Modulating the extracellular matrix to treat wound healing defects in Ehlers-Danlos syndrome.

Classic Ehlers-Danlos syndrome (cEDS) is a genetic disorder of the connective tissue that is characterized by mutations in genes coding type V collagen. Wound healing defects are characteristic of cEDS and no therapeutic strategies exist. Herein we describe a murine model of cEDS that phenocopies wound healing defects seen in humans.

Improved Humoral Immunity and Protection against Influenza Virus Infection with a 3d Porous Biomaterial Vaccine.

New vaccine platforms that activate humoral immunity and generate neutralizing antibodies are required to combat emerging pathogens, including influenza virus. A slurry of antigen-loaded hydrogel microparticles that anneal to form a porous scaffold with high surface area for antigen uptake by infiltrating immune cells as the biomaterial degrades is demonstrated to enhance humoral immunity. Antigen-loaded-microgels elicited a robust cellular humoral immune response, with increased CD4 T follicular helper (Tfh) cells and prolonged germinal center (GC) B cells comparable to the commonly used adjuvant, aluminum hydroxide (Alum).

ER Stress Regulates Immunosuppressive Function of Myeloid Derived Suppressor Cells in Leprosy that Can Be Overcome in the Presence of IFN-γ.

Myeloid derived suppressor cells (MDSCs) are a population of immature myeloid cells that suppress adaptive immune function, yet the factors that regulate their suppressive function in patients with infection remain unclear. We studied MDSCs in patients with leprosy, a disease caused by Mycobacterium leprae, where clinical manifestations present on a spectrum that correlate with immunity to the pathogen. We found that HLA-DRCD33CD15 MDSCs were increased in blood from patients with disseminated/progressive lepromatous leprosy and possessed T cell-suppressive activity as compared with self-limiting tuberculoid leprosy.

A Macrophage Response to Mycobacterium leprae Phenolic Glycolipid Initiates Nerve Damage in Leprosy.

Mycobacterium leprae causes leprosy and is unique among mycobacterial diseases in producing peripheral neuropathy. This debilitating morbidity is attributed to axon demyelination resulting from direct interaction of the M. leprae-specific phenolic glycolipid 1 (PGL-1) with myelinating glia and their subsequent infection.

Opposing roles of Toll-like receptor and cytosolic DNA-STING signaling pathways for Staphylococcus aureus cutaneous host defense.

Successful host defense against pathogens requires innate immune recognition of the correct pathogen associated molecular patterns (PAMPs) by pathogen recognition receptors (PRRs) to trigger the appropriate gene program tailored to the pathogen. While many PRR pathways contribute to the innate immune response to specific pathogens, the relative importance of each pathway for the complete transcriptional program elicited has not been examined in detail. Herein, we used RNA-sequencing with wildtype and mutant macrophages to delineate the innate immune pathways contributing to the early transcriptional response to Staphylococcus aureus, a ubiquitous microorganism that can activate a wide variety of PRRs.

S100A12 Is Part of the Antimicrobial Network against Mycobacterium leprae in Human Macrophages.

Triggering antimicrobial mechanisms in macrophages infected with intracellular pathogens, such as mycobacteria, is critical to host defense against the infection. To uncover the unique and shared antimicrobial networks induced by the innate and adaptive immune systems, gene expression profiles generated by RNA sequencing (RNAseq) from human monocyte-derived macrophages (MDMs) activated with TLR2/1 ligand (TLR2/1L) or IFN-γ were analyzed. Weighed gene correlation network analysis identified modules of genes strongly correlated with TLR2/1L or IFN-γ that were linked by the "defense response" gene ontology term.

IL-27 Suppresses Antimicrobial Activity in Human Leprosy.

The mechanisms by which intracellular pathogens trigger immunosuppressive pathways are critical for understanding the pathogenesis of microbial infection. One pathway that inhibits host defense responses involves the induction of type I interferons and subsequently IL-10, yet the mechanism by which type I IFN induces IL-10 remains unclear. Our studies of gene expression profiles derived from leprosy skin lesions suggested a link between IL-27 and the IFN-β induced IL-10 pathway.

TRIF-dependent innate immune activation is critical for survival to neonatal gram-negative sepsis.

Current evidence suggests that neonatal immunity is functionally distinct from adults. Although TLR signaling through the adaptor protein, MyD88, has been shown to be critical for survival to sepsis in adults, little is known about the role of MyD88 or TRIF in neonatal sepsis. We demonstrate that TRIF(-/-) but not MyD88(-/-) neonates are highly susceptible to Escherichia coli peritonitis and bacteremia.

Novel role for tumor-induced expansion of myeloid-derived cells in cancer cachexia.

Cancer progression is associated with inflammation, increased metabolic demand, infection, cachexia, and eventually death. Myeloid-derived suppressor cells (MDSCs) commonly expand during cancer and are associated with adaptive immune suppression and inflammatory metabolite production. We propose that cancer-induced cachexia is driven at least in part by the expansion of MDSCs.

Alpha-lipoic acid effects on brain glial functions accompanying double-stranded RNA antiviral and inflammatory signaling.

Double-stranded RNAs (dsRNA) serve as viral ligands that trigger innate immunity in astrocytes and microglial, as mediated through Toll-like receptor 3 (TLR3) and dsRNA-dependent protein kinase (PKR). Beneficial transient TLR3 and PKR anti-viral signaling can become deleterious when events devolve into inflammation and cytotoxicity. Viral products in the brain cause glial cell dysfunction, and are a putative etiologic factor in neuropsychiatric disorders, notably schizophrenia, bipolar disorder, Parkinson's, and autism spectrum.

Maintenance of anti-Sm/RNP autoantibody production by plasma cells residing in ectopic lymphoid tissue and bone marrow memory B cells.

Although ectopic lymphoid tissue formation is associated with many autoimmune diseases, it is unclear whether it serves a functional role in autoimmune responses. 2,6,10,14-Tetramethylpentadecane causes chronic peritoneal inflammation and lupus-like disease with autoantibody production and ectopic lymphoid tissue (lipogranuloma) formation. A novel transplantation model was used to show that transplanted lipogranulomas retain their lymphoid structure over a prolonged period in the absence of chronic peritoneal inflammation.

Type I interferon suppresses type II interferon-triggered human anti-mycobacterial responses.

Type I interferons (IFN-α and IFN-β) are important for protection against many viral infections, whereas type II interferon (IFN-γ) is essential for host defense against some bacterial and parasitic pathogens. Study of IFN responses in human leprosy revealed an inverse correlation between IFN-β and IFN-γ gene expression programs. IFN-γ and its downstream vitamin D-dependent antimicrobial genes were preferentially expressed in self-healing tuberculoid lesions and mediated antimicrobial activity against the pathogen Mycobacterium leprae in vitro.

Microfluidics-based capture of human neutrophils for expression analysis in blood and bronchoalveolar lavage.

Gene expression analysis can be a powerful tool in predicting patient outcomes and identifying patients who may benefit from targeted therapies. However, isolating human blood polymorphonuclear cells (PMNs) for genomic analysis has been challenging. We used a novel microfluidic technique that isolates PMNs by capturing CD66b(+) cells and compared it with dextran-Ficoll gradient isolation.

Pathogenic role of B cells in the development of diffuse alveolar hemorrhage induced by pristane.

Diffuse alveolar hemorrhage is an uncommon, yet often fatal, complication of systemic lupus erythematosus (SLE). Advances in the treatment of alveolar hemorrhage have been hampered because of the heterogeneity of clinical findings and the lack of suitable animal models. A single intraperitoneal injection of pristane induces a lupus-like syndrome characterized by lupus-related autoantibodies and glomerulonephritis in non-autoimmune-prone strains of mice.

B cells enhance early innate immune responses during bacterial sepsis.

Microbes activate pattern recognition receptors to initiate adaptive immunity. T cells affect early innate inflammatory responses to viral infection, but both activation and suppression have been demonstrated. We identify a novel role for B cells in the early innate immune response during bacterial sepsis.

Neutrophil mobilization from the bone marrow during polymicrobial sepsis is dependent on CXCL12 signaling.

Neutrophils are essential for successful host eradication of bacterial pathogens and for survival to polymicrobial sepsis. During inflammation, the bone marrow provides a large reserve of neutrophils that are released into the peripheral circulation where they traverse to sites of infection. Although neutrophils are essential for survival, few studies have investigated the mechanisms responsible for neutrophil mobilization from the bone marrow during polymicrobial sepsis.

Critical role for CXC ligand 10/CXC receptor 3 signaling in the murine neonatal response to sepsis.

Previous studies have suggested that neonates rely heavily on innate immunity for their antimicrobial response to bacterial infections. However, the innate immune response by neonates to bacterial infection remains poorly characterized. Here, we show that in a murine model of neonatal polymicrobial sepsis, CXC ligand 10 (CXCL10) concentrations increase in the blood and peritoneum concordant with the peritoneal recruitment of granulocytes and macrophages.

Sepsis induces early alterations in innate immunity that impact mortality to secondary infection.

Sepsis, the systemic inflammatory response to microbial infection, induces changes in both innate and adaptive immunity that presumably lead to increased susceptibility to secondary infections, multiorgan failure, and death. Using a model of murine polymicrobial sepsis whose severity approximates human sepsis, we examined outcomes and defined requirements for survival after secondary Pseudomonas aeruginosa pneumonia or disseminated Listeria monocytogenes infection. We demonstrate that early after sepsis neutrophil numbers and function are decreased, whereas monocyte recruitment through the CCR2/MCP-1 pathway and function are enhanced.

A paradoxical role for myeloid-derived suppressor cells in sepsis and trauma.

Myeloid-derived suppressor cells (MDSCs) are a heterogenous population of immature myeloid cells whose numbers dramatically increase in chronic and acute inflammatory diseases, including cancer, autoimmune disease, trauma, burns and sepsis. Studied originally in cancer, these cells are potently immunosuppressive, particularly in their ability to suppress antigen-specific CD8(+) and CD4(+) T-cell activation through multiple mechanisms, including depletion of extracellular arginine, nitrosylation of regulatory proteins, and secretion of interleukin 10, prostaglandins and other immunosuppressive mediators. However, additional properties of these cells, including increased reactive oxygen species and inflammatory cytokine production, as well as their universal expansion in nearly all inflammatory conditions, suggest that MDSCs may be more of a normal component of the inflammatory response ("emergency myelopoiesis") than simply a pathological response to a growing tumor.

Cecal ligation and puncture.

The cecum contains a high concentration of microbes, which are a combination of Gram-negative and Gram-positive flora. These bacteria range from anaerobic to facultative aerobic to aerobic organisms. In the procedure described in this unit, the ligation of the cecum produces a source of ischemic tissue as well as polymicrobial infection.

Cutting edge: bacterial infection induces hematopoietic stem and progenitor cell expansion in the absence of TLR signaling.

Bone marrow (BM) hematopoietic stem and progenitor cells (HSPCs) can be activated by type I IFNs, TLR agonists, viruses, and bacteria to increase hematopoiesis. In this study, we report that endotoxin treatment in vivo induces TLR4, MyD88, and Toll/IL-1 resistance domain-containing adaptor-inducing IFN-beta (TRIF)-dependent expansion of BM HSPCs. Bacterial infection by Staphylococcus aureus or cecal ligation and puncture also induces HSPC expansion, but MyD88, TRIF, type I IFN, cytokine, PG, or oxidative stress pathways are not required for their expansion.

Type I interferon signaling in hematopoietic cells is required for survival in mouse polymicrobial sepsis by regulating CXCL10.

Type I interferon (IFN) alpha/beta is critical for host defense. During endotoxicosis or highly lethal bacterial infections where systemic inflammation predominates, mice deficient in IFN-alpha/beta receptor (IFNAR) display decreased systemic inflammation and improved outcome. However, human sepsis mortality often occurs during a prolonged period of immunosuppression and not from exaggerated inflammation.

B cell proliferation, somatic hypermutation, class switch recombination, and autoantibody production in ectopic lymphoid tissue in murine lupus.

Intraperitoneal exposure of nonautoimmune mice to 2,6,10,14-tetramethylpentadecane (TMPD) causes lupus and the formation of ectopic lymphoid tissue. Although associated with humoral autoimmunity, it is not known whether Ab responses develop within ectopic lymphoid tissue or if B cells only secondarily migrate there. We show that ectopic lymphoid tissue induced by TMPD not only resembles secondary lymphoid tissue morphologically, but it also displays characteristics of germinal center reactions.

TLR7-dependent and FcgammaR-independent production of type I interferon in experimental mouse lupus.

Increased type I interferon (IFN-I) production and IFN-stimulated gene (ISG) expression are linked to the pathogenesis of systemic lupus erythematosus (SLE). Although the mechanisms responsible for dysregulated IFN-I production in SLE remain unclear, autoantibody-mediated uptake of endogenous nucleic acids is thought to play a role. 2,6,10,14-tetramethylpentadecane (TMPD; also known as pristane) induces a lupus-like disease in mice characterized by immune complex nephritis with autoantibodies to DNA and ribonucleoproteins.

Colocalization of antigen-specific B and T cells within ectopic lymphoid tissue following immunization with exogenous antigen.

Chronic inflammation promotes the formation of ectopic lymphoid tissue morphologically resembling secondary lymphoid tissues, though it is unclear whether this is a location where Ag-specific immune responses develop or merely a site of lymphocyte accumulation. Ectopic lymphoid tissue formation is associated with many humoral autoimmune diseases, including lupus induced by tetramethylpecadentane in mice. We examined whether an immune response to 4-hydroxy-3-nitrophenyl acetyl-keyhole limpet hemocyanin (NP-KLH) and NP-OVA develops within ectopic lymphoid tissue ("lipogranulomas") induced by tetramethylpecadentane in C57BL/6 mice.