Uncovering the multifaceted roles played by neutrophils in allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a life-saving procedure used for the treatment of selected hematological malignancies, inborn errors of metabolism, and bone marrow failures. The role of neutrophils in alloHSCT has been traditionally evaluated only in the context of their ability to act as a first line of defense against infection. However, recent evidence has highlighted neutrophils as key effectors of innate and adaptive immune responses through a wide array of newly discovered functions. Accordingly, neutrophils are emerging as highly versatile cells that are able to acquire different, often opposite, functional capacities depending on the microenvironment and their differentiation status. Herein, we review the current knowledge on the multiple functions that neutrophils exhibit through the different stages of alloHSCT, from the hematopoietic stem cell (HSC) mobilization in the donor to the immunological reconstitution that occurs in the recipient following HSC infusion. We also discuss the influence exerted on neutrophils by the immunosuppressive drugs delivered in the course of alloHSCT as part of graft-versus-host disease (GVHD) prophylaxis. Finally, the potential involvement of neutrophils in alloHSCT-related complications, such as transplant-associated thrombotic microangiopathy (TA-TMA), acute and chronic GVHD, and cytomegalovirus (CMV) reactivation, is also discussed. Based on the data reviewed herein, the role played by neutrophils in alloHSCT is far greater than a simple antimicrobial role. However, much remains to be investigated in terms of the potential functions that neutrophils might exert during a highly complex procedure such as alloHSCT

Low density neutrophils in patients with juvenile idiopathic arthritis

Objectives: (1) To study the correlation among conventional clinical and laboratory parameters and the relation between the number of lymphocytes and neutrophils (L/N) in cell suspensions from peripheral blood of patients with juvenile idiopathic arthritis (JIA). (2) To evaluate the L/N relation of RA patients after an 8 year follow-up period. Methods: Fifty-one JIA patients (25 female, disease course: 19 systemic, 15 polyarticular, 17 pauciarticular) were enrolled in the study. To measure the L/N relation, we used Boyum's method: The leucocyte separation was done by centrifugation of peripheral blood on Ficoll-Hypaque (FH) gradient, and the number of lymphocytes, monocytes, and neutrophils in 500 cells was determined. The following clinical and laboratory parameters were evaluated: disease activity, number of active and limited joints, functional capacity, erythrocyte sedimentation rate (ESR), and C reactive protein (CRP). Twenty-four healthy children were used as controls. We also studied 13/51 patients from our Pediatric Rheumatology Unit who had been evaluated by the same method 8 years before. Results: We observed the lowest L/N relation in patients with active disease, especially those with polyarticular course. A statistical con-elation was also observed with the acute-phase reactants (ESR and CRP, p < 0.05). The majority of patients who had presented a low L/N relation at the first evaluation (8 years before) had a worse outcome. Conclusion: The measure of L/N relation from peripheral blood could be used as an auxiliary tool in the assessment of the activity and outcome of JIA patients, especially at disease onset.Univ Fed Sao Paulo, Escola Paulista Med, Dept Pediat, Pediat Rheumatol Unit, Sao Paulo, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Dept Med, Rheumatol Unit, Sao Paulo, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Dept Pediat, Pediat Rheumatol Unit, Sao Paulo, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Dept Med, Rheumatol Unit, Sao Paulo, BrazilWeb of Scienc

A20-binding inhibitor of NF-κB (ABIN1) controls Toll-like receptor-mediated CCAAT/enhancer-binding protein β activation and protects from inflammatory disease

Toll-like receptors (TLRs) are expressed on innate immune cells and trigger inflammation upon detection of pathogens and host tissue injury. TLR-mediated proinflammatory-signaling pathways are counteracted by partially characterized anti-inflammatory mechanisms that prevent exaggerated inflammation and host tissue damage as manifested in inflammatory diseases. We biochemically identified a component of TLR-signaling pathways, A20-binding inhibitor of NF-κB (ABIN1), which recently has been linked by genome-wide association studies to the inflammatory diseases systemic lupus erythematosus and psoriasis. We generated ABIN1-deficient mice to study the function of ABIN1 in vivo and during TLR activation. Here we show that ABIN1-deficient mice develop a progressive, lupus-like inflammatory disease characterized by expansion of myeloid cells, leukocyte infiltrations in different parenchymatous organs, activated T and B lymphocytes, elevated serum Ig levels, and the appearance of autoreactive antibodies. Kidneys develop glomerulonephritis and proteinuria, reflecting tissue injury. Surprisingly, ABIN1-deficient macrophages exhibit normal regulation of major proinflammatory signaling pathways and mediators but show selective deregulation of the transcription factor CCAAT/enhancer binding protein β (C/EBPβ) and its target genes, such as colony-stimulating factor 3 (Csf3), nitric oxide synthase, inducible (Nos2), and S100 calcium-binding protein A8 (S100a8). Their gene products, which are intimately linked to innate immune cell expansion (granulocyte colony-stimulating factor), cytotoxicity (inducible nitric oxide synthase), and host factor-derived inflammation (S100A8), may explain, at least in part, the inflammatory phenotype observed. Together, our data reveal ABIN1 as an essential anti-inflammatory component of TLR-signaling pathways that controls C/EBPβ activity