Chemotaxis and its significance in biology and clinics

1. Chemotaxis and its significance in biology and clinics Dr. habil. Kőhidai László 2012.

2. Other Cell-physiological effects (e.g. proliferation) Adhesion Chemotaxis Phagocytosis

3. Chemotaxis – Significance in biology • Helps to distinguish / to approach food molecules • Helps to avoid biologically harmful/toxic substances • Sperm to approach oocyte - fertilization • Tissue transformation processes (e.g. CNS) • Immune reaction of multicellular organisms • Proliferation and growing of tumors, formation of metastasis

5. Chemorepellent materials Chemoattractant materials

6. Basic concepts – Definitions 1 Chemotaxis: Migratory response of self-directed, motile cells. Direction and speed of migration is influenced by the concentration of molecules solved in the environment. VECTORIAL movement

7. Chemotaxis

8. Basic concepts – Definitions 2 Chemokinesis: Characteristic parameters (speed, frequency, amplitude) of motile cells are randomely changing due to the influence of environmental factors. NON vectorial !

9. Chemokinesis

10. Chemotaxis – Induced by dissolved molecules Concentration of meolacules inducing migration

11. Effect of molecules bound to the surface Haptotaxis Concentration gradient of molecules bound onto the surface

12. Necrotaxis LASER Migration of cells is modulated (induced or blocked) by the biologically active substances released from the dead cells.

13. Nekrotaxis

14. Conditions of migration • Ligands/substances inducing the migration • Motile cells • Receptors capable to detect ligands • Effector mechanisms – e.g. cytoskeletal system

15. Main steps accompanying receptor dependent migration of eukaryotes • Deformation of the cell • Cell adhesion • Cilliary/ flagellar movement

16. Chemotactic substances

17. Main groups of chemoattractant ligands • ions of inorganic salts (K+, Cl-) • amino acids (methionine, serine) • biogenic amines • oligopeptides (bacterial tripeptides) • hormones (insulin) • chemokines (interleukin 8) • feromones • synthetic substances (drugs)

18. Target cells

19. bacteria amebas ciliated eukaryotes „Classical” target cells

20. Target cells in higher ranked organisms neutrophil granulocyte endothel monocyte eosinophil granulocyte lymphocyte

21. Receptors

22. Ligand • Hormone • Immune • Nerve system • Drug Location • Surface membrane • Cytoplasme • Nucleus Receptor classes

23. Main characteristics of receptors • Specificity – structure • Affinity – effect at low conc. • Saturabiliy – number of receptors • Reversibility • Specific response of the cell