<i>Cyba</i>-deficient mice display an increase in hematopoietic stem cells and an overproduction of immunoglobulins

Abstract

The regulation of protein function by reversible oxidation is increasingly recognized as a key mechanism for the control of cellular signaling, modulating crucial biological processes such as cell differentiation. In this scenario, NADPH oxidases must occupy a prominent position. Our results show that hematopoietic stem and progenitor cells express three p22phox-dependent NADPH oxidases members (NOX1, NOX2 and NOX4). By deleting the p22phox coding gene (Cyba), here we have analyzed the importance of this family of enzymes during in vivo hematopoiesis. Cyba-/- mice show a myeloid bias, and an enrichment of hematopoietic stem cell populations. By means of hematopoietic transplant experiments we have also tried to dissect the specific role of the NADPH oxidases. While the absence of NOX1 or NOX2 provides a higher level of reconstitution, a lack of NOX4 rendered the opposite result, suggesting a functional specificity among the different NADPH oxidases. Cyba-/- cells showed a hampered activation of AKT1 and a sharp decrease in STAT5 protein. This is in line with the diminished response to IL-7 shown by our results, which could explain the overproduction of immunoglobulins observed in Cyba-/- mice.

Granuloma Formation in a Cyba-Deficient Model of Chronic Granulomatous Disease Is Associated with Myeloid Hyperplasia and the Exhaustion of B-Cell Lineage

“…Of interest, a significant decrease in Lin Sca-1 c-Kit + (LK) (Figure 4F), megakaryocyte-erythrocyte progenitors (MEP), common myeloid progenitors (CMP) and common lymphoid progenitors (CLP) (Figure 4G) was observed in granuloma-bearing Cyba −/− mice. This is in contrast with our previous results in granuloma-free Cyba −/− mice, which did not show this difference versus wild-type animals [22]. In summary, CGD-associated inflammation induced a sharp decrease in Lin cells, which could be explained by the exhaustion of committed progenitor populations.…”

“…We have recently generated a Cyba −/− model through CRISPR/Cas9 editing technology [22]. Here, we report that these mice spontaneously developed granuloma and, therefore, constitute a CGD animal model, as expected.…”

“…Strikingly, Lin Sca-1 + c-Kit + (LSK), long-term (LT-HSC) and short-term haematopoietic stem cell (ST-HSC) populations were significantly overrepresented in Cyba −/− mice (Figure 4C-E). It is worth noting that this increase cannot be attributed to granulomatous lesions, as this has been previously observed in the absence of inflammatory alterations [22]. Of interest, a significant decrease in Lin Sca-1 c-Kit + (LK) (Figure 4F), megakaryocyte-erythrocyte progenitors (MEP), common myeloid progenitors (CMP) and common lymphoid progenitors (CLP) (Figure 4G) was observed in granuloma-bearing Cyba −/− mice.…”

“…Compared to wild-type animals, Cyba −/− mice bearing abscesses showed a significant increase in CD11b + myeloid cells and a decrease in CD3 + and CD19 + lymphoid cells in PB (Figure 3A). These alterations would be attributable to the inflammatory process associated with CGD, as no differences between wild-type and granuloma-free Cyba −/− mice were found in our previous work [22].…”

“…We have recently described the generation of a Cyba −/− mouse model using CRISPR/ Cas9 technology [22]. Similar to what has been reported before for Nox2-deficient mice [23], despite being housed in a specific pathogen-free (SPF) environment, a significant number of Cyba −/− mice (around 30% of males and almost 70% of females) spontaneously developed abscesses.…”