Studies on cytokines and chemokines in cerebrovascular diseases and experimental cerebral ischemia hypoxia and anoxia

Ischemic brain injury secondary to arterial occlusion, a major cause of

Stroke, is characterized by acute local inflammation, which involves the

Accumulation of polymorphonuclear neutrophils and other immune cells.

Tissue damage resulting from ischemic stroke can be reduced in

Experimental animal models by blocking leukocyte accumulation. Cytokines

And chemokines are factors that regulate leukocyte trafficking, and could

Play a pivotal role in the accumulation of leukocytes at sites of brain

Ischemia. The factors responsible for secondary brain damage in cerebral

Ischemia are incompletely defined, and studies in human stroke on


Cytokines and chemokines have been few.

Aims of the study

1. To investigate mrna expression of the chemokines IL-8, MCP-1,

hypoxia and anoxia

MIP-1alpha and MIP-1beta by blood mononuclear cells (MNC) in patients

With acute ischemic stroke and healthy controls;

2. To study mrna expression of IL-8 and MIP-1alpha in parallel with the

Pro-inflammatory IL- I beta and IL- 17 by blood MNC in a prospective

Study of ischemic stroke;

3. To investigate cytokines with anti-inflammatory properties, like IL-4

And IL-10 secreted by blood N/fnc from patients with acute stroke vs.

Healthy controls, using ELISPOT assays;

4. To examine leukocyte and cytokine alterations both systemically and

Locally in the brain over the course of an experimental rat model of

Permanent middle cerebral artery occlusion (pmcao);

5. To analyze involvement of dendritic cells (DC) in pmcao in the rat.Hypoxia and anoxia

Results

Ischemic stroke in the human is associated with high numbers of IL-8 mrna

Expressing blood MNC over the time interval of 1-7 days between onset of

Symptoms and examination. IL-8 concentrations in plasma correlated

Positively to IL-8 mrna expressing blood MNC in examined patients.

In the prospective ischemic stroke study, most patients with ischemic

Stroke had clearly elevated numbers of IL- I beta, IL-8 and IL- 17 mrna

Expressing blood MNC 1-3 days after onset of symptoms compared to healthy

Controls. At follow-up after 20-31 days, numbers of IL-8 mrna expressing

Blood MNC were lower than during the acute stage, and numbers of IL- I

Beta and IL- 17 mrna expressing blood MNC had returned to levels in

hypoxia and anoxia

Healthy controls. Numbers of MIP-1alpha mrna expressing blood MNC did not

Differ between patients with ischemic stroke and healthy controls at any

Timepoint examined.

IL-10-secreting blood MNC are elevated in patients with ischemic stroke

As well as in intracerebral hemorrhage when examined up to 10 days after

Symptom onset. Levels of IL-4 secreting blood MNC are not different in

Stroke compared to healthy controls.

Elevated levels of IL-17 and IFN-gamma mrna are observed both in the

Ischemic hemispheres vs. Sham, and systemically at 1 h to 6 days after

Experimental pmcao. Increased levels of T cells expressing IL-17,

IFN-gamma IL-8, MIP-2 and IP-10 mrna in the ischemic vs. Sham hemispheres

Are present in cerebral ischemia.Hypoxia and anoxia

OX 62+ DC are present at 1 h in the ischemic hemispheres, peaking at 6

Days after pmcao. Activated DC, expressing MHC class II (OX 62+OX 6),

Peak at 6 days in the ischemic vs. Sham hemispheres. Microglia develop

Into OX 62+ DC in the ischemic hemispheres during the course of cerebral

Ischemia.

Conclusions

Systemic increases of pro-inflammatory IL-8, IL-1beta and IL-17, and the

Anti-inflammatory cytokine IL-10 early after human ischemic stroke

Indicate a role for these mediators in potentiating the inflammation

Secondary to brain ischemia. This is further supported by upregulated

MRNA levels of these and other cytokines and chemokines in the ischemic

Hemispheres and systemically of pmcao-operated rats. Increased levels of

hypoxia and anoxia

T cells expressing cytokines and presence of DC indicate a role for these

Immune cells in cerebral ischemia.

List of papers:

I. Kostulas N, kivisakk P, huang Y, matusevicius D, kostulas V, link H (1998). Ischemic stroke is associated with a systemic increase of blood mononuclear cells expressing interleukin-8 mrna. Stroke 29(2): 462-6

Pubmed

II. Kostulas N, pelidou SH, kivisakk P, kostulas V, link H (1999). Increased IL-1beta, IL-8, and IL-17 mrna expression in blood mononuclear cells observed in a prospective ischemic stroke study. Stroke 30(10): 2174-9

Pubmed

III. Pelidou SH, kostulas N, matusevicius D, kivisakk P, kostulas V, link H (1999). High levels of IL-10 secreting cells are present in blood in cerebrovascular diseases.Hypoxia and anoxia eur J neurol 6(4): 437-42

Pubmed

IV. Li H, kostulas N, huang Y, xiao B, van der meide P, kostulas V, giedraitas V, link H (2001). IL-17 and IFN-gamma mrna expression is increased in the brain and systemically after permanent middle cerebral artery occlusion in the rat J neuroimmunol 116(1): 5-14 (in print)

Pubmed

V. Kosulas N, li HL, huang YM, xiao BG, kostulas V, link H (2001). Dentric cells are present in the ischemic brain after permanent middle cerebral artery occlusion. (submitted)