CpG-ODN-induced sustained expression of BTLA mediating selective inhibition of human B cells

BTLA (B- and T-lymphocyte attenuator) is a prominent co-receptor that is structurally and functionally related to CTLA-4 and PD-1. In T cells, BTLA inhibits TCR-mediated activation. In B cells, roles and functions of BTLA are still poorly understood and have never been studied in the context of B cells activated by CpG via TLR9. In this study, we evaluated the expression of BTLA depending on activation and differentiation of human B cell subsets in peripheral blood and lymph nodes. Stimulation with CpG upregulated BTLA, but not its ligand: herpes virus entry mediator (HVEM), on B cells in vitro and sustained its expression in vivo in melanoma patients after vaccination. Upon ligation with HVEM, BTLA inhibited CpG-mediated B cell functions (proliferation, cytokine production, and upregulation of co-stimulatory molecules), which was reversed by blocking BTLA/HVEM interactions. Interestingly, chemokine secretion (IL-8 and MIP1β) was not affected by BTLA/HVEM ligation, suggesting that BTLA-mediated inhibition is selective for some but not all B cell functions. We conclude that BTLA is an important immune checkpoint for B cells, as similarly known for T cells.     

Zip14 expression induced by lipopolysaccharides in macrophages attenuates inflammatory response

Objective and design

We investigated the role and regulation of zinc transporters in the activation of the inflammatory response in macrophages. Our exploratory computational study found that Zip14 (SLC39A14) was consistently up-regulated in activated macrophages; we therefore focused subsequently on that gene in the mechanistic study.

Material

The expression and function of Zip14 was assessed in primary macrophages obtained by in-vitro differentiation of monocytes from human blood.

Methods

Primary macrophages were subjected to treatments with lipopolysaccharides, cytokines, chemicals, and pharmacological agents. SLC39A14 and inflammatory cytokine gene expressions were assessed by RT-qPCR. Zip14 siRNA knockdown was performed to explore the gene function.

Results

Lipopolysaccharide’s inflammatory stimulus was a strong inducer of SLC39A14 mRNA expression in macrophages. This induction was dependent on calcium signaling, GC-rich DNA-binding, and NF-κB down-regulation. Impregnation of lipopolysaccharide-stimulated macrophages with the glucocorticoid dexamethasone further enhanced Zip14 expression while reducing interleukin-6 and tumor necrosis factor-α production. Zip14 knockdown in macrophages attenuated the expression and secretion of cytokines, indicating a buffering function for this zinc transporter.

Conclusions

Collectively, our results identified the zinc transporter Zip14 as expressed downstream of lipopolysaccharide signals in macrophages. Zip14 induction had a regulatory function in cytokine production.     

Assessment of family history of colorectal cancer in primary care: Perceptions of first degree relatives of people with colorectal cancer

Objective

First degree relatives (FDRs) of someone with colorectal cancer (CRC) are at increased risk of the disease. In this study we examine the factors associated with discussing family history of CRC with a health professional.

Methods

People with CRC, recruited through the population-based Victorian Cancer Registry in Australia, were asked to refer FDRs to the study. Eight hundred and nineteen FDRs completed a telephone interview.

Results

Thirty-six percent of FDRs recalled ever being asked about their family history of bowel cancer by a health professional. Factors associated with having this discussion were being aged 50–60 years, having a university education, being in the potentially high risk category, being very worried about getting bowel cancer and knowing that family history increases risk through discussions with family, friends or their own education.

Conclusion

Despite evidence that doctor endorsement is a key factor in the uptake of CRC screening, our study shows that the majority of FDRs do not recall being asked by a health professional about their family history.

Practice implications

There is a need to identify the most appropriate method to improve rates of health professional discussion of family history with relatives of CRC patients in order to improve screening rates.     

Experimental selection of paromomycin and miltefosine resistance in intracellular amastigotes of Leishmania donovani and L. infantum

Although widespread resistance of Leishmania donovani and L. infantum against miltefosine (MIL) and paromomycin (PMM) has not yet been demonstrated, both run the risk of resistance selection. Unraveling the dynamics and mechanisms of resistance development is key to preserve drug efficacy in the field. In this study, resistance against PMM and MIL was experimentally selected in vitro in intracellular amastigotes of several strains of both species with different antimony susceptibility background. To monitor amastigote susceptibility, microscopic determination of IC₅₀-values and promastigote back-transformation assays were performed. Both techniques were also used to evaluate the susceptibility of field isolates from MIL-relapse patients. PMM-resistance could readily be selected in all species/strains, although promastigotes remained fully PMM-susceptible. Successful MIL-resistance selection was demonstrated only by promastigote back-transformation at increasing MIL-concentrations upon successive selection cycles. Important to note is that amastigotes with the MIL-resistant phenotype could not be visualized after Giemsa staining; hence, MIL-IC₅₀-values showed no shift. The same phenomenon was observed in a set of recent clinical isolates from MIL-relapse patients. This study clearly endorses the need to use intracellular amastigotes for PMM- and MIL-susceptibility testing. When monitoring MIL-resistance, promastigote back-transformation should be used instead of the standard Giemsa staining. In-depth exploration of the mechanistic background of this finding is warranted.