Factor Knockout Mice Research Articles

Decreased neutrophil counts prolong inflammation in acute pancreatitis and cause inflammation spillover to distant organs

Background/objectiveAcute pancreatitis is an aseptic inflammation caused by pathologically activated pancreatic enzymes and inflammatory mediators produced secondarily by neutrophils and other inflammatory cells and is one of the most difficult diseases to treat. This study aimed to investigate the role of neutrophils in pancreatitis by examining tissue dynamics. MethodsWe created a model of caerulein-induced pancreatitis in 12-week-old male granulocyte colony-stimulating factor knockout mice (G–CSF–KO) and wild-type littermate control mice (six intraperitoneal injections of caerulein [80 μg/kg body weight] at hourly intervals for 2 days). Mice were sacrificed 0, 3, 6, 12, 24, 36, 48, 72, and 168 h after caerulein administration and examined histologically. ResultsThe survival rate after one week of caerulein administration was 100 % in the control mice, whereas it was significantly lower (10 %) in the G–CSF–KO mice. Histological examination revealed significant hemorrhage and inflammatory cell migration in the G–CSF–KO mice, indicating prolonged inflammation. ConclusionProlonged inflammation was observed in the G–CSF–KO mice. Tissue cleanup by neutrophils during the acute phase of inflammation may influence healing through the chronic phase.

WED-395 - Brain-derived neurotrophic factor knock-out mice develop non-alcoholic steatohepatitis

WED-395 - Brain-derived neurotrophic factor knock-out mice develop non-alcoholic steatohepatitis

P.0851 Fluoxetine treatment effect on photoperiodic alterations in behavior, brain serotonin and brain-derived neurotrophic factor in tumor necrosis factor knockout mice

P.0851 Fluoxetine treatment effect on photoperiodic alterations in behavior, brain serotonin and brain-derived neurotrophic factor in tumor necrosis factor knockout mice

The effects of genetic deletion of Macrophage migration inhibitory factor on the chronically hypoxic pulmonary circulation.

While it is well established that the haemodynamic cause of hypoxic pulmonary hypertension is increased pulmonary vascular resistance, the molecular pathogenesis of the increased resistance remains incompletely understood. Macrophage migration inhibitory factor is a pleiotropic cytokine with endogenous tautomerase enzymatic activity as well as both intracellular and extracellular signalling functions. In several diseases, macrophage migration inhibitory factor has pro-inflammatory roles that are dependent upon signalling through the cell surface receptors CD74, CXCR2 and CXCR4. Macrophage migration inhibitory factor expression is increased in animal models of hypoxic pulmonary hypertension and macrophage migration inhibitory factor tautomerase inhibitors, which block some of the functions of macrophage migration inhibitory factor, and have been shown to attenuate hypoxic pulmonary hypertension in mice and monocrotaline-induced pulmonary hypertension in rats. However, because of the multiple pathways through which it acts, the integrated actions of macrophage migration inhibitory factor during the development of hypoxic pulmonary hypertension were unclear. We report here that isolated lungs from adult macrophage migration inhibitory factor knockout (MIF–/–) mice maintained in normoxic conditions showed greater acute hypoxic vasoconstriction than the lungs of wild type mice (MIF+/+). Following exposure to hypoxia for three weeks, isolated lungs from MIF–/– mice had significantly higher pulmonary vascular resistance than those from MIF+/+ mice. The major mechanism underlying the greater increase in pulmonary vascular resistance in the hypoxic MIF–/– mice was reduction of the pulmonary vascular bed due to an impairment of the normal hypoxia-induced expansion of the alveolar capillary network. Taken together, these results demonstrate that macrophage migration inhibitory factor plays a central role in the development of the pulmonary vascular responses to chronic alveolar hypoxia.

Tau accumulates in Crohn's disease gut.

A sizeable body of evidence has recently emerged to suggest that gastrointestinal (GI) inflammation might be involved in the development of Parkinson's disease (PD). There is now strong epidemiological and genetical evidence linking PD to inflammatory bowel diseases and we recently demonstrated that the neuronal protein alpha-synuclein, which is critically involved in PD pathophysiology, is upregulated in inflamed segments of Crohn's colon. The microtubule associated protein tau is another neuronal protein critically involved in neurodegenerative disorders but, in contrast to alpha-synuclein, no data are available about its expression and phosphorylation patterns in inflammatory bowel diseases. Here, we examined the expression levels of tau isoforms, their phosphorylation profile and truncation in colon biopsy specimens from 16 Crohn's disease (CD) and 6 ulcerative colitis (UC) patients and compared them to samples from 16 controls. Additional experiments were performed in full thickness segments of colon of five CD and five control subjects, in primary cultures of rat enteric neurons and in nuclear factor erythroid 2-related factor (Nrf2) knockout mice. Our results show the upregulation of two main human tau isoforms in the enteric nervous system (ENS) in CD but not in UC. This upregulation was not transcriptionally regulated but instead likely resulted from a decrease in protein clearance via an Nrf2 pathway. Our findings, which provide the first detailed characterization of tau in CD, suggest that the key proteins involved in neurodegenerative disorders such as alpha-synuclein and tau, might also play a role in CD.

Light-induced Nrf2\u2212/\u2212 mice as atrophic age-related macular degeneration model and treatment with nanoceria laden injectable hydrogel

Elevated oxidative stress and associated reactive oxygen species (ROS) accumulation are hallmarks in the induction and progression of age-related macular degeneration (AMD). By exposing nuclear factor erythroid 2-related factor (Nrf2) knockout (Nrf2−/−) mice to mild white light, we were able to generate a new dry-AMD like murine model to the study. This animal model developed phenotypes of photoreceptor degeneration, retinal function impairment, ROS accumulation, and inflammation reaction in a relatively shorter time. In the treatment of this animal model we utilized an antioxidative and water soluble nanoparticle known as glycol chitosan coated cerium oxide nanoparticles (GCCNP). The delivery of GCCNP protected retina against progressive retinal oxidative damage. Further combination of GCCNP with alginate-gelatin based injectable hydrogel provided synergistic antioxidant effects and achieved a more rapid recovery of the retinal pigment epithelium and photoreceptor cells. This combined treatment technique has the potential to translate into a clinical intervention for the treatment of AMD.

Hemophilia A and B mice, but not VWF\u2212/\u2212mice, display bone defects in congenital development and remodeling after injury

While joint damage is the primary co-morbidity of hemophilia, osteoporosis and osteopenia are also observed. Coagulation factor VIII deficient (FVIII−/−) mice develop an osteoporotic phenotype in the absence of induced hemarthrosis that is exacerbated two weeks after an induced joint injury. Here we have compared comprehensively the bone health of clotting factor VIII, factor IX, and Von Willebrand Factor knockout (FVIII−/−, FIX−/−, and VWF−/− respectively) mice both in the absence of joint hemorrhage and following induced joint injury. We found FVIII−/− and FIX−/− mice, but not VWF−/− mice, developmentally have an osteoporotic phenotype. Unilateral induced hemarthrosis causes further bone damage in both FVIII−/− and FIX−/− mice, but has little effect on VWF−/− bone health, indicating that the FVIII.VWF complex is not required for normal bone remodeling in vivo. To further investigate the bone healing following hemarthrosis in hemophilia we examined a two week time course using microCT, serum chemistry, and histological analysis. Elevated ratio of osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B ligand (RANKL), increased osterix+ osteoblastic cells, and decreased smoothness of the cortical bone surface were evident within several days of injury, indicative of acute heterotopic mineralization along the cortical surface. This was closely followed by increased interleukin-6 (IL-6) levels, increased osteoclast numbers, and significant trabecular bone loss. Uncoupled and disorganized bone formation and resorption continued for the duration of the study resulting in significant deterioration of the joint. Further elucidation of the shared mechanisms underlying abnormal bone homeostasis in the absence of FVIII or FIX is needed to guide evidence-based approaches to the screening and treatment of the prevalent bone defects in hemophilia A and B.

The effect of short photoperiod on behavior, brain-derived neurotrophic factor and brain serotonin system in tumour necrosis factor knockout mice

The effect of short photoperiod on behavior, brain-derived neurotrophic factor and brain serotonin system in tumour necrosis factor knockout mice

Mitochondrial DNA alterations in aged macrophage migration inhibitory factor-knockout mice

The age-induced, exponential accumulation of mitochondrial DNA (mtDNA) deletion mutations contributes to muscle fiber loss. The causes of these mutations are not known. Systemic inflammation is associated with decreased muscle mass in older adults and is implicated in the formation of sporadic mtDNA deletions. Macrophage migration inhibitory factor knockout (MIF-KO) mice are long-lived with decreased inflammation. We hypothesized that aged MIF-KO mice would have lower mtDNA deletion frequencies and fewer electron transport chain (ETC) deficient fibers.We measured mtDNA copy number and mutation frequency as well as the number and length of ETC deficient fibers in 22-month old MIF-KO and F2 hybrid control mice. We also measured mtDNA copy number and deletion frequency in female UM-HET3 mice, a strain whose lifespan matches the MIF-KO mice.We did not observe a significant effect of MIF ablation on muscle mtDNA deletion frequency. There was a significantly lower mtDNA copy number in the MIF-KO mice and the lifespan-matched UM-HET3 mice compared to the F2 hybrids, suggesting the importance of genetic background in mtDNA copy number control. Our data do not support a definitive role for MIF in age-induced mtDNA deletions.

Neutrophil Elastase Damages the Pulmonary Endothelial Glycocalyx in Lipopolysaccharide-Induced Experimental Endotoxemia

Neutrophil elastase (NE) is necessary for effective sterilization of phagocytosed bacterial and fungal pathogens; however, NE increases alveolocapillary permeability and induces proinflammatory cytokine production in sepsis-induced acute respiratory distress syndrome. Under septic conditions, the pulmonary endothelial glycocalyx covering on the healthy endothelium surface is injured, but the contribution of NE to this injury remains unknown. Our aim was to examine whether NE-induced pulmonary endothelial injury is associated with endotoxemia. Lipopolysaccharide (LPS; 20 mg/kg) was injected intraperitoneally into 9- to 12-week-old granulocyte colony-stimulating factor knockout (G-CSFKO) mice, which harbor few neutrophils, and littermate control mice; in a second assay, mice were injected with the NE-inhibitor sivelestat (0.2 mg/kg) at 3, 6, 9, and 12 hours after LPS administration. Subsequently, vascular endothelial injury was evaluated through ultrastructural analysis. At 48 hours after LPS injection, survival rate was more than threefold higher among G-CSFKO than control mice, and degradation of both thrombomodulin and syndecan-1 was markedly attenuated in G-CSFKO compared with control mice. Ultrastructural analysis revealed attenuated vascular endothelial injury and clear preservation of the endothelial glycocalyx in G-CSFKO mice. Moreover, after LPS exposure, survival rate was approximately ninefold higher among sivelestat-injected mice than control mice, and sivelestat treatment potently preserved vascular endothelial structures and the endothelial glycocalyx. In conclusion, NE is associated with pulmonary endothelial injury under LPS-induced endotoxemic conditions.

Impaired social contacts with familiar anesthetized conspecific in CA3-restricted brain-derived neurotrophic factor knockout mice.

Familiarity is conveyed by social cues and determines behaviors toward conspecifics. Here, we characterize a novel assay for social behaviors in mice-contacts with anesthetized conspecific-which eliminates reciprocal interactions, including intermale aggression and shows behaviors that are independent of the demonstrator's activity. During the initial 10 minutes (phase-1), the wild-type (WT) subjects contacted the anesthetized conspecifics vigorously regardless of familiarity. During the subsequent 80 minutes (phase-2), however, they contacted more with familiar than unfamiliar conspecifics. We then applied this test to highly aggressive mice with a hippocampal CA3-restricted knockout (KO) of brain-derived neurotrophic factor (BDNF), in which aggression may mask other social behaviors. The KO mice showed less preference for contacting familiar conspecifics than did WT mice during phase-2 but no differences during phase-1. Among nonsocial behaviors, WT mice also spent less time eating in the presence of familiar than with unfamiliar conspecifics, which was not seen in KO mice. In addition, KO mice exhibited reduced pain sensitization. Altogether, these findings suggest that CA3-specific deletion of BDNF results in deficits in circuits that process social cues from familiar conspecifics as well as pain and may underlie empathy-like behaviors.

Thyroid Hemiagenesis in a Thyroiditis Prone Mouse Strain

Background: Thyroid hemiagenesis, a rare congenital condition detected by ultrasound screening of the neck, is usually not manifested clinically in humans. This condition has been reported in mice with hypothyroidism associated with induced deficiency in paired box 8 and NK2 homeobox 1, sonic hedgehog, or T-box 1. Unexpectedly, we observed thyroid hemiagenesis in NOD.H2^h4 mice, an unusual strain that spontaneously develops iodide enhanced thyroid autoimmunity but remains euthyroid. Objectives and Methods: First, to compare mice with thyroid hemiagenesis versus bilobed littermates for serum T4, autoantibodies to thyroglobulin (ELISA) and thyroid peroxidase (TPO; flow cytometry with eukaryotic cells expressing mouse TPO), gross anatomy, and thyroid histology; second, to estimate the percentage of mice with thyroid hemiagenesis in the NOD.H2^h4 mice we have studied over 6 years. Results: Thyroid hemiagenesis was observed in 3 of 1,025 NOD.H2^h4 mice (2 females, 1 male; 0.3%). Two instances of hemiagenesis were in wild-type females and one in a transgenic male expressing the human TSHR A-subunit in the thyroid. Two mice had very large unilobed glands, as in some human cases with this condition. Thyroid lymphocytic infiltration, serum T4, and the levels of thyroid autoantibodies were similar in mice with thyroid hemiagenesis and bilobed littermates. Conclusions: Unlike hypothyroidism associated with hemiagenesis in transcription factor knockout mice, hemiagenesis in euthyroid NOD.H2^h4 mice occurs spontaneously and is phenotypically similar to that occasionally observed in humans.

Tissue Factor Enhances the Alveolar Epithelial Barrier Integrity during Acute Lung Injury

IntroductionWe have previously reported that lung epithelial tissue factor (TF) knockout (TFΔEpi) mice have increased alveolar capillary barrier permeability. Ultrastructurally, these mouse lungs have profound morphological defects in epithelial attachment to the basement membrane. Adhesion/migration are regulated in part by integrins which bind the extracellular matrix proteins to modulate cytoskeletal dynamics. In cancer cells, TF binds β1 integrin and increases cell migration, a finding that suggests a role for non‐coagulative mechanisms of TF in cell adhesion and migration. We hypothesize that TF‐β1 integrin binding promotes alveolar epithelial barrier integrity through cell adhesion and migration during acute lung injury (ALI).MethodTF overexpressing (TF+Epi) and knockout (TFΔEpi) mice, along with TF knockout A549 cells (A549ΔTF) were used to test whether lung epithelial TF is critical for the integrity of the alveolar epithelial barrier. TF+Epi mice were treated with intratracheal PBS or LPS and lung permeability was measured by bronchoalveolar lavage (BAL) fluid protein level. Alveolar type II epithelial cells (ATII) were isolated from TFΔEpi and TF+Epi mice to measure β1 integrin protein levels. A549ΔTF cells were treated with LPS (100ug/mL) or PBS for 24 hours before western blot of β1 integrin expression. Migration was assessed in wild‐type and A549ΔTF cells using Electric Cell‐substrate Impedance Sensing (ECIS) on cell monolayers. Adhesion was assayed by plating wild‐type and A549ΔTF cells on matrigel and quantifying the absorbance of crystal violet stained adherent cells.ResultsTF+Epi mice had decreased lung permeability (BAL protein 303 μg/mL +/− 62 versus 416 +/− 137 in control, p=0.025) following LPS challenge. A549ΔTF cells had significantly decreased cell adhesion (Figure) (absorbance 0.308 +/− 0.119 versus 0.603 +/− 0.246 in wild type, *p<0.001) along with decreased migration (p=0.017) compared to control A549 cells with wild type TF expression levels. A549ΔTF cells had decreased β1 integrin protein levels (relative expression 0.017 +/− 0.01 versus 0.61 +/− 0.02 control, p=0.036) following LPS challenge. ATII cells isolated from TFΔEpi mice also have decreased β1 integrin protein levels.ConclusionsTF contributes to alveolar barrier integrity in part through a mechanism dependent on β1 integrin. These data provide support that lung epithelial TF may play a non‐coagulative role in protection during ALI. This novel role for TF in maintaining alveolar epithelial barrier integrity offers a potential therapeutic target during ALI.Support or Funding InformationVanderbilt University Initiative for Maximizing Student Diversity funding through the NIH, Nashville Veterans Affairs Medical Center, Funding: HL090785, HL103836This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Goblet Cells Contribute to Ocular Surface Immune Tolerance-Implications for Dry Eye Disease.

Conjunctival goblet cell (GC) loss in dry eye is associated with ocular surface inflammation. This study investigated if conjunctival GCs contribute to ocular surface immune tolerance. Antigens applied to the ocular surface, imaged by confocal microscopy, passed into the conjunctival stroma through goblet cell associated passages (GAPs) in wild type C57BL/6 (WT), while ovalbumin (OVA) was retained in the epithelium of SAM pointed domain containing ETS transcription factor (Spdef) knockout mice (Spdef−/−) that lack GCs and are a novel model of dry eye. Stimulated GC degranulation increased antigen binding to GC mucins. Induction of tolerance to topically applied OVA measured by cutaneous delayed type hypersensitivity (DTH) was observed in WT, but not Spdef−/−. OTII CD4+ T cells primed by dendritic cells (DCs) from the conjunctival draining lymph nodes of Spdef−/− had greater IFN-γ production and lower Foxp3 positivity than those primed by WT DCs. These findings indicate that conjunctival GCs contribute to ocular surface immune tolerance by modulating antigen distribution and antigen specific immune response. GC loss may contribute to the abrogation of ocular surface immune tolerance that is observed in dry eye.

Genetic ablation of soluble tumor necrosis factor with preservation of membrane tumor necrosis factor is associated with neuroprotection after focal cerebral ischemia

Microglia respond to focal cerebral ischemia by increasing their production of the neuromodulatory cytokine tumor necrosis factor, which exists both as membrane-anchored tumor necrosis factor and as cleaved soluble tumor necrosis factor forms. We previously demonstrated that tumor necrosis factor knockout mice display increased lesion volume after focal cerebral ischemia, suggesting that tumor necrosis factor is neuroprotective in experimental stroke. Here, we extend our studies to show that mice with intact membrane-anchored tumor necrosis factor, but no soluble tumor necrosis factor, display reduced infarct volumes at one and five days after stroke. This was associated with improved functional outcome after experimental stroke. No changes were found in the mRNA levels of tumor necrosis factor and tumor necrosis factor-related genes (TNFR1, TNFR2, TACE), pro-inflammatory cytokines (IL-1β, IL-6) or chemokines (CXCL1, CXCL10, CCL2); however, protein expression of TNF, IL-1β, IL-6 and CXCL1 was reduced in membrane-anchored tumor necrosis factorΔ/Δ compared to membrane-anchored tumor necrosis factorwt/wt mice one day after experimental stroke. This was paralleled by reduced MHCII expression and a reduction in macrophage infiltration in the ipsilateral cortex of membrane-anchored tumor necrosis factorΔ/Δ mice. Collectively, these findings indicate that membrane-anchored tumor necrosis factor mediates the protective effects of tumor necrosis factor signaling in experimental stroke, and therapeutic strategies specifically targeting soluble tumor necrosis factor could be beneficial in clinical stroke therapy.

Tumor necrosis factor drives increased splenic monopoiesis in old mice.

Aging is accompanied by changes in hematopoiesis and consequently in leukocyte phenotype and function. Although age-related changes in bone marrow hematopoiesis are fairly well documented, changes in extramedullary hematopoiesis are less well described. We observed that 18-22-mo-old mice had larger spleens than young controls and found that the enlargement was caused by increased monopoiesis. Because extramedullary hematopoiesis is often driven by inflammation, we hypothesized that the chronic, low-level inflammation that occurs with age is a causal agent in splenomegaly. To test this theory, we compared the number of monocytes in 18-mo-old tumor necrosis factor-knockout mice, which are protected from age-associated inflammation, and found that they did not have increased extramedullary monopoiesis. To determine whether increased splenic monopoiesis is caused by intrinsic changes in the myeloid precursors that occur with age or by the aging microenvironment, we created heterochronic bone marrow chimeras. Increased splenic monopoiesis occurred in old recipient mice, regardless of the age of the donor mouse, but not in young recipient mice, demonstrating that these cells respond to signals from the microenvironment. These data suggest that decreasing the inflammatory microenvironment with age would be an effective strategy for reducing inflammatory diseases propagated by cells of myeloid lineage, which increase in number with age.

Susceptibility of Mycobacterium abscessus to antimycobacterial drugs in preclinical models.

Over the last 10 years, Mycobacterium abscessus group strains have emerged as important human pathogens, which are associated with significantly higher fatality rates than any other rapidly growing mycobacteria. These opportunistic pathogens are widespread in the environment and can cause a wide range of clinical diseases, including skin, soft tissue, central nervous system, and disseminated infections; by far, the most difficult to treat is the pulmonary form. Infections with M. abscessus are often multidrug-resistant (MDR) and require prolonged treatment with various regimens and, many times, result in high mortality despite maximal therapy. We report here the evaluation of diverse mouse infection models for their ability to produce a progressive high level of infection with M. abscessus. The nude (nu/nu), SCID (severe combined immunodeficiency), gamma interferon knockout (GKO), and granulocyte-macrophage colony-stimulating factor (GMCSF) knockout mice fulfilled the criteria for an optimal model for compound screening. Thus, we set out to assess the antimycobacterial activity of clarithromycin, clofazimine, bedaquiline, and clofazimine-bedaquiline combinations against M. abscessus-infected GKO and SCID murine infection models. Treatment of GKO and SCID mice with a combination of clofazimine and bedaquiline was the most effective in decreasing the M. abscessus organ burden.

Thymic stromal lymphopoietin induction by skin irritation is independent of tumour necrosis factor-α, but supported by interleukin-1.

Thymic stromal lymphopoietin (TSLP) is an extensively studied cytokine linked to the pathogenesis of allergic diseases, but the inherent activities behind TSLP expression are not well defined. To explore the conditions favourable to TSLP induction outside of a typically allergic set-up and determine the associated mechanisms, and to assess whether TSLP is similarly controlled in murine and human skin. A combination of primary keratinocytes, skin explants/epidermal sheets and in vivo strategies was employed. The skin of wild-type and tumour necrosis factor knockout (TNF-/-) mice was subjected to acute irritation. Cells and specimens were stimulated with a range of TSLP inducers in the presence or absence of neutralizing antibodies. TSLP was quantitated by quantitative reverse-transcriptase polymerase chain reaction, enzyme-linked immunosorbent assay and immunohistochemistry. In addition to cytokines, skin irritation brought about by various causes (e.g. shaving, scratching and chemical perturbation) elicited uniformly high-level production of TSLP, which entered the circulatory system. Despite the potency of TNF-α as an in vitro TSLP inducer, the use of TNF-/- mice revealed that this mechanism was completely independent of endogenous TNF-α. Conversely, irritation-elicited TSLP depended on interleukin (IL)-1, which had a more pronounced influence in human skin than in murine skin. Murine and human skin differed considerably regarding TSLP regulation. Thymic stromal lymphopoietin is a general responder to disrupted skin homeostasis and may have a role in triggering the alarm system of the skin. TSLP induction is rapid, transient and driven by a mechanism that does not involve TNF-α, but partially relies on the evolutionarily ancient IL-1 system. The irritated skin secretes TSLP into the circulatory system. TSLP regulation varies between species.

Neuronal BDNF signaling is necessary for the effects of treadmill exercise on synaptic stripping of axotomized motoneurons.

The withdrawal of synaptic inputs from the somata and proximal dendrites of spinal motoneurons following peripheral nerve injury could contribute to poor functional recovery. Decreased availability of neurotrophins to afferent terminals on axotomized motoneurons has been implicated as one cause of the withdrawal. No reduction in contacts made by synaptic inputs immunoreactive to the vesicular glutamate transporter 1 and glutamic acid decarboxylase 67 is noted on axotomized motoneurons if modest treadmill exercise, which stimulates the production of neurotrophins by spinal motoneurons, is applied after nerve injury. In conditional, neuron-specific brain-derived neurotrophic factor (BDNF) knockout mice, a reduction in synaptic contacts onto motoneurons was noted in intact animals which was similar in magnitude to that observed after nerve transection in wild-type controls. No further reduction in coverage was found if nerves were cut in knockout mice. Two weeks of moderate daily treadmill exercise following nerve injury in these BDNF knockout mice did not affect synaptic inputs onto motoneurons. Treadmill exercise has a profound effect on synaptic inputs to motoneurons after peripheral nerve injury which requires BDNF production by those postsynaptic cells.

The role of CD4+ T cell subsets in the clearance of Pneumocystis murina pneumonia in mice (MPF6P.734)

Abstract Pneumocystis (PC) Pneumonia remains a serious complication in the immuno-compromised host. The host defense against PC is critically dependent upon CD4+ T cells. The role of specific T-cell subsets that mediate host resistance against PC infection remains unclear. We use STAT transcription factor knockout (KO) mice to determine the role of Th1, Th2, and Th17 cells in PC infection. After 28 days infection with PC, serum, lung tissue, and mediastinal lymph node (LN) were collected. LN and lung tissue cells were measured for cytokines by ELISpot and intracellular staining. Total lung RNA was measured for PC burden by RT-qPCR. Cytokines were assayed from cell culture supernatant. Anti-PC antibody was measured by ELISA.Stat4, Stat6 single KO, and Stat4/6 double KO mice all were resistant to PC compared to the Rag2/gc KO mice. Stat4 was required for a Th1 response and Stat6 was required for a Th2 response. STAT3fl/fl/CD4Cre+ mice had partial susceptibility of PC. Stat3 expression was required in CD4+ T cells for PC specific Th17 responses. STAT4/6 double KO crossed to STAT3fl/fl/CD4Cre+ (Triple KO) mice were highly susceptible to PC infection compare to single and double KO mice. Individual Stat4 and 6 and double mutants clear PC. STAT3fl/fl/CD4Cre+ conferred partial susceptibility to PC. Triple KO were as susceptible for PC as Rag2/gc KO mice. These data support the hypothesis that PC is a true opportunist and that various T-cell subsets can confer protection against infection.