Questions about Angiogenesis?

[Kumar]

Hello,

I am trying to understand Angiogenesis deeply. There can be two conditions for which I want to know as under:-

1. When angiogenic growth factors are produced in excess of angiogenesis inhibitors (may be under presence of strong/suitable immune system):-

Can Angiogenesis be immune system oriented & meant for transmission of immune defence agents in tumor to kill cancer cells within tumor when immune system is being strengthened-naturally or medicated?
OR
Can Angiogenesis be meant to encourage cancer cell to come out of tumor & exposed to immune system to handle them by it, in case of immune system is being strengthened-natural or medicated?

2.When stimulators are present in excess of inhibitors (may be under weak immune system pursued by cancer cells or weak surrounded tissues):-

Will Angiogenesis be cancer cell/surrounded weak tissue's oriented which will aid to cancer progression & spread?

Are angiogenic growth factors and angiogenesis inhibitors are tissue/cancer specific & if can be measured in lab?

I think Angiogenesis is not considered as a part of immune respose/system but It should be. I also think that, it is not yet suitably documented/researched about, what happens to tumors & other latencies on immune system is being naturally strengthened?

Being important & dynamic thoughts, I request you to reply to above questions after deep thinking.

Ref:

Angiogenesis: http://www.angio.org/understanding/understanding.html

The immune system:http://www.cancerhelp.org.uk/help/default.asp?page=118

Best wishes.

Edited to correct.

 

[Hercules Rockefeller]

I think Angiogenesis is not considered as a part of immune respose/system but It should be.

I do not believe that anyone considers angiogenesis to be a part of the immune system. From reading your post I think you have one major misunderstanding of the process of vasculogenesis and angiogenesis – they are embryonic processes. Once the vascular system is formed during embryonic development, angiogenesis ceases. In other words, angiogenesis does not occur in an adult except in some specific instances.....

(i) tissue regeneration during wound healing

(ii) placental formation during pregnancy

I can see why you are linking the immune system with angiogenesis. When tissue is damaged by infection or acute injury, cells that are short of oxygen increase their concentration of hypoxia-inducible factor 1 (HIF-1), which stimulates the production of vascular endothelial growth factor (VEGF). VEGF acts on endothelial cells, causing them to proliferate and invade the hypoxic tissue to supply it with new blood vessels. But whilst the immune system might use the newly formed blood vessels to transport immune system components to the site of infection or injury, the biochemical processes of angiogenesis are separate to the immune system (as far as I know). In other words, there is no feedback or communication between the two systems.

(I stand to be corrected by something with more specific knowledge of this topic.)

Of course, there is another significant example of angiogenesis in an adult, one that is not part of normal physiological functioning – solid tumor formation. Angiogenesis is critical in the growth of any tissue, including tumors. Tumors are "successful" only when they are able to direct blood vessels into them. Therefore, tumors must secrete angiogenesis factors if they are to grow beyond a certain size. aimed at preventing tumor growth and metastasis. Anti-angiogenesis therapies probably represent the closest thing we have to a “magic bullet” cancer treatment (ie. a treatment that specifically targets cancer cells and not any ‘normal’ cells of the body) because in an adult the only cells producing angiogenic factors will be the tumor cells.<P>

 

[Kumar]

Hercules Rockefeller, Thanks. But what keep/trigger a balance or imbalance of angiogenic growth factors and angiogenesis inhibitors in cancer? Let us look at the other side:-

1a. When angiogenic growth factors are produced in excess of angiogenesis inhibitors (may be under presence of weak/unsuitable immune system & initiated by cancer cells or weak surrounded tissues):-

Will it cause Angiogenesis to progress & spread the disease/cancer?

2a.When inhibitors are present in excess of stimulators(may be under strong/suitable immune system initiated by immune system):-

Will it not inhibit/cure the disease/cancer in tumor, by starving cancer cells of oxygen & nutrients?

I think the purpose of tumor forming or creating other latencies are "immune system's oriented" for the purpose (a) To restrict their growth by encapsuling them (2) To starve them from Oxygen & nutrients (3) To wait till immune strength is suitably strengthened to handle/kill those cancer cells/disease causing agents, when it can't handle evading disease causing agents on their initial exposures.

It can be important to understand, what happens when immune system is strenthened-naturally or medicated? How Biological/Immunotherapy works? Does it handle disease causing agents/cancer cells when these are still in latent condition/tumor or resurface & expose them to immune system by presenting an impression of spread of disease? If in encapsuled state, does it handle/kill them by trasmission of immune agents within tumor by encouraging Angiogenesis OR starving them to death by discouraging Angiogenesis??

 

[zyncod]

Actually, the immune system is pretty intimately linked with angiogenesis. When lymphocytes extravasate from vessels to surrounding tissue, they activate endothelial cells and cause remodeling of the vascular architecture. Circulating endothelial cell precursors are activated by cells like granulocytes and dendritic cells to form new vessels. And recent research (a few months ago) is indicating that, in tumors at least, dendritic cells can actually form new vessels. And there is a VEGF system that is wholly relegated to the immune system - VEGFR3 and VEGF-C control lymphatic vessel growth.

And there's one other instance of angiogenesis and lymphangiogenesis in adults- immune responses. When you get sick and your lymph nodes grow (those lumps on your neck that the doctor palpates), the blood vessels must also grow to supply the increased amount of oxygen and nutrients that the recruited leukocytes will require.

As far as your questions go - the immune response is actually detrimental in terms of angiogenesis. Interleukins secreted during an inflammatory response to, say tumor cells, will tend to downregulate angiogenesis inhibitors. And if the dendritic cells are forming new vessels, recruitment of these cells to an inflammation will tend to increase angiogenesis and perhaps make the tumor worse.

 

[Kumar]

zyncod,

Thanks for reply. But, how strengthened immune system-medicated or natural, can handle/kill cancer cells still within tumor esp. when bilological immunotherapy is tried?

By tumor forming, we can understand that immune system is recognizing caner cells as diiferent and is doing its work by resisting or restricting cancer cells and starving them, but how improved immune system can kill them entirely?

It may be a delicate question to know, whether coming out of cancer cells are for progress of disease or for exposure to immune system unabling it to kill them.

 

[Kumar]

One more aspect to think:-

We may need to understand about cancer & other latent conditions more deeply--what is body's immune defence mechanism on strengthning of it--medicated or natural? Whether strong immune system can handle cncer cells within tumor or they need to be exposed & come out of tumor unabling to kill them by immune system? Can immune system kill cancer cells within tumor, when it is suitably strong or not?

Taruma, injury, stresses, infections etc. can weaken immune system, so we should understand surgery to this effect AND SO THESE and wounds may encourage angiogenesis. I feel angiogenesis may be encouraged both on weakening the immune defence systemAND may be on strengthening it--as a direction towards progress of disease or probably as a direction towards cure.