Fish Oil for HIV-Related Inflamm-aging and Immune Senescence

Due to treatment advances, the number of persons > 50 years old who are living with HIV/AIDS in the United States (US) has steadily increased. African Americans (AA) represent a disproportionate number of HIV/AIDS cases in this age group, with infection rates 12 times higher than among whites (51.7 per 100,000 compared to 4.2 per 100,000). Limited data suggest that older HIV+ AA are characterized by health status disparities. One cohort study of older, largely minority HIV+ persons (N=121, AA=83%;mean age=54), found that 34% had metabolic syndrome and 50% had a Framingham Cardiac Risk score > 10%. HIV+ older adults of all races show a premature onset of other age-associated co-morbidities, such as osteoporosis, non-AIDS malignancies, and cardiovascular disease (CVD). These co-morbidities have been linked to persistent inflammation and persistently elevated serum levels of proinflammatory cytokines that mimic an aging phenotype known as "inflamm-aging." In both middle-aged HIV+ persons and older HIV seronegative adults, inflamm-aging is associated with more limited T cell repertoires and increased risk for morbidities and mortality. In HIV infection, inflamm-aging is postulated to be maintained (a) by the constant antigen burden imposed by HIV and other chronic viral co-pathogens, such as cytomegalovirus (CMV), and (b) by HIV-induced disruption of intestinal epithelial integrity with subsequent translocation of gut microflora into the systemic circulation. Our hypothesis is that inflamm-aging is responsible for the premature immune senescence associated with HIV infection in aging individuals. Immune senescence, characterized by diminished replicative capacity, has been observed in middle-aged persons treated with highly active antiretroviral therapy (HAART) who achieve immune reconstitution and undetectable viral loads. Senescent cells are characterized by the absence of the surface marker CD28, and in advanced senescence express CD57 (CD28-/CD57+ phenotype). Because premature senescence leads to loss of anti-HIV cell-mediated immune responses and accelerated HIV disease progression,there is an urgent need to test new treatment strategies to reduce inflamm-aging and subsequent immune senescence.

Fish oil may be an effective treatment option for reducing HIV-related inflamm-aging. Cold water fish are rich in the omega-3 highly unsaturated fatty acids (HUFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which have anti-inflammatory effects. When consumed as fish or fish oil supplements, EPA and DHA replace arachidonic acid in cell membranes and inhibit the synthesis of proinflammatory arachidonic acid metabolites, such as prostaglandins and leukotrienes. Moreover, animal and in vitro studies have shown that EPA and DHA stimulate regeneration of intestinal mucosa damaged by methotrexate,16 IL-4, and experimental ulcerative colitis. Yet, to date, no studies have been conducted on the effects of fish oil for reducing HIV-related inflamm-aging and reversing immune senescence.

The purpose of this study is to explore the safety and estimate the effect size of fish oil to modulate parameters of inflamm-aging and immune senescence in HIV+ older adults. Participants will receive either 1.6 grams of omega-3 fatty acids (800 mg of EPA, 600 mg DHA, 200 mg other omega-3 fatty acids) or placebo for 12 weeks. We expect to find a reduction in inflammatory markers and the percentage of CD8+ and CD4+ T lymphocytes that exhibit a senescent phenotype in the fish oil condition, but not in the control condition, at 12 weeks. We expect to find no difference between the conditions on the safety parameters at 4 and 12 weeks.

The specific aims are:

Aim 1. To assess the safety of the fish oil condition by comparing it to the control condition at 4 and 12 weeks, controlling for covariates (demographics, lifestyle, medications including HAART, fish oil supplement adherence, intercurrent illnesses), on

1. HIV disease parameters (CD4+ T cell counts and HIV RNA levels)
2. Drug toxicity (liver function tests and serum creatinine)
3. Adverse events (e.g., diarrhea, vomiting)

Aim 2. To estimate the effect size of the fish oil condition at 12 weeks, controlling for covariates, by comparing the following cell surface molecules and intracellular and soluble inflammatory markers before and after fish oil

1. Markers of immune senescence on CD8+ T lymphocytes: percentage of CD8+/CD28- T lymphocytes, a phenotype of immune senescence (primary outcome); percentage of CD8+/CD28-/CD57- T lymphocytes (an intermediate senescent phenotype); percentage of CD8+/CD28-/CD57+ T lymphocytes (a terminally differentiated senescent phenotype)
2. Markers of immune senescence on CD4+ T lymphocytes: percentage of CD4+/CD28- T lymphocytes; percentage of CD4+/CD28-/CD57- T lymphocytes; percentage of CD4+/CD28-/CD57+ T lymphocytes
3. Markers of inflammation: plasma hsCRP and intracellular concentrations of TNF-alpha, IL-6, and gamma IFN

Aim 3: To estimate the effect size of the fish oil condition at 12 weeks on gut permeability, controlling for covariates, by comparing the following indirect markers of gut permeability before and after fish oil

1. Endotoxin
2. Soluble mouse CD14
3. Endotoxin binding antibody
4. Lipopolysaccharide binding protein