Lack of CD24 expression in mice reduces the number of leukocytes in the colon

CD24 and Fc fusion protein protects SIVmac239-infected Chinese rhesus macaque against progression to AIDS

Chronic immune activation and systemic inflammation are underlying causes of acquired immunodeficiency syndrome (AIDS). Products of virus replication and microbial translocation, co-infection or opportunistic pathogens, and danger-associated molecular patterns have been reported to contribute to chronic immune activation and inflammation in human immunodeficiency virus type-1/simian immunodeficiency virus (HIV-1/SIV) infection or other disease. To develop new strategies and therapies for HIV-1/AIDS, we tested if the CD24 and Fc fusion protein (CD24Fc), which interacts with danger-associated molecular patterns and sialic acid binding Ig-like lectin to attenuate inflammation, can protect Chinese rhesus macaques (ChRMs) with SIV infection. We found that CD24Fc treatment decreased weight loss, wasting syndrome, intractable diarrhea, and AIDS morbidity and mortality, while it was well tolerated by SIV-infected animals. Corresponding to the elimination of intractable diarrhea, CD24Fc significantly reduced the expression of IL-6 and indoleamine 2, 3-dioxygenase-1 in peripheral blood mononuclear cell and inflammation in the ileum, colon and rectum based on the reduction of inflammatory cells, pathological scores and expression of inflammatory cytokines. Furthermore, although CD24Fc did not restore CD4⁺ T cell number or significantly change T cell subsets or CD4⁺ T cell activation, it maintained low levels of plasma soluble CD14, CD8⁺ T cell activation, viral load and proviral load in the peripheral blood mononuclear cells and marrow. These results suggested that CD24Fc confers protection to SIV-infected ChRMs against progression to AIDS. It was also implied that CD24Fc may be a potential therapeutic approach for the control of HIV-1/AIDS.

Systemic Chromosome Instability Resulted in Colonic Transcriptomic Changes in Metabolic, Proliferation, and Stem Cell Regulators in Sgo1-/+ Mice

Colon cancer is the second most lethal cancer and is predicted to claim 49,700 lives in the United States this year. Chromosome instability (CIN) is observed in 80% to 90% of colon cancers and is thought to contribute to colon cancer progression and recurrence. To investigate the impact of CIN on colon cancer development, we developed shugoshin-1 (Sgo1) haploinsufficient (-/+) mice, an animal model focusing on mitotic error-induced CIN. In this study, we analyzed signature changes in the colonic transcriptome of Sgo1(-/+) mice to examine the molecular events underlying the altered carcinogenesis profiles in Sgo1(-/+) mice. We performed next-generation sequencing of normal-looking colonic mucosal tissue from mice treated with the carcinogen azoxymethane after 24 weeks. Transcriptome profiling revealed 349 hits with a 2-fold expression difference threshold (217 upregulated genes, 132 downregulated genes, P < 0.05). Pathway analyses indicated that the Sgo1-CIN tissues upregulated pathways known to be activated in colon cancer, including lipid metabolism (z score 4.47), Notch signaling (4.47), insulin signaling (3.81), and PPAR pathways (3.75), and downregulated pathways involved in immune responses including allograft rejection (6.69) and graft-versus-host disease (6.54). Notably, stem cell markers were also misregulated. Collectively, our findings demonstrate that systemic CIN results in transcriptomic changes in metabolism, proliferation, cell fate, and immune responses in the colon, which may foster a microenvironment amenable to cancer development. Therefore, therapeutic approaches focusing on these identified pathways may be valuable for colon cancer prevention and treatment.