SARS-CoV-2 spike protein induces endothelial inflammation via ACE2 independently of viral replication.

COVID-19, caused by SARS-CoV-2, is a respiratory disease associated with inflammation and endotheliitis. Mechanisms underling inflammatory processes are unclear, but angiotensin converting enzyme 2 (ACE2), the receptor which binds the spike protein of SARS-CoV-2 may be important. Here we investigated whether spike protein binding to ACE2 induces inflammation in endothelial cells and determined the role of ACE2 in this process. Human endothelial cells were exposed to SARS-CoV-2 spike protein, S1 subunit (rS1p) and pro-inflammatory signaling and inflammatory mediators assessed. ACE2 was modulated pharmacologically and by siRNA. Endothelial cells were also exposed to SARS-CoV-2. rSP1 increased production of IL-6, MCP-1, ICAM-1 and PAI-1, and induced NFkB activation via ACE2 in endothelial cells. rS1p increased microparticle formation, a functional marker of endothelial injury. ACE2 interacting proteins involved in inflammation and RNA biology were identified in rS1p-treated cells. Neither ACE2 expression nor ACE2 enzymatic function were affected by rSP1. Endothelial cells exposed to SARS-CoV-2 virus did not exhibit viral replication. We demonstrate that rSP1 induces endothelial inflammation via ACE2 through processes that are independent of ACE2 enzymatic activity and viral replication. We define a novel role for ACE2 in COVID-19- associated endotheliitis.

Is Haploidentical Hematopoietic Cell Transplantation Using Post-Transplantation Cyclophosphamide Feasible in Sub-Saharan Africa?

Identifying a suitable volunteer unrelated donor (UD) in South Africa is challenging due to the highly diverse ethnic groups and mixed-race populations in this region. Haploidentical hematopoietic cell transplantation (haploHCT) is thus an attractive procedure for patients with high-risk hematologic malignancies. This study was conducted to assess the safety and feasibility of haploHCT in South Africa. We retrospectively analyzed the outcome of 134 patients with hematologic malignancies who received unmanipulated haploHCT with post-transplantation cyclophosphamide at 2 high-volume HCT centers between 2014 and 2019. We assessed overall survival (OS), disease-free survival (DFS), nonrelapse mortality (NRM), relapse incidence (RI), and incidence of acute GVHD. The median recipient age was 44 years (range, 15 to 73 years) and the median donor age was 36 years (range, 9 to 68 years). Acute myelogenous leukemia or myelodysplastic syndrome (AML/MDS) and acute lymphoblastic leukemia (ALL) were the most common indications for haploHCT (61.2%). The European Society for Blood and Marrow Transplantation risk score was ≥5 in 44 patients (32.8%). Seventy-seven patients (57.4%) received a myeloablative conditioning regimen. The majority of patients received a sex-matched transplant (57.4%) and had peripheral blood stem cells (PBSCs) as the stem cell source (70.9%). Sixteen patients (11.9%) had an incongruent cytomegalovirus serostatus at transplantation. The median duration of follow-up was 10.8 months (range, 0.36 to 70.8 months). OS was 56% (95% confidence interval [CI], 47% to 64%) at 1 year and 37% (95% CI, 28% to 47%) at 3 years. DFS was 47% (95% CI, 38% to 55%) at 1 year and 32% (95% CI, 24% to 41%) at 3 years. The 100-day and 3-year cumulative incidence of NRM was 18% (95% CI, 11% to 25%) and 41% (95% CI, 32% to 50%), respectively, and the 1- and 3-year cumulative RI was 16% (95% CI, 11% to 24%) and 21% (95% CI, 14% to 29%), respectively. The 1-year OS was 55% (95% CI, 40% to 67%) for the patients with AML/MDS versus 41% (95% CI, 21% to 60%) for those with ALL. Forty-five patients (41.7%) developed acute GVHD by day +100; of these, 80% had grade I-II disease. Fifty patients (37.5%) developed cytomegalovirus infection that required therapy. On multivariable analysis, older donor age was an independent risk factor for lower DFS. RI was higher for diagnoses other than acute leukemia/MDS (relative risk [RR], 2.62; 95% CI, 1.12 to 6.15; P = .027), decreased for PBSC versus bone marrow (RR, 0.43; 95% CI, 0.19 to 0.95; P = .038) and decreased for offspring donors (RR, 0.25; 95% CI, 0.09 to 0.67; P = .006). These data support the feasibility of haploHCT and suggest that unmanipulated haploHCT using a younger parent or offspring donor is a viable option for adults in sub-Saharan Africa with acute leukemia and MDS who lack a suitable related or unrelated donor.

Microvesicles but Not Exosomes from Pathfinder Cells Stimulate Functional Recovery of the Pancreas in a Mouse Streptozotocin-Induced Diabetes Model.

Pathfinder cells (PCs), a novel cell type derived from the pancreas of adult rats, have been demonstrated to stimulate recovery of tissue structure and function in two animal models of acute tissue damage to date-streptozotocin (STZ)-induced diabetes and ischemia-reperfusion damage to the kidney. In repaired tissue, PCs and their progeny typically represent only 0.02% of the repaired tissue, suggesting that they act via a paracrine mechanism on native cells in the damaged area. Extracellular vesicles are strong candidates for mediating such a paracrine effect. Therefore, we studied the effects of two PC-derived extracellular vesicle fractions on tissue repair in the STZ diabetes model, one containing primarily microvesicles and the second containing predominantly exosomes. Treatment of STZ-induced diabetic mice with the microvesicles preparation led to blood glucose, insulin, glucagon, and C-peptide levels similar to those found with PC treatment. Furthermore, analysis of the histopathology of the pancreas indicated islet regeneration. In contrast, the exosome fraction demonstrated no repair activity, and STZ diabetic mice treated with exosome preparations had blood glucose values that were indistinguishable from those of vehicle-only treated controls. Therefore, we conclude that exosomes play no part in PC action as detected by this assay, whereas microvesicles provide all or a large component of the paracrine activity of PCs. Because they act to stimulate repair of multiple tissues, PC-derived microvesicles may similarly have the potential to stimulate repair of many damaged tissues, identifying a very significant cell-free therapeutic opportunity in regenerative medicine.

A pilot study of trimodality breast imaging surveillance in young women at high risk of breast cancer in Western Australia.

OBJECTIVE: To determine whether a surveillance program including clinical breast examination (CBE) and three screening modalities (magnetic resonance imaging [MRI], high-resolution ultrasound [U/S] and mammographic x-ray [MMX]) was feasible, and whether it could improve detection of pathological lesions in young women at high risk of developing breast cancer. DESIGN, SETTING AND PARTICIPANTS: Western Australian women aged 50 years or under at high risk of developing breast cancer were recruited to our study. For a 2-year period, they were offered breast MRI and U/S scans in addition to their annual MMX and CBE. Our study was conducted between June 2002 and October 2005. MAIN OUTCOME MEASURES: Number and type of cancerous or precancerous lesions; recall rates after screening; comparative sensitivity of screening modalities. RESULTS: Of 102 women approached, 72 agreed to participate. Fifteen lesions were detected, of which three were significant: a metastatic papillary cancer in an axillary lymph node, a borderline lesion (multiple papillomatosis with atypia), and a papilloma. All 15 lesions were visible on MRI, and four were detected by MRI only. Only one lesion was visible on all three imaging modalities. Nothing significant was detected by CBE. The recall rate after MRI scans fell from 9/72 (12.5%) in the first year to 5/67 (7.5%) in the second year. CONCLUSION: Our study gave valuable experience in a team approach to screening MRI, and showed that MRI can detect more lesions than MMX or U/S in women at high risk of developing breast cancer. Screening U/S may not add value to MMX and MRI screening, and we suggest a single oblique-view MMX may be used in some cases.

Statins inhibit NK cell cytotoxicity by membrane raft depletion rather than inhibition of isoprenylation.

To investigate the potential determinants of the pleiotropic effects of statins, we measured NK cell cytotoxicity in samples from normal subjects and patients, including patients receiving statin therapy. In a multivariate analysis, NK cell cytotoxicity was related to total plasma cholesterol concentration rather than statin use. In vitro, we investigated the role of lipid modification, specifically the effects on membrane rafts and raft-dependent signal transduction. We demonstrate that statins reduce NK cell cytotoxicity and that membrane cholesterol depletion by cyclodextrins has a similar effect. In contrast, isoprenyl transferase inhibitors had little or no effect on NK cell function. We hypothesise that the pleiotropic effects of statins reflect changes in membrane cholesterol and, specifically, the density of membrane rafts. Moreover, there is likely to be a relationship between membrane cholesterol, membrane rafts and cell function that may be involved in the pathogenesis of cardiovascular and metabolic diseases.

Thrombotic thrombocytopenic purpura in patients with retroviral infection is highly responsive to plasma infusion therapy.

We prospectively studied presentation biological differences and the response to therapy in patients with thrombotic thrombocytopenic purpura (TTP) associated with, or unrelated to human immunodeficiency virus (HIV) infection. TTP patients underwent standard evaluations and were treated with prednisone 1 mg/kg in addition to infusions of fresh frozen plasma (FFP; 30 ml/kg/d) until normalization of the platelet count. Unresponsive patients were referred for plasma exchange. Compared with HIV- TTP patients (n=23), in HIV+ subjects (n=21) microangiopathy was dominant among Black females, who had lower presentation Hb (median 5.8 g/dl; P=0.03), platelet count (13 x 10(9)/l; P=0.05) and a CD4 count of 0.096 x 10(9)/l. HIV+ individuals responded to FFP faster than HIV- patients and none of them required apheresis. Ten HIV- TTP patients required apheresis (P=0.03) and four died. Responses in the HIV+ and HIV- groups occurred after treatment with a median of 33 and 55 units (one unit=320 ml) of FFP (P=0.004) respectively. Response to this protocol was seen in 84% (95% response in HIV+ patients). Regression analysis showed that survival was associated with younger age (P=0.001), rapid platelet (P=0.001) and Hb (P=0.0009) recovery, and fewer FFP units to normal lactate dehydrogenase levels (P=0.006). We conclude that in HIV+ individuals, microangiopathy is highly responsive to plasma infusions. This observation is important particularly when apheresis is not available.

Simvastatin inhibits lymphocyte function in normal subjects and patients with cardiovascular disease.

HMG-CoA reductase inhibitors (statins) block the mevalonate pathway, preventing biosynthesis of cholesterol and isoprenoids. We investigated the effect of simvastatin on lymphocytes from normal human subjects and cardiovascular disease patients in order to provide a model for the in vivo actions of statins. Thirteen healthy volunteers were treated with 40 mg per day of simvastatin following which mean total cholesterol was reduced by 23% (S.D.+/- 11.7%) and mean LDL-cholesterol by 36% (S.D.+/- 16.3%). Lymphocyte lipid raft levels, represented by Lyn and Fyn, were also reduced by simvastatin. Treatment with simvastatin did not alter ex vivo T-lymphocyte proliferation. However, the in vitro addition of 1 microM simvastatin reduced T-lymphocyte proliferation by 39% (S.D.+/- 18.1%) and a combination of prenyl transferase inhibitors reduced proliferation by 19% (S.D.+/- 22.7%). We also assessed the cytotoxicity of natural killer (NK) cells-a T-lymphocyte subset. NK cell cytotoxicity ex vivo was reduced by 30% (S.D.+/- 33.6%) following oral simvastatin treatment and by 56% (S.D.+/- 24.68%) after the in vitro addition of 1 microM simvastatin. Significant ex vivo reductions in T-cell proliferation and NK cell cytotoxicity were observed in patients with cardiovascular disease on treatment with statins. NK cells have been implicated in the pathogenesis of atherosclerosis, so the effect of statin therapy on NK cell cytotoxicity may contribute to the benefits of statins in cardiovascular disease.

A comparison of the anti-inflammatory and immuno-stimulatory activities of orf virus and ovine interleukin-10.

Orf virus causes pustular skin lesions (orf) in sheep, goats and humans. The virus encodes an interleukin-10 (orfvIL-10) that is identical in amino acid composition to ovine IL-10 (ovIL-10) over the C terminal two-thirds of the polypeptide, but not in the N terminal third. The immuno-suppressive and immuno-stimulatory activities of orfvIL-10 and ovIL-10 were compared. Both orfvIL-10 and ovIL-10 inhibited TNF-alpha and IL-8 cytokine production from stimulated ovine macrophages and keratinocytes and IFN-gamma and GM-CSF production from peripheral blood lymphocytes. OrfvIL-10 and ovIL-10 co-stimulated both ovine and murine mast cell proliferation in conjunction with IL-3 (ovine) or IL-4 (murine). Isoleucine at position 87 (Ile(87)) of the mature human IL-10 (huIL-10) has been reported as essential for the immuno-stimulatory activity of huIL-10. In spite of the differences in amino acids within the N-terminal third of orfvIL-10 compared with ovIL-10 and substitution of Ile(87) with Ala(87) in ovIL-10, these variants of ovIL-10 and orfvIL-10 all co-stimulated mast cell proliferation and inhibited macrophage IL-8 production. As ovIL-10 and orfvIL-10 have a similar structure to huIL-10 and conserved receptor-binding residues, it was concluded that Ile(87) is not essential for IL-10 immuno-stimulatory activity. Finally, ovine keratinocytes do not express ovIL-10. This might explain why orf virus has evolved a viral IL-10.