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While loss-of-function variants in the WAS gene are associated with Wiskott-Aldrich syndrome and lead to microthrombocytopenia, gain-of-function variants of WAS are associated with X-linked neutropenia (XLN) and the absence of microthrombocytopenia. Only a few XLN families have been reported so far, and their platelet phenotype was not described in detail. To date, no renal involvement was described in XLN. In the present study, we report exome sequencing of individuals from 3 generations of a family with a dominant disease combining neutropenia, macrothrombocytopenia, and renal failure. We identified a heterozygous missense gain-of-function variant in the WAS gene (c.881T>C, p.I294T) that segregates with the disease and is already known to cause XLN. There was no pathogenic variant in MYH9, TUBB1, or ACTN1. This is the first report of a WAS gain-of-function variant associated with both the hematological phenotype of XLN (neutropenia, macrothrombocytopenia) and renal disease (proteinuria, renal failure) with glomerular tip lesion hyalinosis and actin condensations in effaced podocytes foot processes.

Cell metabolism is crucial for orchestrating the differentiation and function of regulatory T cells (Tregs). However, the underlying signaling mechanism that coordinates cell metabolism to regulate Treg activity is not completely understood. As a pivotal molecule in lipid metabolism, the role of SHIP-1 has been studied extensively in B cells and CD4 T cells, yet its regulatory role in Tregs remains unknown. In this study, we generated “SHIP-1 KO mice” that have SHIP-1 specifically deleted in regulatory T cells by crossing Foxp3YFP-cre mice with SHIP-1fl/fl mice. Surprisingly, SHIP-1 KO mice had severe autoimmunity with increased Tregs in the thymus and disrupted peripheral T cell homeostasis. Mechanistically, CD4Cre SHIP-1flox/flox mice were found to have increased Treg precursors and SHIP-1 KO Tregs had reduced migration and stability, which caused decreased Tregs in the spleen. Additionally, the suppressive function of Tregs from SHIP-1 KO mice was diminished, along with their promotion of anti-tumor immunity. Interestingly, the PI3K-mTORC1, but not mTORC2, signaling axis was enhanced in SHIP-1 KO Tregs. In vivo treatment of SHIP-1 KO mice with rapamycin rescued the abnormal Treg percentages and peripheral T cell homeostasis, as well as Treg suppressive function. Furthermore, the treatment of wild-type mice with SHIP-1 inhibitor enhanced anti-tumor activity. Our study has revealed a previously unrecognized underlying function of SHIP-1 in Tregs, which highlights the SHIP-1-PI3K-mTORC1 axis that regulates Treg differentiation and function.

The pre-operative body wash is a strategy for reducing post-operative infection. However, there is a lack of knowledge about its importance. The purpose of the present study was to evaluate the quality of guidelines for the pre-operative body wash using the AGREE instrument—35 guidelines containing instructions for the pre-operative body wash or preparation were included. The AGREE instrument was employed to establish a quality assessment framework that facilitated a comparison of the guidelines. The results were based on the six domains of the AGREE instrument, all of which were found to have low adherence. Descriptive statistics were used to present the assessment score. The AGREE instrument is useful for evaluating the quality of clinical guidelines. The development of evidence-based guidelines must include clinical activities. Further research is required to clarify the pre-operative body wash process and how it should be performed to reduce post-operative infection.

Scavenger receptor CD36 has been shown to mediate uptake of modified self-antigens such as apoptotic cells and oxidized LDL in macrophages and dendritic cells. Interestingly, CD36 was discovered to be preferentially expressed also on an innate B cell subtype, marginal zone B cells (MZB). Here we investigate the role of CD36 in B cell activation in the context of apoptotic cell clearance and break of tolerance to self. We found that formation of germinal center B cells and autoantibody production in response to an increased load of apoptotic cells coincide with downregulation of CD36 on MZB. We could also in connection to this show that systemic lupus erythematosus (SLE) patients have lower levels of peripheral MZB compared to healthy individuals. B cells lacking CD36 proved more easily activated in response to apoptotic cells, as was shown in bone marrow (BM) chimeras reconstituted with wild type and CD36-deficient BM. In steady-state, we found that CD36 co-localizes with the B cell receptor and the tyrosine kinase Lyn. Interestingly, upon cross-linking of the inhibitory Fc receptor, FcgRIIb, CD36 instead co-localizes with this receptor. This suggests that CD36 interacts with FcgRIIb to activate a negative signaling cascade in B cells. Our data implicate CD36 in the early regulation of B cell responses towards apoptotic cells and autoantibody production. In line with this we find that CD36-deficient B cells are more resistant to FcgRIIb-induced cell death. Thus, CD36 exerts its regulatory function by associating with a known negative signaling pathway in B cells involving Lyn and FcgRIIb. This finding could have implications for autoimmune diseases involving apoptotic cell-derived self-antigens, such as SLE.

It remains puzzling how immunodeficiency with hypo-responsive cells can be associated with increased immune cell activation to seemingly harmless substances such as allergens. Here, we have investigated skin pathology in the severe primary immunodeficiency Wiskott-Aldrich syndrome (WAS). Wildtype and WAS protein-deficient (WASp KO) mice were challenged with the allergen Der p 2 to induce eczema or infected with Leishmania major to induce robust skin inflammation. Der p 2 challenge of wildtype mice induced eczema with epidermal hyperplasia and egress of Langerhans cells from the skin. WASp KO mice had increased accumulation of mature DCs in the skin and, in contrast to wildtype cells, Der p 2 induced expansion of WASp KO CD8+ T cells that produced IFNγ. Similar to challenge with Der p 2 and unlike wildtype mice, WASp KO mice infected with L. major showed a skewed immune response with increased expansion of IFNγ-producing CD8+ T cells in the draining lymph node. Finally, we show that WASp KO DCs have increased capacity to cross-present exogenous antigen and activate CD8+ T cells. Our results imply that WASp deficiency in skin inflammation causes a breach in tolerance and skews the immune system to DC mediated CD8+ T cell responses at incorrect sites.

Lymphocytes express both Wiskott-Aldrich syndrome protein (WASP) and N-WASP. WASP deficiency, the cause of WAS, generates more severe defects in T-cells than B cells, suggesting a strong compensatory role of N-WASP in B cells. Using knockout mouse models, this study shows that WASP knockout (WKO) reduces B cell spreading, B cell receptor (BCR) aggregation, tyrosine phosphorylation, Btk phosphorylation and F-actin accumulation at the B cell surface induced by membrane-associated antigen, and WASP/N-WASP double knockout nearly abolished these activities. However, in B cells with N-WASP conditional knockout (cNKO), B cell spreading and F-actin accumulation are enhanced, while the merge of BCR aggregates and attenuation of tyrosine and Btk phosphorylation are inhibited. Additionally, cNKO has a much stronger inhibitory effect on BCR endocytosis than WKO. In contrast to Btk-dependent activation of WASP, N-WASP phosphorylation is upregulated by Btk-deficiency but downregulated by SHIP KO. Furthermore, the phosphorylation of WASP and N-WASP is inversely regulated by each other. These results reveal that the combined function of WASP and N-WASP is required for the optimal activation of the BCR and its signaling attenuation, but these two proteins function distinctively: WASP and N-WASP play dominant roles in the initiation and attenuation of BCR activation respectively. Thus, the integrated action of WASP and N-WASP provide a critical regulatory mechanism for BCR activation.