ML Watson Lec 5

Question 1

In RA, activated tissue cells produce ______ (especially ______)

Answer 1

Chemotaxins

- Especially chemokines

Question 2

Chemokine attract leukocytes such as n____, m____ and _ and _ _____

Answer 2

Neutrophils, monocytes and T and B lymphocytes

Question 3

Tissue cells and invading leukocytes can be further activated after being attracted to the synovium leading to the product of…

1) Cytokines (TNFalpha and IL-1b)
2) Chemoattractants
3) P______
4) R______ O____ and N_____ S_____

Answer 3

Proteases

Reactive Oxygen and Nitrogen Species (RONS)

Question 4

Cartilage is made by _____ in the matrix

Answer 4

Chondrocytes

Question 5

Joint cartilage comprises mainly

1) F____ _____ (collagen)
2) P_______

Answer 5

Fibrous Protein (collagen)
Proteoglycan

Question 6

Bone is a dense connective tissue made up of cells and matrix it comprises:

1) Mineralised (C_____ P____) matrix
2) Fibrous protein C_____

Answer 6

Mineralised Calcium Phosphate Matrix

Fibrous protein - Collagen

Question 7

______ break down bone when activated by cytokines (that may be released from T cells and macrophages)

Answer 7

Osteoclasts

Question 8

Osteoclasts release

1) ____ _____
2) _ _ _s
3) ____ _____

Answer 8

1) Carbonic anhydrase - H+
2) Matrix metallo proteinases
3) Cysteine proteases

Question 9

P____ is lost rapidly in RA

• Shock absorption is impaired
• Loss of joint function, pain

Answer 9

Proteoglycans

Question 10

P______ breakdown proteoglycans (in cartilage)

Answer 10

Proteinases

Question 11

Native collagen is only susceptible to degradation by ______

Answer 11

Collagenases

Question 12

S_____ F_____ secrete the following when activated:

• Lipid mediators (PGE2)
• Cytokines (IL-6, IL-8, etc.)
• Enzymes
• Matrix materials

They act to ‘nurse’ T cells and may exhibit ‘malignant’ phenotype

Answer 12

Synovial Fibroblasts

Question 13

Proteoglycan has a ‘shock absorber’ function

1) - It consists of chondroitin sulphate (polysaccharide) linked to ______ (core protein)
2) - It is charged (as it is highly S______ ) and binds water

What happens if it breakdown and cannot bind water?

Answer 13

1) Aggrecan
2) Sulphated

Friction in the joint will increase

Question 14

MMPs are activated by removal of the propeptide.

This is done by S____ P_____

Answer 14

Serine Proteases

Question 15

What is important on a matrix metalloproteinases’ domain structure for specificity and regulation?

Answer 15

• The C terminus

Question 16

What is the active site on a MMP?

Answer 16

Zn+

Question 17

What series of MMP inhibitors target the active site?

Answer 17

• Hydroxamate series e.g marimastat

Question 18

What are MMPs inhibited by?

Answer 18

• TIMPs - tissue inhibitors of Metallo-Proteinases

Question 19

Synthetic MMP inhibitors include Peptidomimetics. What acid are these based on?

Answer 19

• Hydroxamic acid based molecules
• Zinc binding
• Mimic MMP substrate - collagen
• Inhibit MMP activity

Question 20

Give an example of a Peptidomimetic that lacks specificity and acts on most metalloenzymes (similar structure to the substrate that acts on Zn binding region)

Answer 20

• Marimastat

Question 21

Give an example of a Non-peptide hydroxamate that is involved in Zn binding by binding to the MMP active site.

Answer 21

• Prinomastat

Better selectivity for collagenases

Question 22

Name the last type of MMP inhibitor after Peptidomimetics and Non-peptide hydroxcamates…

Answer 22

• Tetracycline and derivatives e.g Doxycycline (periostat)

Used in periodontal and skin disease

Question 23

Name 3 roles the MMP’s have in the body involved with homeostatic connective tissue turnover…

Answer 23

1) Embryogenesis
2) Wound healing
3) Growth and repair

Question 24

Serine and Cysteine proteases are products of _____?

Answer 24

• Leukocytes

Question 25

Give an example of 3 Serine and Cysteine proteases that break down matrix proteins such as elastin, laminin and Chondroitin sulphate and proteoglycans.

Answer 25

1) Neutrophil elastase 2) Cathepsin G 3) Kallikrein

Question 26

What are Serine and Cysteine proteinases inhibited by endogenously? How are these inhibitors inactivated?

Answer 26

Serpins (SERine Protease INhibitors) - Inhibited by oxidation

Question 27

What produces RONS?

Answer 27

- Infiltrating leukocytes and tissue resident cells

Question 28

- NADPH catalyses formation of ______ (O2-) - O2- dismuted to form _____ H2O2 - H2O2 further decomposes to form - hydroxyl radical OH - hypohalous acids e.g HOCl- - These are powerful anti-bacterial agents

Answer 28

- Superoxide | - Peroxide

Question 29

Leukocytes phagocytose: - Bacteria - Yeast - Immune complexes - DAMAGED TISSUE (produced in response to this) What do leukocytes generate as part of their defence?

Answer 29

- ROS - Reactive oxygen species - These are released into the joint space and cause further damage and inflammation

Question 30

Rheumatoid synovial tissue undergoes cycles of hypoxia and reperfusion leading to oxidative stress. This can cause immune complex formation in some diseases leading to the generation of... S______ (O2-), H2O2 and NO

Answer 30

Superoxide

Question 31

Superoxide (O2-), ____ and __ can: - Mediate important cell functions - Promote formation of hydroxy radical (OH), peroxynitrite (ONOO-) - Tissue injury, modulation of cell function

Answer 31

1) H2O2 | 2) NO

Question 32

RONS can lead to DNA damage and activation of inflammatory gene transcription (NFkB) RONS can also cause amino acid modifications that can make host proteins immunogenic and inactivate serpins What happens when serpins are inactivated?

Answer 32

- Inactivation of serine protease inhibitors causes serine proteases to continue breaking down peptides in cartilage and bone

Question 33

Tissue damage in RA: 1) Inflammatory mediators and RONS from infiltrating leukocytes act on resident cells such as C_____, O_____ and F_____ 2) These produce Proteases, MMPs, Elastases and _ _ _s and so do infiltrating leukocytes 3) These destroy cartilage and bone

Answer 33

- Chondrocytes, osteoclasts and fibroblasts | - RONs (reactive oxygen and nitrogen species)