Visualizing the Immune System: Providing Key Insights into HIV/SIV Infections

Abstract

Immunological inductive tissues, such as secondary lymphoid organs, are composed of distinct anatomical microenvironments for the generation of immune responses to pathogens and immunogens. These microenvironments are characterized by the compartmentalization of highly specialized immune and stromal cell populations, as well as the presence of a complex network of soluble factors and chemokines that direct the intra-tissue trafficking of naïve and effector cell populations. Imaging platforms have provided critical contextual information regarding the molecular and cellular interactions that orchestrate the spatial microanatomy of relevant cells and the development of immune responses against pathogens. Particularly in HIV/SIV disease, imaging technologies are of great importance in the investigation of the local interplay between the virus and host cells, with respect to understanding viral dynamics and persistence, immune responses (i.e., adaptive and innate inflammatory responses), tissue structure and pathologies, and changes to the surrounding milieu and function of immune cells. Merging imaging platforms with other cutting-edge technologies could lead to novel findings regarding the phenotype, function, and molecular signatures of particular immune cell targets, further promoting the development of new antiviral treatments and vaccination strategies.

Keywords: HIV; T cells; imaging; immune cells; lymph nodes; mucosa.

Figure 1

Heterogeneity of follicular cell populations. (A) Confocal images showing the relative distribution of proliferating B cells (CD20hi/dimKi67hi, CD20/cyan, and Ki67/magenta) and CD4 Tfh subsets (PD-lhiCD57hi, PD-lhiCD57lo, PD-1/green, and CD57/red) in a tonsillar follicular area. (B) Flow-cytometry plots showing the phenotype of tonsillar Tfh subsets based on the combined expression of PD-1, CXCR5, and CD57 surface receptors.