Immunomodulation of T Helper Cells by Tumor Microenvironment in Oral Cancer Is Associated With CCR8 Expression and Rapid Membrane Vitamin D Signaling Pathway

The immune system plays a key role in the protective response against oral cancer; however, the tumor microenvironment (TME) impairs this anti-cancer response by modulating T helper (Th) responses and promoting an anti-inflammatory environment. Regulatory T cells (Tregs) and Th2 effector cells (Teff) are associated with poor prognosis in oral squamous cell carcinoma (OSCC). However, the main immunomodulatory mechanisms associated with the enrichment of these subsets in OSCC remain unknown. We characterized Th-like lineages in Tregs and Teff and evaluated immunomodulatory changes induced by the TME in OSCC. Our phenotypic data revealed a higher distribution of tumour-infiltrating CCR8⁺ and Th2-like Treg in OSCC compared with non-malignant samples, whereas the percentages of Th1 cells were reduced in cancer. We then analyzed the direct effect of the TME by exposing T cell subsets to cancer secretomes and observed the OSCC secretome induced CCR8 expression and reduced cytokine production from both subsets. Transcriptomic analysis showed that the co-culture with OSCC secretome induced several gene changes associated with the vitamin D (VitD) signaling pathway in T cells. In addition, proteomic analysis identified the presence of several proteins associated with prostaglandin E2 (PGE2) production by rapid membrane VitD signaling and a reduced presence of the VitD binding protein. Thus, we analyzed the effect of VitD and PGE2 and observed that VitD promotes a regulatory Th2-like response with CCR8 expression whilst PGE2 also modulated CCR8 but inhibited cytokine production in combination with VitD. Finally, we evaluated the presence of CCR8 ligand in OSCC and observed increased chemokine CCL18, which was also able to upregulate CCR8 in activated Th cells. Overall, our data showed the immunomodulatory changes induced by the TME involving CCR8 expression and regulatory Th2 phenotypes, which are associated with PGE2 mediated VitD signaling pathway and CCL18 expression in OSCC.

Loss of hepatitis A virus (HAV) antibodies after peripheral stem cell transplantation (PSCT)

The majority of patients with hepatitis A have a benign course, but some may develop fulminant hepatitis and hematological complications. Peripheral stem cell transplantation (PSCT) is associated with loss of immunity. There are no data regarding loss of HAV antibodies (anti-HAV) after PSCT. We retrospectively evaluated the persistence of anti-HAV in a nonvaccinated population that underwent PSCT. Serum detection of anti-HAV was determined before and after PSCT using a qualitative commercially available enzyme immunoassay. From January 1997 to March 2001, 136 (68%) of 201 patients tested (+) for anti-HAV prior to PSCT. Subsequent investigation of anti-HAV was possible in 36 of these patients at a median of 12 months after PSCT. The median age of patients was 47 years old; they had diagnoses of hematological malignancies (33) and solid tumors (three), and underwent autologous (31) and allogenic (five) PSCT. A total of 31 (86%) of 36 patients remained anti-HAV (+) and five (14%) became (-) after PSCT. The variables age, sex, diagnosis, type of PSCT, time of testing, and number of CD34 cells infused were not predictors of loss of anti-HAV. In conclusion, 14% of 36 nonvaccinated anti-HAV (+) patients lost their antibodies at a median of 12 months after PSCT.

Molecular cloning and characterization of a rat homolog of CAP, the adenylyl cyclase-associated protein from Saccharomyces cerevisiae

We have isolated a rat cDNA whose expression suppresses the physiological consequences of the chromosomal disruption of CAP, the gene encoding the adenylyl cyclase-associated protein of Saccharomyces cerevisiae. Yeast CAP is a bifunctional protein: the NH2 terminus is necessary and sufficient for cellular responsiveness to activated RAS proteins, while the COOH terminus is required for normal cellular morphology and growth control. The rat MCH1 cDNA encodes a protein of 474 amino acids that is 36% identical to S. cerevisiae CAP and is capable of suppressing the loss of the COOH-terminal functions of CAP when expressed in yeast. The MCH1 protein therefore appears to be a structural and functional homolog of the yeast cyclase-associated proteins. Northern analysis of MCH1 gene expression shows it to be constitutively expressed in all cell and tissue types examined. The cloning of a rat homolog of CAP, in addition to the cloning of a human CAP homolog by Matviw et al. (Matviw, H., Yu, G., and Young, D. (1992) Mol. Cell. Biol. 12, 5033-5040), demonstrates that both cyclase-associated proteins and their functions may have evolved with mammalian cells.