whether rTs-Pmy affected C1q binding to THP-1-derived macrophages [25,30], C1q was pre-incubated with rTs-Pmy before adding to THP-1-derived macrophages. Immunofluorescence staining with anti-C1q mAb showed that the fluorescence intensity on macrophage cells was decreased after C1q was incubated with rTs-Pmy (C1q+rTs-Pmy) (Fig 6A). No fluorescence was detected in the PBS and rTs-Pmy alone control group. The quantitative measurement showed that the fluorescence intensity was significantly decreased in C1q with rTs-Pmy group compared with C1q only group (Fig 6B). The results indicated that rTs-Pmy interfered with the binding of C1q to macrophages.


Trichinella spiralis Paramyosin Binds Human Complement C1q and Inhibits Classical Complement Activation.

Sun R, Zhao X, Wang Z, Yang J, Zhao L, Zhan B, Zhu X - PLoS Negl Trop Dis (2015)

The binding of C1q to THP-1-derived macrophages was inhibited by rTs-Pmy.(A) After fixing with 4% paraformaldehyde and blocking with goat serum, M2 type macrophage cells were incubated with C1q, C1q plus rTs-Pmy or PBS alone for 1 h at 37°C, and then detected with an anti-C1q mAb or anti-Ts-Pmy mAb 9G3. Dylight 488 was used as a secondary antibody (green). The nuclei were stained with DAPI (blue). The imagine magnitude is 400 X with one cell 1000 X at the bottom right corner. (B) The fluorescence intensity was measured with high content analysis. The results shown are means ± SD and are representative of three independent experiments. ***p<0.001.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4697845&req=5

pntd.0004310.g006: The binding of C1q to THP-1-derived macrophages was inhibited by rTs-Pmy.(A) After fixing with 4% paraformaldehyde and blocking with goat serum, M2 type macrophage cells were incubated with C1q, C1q plus rTs-Pmy or PBS alone for 1 h at 37°C, and then detected with an anti-C1q mAb or anti-Ts-Pmy mAb 9G3. Dylight 488 was used as a secondary antibody (green). The nuclei were stained with DAPI (blue). The imagine magnitude is 400 X with one cell 1000 X at the bottom right corner. (B) The fluorescence intensity was measured with high content analysis. The results shown are means ± SD and are representative of three independent experiments. ***p<0.001.
Mentions: To assess whether rTs-Pmy affected C1q binding to THP-1-derived macrophages [25,30], C1q was pre-incubated with rTs-Pmy before adding to THP-1-derived macrophages. Immunofluorescence staining with anti-C1q mAb showed that the fluorescence intensity on macrophage cells was decreased after C1q was incubated with rTs-Pmy (C1q+rTs-Pmy) (Fig 6A). No fluorescence was detected in the PBS and rTs-Pmy alone control group. The quantitative measurement showed that the fluorescence intensity was significantly decreased in C1q with rTs-Pmy group compared with C1q only group (Fig 6B). The results indicated that rTs-Pmy interfered with the binding of C1q to macrophages.

Bottom Line: Trichinella spiralis expresses paramyosin (Ts-Pmy) as a defense mechanism.The binding of recombinant and natural Ts-Pmy to human C1q were determined by ELISA, Far Western blotting and immunoprecipitation, respectively.Binding of recombinant Ts-Pmy (rTs-Pmy) to C1q inhibited C1q binding to IgM and consequently inhibited C3 deposition.

View Article: PubMed Central - PubMed

Affiliation: Department of Parasitology, School of Basic Medical Sciences, Capital Medical University, Beijing, PR China.

ABSTRACT

Background: Trichinella spiralis expresses paramyosin (Ts-Pmy) as a defense mechanism. Ts-Pmy is a functional protein with binding activity to human complement C8 and C9 and thus plays a role in evading the attack of the host's immune system. In the present study, the binding activity of Ts-Pmy to human complement C1q and its ability to inhibit classical complement activation were investigated.

Methods and findings: The binding of recombinant and natural Ts-Pmy to human C1q were determined by ELISA, Far Western blotting and immunoprecipitation, respectively. Binding of recombinant Ts-Pmy (rTs-Pmy) to C1q inhibited C1q binding to IgM and consequently inhibited C3 deposition. The lysis of antibody-sensitized erythrocytes (EAs) elicited by the classical complement pathway was also inhibited in the presence of rTs-Pmy. In addition to inhibiting classical complement activation, rTs-Pmy also suppressed C1q binding to THP-1-derived macrophages, thereby reducing C1q-induced macrophages migration.

Conclusion: Our results suggest that T. spiralis paramyosin plays an important role in immune evasion by interfering with complement activation through binding to C1q in addition to C8 and C9.

Show MeSH
Related in: MedlinePlus