Mesenchymal Stromal Cells Facilitate Neutrophil-Trained Immunity by Reprogramming Hematopoietic Stem Cells.

Novel therapeutics are urgently needed to prevent opportunistic infections in immunocompromised individuals undergoing cancer treatments or other immune-suppressive therapies. Trained immunity is a promising strategy to reduce this burden of disease. We previously demonstrated that mesenchymal stromal cells (MSCs) preconditioned with a class A CpG oligodeoxynucleotide (CpG-ODN), a Toll-like receptor 9 (TLR9) agonist, can augment emergency granulopoiesis in a murine model of neutropenic sepsis. Here, we used a chimeric mouse model to demonstrate that MSCs secrete paracrine factors that act on lineage-negative c-kit+ hematopoietic stem cells (HSCs), leaving them "poised" to enhance emergency granulopoiesis months after transplantation. Chimeric mice developed from HSCs exposed to conditioned media from MSCs and CpG-ODN-preconditioned MSCs showed significantly higher bacterial clearance and increased neutrophil granulopoiesis following lung infection than control mice. By Cleavage Under Targets and Release Using Nuclease (CUT&RUN) chromatin sequencing, we identified that MSC-conditioned media leaves H3K4me3 histone marks in HSCs at genes involved in myelopoiesis and in signaling persistence by the mTOR pathway. Both soluble factors and extracellular vesicles from MSCs mediated these effects on HSCs and proteomic analysis by mass spectrometry revealed soluble calreticulin as a potential mediator. In summary, this study demonstrates that trained immunity can be mediated by paracrine factors from MSCs to induce neutrophil-trained immunity by reprogramming HSCs for long-lasting functional changes in neutrophil-mediated antimicrobial immunity.

ETV2 regulates PARP-1 binding protein to induce ER stress-mediated death in tuberin-deficient cells.

Lymphangioleiomyomatosis (LAM) is a rare progressive disease, characterized by mutations in the tuberous sclerosis complex genes (TSC1 or TSC2) and hyperactivation of mechanistic target of rapamycin complex 1 (mTORC1). Here, we report that E26 transformation-specific (ETS) variant transcription factor 2 (ETV2) is a critical regulator of Tsc2-deficient cell survival. ETV2 nuclear localization in Tsc2-deficient cells is mTORC1-independent and is enhanced by spleen tyrosine kinase (Syk) inhibition. In the nucleus, ETV2 transcriptionally regulates poly(ADP-ribose) polymerase 1 binding protein (PARPBP) mRNA and protein expression, partially reversing the observed down-regulation of PARPBP expression induced by mTORC1 blockade during treatment with both Syk and mTORC1 inhibitors. In addition, silencing Etv2 or Parpbp in Tsc2-deficient cells induced ER stress and increased cell death in vitro and in vivo. We also found ETV2 expression in human cells with loss of heterozygosity for TSC2, lending support to the translational relevance of our findings. In conclusion, we report a novel ETV2 signaling axis unique to Syk inhibition that promotes a cytocidal response in Tsc2-deficient cells and therefore maybe a potential alternative therapeutic target in LAM.

Mesenchymal stromal cell-derived syndecan-2 regulates the immune response during sepsis to foster bacterial clearance and resolution of inflammation.

Sepsis is a life-threatening process related to a dysregulated host response to an underlying infection, which results in organ dysfunction and poor outcomes. Therapeutic strategies using mesenchymal stromal cells (MSCs) are under investigation for sepsis, with efforts to improve cellular utility. Syndecan (SDC) proteins are transmembrane proteoglycans involved with cellular signaling events including tissue repair and modulating inflammation. Bone marrow-derived human MSCs express syndecan-2 (SDC2) at a level higher than other SDC family members; thus, we explored SDC2 in MSC function. Administration of human MSCs silenced for SDC2 in experimental sepsis resulted in decreased bacterial clearance, and increased tissue injury and mortality compared with wild-type MSCs. These findings were associated with a loss of resolution of inflammation in the peritoneal cavity, and higher levels of proinflammatory mediators in organs. MSCs silenced for SDC2 had a decreased ability to promote phagocytosis of apoptotic neutrophils by macrophages in the peritoneum, and also a diminished capability to convert macrophages from a proinflammatory to a proresolution phenotype via cellular or paracrine actions. Extracellular vesicles are a paracrine effector of MSCs that may contribute to resolution of inflammation, and their production was dramatically reduced in SDC2-silenced human MSCs. Collectively, these data demonstrate the importance of SDC2 for cellular and paracrine function of human MSCs during sepsis.

The lung microbiome in end-stage Lymphangioleiomyomatosis.

Lymphangioleiomyomatosis (LAM) is a progressive cystic lung disease with mortality driven primarily by respiratory failure. Patients with LAM frequently have respiratory infections, suggestive of a dysregulated microbiome. Here we demonstrate that end-stage LAM patients have a distinct microbiome signature compared to patients with end-stage chronic obstructive pulmonary disease.

Intratracheal transplantation of trophoblast stem cells attenuates acute lung injury in mice.

BACKGROUND: Acute lung injury (ALI) is a common lung disorder that affects millions of people every year. The infiltration of inflammatory cells into the lungs and death of the alveolar epithelial cells are key factors to trigger a pathological cascade. Trophoblast stem cells (TSCs) are immune privileged, and demonstrate the capability of self-renewal and multipotency with differentiation into three germ layers. We hypothesized that intratracheal transplantation of TSCs may alleviate ALI. METHODS: ALI was induced by intratracheal delivery of bleomycin (BLM) in mice. After exposure to BLM, pre-labeled TSCs or fibroblasts (FBs) were intratracheally administered into the lungs. Analyses of the lungs were performed for inflammatory infiltrates, cell apoptosis, and engraftment of TSCs. Pro-inflammatory cytokines/chemokines of lung tissue and in bronchoalveolar lavage fluid (BALF) were also assessed. RESULTS: The lungs displayed a reduction in cellularity, with decreased CD45+ cells, and less thickening of the alveolar walls in ALI mice that received TSCs compared with ALI mice receiving PBS or FBs. TSCs decreased infiltration of neutrophils and macrophages, and the expression of interleukin (IL) 6, monocyte chemoattractant protein-1 (MCP-1) and keratinocyte-derived chemokine (KC) in the injured lungs. The levels of inflammatory cytokines in BALF, particularly IL-6, were decreased in ALI mice receiving TSCs, compared to ALI mice that received PBS or FBs. TSCs also significantly reduced BLM-induced apoptosis of alveolar epithelial cells in vitro and in vivo. Transplanted TSCs integrated into the alveolar walls and expressed aquaporin 5 and prosurfactant protein C, markers for alveolar epithelial type I and II cells, respectively. CONCLUSION: Intratracheal transplantation of TSCs into the lungs of mice after acute exposure to BLM reduced pulmonary inflammation and cell death. Furthermore, TSCs engrafted into the alveolar walls to form alveolar epithelial type I and II cells. These data support the use of TSCs for the treatment of ALI.

Mesenchymal stromal cells expressing a dominant-negative high mobility group A1 transgene exhibit improved function during sepsis.

High mobility group (HMG)A proteins are nonhistone chromatin proteins that bind to the minor groove of DNA, interact with transcriptional machinery, and facilitate DNA-directed nuclear processes. HMGA1 has been shown to regulate genes involved with systemic inflammatory processes. We hypothesized that HMGA1 is important in the function of mesenchymal stromal cells (MSCs), which are known to modulate inflammatory responses due to sepsis. To study this process, we harvested MSCs from transgenic (Tg) mice expressing a dominant-negative (dn) form of HMGA1 in mesenchymal cells. MSCs harvested from Tg mice contained the dnHMGA1 transgene, and transgene expression did not change endogenous HMGA1 levels. Immunophenotyping of the cells, along with trilineage differentiation revealed no striking differences between Tg and wild-type (WT) MSCs. However, Tg MSCs growth was decreased compared with WT MSCs, although Tg MSCs were more resistant to oxidative stress-induced death and expressed less IL-6. Tg MSCs administered after the onset of Escherichia coli-induced sepsis maintained their ability to improve survival when given in a single dose, in contrast with WT MSCs. This survival benefit of Tg MSCs was associated with less tissue cell death, and also a reduction in tissue neutrophil infiltration and expression of neutrophil chemokines. Finally, Tg MSCs promoted bacterial clearance and enhanced neutrophil phagocytosis, in part through their increased expression of stromal cell-derived factor-1 compared with WT MSCs. Taken together, these data demonstrate that expression of dnHMGA1 in MSCs provides a functional advantage of the cells when administered during bacterial sepsis.

Augmenting emergency granulopoiesis with CpG conditioned mesenchymal stromal cells in murine neutropenic sepsis.

Patients with immune deficiencies from cancers and associated treatments represent a growing population within the intensive care unit with increased risk of morbidity and mortality from sepsis. Mesenchymal stromal cells (MSCs) are an integral part of the hematopoietic niche and express toll-like receptors, making them candidate cells to sense and translate pathogenic signals into an innate immune response. In this study, we demonstrate that MSCs administered therapeutically in a murine model of radiation-associated neutropenia have dual actions to confer a survival benefit in Pseudomonas aeruginosa pneumo-sepsis that is not from improved bacterial clearance. First, MSCs augment the neutrophil response to infection, an effect that is enhanced when MSCs are preconditioned with CpG oligodeoxynucleotide, a toll-like receptor 9 agonist. Using cytometry by time of flight, we identified proliferating neutrophils (Ly6GlowKi-67+) as the main expanded cell population within the bone marrow. Further analysis revealed that CpG-MSCs expand a lineage restricted progenitor population (Lin-Sca1+C-kit+CD150-CD48+) in the bone marrow, which corresponded to a doubling in the myeloid proliferation and differentiation potential in response to infection compared with control. Despite increased neutrophils, no reduction in organ bacterial count was observed between experimental groups. However, the second effect exerted by CpG-MSCs is to attenuate organ damage, particularly in the lungs. Neutrophils obtained from irradiated mice and cocultured with CpG-MSCs had decreased neutrophil extracellular trap formation, which was associated with decreased citrullinated H3 staining in the lungs of mice given CpG-MSCs in vivo. Thus, this preclinical study provides evidence for the therapeutic potential of MSCs in neutropenic sepsis.

Expression of Stromal Cell-Derived Factor-1 by Mesenchymal Stromal Cells Impacts Neutrophil Function During Sepsis.

OBJECTIVES: Sepsis results in organ dysfunction caused by a dysregulated host response, in part related to the immune response of a severe infection. Mesenchymal stromal cells are known to modulate the immune response, and expression of stromal cell-derived factor-1 regulates mobilization of neutrophils from the bone marrow. We are investigating the importance of stromal cell-derived factor-1 in mesenchymal stromal cells and its role in promoting neutrophil function after the onset of cecal ligation and puncture-induced sepsis. Stromal cell-derived factor-1 expression was silenced in mesenchymal stromal cells, compared with the control scrambled construct mesenchymal stromal cells. DESIGN: Animal study and cell culture. SETTING: Laboratory investigation. SUBJECTS: BALB/c mice. INTERVENTIONS: Polymicrobial sepsis was induced by cecal ligation and puncture. shSCR mesenchymal stromal cells and shSDF-1 mesenchymal stromal cells were delivered by tail vein injections to septic mice. The mice were assessed for survival, bacterial clearance, and the inflammatory response during sepsis in each of the groups. Mesenchymal stromal cells were also assessed for their ability to promote bacterial phagocytosis by neutrophils. MEASUREMENTS AND MAIN RESULTS: Injection of shSCR mesenchymal stromal cells after the onset of sepsis led to an increase in mouse survival (70%) at 7 days, whereas survival of mice receiving shSDF-1 mesenchymal stromal cells was significantly diminished (33%). The loss of survival benefit in mice receiving shSDF-1 mesenchymal stromal cells was associated with less efficient bacterial clearance compared with shSCR mesenchymal stromal cells. Although shSCR mesenchymal stromal cells, or their conditioned medium, were able to increase neutrophil phagocytosis of bacteria, this effect was significantly blunted with shSDF-1 mesenchymal stromal cells. Assessment of peritoneal inflammation revealed that neutrophils were significantly increased and more immature in septic mice receiving shSDF-1 mesenchymal stromal cells. This response was associated with hypocellularity and increased neutrophil death in the bone marrow of mice receiving shSDF-1 mesenchymal stromal cells. CONCLUSIONS: Expression of stromal cell-derived factor-1 in mesenchymal stromal cells enhances neutrophil function with increased phagocytosis, more efficient clearance of bacteria, and bone marrow protection from depletion of cellular reserves during sepsis.

Rituximab Monotherapy for Common Variable Immune Deficiency-Associated Granulomatous-Lymphocytic Interstitial Lung Disease.

Patients with common variable immunodeficiency (CVID) can develop granulomatous-lymphocytic interstitial lung disease (GLILD), which is associated with increased morbidity and mortality. Treating GLILD is a significant challenge because it is rare and can be pathologically heterogeneous. Here we describe two cases of patients with CVID-associated GLILD with biopsies demonstrating loosely organized tertiary lymphoid structures (TLSs). Based on the pivotal role that B cells play in TLS initiation and maintenance, we hypothesized that using rituximab monotherapy for B-cell depletion alone would be sufficient for the disruption of the pathologic process underlying GLILD. These two cases demonstrate that adapting a strategy of B cell depletion monotherapy may be effective in TLS-associated conditions such as GLILD.

A new transcriptional role for matrix metalloproteinase-12 in antiviral immunity.

Interferon-α (IFN-α) is essential for antiviral immunity, but in the absence of matrix metalloproteinase-12 (MMP-12) or IκBα (encoded by NFKBIA) we show that IFN-α is retained in the cytosol of virus-infected cells and is not secreted. Our findings suggest that activated IκBα mediates the export of IFN-α from virus-infected cells and that the inability of cells in Mmp12(-/-) but not wild-type mice to express IκBα and thus export IFN-α makes coxsackievirus type B3 infection lethal and renders respiratory syncytial virus more pathogenic. We show here that after macrophage secretion, MMP-12 is transported into virus-infected cells. In HeLa cells MMP-12 is also translocated to the nucleus, where it binds to the NFKBIA promoter, driving transcription. We also identified dual-regulated substrates that are repressed both by MMP-12 binding to the substrate's gene exons and by MMP-12-mediated cleavage of the substrate protein itself. Whereas intracellular MMP-12 mediates NFKBIA transcription, leading to IFN-α secretion and host protection, extracellular MMP-12 cleaves off the IFN-α receptor 2 binding site of systemic IFN-α, preventing an unchecked immune response. Consistent with an unexpected role for MMP-12 in clearing systemic IFN-α, treatment of coxsackievirus type B3-infected wild-type mice with a membrane-impermeable MMP-12 inhibitor elevates systemic IFN-α levels and reduces viral replication in pancreas while sparing intracellular MMP-12. These findings suggest that inhibiting extracellular MMP-12 could be a new avenue for the development of antiviral treatments.

Extent of pancreatic fibrosis as a determinant of symptom resolution after the Frey procedure: a clinico-pathologic analysis.

OBJECTIVE: The aim of this study was to evaluate the association of histopathologic features of chronic pancreatitis and pain relief after the Frey procedure. DESIGN: We retrospectively analyzed 35 patients who underwent the Frey procedure for chronic pancreatitis over a 5-year period (November 2005 to February 2011). SETTING: Thirty-five patients with varied etiologies of chronic pancreatitis and persistent symptoms were referred to a multi-disciplinary pancreatitis clinic where a consensus decision to recommend surgery was established. The Frey procedure was then performed. MAIN OUTCOME MEASURES: We compared symptomatic outcomes with the degree of pancreatic fibrosis, duct dilatation, and presence of pancreatic duct stones based on a blinded evaluation of resected pancreatic tissue. RESULTS: Symptom resolution was associated with severe or extensive (>75 %) fibrosis and absence of symptom resolution was associated with mild or minimal (<25 %) fibrosis (chi-squared, p value < 0.05). Symptom resolution was associated with pancreatic duct >4 mm and absence of symptom resolution was associated with pancreatic duct ≤4 mm (chi-squared, p value < 0.05). There was no difference in outcomes for patients with and without pancreatic duct stones. CONCLUSION: Symptom resolution after the Frey procedure is more likely in the setting of severe or extensive fibrosis due to chronic pancreatitis.

Perioperative stroke in noncardiac, nonneurosurgical surgery.

Perioperative stroke after noncardiac, nonneurosurgical procedures is more common than generally acknowledged. It is reported to have an incidence of 0.05-7% of patients. Most are thrombotic in origin and are noted after discharge from the postanesthetic care unit. Common predisposing factors include age, a previous stroke, atrial fibrillation, and vascular and metabolic diseases. The mortality is more than two times greater than in strokes occurring outside the hospital. Delayed diagnosis and a synergistic interaction between the inflammatory changes normally associated with stroke, and those normally occurring after surgery, may explain this increase. Intraoperative hypotension is an infrequent direct cause of stroke. Hypotension will augment the injury produced by embolism or other causes, and this may be especially important in the postoperative period, during which monitoring is not nearly as attentive as in the operating room. Increased awareness and management of predisposing risk factors with early detection should result in improved outcomes.

Sarcopenia negatively impacts short-term outcomes in patients undergoing hepatic resection for colorectal liver metastasis.

BACKGROUND: As indications for liver resection expand, objective measures to assess the risk of peri-operative morbidity are needed. The impact of sarcopenia on patients undergoing liver resection for colorectal liver metastasis (CRLM) was investigated. METHODS: Sarcopenia was assessed in 259 patients undergoing liver resection for CRLM by measuring total psoas area (TPA) on computed tomography (CT). The impact of sarcopenia was assessed after controlling for clinicopathological factors using multivariate modelling. RESULTS: Median patient age was 58 years and most patients (60%) were male. Forty-one (16%) patients had sarcopenia (TPA ≤ 500 mm(2) /m(2) ). Post-operatively, 60 patients had a complication for an overall morbidity of 23%; 26 patients (10%) had a major complication (Clavien grade ≥3). The presence of sarcopenia was strongly associated with an increased risk of major post-operative complications [odds ratio (OR) 3.33; P= 0.008]. Patients with sarcopenia had longer hospital stays (6.6 vs. 5.4 days; P= 0.03) and a higher chance of an extended intensive care unit (ICU) stay (>2 days; P= 0.004). On multivariate analysis, sarcopenia remained independently associated with an increased risk of post-operative complications (OR 3.12; P= 0.02). Sarcopenia was not significantly associated with recurrence-free [hazard ratio (HR) = 1.07] or overall (HR = 1.05) survival (both P > 0.05). CONCLUSIONS: Sarcopenia impacts short-, but not long-term outcomes after resection of CRLM. While patients with sarcopenia are at an increased risk of post-operative morbidity and longer hospital stay, long-term survival is not impacted by the presence of sarcopenia.

Assessment of surgical and obstetrical care at 10 district hospitals in Ghana using on-site interviews.

BACKGROUND: For most of the population in Africa, district hospitals represent the first level of access for emergency and essential surgical services. The present study documents the number and availability of surgical and obstetrical care providers as well as the types of surgical and obstetrical procedures being performed at 10 first-referral district hospitals in Ghana. MATERIALS AND METHODS: After institutional review board and governmental approval, a study team composed of Ghanaian and American surgeons performed on-site surveys at 10 district hospitals in 10 different regions of Ghana in August 2009. Face-to-face interviews were conducted documenting the numbers and availability of surgical and obstetrical personnel as well as gathering data relating to the number and types of procedures being performed at the facilities. RESULTS: A total of 68 surgical and obstetrical providers were interviewed. Surgical and obstetrical care providers consisted of Medical Officers (8.5%), nurse anesthetists (6%), theatre nurses (33%), midwives (50.7%), and others (4.5%). Major surgical cases represented 37% of overall case volumes with cesarean section as the most common type of major surgical procedure performed. The most common minor surgical procedures performed were suturing of lacerations or episiotomies. CONCLUSIONS: The present study demonstrates that there is a substantial shortage of adequately trained surgeons who can perform surgical and obstetrical procedures at first-referral facilities. Addressing human resource needs and further defining practice constraints at the district hospital level are important facets of future planning and policy implementation.