Lymphotoxin-β-receptor (LTβR) signaling on hepatocytes is required for liver regeneration after partial hepatectomy.

Lymphotoxin-β-receptor deficient (LTβR) and Tumor Necrosis Factor Receptor p55 deficient (TNFRp55) mice show defects in liver regeneration (LR) after partial hepatectomy (PHx) with significantly increased mortality. LTβR and TNFRp55 belong to the core members of the TNF/TNFR superfamily. Interestingly, combined failure of LTβR and TNFRp55 signaling after PHx leads to a complete defect in LR.

Lymphotoxin β Receptor: a Crucial Role in Innate and Adaptive Immune Responses against Toxoplasma gondii.

The lymphotoxin β receptor (LTβR) plays an essential role in the initiation of immune responses to intracellular pathogens. In mice, the LTβR is crucial for surviving acute toxoplasmosis; however, until now, a functional analysis was largely incomplete. Here, we demonstrate that the LTβR is a key regulator required for the intricate balance of adaptive immune responses.

Indoleamine 2,3-Dioxygenase Activity During Acute Toxoplasmosis and the Suppressed T Cell Proliferation in Mice.

() is an obligate intracellular parasite and belongs to the phylum Apicomplexa. is of medical and veterinary importance, because causes the parasitic disease toxoplasmosis. In human cells, the interferon-gamma inducible indoleamine 2,3-dioxygenase 1 (IDO1) is an antimicrobial effector mechanism that degrades tryptophan to kynurenine and thus limits pathogen proliferation .

IL-6 Trans-signaling Controls Liver Regeneration After Partial Hepatectomy.

Interleukin-6 (IL-6) is critically involved in liver regeneration after partial hepatectomy (PHX). Previous reports suggest that IL-6 trans-signaling through the soluble IL-6/IL-6R complex is involved in this process. However, the long-term contribution of IL-6 trans-signaling for liver regeneration after PHX is unknown.

The Lymphotoxin Receptor Is Essential for Upregulation of IFN-Induced Guanylate-Binding Proteins and Survival after Infection.

Lymphotoxin receptor (LTR) signaling plays an important role in efficient initiation of host responses to a variety of pathogens, encompassing viruses, bacteria, and protozoans via induction of the type I interferon response. The present study reveals that after infection, LTR mice show a substantially reduced survival rate when compared to wild-type mice. LTR mice exhibit an increased parasite load and a more pronounced organ pathology.

Cooperative role of lymphotoxin β receptor and tumor necrosis factor receptor p55 in murine liver regeneration.

Background & Aims: The liver exhibits a unique capacity for regeneration in response to injury. Lymphotoxin-β receptor (LTβR), a core member of the tumor necrosis factor (TNF)/tumor necrosis factor receptor (TNFR) superfamily is known to play an important role in this process. However, the function of LTβR during pathophysiological alterations and its molecular mechanisms during liver regeneration are so far ill-characterized.

Enforced viral replication activates adaptive immunity and is essential for the control of a cytopathic virus.

The innate immune system limits viral replication via type I interferon and also induces the presentation of viral antigens to cells of the adaptive immune response. Using infection of mice with vesicular stomatitis virus, we analyzed how the innate immune system inhibits viral propagation but still allows the presentation of antigen to cells of the adaptive immune response. We found that expression of the gene encoding the inhibitory protein Usp18 in metallophilic macrophages led to lower type I interferon responsiveness, thereby allowing locally restricted replication of virus.

Clonal inventory screens uncover monoclonality following serial transplantation of MGMT P140K-transduced stem cells and dose-intense chemotherapy.

Gene transfer of mutant O(6)-methylguanine-DNA-methyltransferase (MGMT(P140K)) into hematopoietic stem cells (HSCs) protects hematopoiesis from alkylating agents and allows efficient in vivo selection of transduced HSCs. However, insertional mutagenesis, high regenerative stress associated with selection, and the genotoxic potential of alkylating drugs represent considerable risk factors for clinical applications of this approach. Therefore, we investigated the long-term effect of MGMT(P140K) gene transfer followed by repetitive, dose-intensive treatment with alkylating agents in a murine serial bone marrow transplant model and assessed clonality of hematopoiesis up to tertiary recipients.

Gene Therapy of βc-Deficient Pulmonary Alveolar Proteinosis (βc-PAP): Studies in a Murine in vivo Model.

Pulmonary alveolar proteinosis (PAP) due to deficiency of the common β-chain (βc) of the interleukin-3 (IL-3)/IL-5/granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors is a rare monogeneic disease characterized by functional insufficiency of pulmonary macrophages. Hematopoietic stem cell gene therapy for restoring expression of βc-protein in the hematopoietic system may offer a curative approach. Toward this end, we generated a retroviral construct expressing the murine βc (mβc) gene and conducted investigations in a murine model of βc-deficient PAP.

Gene therapy of beta(c)-deficient pulmonary alveolar proteinosis (beta(c)-PAP): studies in a murine in vivo model.

Pulmonary alveolar proteinosis (PAP) due to deficiency of the common beta-chain (beta(c)) of the interleukin-3 (IL-3)/IL-5/granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors is a rare monogeneic disease characterized by functional insufficiency of pulmonary macrophages. Hematopoietic stem cell gene therapy for restoring expression of beta(c)-protein in the hematopoietic system may offer a curative approach. Toward this end, we generated a retroviral construct expressing the murine beta(c) (mbeta(c)) gene and conducted investigations in a murine model of beta(c)-deficient PAP.

A novel nonobese diabetic/severe combined immunodeficient xenograft model for chronic lymphocytic leukemia reflects important clinical characteristics of the disease.

We here describe a novel xenograft model of chronic lymphocytic leukemia (CLL) generated by infusion of human primary CLL cells into immunodeficient nonobese/severe combined immunodeficient (NOD/SCID) mice. Combined i.v.

O6-methylguanine-DNA-methyltransferase (MGMT) gene therapy targeting haematopoietic stem cells: studies addressing safety issues.

As haematopoietic stem cell gene therapy utilizing O(6)-methylguanine-DNA-methyltransferase has reached the clinical stage, safety-related questions become increasingly important. These issues concern insertional mutagenesis of viral vectors, the acute toxicity of pre-transplant conditioning protocols and in vivo selection regimens as well as potential genotoxic side effects of the alkylating drugs administered in this context. To address these questions, we have investigated toxicity-reduced conditioning regimens combining low-dose alkylator application with sublethal irradiation and have analysed their influence on engraftment and subsequent selectability of transduced haematopoietic stem cells.

Reliable generation of stable high titer producer cell lines for gene therapy.

Objective: Retroviral vectors represent one of the most robust technologies for in vivo expression of heterologous gene sequences and are still the most commonly used vectors in clinical gene therapy trials. The production of high titer retroviral preparations, however, can be a problematic procedure for certain constructs.

Methods: GALV- or RD114-pseudotyped retroviral particles carrying selectable fluorescence markers or drug resistance genes, such as the green fluorescent protein (GFP) or the O(6)-methylguanine-DNA-methyltransferase (MGMT) mutants, were used to stably transduce Phoenix-(FNX-)eco cells.

Gene transfer of cytidine deaminase protects myelopoiesis from cytidine analogs in an in vivo murine transplant model.

Hematopoietic stem cell gene transfer of the drug-resistance gene cytidine deaminase (CDD) protecting cells from the cytotoxic cytidine analogs cytarabine and gemcitabine was investigated in a murine transplant model. Following transplantation of CDD-transduced cells and cytarabine application (500 mg/kg; days 1-4; intraperitoneally) significant myeloprotection was demonstrated with nadir counts of peripheral blood granulocytes and thrombocytes of 2.9 +/- 0.

Stringent regulation of DNA repair during human hematopoietic differentiation: a gene expression and functional analysis.

For the lymphohematopoietic system, maturation-dependent alterations in DNA repair function have been demonstrated. Because little information is available on the regulatory mechanisms underlying these changes, we have correlated the expression of DNA damage response genes and the functional repair capacity of cells at distinct stages of human hematopoietic differentiation. Comparing fractions of mature (CD34-), progenitor (CD34+ 38+), and stem cells (CD34+ 38-) isolated from umbilical cord blood, we observed: 1) stringently regulated differentiation-dependent shifts in both the cellular processing of DNA lesions and the expression profiles of related genes and 2) considerable interindividual variability of DNA repair at transcriptional and functional levels.

Efficient protection from methotrexate toxicity and selection of transduced human hematopoietic cells following gene transfer of dihydrofolate reductase mutants.

Objective: While retrovirally mediated gene transfer of dihydrofolate reductase mutants (mutDHFR) has convincingly been demonstrated to confer methotrexate (MTX) resistance to murine hematopoietic cells, clinical application of this technology will require high efficacy in human cells. Therefore, we investigated retroviral constructs expressing various point mutants of human DHFR for their ability to confer MTX resistance to human clonogenic progenitor cells (CFU-C) and to allow for in vitro selection of transduced CFU-C.

Methods: Primary human hematopoietic cells were retrovirally transduced using MMLV- and SFFV/MESV-based vectors expressing DHFR(Ser31), DHFR(Phe22/Ser31), or DHFR(Tyr22/Gly31).

Hematoprotection and enrichment of transduced cells in vivo after gene transfer of MGMT(P140K) into hematopoietic stem cells.

The overexpression of mutant forms of O(6)-methylguanine-DNA-methyltransferase (MGMT), resistant to the MGMT inhibitor O(6)-benzylguanine (BG), protects hematopoietic cells from the toxicity of combined BG plus O(6)-alkylating agent chemotherapy. To evaluate the feasibility of this approach for clinically relevant O(6)-alkylating agents, combined therapy with BG and two chloroethylnitrosourea-type drugs, ACNU or BCNU, or the triazene derivative temozolomide (TMZ) was investigated in a murine bone marrow transplant model allowing transgenic expression of the highly BG-resistant MGMT(P140K) mutant. Whereas 20/20 control animals transplanted with nontransduced cells died of progressive myelosuppression during therapy, nearly all animals transplanted with MGMT(P140K)-transduced cells survived treatment with BG/ACNU (12/15), BG/TMZ (10/10), or BG/BCNU (5/5).