A Dynamic Functional Immune Assay To Evaluate The Immune Response Of A Patient With Diabetes And A Foot Infection
Posted Date: Aug 26, 2020
- Investigator: Michael Liette
- Type of Study: Observational/Survey
There is a worldwide epidemic of diabetes. According to data from the World Health Organization, the world prevalence of diabetes among adults was 6.4% in 2010, affecting 285 million adults worldwide. The prevalence of diabetes is expected to increase to 7.7% by 2030 (439 million adults). In the United States, the prevalence of diabetes increased by 26% from 2007 to 2012, and the associated cost of managing this disease increased from $174 to $245 billion (41% increases) in the same time period. The U.S. Centers for Disease Control and Prevention estimate that 26 million people in the US have diabetes. By 2034 this is expected to increase to 44 million people. Diabetic foot infections are a common, costly, and life altering complication. One of the most frequent causes of hospitalization among persons with diabetes is an infected foot wound. In the United States, approximately one-quarter of the costs associated with diabetes mellitus is spent on lower extremity manifestations of diabetes. The incidence of diabetic foot ulcers in Medicare enrollees is about 7% per year. The incidence of lower extremity amputation is 0.5-1.0% per year (>130,000 amputations a year). The annual mortality rate for persons with diabetes with foot ulcers is about 11%; after amputation mortality doubles. Functional immune compromise has been studied in the sepsis literature and this work shows promise for application in the diabetic foot infection patient base. Enzyme-linked immune absorbent spot (ELISpot) is a highly sensitive immunoassay that measures the frequency of cytokine-secreting cells at the single-cell level. A key advantage of ELISpot is that the assay has excellent dynamic range. ELISpot can detect as little as 1 cytokine secreting cell in 100,000 cells or as many as several thousand cytokine secreting cells per individual chamber well. In addition to detecting the number of cytokine secreting cells, the relative amount of cytokine that is produced by each cell can be determined by quantitating the area of each spot expressed as µm2. Importantly, ELISpot is technically much easier to perform than other methods that are used to quantitate cytokine production such as flow cytometry. Furthermore, because ELISpot can quantitate the total amount of cell cytokine production over an extended period (=24 hours), it is more sensitive at revealing group differences in cell function compared to other methods employing shorter incubation times. Diluted blood is incubated overnight on plates coated with a specific capture antibody in the presence or absence of stimuli. Another major advantage of ELISpot is that it can independently assess the functional status of the two major arms of immunity. The functional state of adaptive immunity can be evaluated by anti-CD3/CD28 stimulated IFN-? production, while innate immunity is evaluated by lipopolysaccharide (LPS) stimulated monocyte production of TNFa. Additional advantages of ELISpot are that it allows for clinicians to follow the condition of the patient’s immune status serially over time. Preliminary data from our laboratory indicate that septic patients whose ELISpot shows changes from baseline immunity of T cell and/or myeloid cell-stimulated cytokine production have a higher incidence of secondary hospital-acquired infections and high mortality. Therefore, ELISpot may provide insight into selection of the personalized immune therapeutic to treat the immune dysfunction in individual patients. Although functional assays have been used as predictive or prognostic biomarkers, they have not been readily amenable to clinical development. ELISpot technology, however, is already FDA-cleared, 510(k) instrumentation is readily available, and can be readily applied to the clinical setting.
Patients May Be Considered For Inclusion If They Are Patients Of The Investigators, Male Or Female, Ages 18-89 Years Old, A Documented Diagnosis Of Type 1 Or 2 Diabetes Mellitus, And Presentation With A Level 3 Or Greater Foot Infection As Defined By The Infectious Diseases Society Of America. Patients Are Ineligible If They Have A History Of Solid Organ Transplantation, On Immunosuppressant Therapy, On Chronic Steroid Therapy, Active Charcot Arthropathy, Does Not Wish To Proceed With Standard Of Care Treatment Of The Foot Infection, Unable To Keep Follow Up Appointments, Patient Whose Initial Surgery Is A Major Lower Extremity Amputation, Or A Diagnosis Of Hiv Or Aids.
Foot Ulcer, Infection, Diabetes
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