Effect of Fasting and Refeeding on T-cell Fate

Background:

Researchers want to better understand the body s immune response to calorie restriction. To do this, they are asking healthy volunteers to fast for 24 hours. Researchers will test immune response before and after fasting.

Objectives:

To explore the benefits of calorie restriction on immune health.

Eligibility:

Healthy volunteers ages 21 to 37 with a body mass index between 22 and 29.

Design:

Participants will be screened with medical history, physical exam, and blood tests.

Participants will visit NIH after an overnight fast. Their baseline immune response will be taken. They will give blood and urine samples. Then they will be given breakfast. This visit will take about 2 hours.

Participants will fast (not eat or drink anything except water) for the next 24 hours. They will return to NIH the next morning. Their immune response will be taken. They will give blood and urine samples. Then they will be given breakfast. Their immune response will be taken 3 hours later. They will give a blood sample. This visit will take about 4 hours.

Intermittent caloric restricted or fasting has numerous health effects including the reduction in numerous cardiovascular and pulmonary disease risk factors. The cellular programs activated by caloric restriction are similarly regulated in preclinical and clinical studies in response to a 24-hour fast. We have found that a beneficial effect of a 24-hour fasting blunts the activation of a component of the innate immune system, termed the NLRP3 inflammasome. This inflammasome, as a mediator of sterile inflammation, is associated with the development of diabetes, asthma and atherosclerosis. At the same time, we found that refeeding after the 24-hour fast significantly increased NLRP3 protein levels. As NLRP3 is increased in obesity, the nutrient intervention (24 hour fast and then refeeding) we studied may be useful to evaluate nutrient-overload effects on the immune system. Pertaining to this it has recently been found in a preclinical study that NLRP3 can also orchestrate differentiation of na(SqrRoot) ve T cells into T(H)2 cells. Interestingly both the NLRP3 inflammasome and T(H)2 cell activation contribute to asthma. In this context we hypothesize that the assessment of the effect on refeeding on T(H)2 cell differentiation (polarity) may allow us to dissect out the mechanisms underpinning nutrient overload induced T(H)2 cell activation. To evaluate this blood samples to test T-cell biology will be collected in subjects, at baseline, after a fixed caloric meal and in response to a 24-hour fast (water intake will not be restricted). The objective of this pilot study is to identify if nutrient-load regulates T-Cell differentiation capacity and to test whether this pathway could be investigated as a therapeutic target to blunt/negate the inflammation associated with nutrient-excess associated diseases including asthma.

Eligibility Criteria:
* INCLUSION CRITERIA:

As this is a pilot study, the age-range and BMI range of subjects will be restricted to potentially reduce metabolic variables associated with a wide age- and BMI-range.

* Males and females between the ages of 21 and 37
* BMI greater than or equal to 22 and less than 30

EXCLUSION CRITERIA:

* Subjects with an acute or chronic illness as per history, on laboratory analysis or due to use of medications
* Subjects taking vitamins or supplements or any medications, except oral contraceptives, within 4 weeks of participation into this study
* BMI less than 22 or greater than or equal to 30
* Female subjects who are pregnant or lactating
* Subjects who have donated blood or participated in another clinical trial involving blood draws in the last 8 weeks
* Subjects who use nicotine products