Soluble CD16 in plasma cell dyscrasias

Elevated activating Fc gamma receptors levels correlated with susceptibility and severity of IgA nephropathy

Background:

It is still uncertain if a dysregulated expression of activating Fc gamma receptors (FcγRs) is associated with the development of immunoglobulin A nephropathy (IgAN).

Methods:

RNA sequencing was used to determine the mRNA levels of type I FcγRs, which were then verified by quantitative reverse transcription–polymerase chain reaction (qRT-PCR). Commercial ELISA kits were used to detect plasma soluble FcγRIIIb (sFcγRIIIb).

Results:

We first examined the expression of FcγRs genes in 17 patients with IgAN and six healthy controls. The expression of FcγRIa, FcγRIb, FcγRIIa, FcγRIIc, FcγRIIIa, and FcγRIIIb was shown to be higher in IgAN patients. Even without statistical significance, there was a downward trend in FcγRIIb mRNA levels in IgAN. We observed that the expression levels of activating FcγR mRNAs were consistently higher in an independent set of 20 IgAN patients and 20 healthy controls, confirming the RNA-seq results. FcγRIIIb was the IgG receptor with the greatest difference in expression between the two groups (log₂ fold-change = 1.82). We observed a much higher percent of FcγRIIIb positive cells in IgAN by flow cytometry. Next, we measured plasma sFcRIIIb levels in 50 patients with IgAN and 50 healthy controls. The findings revealed that the mean sFcγRIIIb level in plasma in participants with IgAN was much higher than that of healthy controls. Increased sFcγRIIIb levels were associated with a substantial increase in body mass index (BMI), lipid levels, serum creatinine level, and a larger percentage of sclerosis compared with lower sFcRIIIb levels. Patients in the group with higher sFcγRIIIb levels were more likely to get glucocorticoid treatment.

Conclusion:

The results demonstrated that the mRNA levels of the activating Fc receptor of IgG were significantly increased in IgAN. Patients with higher plasma sFcγRIIIb levels may have had more severe illness than those with lower levels.

CD24, CD27, CD36 and CD302 gene expression for outcome prediction in patients with multiple myeloma

Multiple myeloma (MM) is a B cell neoplasia characterized by clonal plasma cell (PC) proliferation. Minimal residual disease monitoring by multi-parameter flow cytometry is a powerful tool for predicting treatment efficacy and MM outcome. In this study, we compared CD antigens expression between normal and malignant plasma cells to identify new potential markers to discriminate normal from malignant plasma cells, new potential therapeutic targets for monoclonal-based treatments and new prognostic factors. Nine genes were significantly overexpressed and 16 were significantly downregulated in MMC compared with BMPC (ratio ≥2; FDR CD24, CD27, CD36 and CD302) was associated with a prognostic value in two independent cohorts of patients with MM (HM cohort and TT2 cohort, n=345). The expression level of these four genes was then used to develop a CD gene risk score that classified patients in two groups with different survival (P = 2.06E-6) in the HM training cohort. The prognostic value of the CD gene risk score was validated in two independent cohorts of patients with MM (TT2 cohort and HOVON65/GMMGHD4 cohort, n=282 patients). The CD gene risk score remained a prognostic factor that separated patients in two groups with significantly different overall survival also when using publicly available data from a cohort of relapsing patients treated with bortezomib (n=188). In conclusion, the CD gene risk score allows identifying high risk patients with MM based on CD24, CD27, CD36 and CD302 expression and could represent a powerful tool for simple outcome prediction in MM.