Pf bacteriophage are temperate phages that infect the bacterium Pseudomonas aeruginosa, a major cause of chronic lung infections in cystic fibrosis (CF) and other settings. Pf and other temperate phages have evolved complex, mutualistic relationships with their bacterial hosts that impact both bacterial phenotypes and chronic infection. We and others have reported that Pf phages are a virulence factor that promote the pathogenesis of P. aeruginosa infections in animal models and are associated with worse skin and lung infections in humans. Here we review the biology of Pf phage and what is known about its contributions to pathogenesis and clinical disease. First, we review the structure, genetics, and epidemiology of Pf phage. Next, we address the diverse and surprising ways that Pf phages contribute to P. aeruginosa phenotypes including effects on biofilm formation, antibiotic resistance, and motility. Then, we cover data indicating that Pf phages suppress mammalian immunity at sites of bacterial infection. Finally, we discuss recent literature implicating Pf in chronic P. aeruginosa infections in CF and other settings. Together, these reports suggest that Pf bacteriophage have direct effects on P. aeruginosa infections and that temperate phages are an exciting frontier in microbiology, immunology, and human health.
View details for DOI 10.3389/fimmu.2020.00244
View details for PubMedID 32153575
View details for PubMedCentralID PMC7047154
A coat of pericellular hyaluronan surrounds mature dendritic cells (DC) and contributes to cell-cell interactions. We asked whether 4-methylumbelliferone (4MU), an oral inhibitor of HA synthesis, could inhibit antigen presentation. We find that 4MU treatment reduces pericellular hyaluronan, destabilizes interactions between DC and T-cells, and prevents T-cell proliferation in vitro and in vivo. These effects were observed only when 4MU was added prior to initial antigen presentation but not later, consistent with 4MU-mediated inhibition of de novo antigenic responses. Building on these findings, we find that 4MU delays rejection of allogeneic pancreatic islet transplant and allogeneic cardiac transplants in mice and suppresses allogeneic T-cell activation in human mixed lymphocyte reactions. We conclude that 4MU, an approved drug, may have benefit as an adjunctive agent to delay transplantation rejection.
View details for DOI 10.1016/j.matbio.2020.12.001
View details for PubMedID 33290836
Pseudomonas aeruginosa (P. aeruginosa) is a major nosocomial pathogen of increasing relevance to human health and disease, particularly in the setting of chronic wound infections in diabetic and hospitalized patients. There is an urgent need for chronic infection models to aid in the investigation of wound pathogenesis and the development of new therapies against this pathogen. Here, we describe a protocol that uses delayed inoculation 24 hours after full-thickness excisional wounding. The infection of the provisional wound matrix present at this time forestalls either rapid clearance or dissemination of infection and instead establishes chronic infection lasting 7-10 days without the need for implantation of foreign materials or immune suppression. This protocol mimics a typical temporal course of post-operative infection in humans. The use of a luminescent P. aeruginosa strain (PAO1:lux) allows for quantitative daily assessment of bacterial burden for P. aeruginosa wound infections. This novel model may be a useful tool in the investigation of bacterial pathogenesis and the development of new therapies for chronic P. aeruginosa wound infections.
View details for DOI 10.3791/60599
View details for PubMedID 32150161
CD25CD4 regulatory T cells (Treg) regulate peripheral self-tolerance and possess the ability to suppress antitumor responses, which may explain the poor clinical response of cancer patients undergoing active immunization protocols, and provides the rationale for neutralizing Treg cells in vivo to strengthen local antitumor immune responses. Because interleukin-2 (IL-2) mediates tumor regression in about 15% of treated patients but simultaneously increases Treg cells, we hypothesized that transient elimination of Treg cells will enhance the clinical effectiveness of IL-2 therapy. In the current study, 5 patients with metastatic melanoma who were refractory to prior IL-2 received a lymphodepleting preparative regimen followed by the adoptive transfer of autologous lymphocytes depleted of CD25 Treg cells and high-dose IL-2 administration. CD25 cells were eliminated from patient leukapheresis samples using a clinical-grade, large-scale immunomagnetic system, leaving CD8 and CD25CD4 T cells intact. In the early aftermath of CD25 Treg cell-depleted cell infusion, CD25FOXP3+ CD4 Treg cells rapidly repopulated the peripheral blood of treated patients with 18% to 63% of CD4 T cells expressing FOXP3. Recovering CD25CD4 T cells exhibited suppressive activity against CD25CD4 effector T-cell proliferation in vitro. No patient experienced objective tumor regression or autoimmunity. Our results indicate that in vivo transfer of autologous CD25-depleted mononuclear populations to lymphopenic patients in combination with high-dose IL-2 is not sufficient to mediate prolonged reduction of Treg cells after IL-2 administration.
View details for DOI 10.1097/CJI.0b013e3180600ff9
View details for PubMedID 17457218
View details for PubMedCentralID PMC2140222
Bacteriophage are abundant at sites of bacterial infection, but their effects on mammalian hosts are unclear. We have identified pathogenic roles for filamentous Pf bacteriophage produced by Pseudomonas aeruginosa (Pa) in suppression of immunity against bacterial infection. Pf promote Pa wound infection in mice and are associated with chronic human Pa wound infections. Murine and human leukocytes endocytose Pf, and internalization of this single-stranded DNA virus results in phage RNA production. This triggers Toll-like receptor 3 (TLR3)- and TIR domain-containing adapter-inducing interferon-? (TRIF)-dependent type I interferon production, inhibition of tumor necrosis factor (TNF), and the suppression of phagocytosis. Conversely, immunization of mice against Pf prevents Pa wound infection. Thus, Pf triggers maladaptive innate viral pattern-recognition responses, which impair bacterial clearance. Vaccination against phage virions represents a potential strategy to prevent bacterial infection.
View details for PubMedID 30923196
View details for DOI 10.1038/cgt.2015.11
View details for PubMedID 25721204
Effective immunotherapeutic strategies require the ability to generate a systemic antigen-specific response capable of impacting both primary and metastatic disease. We have built on our oncolytic vaccinia a granulocyte-macrophage colony-stimulating factor (GM-CSF) strategy by adding recombinant tumor antigen to increase the response in the tumor microenvironment and systemically. In the present study, orthotopic growth of a syngeneic HER2/neu-overexpressing mammary carcinoma in FVB/N mice (NBT1) was associated with increased Gr1(+)CD11b(+) myeloid-derived suppressor cells (MDSCs) both systemically and in the tumor microenvironment. This MDSC population had inhibitory effects on the HER2/neu-specific Th1 immune response. VVneu and VVGMCSF are recombinant oncolytic vaccinia viruses that encode HER2/neu and GM-CSF, respectively. Naive FVB mice vaccinated with combined VVneu and VVGMCSF given systemically developed systemic HER2/neu-specific immunity. NBT1-bearing mice became anergic to systemic immunization with combined VVneu and VVGMCSF. Intratumoral VVGMCSF failed to result in systemic antitumor immunity until combined with intratumoral VVneu. Infection/transfection of the tumor microenvironment with combined VVGMCSF and VVneu resulted in development of systemic tumor-specific immunity, reduction in splenic and tumor MDSC and therapeutic efficacy against tumors. These studies demonstrate the enhanced efficacy of oncolytic vaccinia virus recombinants encoding combined tumor antigen and GM-CSF in modulating the microenvironment of MDSC-rich tumors.
View details for DOI 10.1038/cgt.2015.2
View details for PubMedID 25633483
View details for PubMedCentralID PMC4397129
Through the adoptive transfer of lymphocytes after host immunodepletion, it is possible to mediate objective cancer regression in human patients with metastatic melanoma. However, the generation of tumor-specific T cells in this mode of immunotherapy is often limiting. Here we report the ability to specifically confer tumor recognition by autologous lymphocytes from peripheral blood by using a retrovirus that encodes a T cell receptor. Adoptive transfer of these transduced cells in 15 patients resulted in durable engraftment at levels exceeding 10% of peripheral blood lymphocytes for at least 2 months after the infusion. We observed high sustained levels of circulating, engineered cells at 1 year after infusion in two patients who both demonstrated objective regression of metastatic melanoma lesions. This study suggests the therapeutic potential of genetically engineered cells for the biologic therapy of cancer.
View details for DOI 10.1126/science.1129003
View details for Web of Science ID 000241031200051
View details for PubMedID 16946036
View details for PubMedCentralID PMC2267026
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