Differential Expression of CD8+ T Cell Cytotoxic Effector Molecules in Blood and Gastrointestinal Mucosa in HIV-1 Infection1

• Published in: The Journal of immunology (1950) 2018-01, Vol.200 (5), p.1876-1888
• Main Authors: Kiniry, Brenna E., Hunt, Peter W., Hecht, Frederick M., Somsouk, Ma, Deeks, Steven G., Shacklett, Barbara L.
• Format: Article
• Language: English
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.1701532

We previously reported that CD8 + T-cells in human gastrointestinal mucosa exhibit reduced perforin expression and weak or impaired cytotoxic capacity compared to their counterparts in blood. Nevertheless, these cells degranulate and express cytokines and chemokines in response to cognate antigen. In addition to weak expression of perforin, earlier studies suggested differential regulation of perforin and granzymes, with granzymes A and B expressed by significantly higher percentages of mucosal CD8+ T-cells than perforin. However, this topic has not been fully explored. The goal of this study was to elucidate the expression and co-expression patterns of granzymes (Gzm) A, B and K in conjunction with perforin in rectosigmoid CD8 + T-cells during HIV-1 infection. We found that expression of both perforin and GzmB, but not GzmA or GzmK, was reduced in mucosa compared to blood. A large fraction of rectosigmoid CD8 + T-cells either did not express granzymes or were single-positive for GzmA. Rectosigmoid CD8 + T-cells appeared skewed towards cytokine production rather than cytotoxic responses, with cells expressing multiple cytokines/chemokines generally lacking in perforin and granzyme expression. These data support the interpretation that perforin and granzymes are differentially regulated, and display distinct expression patterns in blood and rectosigmoid T-cells. These studies may help inform the development of strategies to combat HIV-1 and other mucosal pathogens.