Browsing by Author "Xu, Li"

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    A cord blood monocyte-derived cell therapy product accelerates brain remyelination.
    (JCI insight, 2016-08-18) Saha, Arjun; Buntz, Susan; Scotland, Paula; Xu, Li; Noeldner, Pamela; Patel, Sachit; Wollish, Amy; Gunaratne, Aruni; Gentry, Tracy; Troy, Jesse; Matsushima, Glenn K; Kurtzberg, Joanne; Balber, Andrew E
    Microglia and monocytes play important roles in regulating brain remyelination. We developed DUOC-01, a cell therapy product intended for treatment of demyelinating diseases, from banked human umbilical cord blood (CB) mononuclear cells. Immunodepletion and selection studies demonstrated that DUOC-01 cells are derived from CB CD14+ monocytes. We compared the ability of freshly isolated CB CD14+ monocytes and DUOC-01 cells to accelerate remyelination of the brains of NOD/SCID/IL2Rγnull mice following cuprizone feeding-mediated demyelination. The corpus callosum of mice intracranially injected with DUOC-01 showed enhanced myelination, a higher proportion of fully myelinated axons, decreased gliosis and cellular infiltration, and more proliferating oligodendrocyte lineage cells than those of mice receiving excipient. Uncultured CB CD14+ monocytes also accelerated remyelination, but to a significantly lesser extent than DUOC-01 cells. Microarray analysis, quantitative PCR studies, Western blotting, and flow cytometry demonstrated that expression of factors that promote remyelination including PDGF-AA, stem cell factor, IGF1, MMP9, MMP12, and triggering receptor expressed on myeloid cells 2 were upregulated in DUOC-01 compared to CB CD14+ monocytes. Collectively, our results show that DUOC-01 accelerates brain remyelination by multiple mechanisms and could be beneficial in treating demyelinating conditions.
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    Association of combined p73 and p53 genetic variants with tumor HPV16-positive oropharyngeal cancer.
    (PloS one, 2012-01) Wang, Zhongqiu; Sturgis, Erich M; Guo, Wei; Song, Xicheng; Zhang, Fenghua; Xu, Li; Wei, Qingyi; Li, Guojun
    p53 and p73 interact with human papillomavirus (HPV) E6 and E7 oncoproteins. The interplay between p53 and p73 and HPV16 may lead to deregulation of cell cycle and apoptosis, through which inflammation/immune responses control the HPV clearance and escape of immune surveillance, and subsequently contribute to tumor HPV16 status. In this case-case comparison study, HPV16 status in tumor specimens was analyzed and p53 codon 72 and p73 G4C14-to-A4T14 polymorphisms were genotyped using genomic DNA from blood of 309 oropharyngeal cancer patients. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated in univariate and multivariable logistic regression models to examine the association. The results from this study showed both p53 variant genotypes (Arg/Pro+Pro/Pro) and p73 variant genotypes (GC/AT+AT/AT) were significantly associated with HPV16-positive tumor in oropharyngeal cancer patients (OR, 1.9, 95% CI, 1.1-3.3 and OR, 2.1, 95% CI, 1.2-3.8, respectively), while the combined variant genotypes (p53 Pro carriers and p73 AT carriers) exhibited a significantly greater association with HPV16-positive tumor (OR, 3.2, 95% CI, 1.4-7.4), compared with combined wild-type genotypes (p53 Arg/Arg and p73 GC/GC), and the association was in a statistically significant dose-effect relationship (p = 0.001). Moreover, such association was more pronounced among several subgroups. These findings suggest that variant genotypes of p53 and p73 genes may be individually, or more likely jointly, associated with tumor HPV16-positive oropharyngeal cancer patients, particularly in never smokers. Identification of such susceptible biomarkers would greatly influence on individualized treatment for an improved prognosis.
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    Genetic variants of p27 and p21 as predictors for risk of second primary malignancy in patients with index squamous cell carcinoma of head and neck.
    (Molecular cancer, 2012-03-26) Wang, Zhongqiu; Sturgis, Erich M; Zhang, Fenghua; Lei, Dapeng; Liu, Zhensheng; Xu, Li; Song, Xicheng; Wei, Qingyi; Li, Guojun
    Cell cycle deregulation is common in human cancer, and alterations of p27 and p21, two critical cell cycle regulators, have been implicated in the development of many human malignancies. Therefore, we hypothesize that p27 T109G polymorphism individually or in combination with p21 (C98A and C70T) polymorphisms modifies risk of second primary malignancy (SPM) in patients with index squamous cell carcinoma of head and neck (SCCHN).A cohort of 1,292 patients with index SCCHN was recruited between May 1995 and January 2007 at the M.D. Anderson Cancer Center and followed for SPM occurrence. Patients were genotyped for the three polymorphisms. A log-rank test and Cox proportional hazards models were used to compare SPM-free survival and SPM risk.We found that patients with p27 109 TG/GG, p21 98 CA/AA and p21 70 CT/TT variant genotypes had a worse SPM-free survival and an increased SPM risk than those with the corresponding p27109 TT, p21 98 CC, and p21 70 CC common genotypes, respectively. After combining the three polymorphisms, there was a trend for significantly increased SPM risk with increasing number of the variant genotypes (Ptrend = 0.0002). Moreover, patients with the variant genotypes had an approximately 2.4-fold significantly increased risk for SPM compared with those with no variant genotypes (HR, 2.4, 95% CI, 1.6-3.6).These results suggest that p27 T109G polymorphism individually or in combination with p21 (C98A and C70T) polymorphisms increases risk of SPM in patients with index SCCHN.
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    Genetic variation in MDM2 and p14ARF and susceptibility to salivary gland carcinoma.
    (PloS one, 2012-01) Jin, Lei; Xu, Li; Song, Xicheng; Wei, Qingyi; Sturgis, Erich M; Li, Guojun
    The p14(ARF)/MDM2/p53 pathway plays an important role in modulation of DNA damage and oxidative stress responses. The aim of this study was to determine whether genetic variants in MDM2 and p14(ARF) are associated with risk of salivary gland carcinoma (SGC).Four single nucleotide polymorphisms (SNPs) in MDM2 and p14(ARF) (MDM2-rs2279744, MDM2-rs937283, p14(ARF)-rs3731217, and p14(ARF)-rs3088440) were genotyped in 156 patients with SGC and 511 cancer-free controls. Multivariate logistic regression analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs).MDM2-rs2279744 was significantly associated with a moderately increased risk of SGC (OR, 1.5, 95% CI, 1.1-2.2). There was a trend toward significantly increased SGC risk with increasing number of risk genotypes of the four polymorphisms (P(trend) = 0.004). Individuals carrying 3-4 risk genotypes in MDM2 and p14(ARF) were at increased SGC risk (OR, 2.0, 95% CI, 1.1-2.7) compared with individuals carrying 0-2 risk genotypes. Moreover, the combined effect of risk genotypes of MDM2 and p14(ARF) was more pronounced among young subjects (≤ 45 years), female subjects, subjects with race/ethnicity other than non-Hispanic white, ever-smokers, and ever-drinkers.Our results support the involvement of SNPs of MDM2 and p14(ARF), either alone or more likely in combination, in susceptibility to SGC. Larger studies are needed to validate our findings.
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    Human umbilical cord blood monocytes, but not adult blood monocytes, rescue brain cells from hypoxic-ischemic injury: Mechanistic and therapeutic implications.
    (PloS one, 2019-01) Saha, Arjun; Patel, Sachit; Xu, Li; Scotland, Paula; Schwartzman, Jonathan; Filiano, Anthony J; Kurtzberg, Joanne; Balber, Andrew E
    Cord blood (CB) mononuclear cells (MNC) are being tested in clinical trials to treat hypoxic-ischemic (HI) brain injuries. Although early results are encouraging, mechanisms underlying potential clinical benefits are not well understood. To explore these mechanisms further, we exposed mouse brain organotypic slice cultures to oxygen and glucose deprivation (OGD) and then treated the brain slices with cells from CB or adult peripheral blood (PB). We found that CB-MNCs protect neurons from OGD-induced death and reduced both microglial and astrocyte activation. PB-MNC failed to affect either outcome. The protective activities were largely mediated by factors secreted by CB-MNC, as direct cell-to-cell contact between the injured brain slices and CB cells was not essential. To determine if a specific subpopulation of CB-MNC are responsible for these protective activities, we depleted CB-MNC of various cell types and found that only removal of CB CD14+ monocytes abolished neuroprotection. We also used positively selected subpopulations of CB-MNC and PB-MNC in this assay and demonstrated that purified CB-CD14+ cells, but not CB-PB CD14+ cells, efficiently protected neuronal cells from death and reduced glial activation following OGD. Gene expression microarray analysis demonstrated that compared to PB-CD14+ monocytes, CB-CD14+ monocytes over-expressed several secreted proteins with potential to protect neurons. Differential expression of five candidate effector molecules, chitinase 3-like protein-1, inhibin-A, interleukin-10, matrix metalloproteinase-9 and thrombospondin-1, were confirmed by western blotting, and immunofluorescence. These findings suggest that CD14+ monocytes are a critical cell-type when treating HI with CB-MNC.
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    Improving thymus implantation for congenital athymia with interleukin-7.
    (Clinical & translational immunology, 2023-01) Min, Hyunjung; Valente, Laura A; Xu, Li; O'Neil, Shane M; Begg, Lauren R; Kurtzberg, Joanne; Filiano, Anthony J

    Objectives

    Thymus implantation is a recently FDA-approved therapy for congenital athymia. Patients receiving thymus implantation develop a functional but incomplete T cell compartment. Our objective was to develop a mouse model to study clinical thymus implantation in congenital athymia and to optimise implantation procedures to maximise T cell education and expansion of naïve T cells.

    Methods

    Using Foxn1 nu athymic mice as recipients, we tested MHC-matched and -mismatched donor thymi that were implanted as fresh tissue or cultured to remove donor T cells. We first implanted thymus under the kidney capsule and then optimised intramuscular implantation. Using competitive adoptive transfer assays, we investigated whether the failure of newly developed T cells to expand into a complete T cell compartment was because of intrinsic deficits or whether there were deficits in engaging MHC molecules in the periphery. Finally, we tested whether recombinant IL-7 would promote the expansion of host naïve T cells educated by the implanted thymus.

    Results

    We determined that thymus implants in Foxn1 nu athymic mice mimic many aspects of clinical thymus implants in patients with congenital athymia. When we implanted cultured, MHC-mismatched donor thymus into Foxn1 nu athymic mice, mice developed a limited T cell compartment with notably underdeveloped naïve populations and overrepresented memory-like T cells. Newly generated T cells were predominantly educated by MHC molecules expressed by the donor thymus, thus potentially undergoing another round of selection once in the peripheral circulation. Using competitive adoptive transfer assays, we compared expansion rates of T cells educated on donor thymus versus T cells educated during typical thymopoiesis in MHC-matched and -mismatched environments. Once in the circulation, regardless of the MHC haplotypes, T cells educated on a donor thymus underwent abnormal expansion with initially more robust proliferation coupled with greater cell death, resembling IL-7 independent spontaneous expansion. Treating implanted mice with recombinant interleukin (IL-7) promoted homeostatic expansion that improved T cell development, expanded the T cell receptor repertoire, and normalised the naïve T cell compartment.

    Conclusion

    We conclude that implanting cultured thymus into the muscle of Foxn1 nu athymic mice is an appropriate system to study thymus implantation for congenital athymia and immunodeficiencies. T cells are educated by the donor thymus, yet naïve T cells have deficits in expansion. IL-7 greatly improves T cell development after thymus implantation and may offer a novel strategy to improve outcomes of clinical thymus implantation.
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    Mesenchymal stromal cells reprogram monocytes and macrophages with processing bodies.
    (Stem cells (Dayton, Ohio), 2021-01) Min, Hyunjung; Xu, Li; Parrott, Roberta; Overall, Christopher C; Lillich, Melina; Rabjohns, Emily M; Rampersad, Rishi R; Tarrant, Teresa K; Meadows, Norin; Fernandez-Castaneda, Anthony; Gaultier, Alban; Kurtzberg, Joanne; Filiano, Anthony J
    Mesenchymal stromal cells (MSCs) are widely used in clinical trials because of their ability to modulate inflammation. The success of MSCs has been variable over 25 years, most likely due to an incomplete understanding of their mechanism. After MSCs are injected, they traffic to the lungs and other tissues where they are rapidly cleared. Despite being cleared, MSCs suppress the inflammatory response in the long term. Using human cord tissue-derived MSCs (hCT-MSCs), we demonstrated that hCT-MSCs directly interact and reprogram monocytes and macrophages. After engaging hCT-MSCs, monocytes and macrophages engulfed cytoplasmic components of live hCT-MSCs, then downregulated gene programs for antigen presentation and costimulation, and functionally suppressed the activation of helper T cells. We determined that low-density lipoprotein receptor-related proteins on monocytes and macrophages mediated the engulfment of hCT-MSCs. Since a large amount of cellular information can be packaged in cytoplasmic RNA processing bodies (p-bodies), we generated p-body deficient hCT-MSCs and confirmed that they failed to reprogram monocytes and macrophages in vitro and in vivo. hCT-MSCs suppressed an inflammatory response caused by a nasal lipopolysaccharide challenge. Although both control and p-body deficient hCT-MSCs were engulfed by infiltrating lung monocytes and macrophages, p-body deficient hCT-MSCs failed to suppress inflammation and downregulate MHC-II. Overall, we identified a novel mechanism by which hCT-MSCs indirectly suppressed a T-cell response by directly interacting and reprogramming monocytes and macrophages via p-bodies. The results of this study suggest a novel mechanism for how MSCs can reprogram the inflammatory response and have long-term effects to suppress inflammation.