R01AR079298

Predictors of Antiretroviral Immunereconstitution Bone Loss - The Gut and the Microbiome

The premise of this work is anchored on the observation by our group and others that:

A) Prior to treatment, the HIV virus inflicts bone loss in persons living with HIV (PWH).

B) Antiretroviral therapy (ART) inflicts additional acute bone loss, but the magnitude of this loss varies widely from person to person, ranging from mild to profound, and occurs within a defined window (~6 months) following ART initiation.

C) As PWH age, HIV/ART-induced bone loss is compounded by natural aging bone loss.

We contend that the acute ART-induced bone loss is due to immune reconstitution and is driven by T cell activation in response to microbial antigens and intensified by HIV-induced gut damage and microbial translocation. Importantly, as this acute bone loss is driven by immune activation, even newer ART drugs cause severe bone loss in susceptible patients. Of note, immune activation driving inflammation is antigen-dependent. T cells recognize antigens via a vast repertoire of unique T cell receptors (TCRs).

Although ART leads to partial T cell recovery, as the adult thymus is atrophic, T cells repopulate mainly via homeostatic expansion of preexisting memory T cells rather than de novo. ART, thus, likely expands T cell clones that have survived HIV as they are hyper-reactive to persistent self- and foreign-antigens. Microbial translocation due to HIV-induced gut damage may intensify inflammation.

Another interesting feature of the gut-immune interaction is Th17 T cell expansion and translocation to the bone marrow where they secrete the osteoclastogenic effector RANKL, as well as IL-17A and TNF, both potent inducers of RANKL. Further, LPS, a marker of gut permeability, is an inflammatory product that promotes bone loss through osteoclastogenic cytokines, including IL-1, IL-6, TNF, and/or direct osteoclast effects via toll-like receptors including TLR4. It is therefore likely that HIV-induced gut damages enhance inflammatory bone loss.

Gut-immune interaction may thus explain the inter-subject variability noted in immune reconstitution bone loss (IRBL) as gut leakiness and microbiome profile vary widely among PWH.

In this application, we therefore propose a mechanistic animal study to establish a role for antigen presentation and microbiota in a mice model of IRBL (Aim 1), and a complimentary human clinical study to validate the role of microbiota, Th17 cells, and gut permeability in ART-induced IRBL in PWH (Aim 2).

Upon completion, we expect to establish strong relationships between gut leakiness, intestinal microbiota, immune activation, and IRBL and demonstrate that these relationships vary widely from person to person. Findings from this work will contribute to ongoing efforts aimed at identifying PWH at risk for severe IRBL and provide strong rationale for exploring targeted preventive interventions including probiotics and/or CD4+ Th17/IL-17A inhibitors.

Emory University

THE NATIONAL INSTITUTE OF AND MUSCULOSKELETAL AND SKIN DISEASES (NIAMS) MISSION IS TO SUPPORT RESEARCH INTO THE CAUSES, TREATMENT, AND PREVENTION OF ARTHRITIS AND MUSCULOSKELETAL AND SKIN DISEASES, TRAINING OF BASIC AND CLINICAL SCIENTISTS TO CARRY OUT THIS RESEARCH, AND DISSEMINATION OF INFORMATION ON RESEARCH PROGRESS IN THESE DISEASES. THE EXTRAMURAL PROGRAM PROMOTES AND SUPPORTS BASIC, TRANSLATIONAL, AND CLINICAL STUDIES OF SYSTEMIC RHEUMATIC AND AUTOIMMUNE DISEASES, SKIN BIOLOGY AND DISEASES, BONE BIOLOGY AND DISEASES, MUSCLE BIOLOGY AND DISEASES, AND JOINT BIOLOGY AND DISEASES AND ORTHOPAEDICS. NIAMS SYSTEMIC RHEUMATIC AND AUTOIMMUNE DISEASES PROGRAMS ADDRESS BASIC, TRANSLATIONAL, AND CLINICAL RESEARCH, INCLUDING CLINICAL TRIALS AND OBSERVATIONAL AND MECHANISTIC STUDIES, FOCUSED ON IMMUNE-MEDIATED ARTHRITIS AND AUTOIMMUNE-RELATED ACUTE AND CHRONIC DISORDERS IN ADULTS AND CHILDREN. NIAMS SKIN BIOLOGY AND DISEASES PROGRAMS SUPPORT BASIC, TRANSLATIONAL, AND CLINICAL RESEARCH IN SKIN, INCLUDING BOTH COMMON AND RARE SKIN DISEASES. THESE PROGRAMS INCLUDE INVESTIGATIONS OF THE BASIC MOLECULAR, CELLULAR, AND DEVELOPMENTAL BIOLOGY OF SKIN, AS WELL AS STUDIES OF SKIN AS AN IMMUNE, SENSORY, ENDOCRINE, AND METABOLIC ORGAN. NIAMS BONE BIOLOGY AND DISEASES PROGRAMS SUPPORT RESEARCH ON THE CONTROL OF BONE FORMATION, RESORPTION, AND MINERALIZATION AS WELL AS THE EFFECTS OF SIGNALING MOLECULES ON BONE CELLS. THEY SUPPORT CLINICAL STUDIES OF INTERVENTIONS TO PREVENT FRACTURES ASSOCIATED WITH OSTEOPOROSIS AND RESEARCH INTO LESS COMMON BONE DISEASES. NIAMS MUSCLE BIOLOGY AND DISEASES PROGRAMS ENCOURAGE RESEARCH ON MUSCLE DEVELOPMENTAL BIOLOGY, GROWTH, MAINTENANCE, AND HYPERTROPHY, PHYSIOLOGY OF CONTRACTION, STRUCTURAL BIOLOGY OF THE CONTRACTILE APPARATUS, DISEASE MECHANISMS, BIOMARKERS AND OUTCOME MEASURES, AND DEVELOPMENT AND CLINICAL TESTING OF THERAPIES FOR CONDITIONS INCLUDING THE MUSCULAR DYSTROPHIES. NIAMS JOINT BIOLOGY, DISEASES, AND ORTHOPAEDICS PROGRAMS SUPPORT A BROAD SPECTRUM OF RESEARCH CENTERED ON THE INTERPLAY AMONG THE BODY'S MUSCLES, BONES, AND CONNECTIVE TISSUES. THEY ENCOURAGE TISSUE ENGINEERING AND REGENERATIVE MEDICINE RESEARCH, MOLECULAR BIOLOGY, IMAGING, AND CLINICAL RESEARCH, AND THE TREATMENT AND PREVENTION OF ORTHOPAEDIC CONDITIONS. NIAMS PARTICIPATES IN THE SMALL BUSINESS INNOVATION RESEARCH (SBIR) AND SMALL BUSINESS TECHNOLOGY TRANSFER (STTR) PROGRAMS. THE SBIR PROGRAM IS INTENDED TO INCREASE PRIVATE SECTOR COMMERCIALIZATION OF INNOVATIONS DERIVED FROM FEDERAL RESEARCH AND DEVELOPMENT, TO INCREASE SMALL BUSINESS PARTICIPATION IN FEDERAL RESEARCH AND DEVELOPMENT, AND TO FOSTER AND ENCOURAGE PARTICIPATION OF SOCIALLY AND ECONOMICALLY DISADVANTAGED SMALL BUSINESS CONCERNS AND WOMEN-OWNED SMALL BUSINESS CONCERNS IN TECHNOLOGICAL INNOVATION. THE STTR PROGRAM IS INTENDED TO STIMULATE AND FOSTER SCIENTIFIC AND TECHNOLOGICAL INNOVATION THROUGH COOPERATIVE RESEARCH AND DEVELOPMENT CARRIED OUT BETWEEN SMALL BUSINESS CONCERNS AND RESEARCH INSTITUTIONS, TO FOSTER TECHNOLOGY TRANSFER BETWEEN SMALL BUSINESS CONCERNS AND RESEARCH INSTITUTIONS, TO INCREASE PRIVATE SECTOR COMMERCIALIZATION OF INNOVATIONS DERIVED FROM FEDERAL RESEARCH AND DEVELOPMENT, AND TO FOSTER AND ENCOURAGE PARTICIPATION OF SOCIALLY AND ECONOMICALLY DISADVANTAGED SMALL BUSINESS CONCERNS AND WOMEN-OWNED SMALL BUSINESS CONCERNS IN TECHNOLOGICAL INNOVATION.

93.846 - Arthritis, Musculoskeletal and Skin Diseases Research

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) [HHS - NIH]

Atlanta, Georgia 303033005 United States

Single Zip Code

NIH Research Project Grant (Parent R01 Clinical Trial Not Allowed) (PA-20-185)

Amendment Since initial award the total obligations have increased 379% from $682,058 to $3,266,890.