Inflammation is an important part of immune defenses against infectious disease, but inflammation may also contribute to the development of chronic degenerative diseases, including cardiovascular disease and diabetes. Historically, humans have lived in environments characterized by high levels of microbial exposure and high rates of mortality due to infectious disease, yet current understandings of inflammation are based primarily on research in industrialized settings with low levels of infectious disease. Methodological obstacles associated with blood collection in non-clinical settings contribute to the limited range of current research. This project is investigating levels of inflammation in an Amazonian population experiencing high levels of infectious disease and validating "field-friendly" methods for measuring pro- and anti-inflammatory cytokines in non-clinical settings. Health-related information and dried blood spot (DBS) samples (drops of whole blood collected on filter paper following a simple finger stick) are collected repeatedly over an 8 week period from fifty adults in remote lowland Amazonia. These samples are measured for C-reactive protein, a key biomarker of inflammation, in order to document levels and patterns of inflammatory activity. In phase two of this project, the researchers are developing methods for quantifying cytokines in the DBS samples taken from these fifty individual.
Results from this project directly address current scientific debates regarding the links among ecology, inflammation, and disease, and advance anthropological research in human ecological immunology. In addition, the development of minimally-invasive methods for measuring cytokines in a single drop of blood will promote future research on inflammation internationally, as well as in community-based settings in the United States. A better understanding of the factors that shape the regulation of inflammation may have significant implications for the prevention and treatment of disease.
Inflammation is an important part of our body’s immune defenses that provide protection against infectious disease. However, recent research has indicated that chronic activation of inflammatory processes can do more harm than good, and can increase risk for a wide range of diseases of aging, including cardiovascular and metabolic diseases. Current scientific understandings of inflammation are based primarily on research conducted in affluent industrialized settings, even though historically, humans have lived in environments characterized by much higher levels of microbial exposure and mortality due to infectious disease. Methodological obstacles associated with blood collection in non-clinical settings contribute to the limited range of current research. The goal of this project was to address both these shortcomings. We conducted a repeat-measures study of C-reactive protein (CRP), a commonly used biomarker of inflammation, in a high infectious disease environment in the Amazon basin. Dried blood spot samples—drops of whole blood collected from a simple finger stick and dried on filter paper—were collected from 52 adults at four weekly intervals. Concentrations of CRP were analyzed in the lab, and the results revealed a pattern of CRP variability that is fundamentally distinct from prior research in the US. At each time point there were substantial numbers of adults with elevated CRP, but no adult had elevated CRP across 2 or more weeks of the study. Prior research in the US has indicated that about 1/3 of adults will have chronically elevated concentrations of CRP. In contrast, we found not a single case of chronic inflammation in this high infectious disease environment. This pattern of results suggests that high levels of microbial exposure in infancy, during critical periods of immune development, have lasting effects on the regulation of inflammation in adulthood. In addition to this field-based study, we worked in the lab to validate new methods for measuring inflammatory cytokines in dried blood spot samples. Dried blood spots facilitate field-based research on human biology because the costs and burdens associated with blood collection are much lower than venipuncture-based methods that are typically used in the clinic. Cytokines are important because they are the signals that turn inflammation on and off. We developed a method for quantifying IL6—a key pro-inflammatory cytokine—that has a lower detection limit of 0.67 pg/mL, high correlation with gold-standard serum results (R=0.88), and levels of within-assay and between-assay variation that indicate high precision and reliability. This project was significant because it studied the dynamics of inflammation in an ecological setting more representative of past human environments, where the impact of high microbial environments on patterns of CRP and cytokine production can be evaluated. The results advance anthropological research in human ecological immunology and evolutionary medicine, and may inform future efforts to prevent and treat inflammation-related diseases. In addition, the development of minimally-invasive methods for measuring cytokines in a single drop of blood will promote future research on inflammation in diverse ecological settings. Lastly, the project has contributed to the infrastructure of science by providing substantive training opportunities for three students (all of whom represent an under-represented group in science).
