Related Experiment Videos
Keratinocyte growth inhibition by streptococcal proteins
U Wollina1, A Hoffmann, D Prochnau
1Department of Dermatology, The Friedrich Schiller University Jena, Jena, Germany.
Abstract:
M proteins are receptor proteins and one of the virulence factors of streptococci. M proteins seem to play a role in inflammatory skin disorders such as psoriasis. It is however unknown whether M proteins have a direct influence on proliferative activity of human keratinocytes. In the present study human HaCaT keratinocytes were exposed to M proteins (M1, M3, M5, M12) and the proliferative and proinflammatory response was analyzed. We found a dose-dependent inhibition of keratinocyte proliferation with crude extract of strain M3 4/55. Following affinity chromatography we found inhibitory activity for keratinocyte proliferation with a maximum of 80% at 10-8 M in the M protein. Additionally tested M1 protein preparation showed an inhibitory activity of 55% whereas other M preparations (5 and 12) did not show any effect. In supernatants from HaCaT cultures IL-1alpha, IL-1beta, IL-6, IL-8, TNFalpha and ICAM-1 were measured by ELISA. The levels of IL-8 were high and TNFalpha was upregulated, whereas ICAM-1 was decreased from around 20 ng/ml to almost zero. In contrast to the streptococcal-derived M3 protein preparation the recombinant M3 did not interfere with the proliferation of HaCaT cells. Because neither recombinant M3 protein nor M3 protein purified by ion exchange chromatography on a Q-resource column had any antiproliferative activity on keratinocytes we suggest, that a component different from M3 protein was responsible.
Insights
Streptococcal M proteins, implicated in skin disorders, were tested for their effect on human keratinocytes. Certain M protein preparations inhibited keratinocyte proliferation and altered inflammatory markers, but a component other than M3 protein was likely responsible.
Area of Science:
- Microbiology
- Dermatology
- Immunology
Background:
- Streptococcal M proteins are virulence factors.
- M proteins are suspected to influence inflammatory skin conditions like psoriasis.
- The direct impact of M proteins on human keratinocyte proliferation remains unclear.
Purpose of the Study:
- To investigate the effect of streptococcal M proteins on the proliferative and inflammatory responses of human keratinocytes.
- To determine if M proteins directly influence keratinocyte activity relevant to skin disorders.
Main Methods:
- Human HaCaT keratinocytes were exposed to various M proteins (M1, M3, M5, M12).
- Proliferative activity was assessed, and inflammatory markers (IL-1α, IL-1β, IL-6, IL-8, TNFα, ICAM-1) were measured using ELISA.
- Purified M protein preparations and recombinant M3 protein were used to isolate the active component.
Main Results:
- Crude M3 protein extract and purified M protein dose-dependently inhibited keratinocyte proliferation (up to 80% at 10⁻⁸ M).
- M1 protein preparation showed 55% inhibitory activity; M5 and M12 had no effect.
- IL-8 and TNFα levels increased, while ICAM-1 decreased in keratinocyte cultures.
- Recombinant M3 protein and M3 purified via ion exchange chromatography did not affect keratinocyte proliferation.
Conclusions:
- A component distinct from the M3 protein itself appears responsible for the observed antiproliferative effects on keratinocytes.
- These findings suggest a complex interaction between streptococcal components and skin cells, potentially relevant to inflammatory skin diseases.
- Further research is needed to identify the specific component responsible for the keratinocyte response.