Cytokines and Growth Factors Wednesday, January 29, 2003

1. Cytokines and Growth FactorsWednesday, January 29, 2003 Leukocytes RBC Platelets

2. “Response to Injury” Thrombin/Clot Formation ____________ cells activated and drawn into wound _________ of fibroblasts, endothelial cells, smooth muscle cells Neovascularization _________ of extracellular matrix Cleaning up the debris ____________/repair tissue to normalcy/scar

3. Introduction Definition- Cytokines are soluble peptides produced by virtually every nucleated cell type in the body that instruct cells to alter their proliferation, differentiation, phenotype, secretion, or migration. Why they exist- Evolution of multicellular organisms required the development of messengers such as hormones and cytokines to coordinate cellular responses.  between hormones and cytokines- Endocrine hormones are generally produced by specialized glands, are present in the circulation and serve to maintain homeostasis.

4. Introduction (continued) In contrast, cytokines usually act over distances as intercellular signals in local tissues, and they occasionally spill over into the circulation and then initiate systemic reactions. Cytokines are generally constitutively produced, but are in emergencies to contend with challenges to the integrity of the host. This is achieved because cytokines mobilize the immune system and they perform damage control and they promote the processes.

5. Historical Perspective Field of cytokine research has evolved from 4 endeavors: --______________ and the field of lymphokine research; --study of interferons; --_____________ growth factors (colony stimulating factors); --growth factors acting on nonhematopoietic cells.  1974-- “cytokine” proposed to denote a protein ________ the growth or functions of many types of cells.

6. Historical Perspective (continued) 1979-- “Interleukin” proposed to develop a system of ____________, based on the ability to act as communication signal between different populations of leukocytes. Some properties are _________ by cytokines and growth factors: -One difference is that the production of growth factors tends to be and not as tightly regulated as that of cytokines. -Another major difference is that growth factors are typically targeted toward cells.

7. Characteristic Features of Cytokines • Cytokines are simple with a MW of ~30 kDa • Constitutive production of cytokines is usually low or absent. • Production is regulated by various inducing stimuli at the level of transcription or translation. • Cytokine production is and the action radius is usually short (typical action is autocrine or paracrinenot endocrine).

8. Characteristic Features of Cytokines (continued) • Cytokines produce their actions by ________ to specific high-affinity cellsurface receptors(Kd10-9-10-12 M) • Most cytokine actions can be attributed to an altered pattern of gene in the target cells: increase (or decrease) in the rate of cell proliferation, change in cell differentiation, or a change in the expression of some differentiated functions. • Although the range of actions displayed by individual cytokines can be broad and diverse, at least some action(s) of each cytokine is (are) targeted at cells.

9. Differences Between Hormones and Cytokines • Hormones Cytokines • Secreted by one type of Made by more than ____ type of cell • ___________ cells • Each hormone is unique in its Structurally dissimilar cytokines have actions an ___________ spectrum of • actions (“redundancy”) • Restricted target cell specificity ___________ target cells and multiple • and a limited spectrum actions (“ambiguity”) • of actions • Act at a distant site (endocrine Usually have a short action _______ • mode of action) (autocrine or paracrine)

10. D Cell Communication Endocrine Autocrine: cell talking to itself via soluble “factors” Paracrine: cell-cell communication via soluble “factors” D D D D TGFb TNFa

11. EGF PDGF IL-1b Cell Communication Juxtracrine: cell-cell communication via membrane bound growth factor precursor on the cell exterior Indirect: Factor A from one cell causes a second cell to release Factor B that causes a response to a third cell

12. Inflammatory Cell Modulation Arachidonic acid/prostaglandin production ( Fast) --Phospholipase A2 stimulation: IL-1b, PDGF, TNFa Degranulation/activation () --Macrophages/monocytes: PDGF --Neutrophils (PMN’s): PDGF, TNFa --Platelets: PDGF, TGFb } Macro- phage Arachidonic acid, Thromboxane, prostaglandin Induces fever PDGF } PMN H2O2, Proteases, Ox. O2 species “Cytotoxic Substances” TNFa

13. Inflammatory Cell Modulation (continued) Chemotaxis ( so Fast) --Macrophages/monocytes: PDGF, TGFb --Neutrophils (PMN’s): PDGF, TGFb --Fibroblasts/endothelium: PDGF, TGFb, EGF, FGF, TNFa . . . . . . . . . EC . . . . . . capillary extravascular . . . . . . . . . TGFb . PMN Fibro- blast migration

14. Inflammatory Cell Modulation (continued) Protein/peroxide synthesis ( Slow) --Macrophage/monocyte (peroxide): TNFa --Fibroblasts/endothelial cells (collagen, ECM proteins): IL-1b, PDGF, TNFa, TGFb, EGF Acts by stimulation of DNA transcription Mitogenesis ( Slow) --Macrophages/monocytes: PDGF (inhibited by TGFb) --Fibroblasts: EGF, PDGF, FGF --Endothelium: IL-1b, TNFa, EGF, PDGF, FGF (inhibited by TGFb)

15. Cytokine Activities Cytokine Network

16. Leukocyte Exudation Cytokine Network in Acute Inflammation

17. Fibrosis

18. Cause of Gene Therapy Death Defies Explanation  18-year old Jesse Gelsinger died from a gene therapy protocol in 1999; he was the first patient to _____ under such therapeutic conditions. He had _____________________ (OTC) deficiency, a rare liver disease. Within 24 hours of being treated, his lungs began to shut down; four days later he died. He had been given the _____________ ever in a human trial for gene therapy, did this high dose cause the death? Many questions, no answers at the time of his death.

19. Cytokines, Cytokines, Cytokines, Cytokines…? Autopsy revealed that all of Gelsinger’s organs were severely damaged, but not from the gene drug! His immune system had attacked/ destroyed his ______. A Penn pulmonary expert remarked about , a quickly fatal lung disease, is marked by an increase in interleukin-6 (IL-6). IL-6 is produced in to infection or other injuries, and prompts inflammation in the lungs, which are very sensitive to this cytokine. Gelsinger’s IL-6 levels were 5x higher than other treated patients, his levels peaked at 6.5 hours after the virus drug, 2 days later ARDS was destroying his lungs.

20. IL-6, IL-10 and Macrophages! Looking back at the patient immediately before Gelsinger, who got the same dose (Jennifer Christenson), they also found very high levels of IL-6 and another . IL-10 IL-6 production when enough has been made. It did what it was supposed to do in Christenson, but not in Gelsinger (his IL-10 was even higher than hers). It said that his body was trying to control the Il-6, but something was stopping it from working.  are a primary source of IL-6 and IL-10; and fluorescently- tagged virus injected into mice, then macrophages in the liver should take up the “tagged-virus”-- they did! Liver macrophages were responsible for the tremendous up-regulation of IL-6 and IL-10 after the virus was infused into Gelsinger’s bloodstream!

21. HIV Disease and AIDS

22. HIV Co-Receptors and Suppressor Molecules HIV of gp120 to CD4 is not sufficient for viral fusion and entry; suggesting a need for an additional cell-surface cofactor. Not all HIV-1 isolates are in their ability to infect CD4+ cells: --virus that only _________ well in T-cells (T cell line-tropic) could not infect monocytes or macrophages; --virus that could infect monocytes/macrophages, do not infect T-cells very well; and --there were “HIV suppressor factors” secreted by CD8+ T-cells in vitro.

23. HIV Co-Receptors and Suppressor Molecules (cont’d) Identity of both the membrane-associated cofactor and the soluble HIV suppressors were long-standing mysteries..… HIV suppressor molecules were identified as , notably RANTES, MIP-1, and MIP-1

24. HIV Co-Receptors and Suppressor Molecules (cont’d) Molecular mechanism of HIV suppressor activity by chemokines has been linked to their chemokine receptors. Chemokines “” the entry of HIV, then HIV may be using the chemokine receptor as a cofactor or a co-receptor for entry. First of these co-receptors to be identified was named “fusin” to denote its function in HIV-1 entry, for -cell tropic forms. Receptor for -tropic virus was also found, CCR5. CCR5 is a chemokine receptor with ligands: RANTES, MIP-1, and MIP-1

25. Chemokine Receptors in Breast Cancer Metastasis It has been recognized for years that ____________ and their receptors control the __________ of leukocytes in the body. Zlotnik and colleagues found that the chemokine receptors CXCR4 and CCR7 are highly expressed in human breast cancer cell, malignant breast tumors and their metastases. Their results suggest that where the ligands of these receptors are expressed, such as lung, liver and bone marrow are all ___________ destinations of metastatic breast cancer cells. This suggests that chemokines and their receptors are __________ of organ specific metastasis.

26. Chemokine Receptors in Breast Cancer Metastasis