Publications

There is intense interest in developing curative interventions for HIV. How such a cure will be quantified and defined is not known. We applied a series of measurements of HIV persistence to the study of an HIV-infected adult who has exhibited evidence of cure after allogeneic hematopoietic stem cell transplant from a homozygous CCR5Δ32 donor. Samples from blood, spinal fluid, lymph node, and gut were analyzed in multiple laboratories using different approaches. No HIV DNA or RNA was detected in peripheral blood mononuclear cells (PBMC), spinal fluid, lymph node, or terminal ileum, and no replication-competent virus could be cultured from PBMCs. However, HIV RNA was detected in plasma (2 laboratories) and HIV DNA was detected in the rectum (1 laboratory) at levels considerably lower than those expected in ART-suppressed patients. It was not possible to obtain sequence data from plasma or gut, while an X4 sequence from PBMC did not match the pre-transplant sequence. HIV antibody levels were readily detectable but declined over time; T cell responses were largely absent. The occasional, low-level PCR signals raise the possibility that some HIV nucleic acid might persist, although they could also be false positives. Since HIV levels in well-treated individuals are near the limits of detection of current assays, more sensitive assays need to be developed and validated. The absence of recrudescent HIV replication and waning HIV-specific immune responses five years after withdrawal of treatment provide proof of a clinical cure.

The field of lymphotoxin biology has seen many advances in the past decade. Notably, a role for lymphotoxin as a key effector cytokine has emerged to add to its foundational contribution to lymphoid organogenesis. It is now clear that lymphotoxin contributes to host defense for a wide variety of pathogens, and the lymphotoxin receptor is a defining feature of and regulatory mechanism in both innate and adaptive immunities. Specifically, lymphotoxin contributes to Th education, licensing of IL-22 production from type 3 innate lymphoid cells, and even maintains innate myeloid populations within the fully developed lymph node. Most recently, lymphotoxin has been implicated in regulation of the microbiota and metabolic disease. Early studies revealed that lymphotoxin might influence composition of the commensal microbiota through its regulation of immunological compartmentalization in the gut. Additionally, several epidemiological studies have linked polymorphisms in lymphotoxin to metabolic disease. Studies exploring the role of lymphotoxin in metabolic disease have demonstrated that lymphotoxin may influence metabolism both directly in the liver and indirectly through regulation of gut immune responses. It now appears that lymphotoxin may bridge the gap between altered composition of the commensal microbiota and metabolism.