Soluble interleukin-1 receptor type II, IL-18 and caspase-1 in mild cognitive impairment and severe Alzheimer's disease.

In the present study, we have determined levels of soluble interleukin-1 (IL-1) receptor type II (sIL-1RII), interleukin-18 (IL-18) and caspase-1 in cerebrospinal fluid and serum from mild cognitive impairment patients that later progressed to Alzheimer's disease (AD) and severe AD patients. Previous studies have shown that a chronic local inflammatory process is a part of AD neuropathology. In this process, activated microglial production of IL-1 seems to play an important role. In a previous study, we have shown increased levels of sIL-1RII in CSF from AD patients in a mild-moderate disease stage. In the present study, we found no significant differences in CSF or serum levels of sIL-1RII in either mild cognitive impairment or advanced AD patients as compared to control subjects. Likewise, there was no significant difference between mild cognitive impairment and severe AD patients. The same was true for caspase-1 and IL-18 serum levels, whereas CSF levels of caspase-1 and IL-18 were below detection limits. Our data indicate that the IL-1 system is relatively intact in the early and late stages of AD.