scholarly journals Skin resident memory cells generated by the L. major centrin gene deleted parasites mediate protective immune response analogous to leishmanization

2021 ◽  
Author(s):  
Nevien Ismail ◽  
Subir Karmakar ◽  
Parna Bhattacharya ◽  
Telly Sepahpour ◽  
Kazuoy Takeda ◽  
...  
Keyword(s):  
T Cells ◽  
Leishmania Major ◽  
Sand Fly ◽  
Ifn Gamma ◽  
Effector Cells ◽  
T Effector Cells ◽  
Host Protection ◽  
Cytokines And Chemokines ◽  
And Function ◽  
Resident Memory T Cells

Leishmaniasis is a vector-borne parasitic disease transmitted through the bite of a sand fly with no available vaccine for humans. Recently, we have developed a live attenuated Leishmania major centrin gene deleted parasite strain (LmCen-/-) that induced protection against a homologous and heterologous challenges. The protection is mediated by IFN-gamma; secreting CD4+ T effector cells and multifunctional T cells, which is analogous to leishmanization. Previously, skin tissue resident memory T cells (TRM cells) were shown to be crucial for host protection in a leishmanization model. In this study, we evaluated generation and function of skin TRM cells following immunization with LmCen-/- parasites and compared those with leishmanization. In the absence of recoverable LmCen-/- parasites, the skin of immunized mice showed functional TRM cells comparable to leishmanized mice. The generation of the skin TRM cells was supported by the induction of cytokines and chemokines essential for their production and survival. Following challenge infection with wild type L. major, TRM cells specific to L. major were rapidly recruited and proliferated at the site of infection in the immunized mice which was similar to leishmanization. Further, upon challenge, CD4+ TRM cells induced higher levels of IFN-gamma; and Granzyme B in the immunized and leishmanized mice than non-immunized mice. Taken together, our studies demonstrate that a genetically modified live attenuated Leishmania vaccine generates functional CD4+ TRM cells that mediate protection and can be a safer alternative to leishmanization.

scholarly journals Leishmania promastigotes evade interleukin 12 (IL-12) induction by macrophages and stimulate a broad range of cytokines from CD4+ T cells during initiation of infection.

1994 ◽  
Vol 179 (2) ◽  
pp. 447-456 ◽  
Author(s):  
S L Reiner ◽  
S Zheng ◽  
Z E Wang ◽  
L Stowring ◽  
R M Locksley
Keyword(s):  
T Cells ◽  
Cd4 T Cells ◽  
Leishmania Major ◽  
Interleukin 12 ◽  
Insect Vector ◽  
T Helper 1 ◽  
Ifn Gamma ◽  
Effector Cells

Leishmania major are intramacrophage parasites whose eradication requires the induction of T helper 1 (Th1) effector cells capable of activating macrophages to a microbicidal state. Interleukin 12 (IL-12) has been recently identified as a macrophage-derived cytokine capable of mediating Th1 effector cell development, and of markedly enhancing interferon gamma (IFN-gamma) production by T cells and natural killer cells. Infection of macrophages in vitro by promastigotes of L. major caused no induction of IL-12 p40 transcripts, whereas stimulation using heat-killed Listeria or bacterial lipopolysaccharide induced readily detectable IL-12 mRNA. Using a competitor construct to quantitate a number of transcripts, a kinetic analysis of cytokine induction during the first few days of infection by L. major was performed. All strains of mice examined, including susceptible BALB/c and resistant C57BL/6, B10.D2, and C3H/HeN, had the appearance of a CD4+ population in the draining lymph nodes that contained transcripts for IL-2, IL-4, and IFN-gamma (and in some cases, IL-10) that peaked 4 d after infection. In resistant mice, the transcripts for IL-2, IL-4, and IL-10 were subsequently downregulated, whereas in susceptible BALB/c mice, these transcripts were only slightly decreased, and IL-4 continued to be reexpressed at high levels. IL-12 transcripts were first detected in vivo by 7 d after infection, consistent with induction by intracellular amastigotes. Challenge of macrophages in vitro confirmed that amastigotes, in contrast to promastigotes, induced IL-12 p40 mRNA. Reexamination of the cytokine mRNA at 4 d revealed expression of IL-13 in all strains analyzed, suggesting that IL-2 and IL-13 may mediate the IL-12-independent production of IFN-gamma during the first days after infection. Leishmania have evolved to avoid inducing IL-12 from host macrophages during transmission from the insect vector, and cause a striking induction of mRNAs for IL-2, IL-4, IL-10, and IL-13 in CD4+ T cells. Each of these activities may favor survival of the organism.

scholarly journals Reduced Numbers and Impaired Function of Regulatory T Cells in Peripheral Blood of Ischemic Stroke Patients

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Johanna Ruhnau ◽  
Juliane Schulze ◽  
Bettina von Sarnowski ◽  
Marie Heinrich ◽  
Sönke Langner ◽  
...  
Keyword(s):  
T Cells ◽  
Regulatory T Cells ◽  
Peripheral Blood ◽  
Experimental Stroke ◽  
Stroke Patients ◽  
Effector Cells ◽  
T Effector Cells ◽  
Treg Function ◽  
Age Dependent ◽  
And Function

Background and Purpose. Regulatory T cells (Tregs) have been suggested to modulate stroke-induced immune responses. However, analyses of Tregs in patients and in experimental stroke have yielded contradictory findings. We performed the current study to assess the regulation and function of Tregs in peripheral blood of stroke patients. Age dependent expression of CD39 on Tregs was quantified in mice and men. Methods. Total FoxP3+ Tregs and CD39+FoxP3+ Tregs were quantified by flow cytometry in controls and stroke patients on admission and on days 1, 3, 5, and 7 thereafter. Treg function was assessed by quantifying the inhibition of activation-induced expression of CD69 and CD154 on T effector cells (Teffs). Results. Total Tregs accounted for 5.0% of CD4+ T cells in controls and <2.8% in stroke patients on admission. They remained below control values until day 7. CD39+ Tregs were most strongly reduced in stroke patients. On day 3 the Treg-mediated inhibition of CD154 upregulation on CD4+ Teff was impaired in stroke patients. CD39 expression on Treg increased with age in peripheral blood of mice and men. Conclusion. We demonstrate a loss of active FoxP3+CD39+ Tregs from stroke patient’s peripheral blood. The suppressive Treg function of remaining Tregs is impaired after stroke.

scholarly journals Cd8αα+T Cells Exert a Pro-inflammatory Role in Patients With Psoriasis 

2021 ◽  
Author(s):  
Yangyang Zhang ◽  
Yiting Lin ◽  
Lei Wang ◽  
Xiuwen Sun ◽  
Erle Dang ◽  
...  
Keyword(s):  
T Cells ◽  
Chronic Inflammatory Disease ◽  
Inflammatory Factors ◽  
Effector Memory ◽  
Effector Cells ◽  
T Effector Cells ◽  
Ifn Γ ◽  
Resident Memory T Cells ◽  
Excessive Activation

Abstract Psoriasis is a common chronic inflammatory disease caused by excessive activation of CD4+T cells, including Th17, Th1, and Th22. The role of CD8+T cells in psoriasis pathogenesis remains poorly understood. In this study, we aimed to identify the phenotype of CD8+T cells in patients with psoriasis and to investigate its role in the formation of lesions. First of all, we identify CD8αα+T cell as a main subset of CD8+T cells infiltrated in lesions of patients with psoriasis. Furthermore, we found that epidermal CD8αα+T cells exhibited tissue-resident memory T cells (TRM) phenotypes and dermal CD8αα+T cells exhibited effector memory (TEM) phenotypes in psoriatic lesions. Thereafter, by coculturing CD8αα+T cells with autogenous CD4+T cells to investigate the function of CD8αα+T cells, we found that CD8αα+T cells from patients with psoriasis could promote the proliferation of CD4+T effector cells; while CD8αα+T cells from healthy controls exerted immunosuppressive function. Finally, we demonstrate that CD8αα+T cells from patients with psoriasis did not express the markers of regulatory T cells, and produce IL-17 and IFN-γ. In conclusion, our findings demonstrate that CD8αα+T cells contribute to the pathogenesis of psoriasis by producing pro-inflammatory factors.

scholarly journals 566 ATOR-1017, a second generation 4–1BB antibody with potential to enhance efficacy of PD-1 therapies

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A595-A595
Author(s):  
Karin Enell Smith ◽  
Anneli Nilsson ◽  
Peter Ellmark
Keyword(s):  
T Cells ◽  
Transgenic Mice ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Effector Cells ◽  
Costimulatory Receptor ◽  
T Effector Cells ◽  
Murine Colon Carcinoma ◽  
Activation Profile

BackgroundATOR-1017 is a Fcγ-receptor (FcγR) crosslinking dependent agonistic IgG4 antibody targeting the costimulatory receptor 4 1BB, designed for improved tolerability and efficacy. 4-1BB is highly expressed on tumor infiltrating CD8+ T effector cells (T effs) in several cancer indications. By binding to 4-1BB, ATOR-1017 enhances the activity of tumor reactive T effs and NK cells within the tumor and induces a potent anti-tumor response. 4-1BB is a promising candidate for immunotherapy and holds great potential for combination with other immunomodulatory antibodies, targeting e.g. the PD-1 pathway.MethodsHuman 4-1BB knock-in transgenic mice with established murine colon carcinoma MC38 tumors were used to demonstrate anti-tumor efficacy after systemic treatment with ATOR-1017 in combination with anti-PD-1. Further, the effect of combining ATOR-1017 with anti-PD-1 on T cell activation (measured as production of IFNγ) was evaluated in a mixed lymphocyte reaction (MLR) assay with human primary CD4+ T cells and mature monocyte-derived DCs (mDC) expressing endogenous levels of both 4-1BB and PD-1.ResultsATOR-1017 in combination with anti-PD-1 improved survival and reduced tumor growth signifcantly in human 4-1BB knock-in transgenic mice with established tumors compared with each monotherapy alone. The potential for combining ATOR-1017 and PD-1 was further supported by data from a MLR assay demonstrating that the combination of ATOR-1017 with anti-PD-1 induced a more potent CD4+ T cells activation than each monotherapy alone.The functional activation profile of ATOR-1017 is expected to minimize the risk of systemic immune activation and toxicity, by directing a potent immune response to immune cells in tumor tissue and tumor draining lymph nodes. This is supported by early data from the ongoing first-in-human phase I study where ATOR-1017 has been shown to be safe and tolerable.ConclusionsIn summary, these results support further clinical development of ATOR-1017 in combination with PD-1 antibodies. By combining ATOR-1017 with anti-PD-1, tumor infiltrating T cells can be more effectively activated and potentially increase the response rate in multiple indications.Ethics ApprovalAll animal procedures were in accordance to IACUC guidance

scholarly journals Phase 2 Study of Combination of Cytarabine, Idarubicin, and Nivolumab for Initial Therapy of Patients with Newly Diagnosed Acute Myeloid Leukemia

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 815-815
Author(s):  
Farhad Ravandi ◽  
Naval Daver ◽  
Guillermo Garcia-Manero ◽  
Christopher B Benton ◽  
Philip A Thompson ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
T Cell Subsets ◽  
Newly Diagnosed ◽  
Effector Cells ◽  
T Effector Cells ◽  
Grade 3

Abstract Background: Blocking PD-1/PD-L1 pathways enhances anti-leukemia responses by enabling T-cells in murine models of AML (Zhang et al, Blood 2009). PD-1 positive CD8 T-cells are increased in bone marrow (BM) of pts with AML (Daver et al, AACR 2016). PD1 inhibition has shown activity in AML (Berger et al, Clin Cancer Res 2008). We hypothesized that addition of nivolumab to an induction regimen of ara-C and idarubicin may prolong relapse-free survival (RFS) and overall survival (OS); this study was designed to determine the feasibility of this combination. Methods: Pts with newly diagnosed acute myeloid leukemia (by WHO criteria; ≥20% blasts) and high risk MDS (≥10% blasts) were eligible to participate if they were 18-65 yrs of age and had adequate performance status (ECOG ≤3) and organ function (LVEF ≥ 50%; creatinine ≤ 1.5 g mg/dL, bilirubin ≤ 1.5 mg/dL and transaminases ≤ 2.5 times upper limit of normal). Treatment included 1 or 2 induction cycles of ara-C 1.5 g/m2 over 24 hours (days 1-4) and Idarubicin 12 mg/m2 (days 1-3). Nivolumab 3 mg/kg was started on day 24 ± 2 days and was continued every 2 weeks for up to a year. For pts achieving complete response (CR) or CR with incomplete count recovery (CRi) up to 5 consolidation cycles of attenuated dose ara-C and idarubicin was administered at approximately monthly intervals. Eligible pts received an allogeneic stem cell transplant (alloSCT) at any time during the consolidation or thereafter. Results: 3 pts with relapsed AML were treated at a run-in phase with a dose of nivolumab 1 mg/kg without specific drug-related toxicity. Subsequently, 32 pts (median age 53 yrs; range, 26-65) were treated as above including 30 with AML (24 de novo AML, 2 therapy-related AML, 3 secondary AML and 1 therapy-related secondary AML) and 2 high risk MDS. Pre-treatment genetic risk by ELN criteria was 11 adverse, 16 intermediate, and 5 favorable, including 2 FLT3 -ITD mutated, 5 NPM1 mutated, and 7 TP53 mutated. All 32 pts were evaluable for response and 23 (72%) achieved CR/CRi (19 CR, 4 CRi). The 4-week and 8 week mortality was 6% and 6%. The median number of doses of nivolumab received was 6 (range, 0-13); one pt did not receive nivolumab due to insurance issues. 9 pts underwent an alloSCT. After a median follow-up of 8.3 mths (range, 1.5-17.0) the median RFS among the responding pts has not been reached (range, 0.1 - 15.8 mths) and the median OS has not been reached (range 0.5-17.0 mths). Grade 3/4 immune mediated toxicities have been observed in 5 pts and include rash, pancreatitis, and colitis. Other grade 3/4 toxicities thought to be potentially related to nivolumab include cholecystitis in one pt. 9 pts proceeded to an alloSCT. Donor source was matched related in 2, matched unrelated in 6 and haplo-identical in 1 pt. Conditioning regimen was Fludarabine plus busulfan-based in 8, and fludarabine plus melphalan in 1 pt. 4 pts developed graft versus host disease (GVHD)(grade I/II in 3, grade III/IV in 1), which responded to treatment in 3. Multicolor flow-cytometry studies are conducted by the Immunotherapy Platform on baseline (prior to first dose of nivolumab) and on-treatment BM aspirate and peripheral blood to assess the T-cell repertoire and expression of co-stimulatory receptors and ligands on T-cell subsets and leukemic blasts, respectively. The baseline BM was evaluated on 23 of the 32 evaluable pts, including 18 responders and 5 non-responders. Pts who achieved a CR/CRi had a trend of higher frequency of live CD3+ total T cell infiltrate as compared to non-responders in the baseline BM aspirates (Fig 1A). We evaluated expression of immune markers on T cell subsets: CD4 T effector cells [Teff]: CD3+CD4+CD127lo/+Foxp3-, CD4 T regulatory cells [Treg]: CD3+CD4+CD127-Foxp3+, and CD8 T cells. At baseline, BM of non-responders had significantly higher percentage of CD4 T effector cells co-expressing the inhibitory markers PD1 and TIM3 (p&lt;0.05) and a trend towards higher percentage of CD4 T effector cells co-expressing PD1 and LAG3 compared to responders (Fig 1B). Co-expression of TIM3 or LAG3 on PD1+ T cells have been shown to be associated with an exhausted immune phenotype in AML (Zhou et al., Blood 2011). Conclusion: Addition of nivolumab to ara-C and anthracycline induction chemotherapy is feasible and safe in younger pts with AML. Among the pts proceeding to alloSCT the risk of GVHD is not significantly increased. Figure 1 Figure 1. Disclosures Daver: Pfizer Inc.: Consultancy, Research Funding; Otsuka America Pharmaceutical, Inc.: Consultancy; Sunesis Pharmaceuticals, Inc.: Consultancy, Research Funding; Novartis Pharmaceuticals Corporation: Consultancy; Bristol-Myers Squibb Company: Consultancy, Research Funding; Kiromic: Research Funding; Karyopharm: Consultancy, Research Funding; Jazz: Consultancy; Immunogen: Research Funding; Daiichi-Sankyo: Research Funding; Incyte Corporation: Honoraria, Research Funding. Thompson: Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees. Jabbour: Bristol-Myers Squibb: Consultancy. Takahashi: Symbio Pharmaceuticals: Consultancy. DiNardo: Novartis: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Sharma: Jounce: Consultancy, Other: stock, Patents & Royalties: Patent licensed to Jounce; Astellas: Consultancy; EMD Serono: Consultancy; Amgen: Consultancy; Astra Zeneca: Consultancy; GSK: Consultancy; Consetellation: Other: stock; Evelo: Consultancy, Other: stock; Neon: Consultancy, Other: stock; Kite Pharma: Consultancy, Other: stock; BMS: Consultancy. Cortes: BMS: Consultancy, Research Funding; Sun Pharma: Research Funding; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding; ImmunoGen: Consultancy, Research Funding; ARIAD: Consultancy, Research Funding. Kantarjian: Delta-Fly Pharma: Research Funding; Amgen: Research Funding; ARIAD: Research Funding; Novartis: Research Funding; Bristol-Meyers Squibb: Research Funding; Pfizer: Research Funding.

scholarly journals T cell and non-T cell compartments can independently determine resistance to Leishmania major.

1995 ◽  
Vol 181 (3) ◽  
pp. 845-855 ◽  
Author(s):  
A H Shankar ◽  
R G Titus
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Leishmania Major ◽  
Cell Receptor ◽  
Disease Outcome ◽  
Chimeric Mice ◽  
Antigen Specificity ◽  
Ifn Gamma ◽  
Cell Compartments

In experimental murine cutaneous leishmaniasis caused by Leishmania major (Lm), the cellular determinants governing development of protective or exacerbative T cells are not well understood. We, therefore, attempted to determine the influence of T cell and non-T cell compartments on disease outcome. To this end, T cell chimeric mice were constructed using adult thymectomized lethally irradiated, bone marrow-reconstituted (ATXBM) animals of genetically resistant, C57BL/6, or susceptible, BALB/c, backgrounds. These hosts were engrafted with naive T cell populations from H-2-congenic susceptible, BALB.B6-H-2b, or resistant, C57BL/6.C-H-2d, animals, respectively. Chimeric mice were then infected with Lm, and disease outcome was monitored. BALB/c T cell chimeric mice, BALB/c ATXBM hosts given naive C57BL/6.C-H-2d T cells, resolved their infections as indicated by reductions in both lesion size and parasite numbers. Furthermore, the mice developed typical Th1 (interferon[IFN]-gamma hiinterleukin[IL]-4lo) cytokine patterns. In contrast, both sham chimeric, BALB/c ATXBM hosts given naive BALB/c T cells, and control irradiated euthymic mice succumbed to infection, producing Th2 profiles (IFN-gamma loIL-4hiIL-10hi). C57BL/6 T cell chimeras, C57BL/6 ATXBM hosts given naive BALB.B6-H-2b T cells, resolved their infections as did C57BL/6 sham chimeras and euthymic controls. Interestingly, whereas C57BL/6 control animals produced Th1 cytokines, chimeric animals progressed from Th0 (IFN-gamma hiIL-4hiIL-10hi) to Th2 (IFN-gamma loIL-4hiIL-10hi) cytokine profiles as cure ensued. Both reconstitution and chimeric status of all mice were confirmed by flow cytometry. In addition, T cell receptor V beta usage of Lm-specific blasts was determined. In all cases, V beta use was multiclonal, involving primarily V beta 2, 4, 6, 8.1, 8.2, 8.3, 10, and 14, with relative V beta frequencies differing between H-2b and H-2d animals. Most importantly, however, these differences did not segregate between cure and noncure outcomes. These findings indicate that: (a) genetic traits determining cure in Lm infection can direct disease outcome from both T cell and non-T cell compartments; (b) the presence of the curing genotype in only one compartment is sufficient to confer cure; (c) curing genotype T cells autonomously assume a Th1 cytokine profile-mediating cure; (d) noncuring genotype T cells can mediate cure in a curing environment, despite the onset of Th2 cytokine production; and lastly, (e) antigen specificity of responding T cells, as assessed by V beta T cell receptor diversity, is not a critical determinant of disease outcome.

Decreased LAG3 expression on T effector cells and regulatory T cells in SAA

2020 ◽  
Vol 112 (6) ◽  
pp. 757-763
Author(s):  
Yingying Sun ◽  
Chunyan Liu ◽  
Ting Jiao ◽  
Ning Xie ◽  
Huaquan Wang ◽  
...  
Keyword(s):  
T Cells ◽  
Regulatory T Cells ◽  
Effector Cells ◽  
T Effector Cells

scholarly journals SOCS5 Is Expressed in Primary B and T Lymphoid Cells but Is Dispensable for Lymphocyte Production and Function

2004 ◽  
Vol 24 (13) ◽  
pp. 6094-6103 ◽  
Author(s):  
Christine Brender ◽  
Ruth Columbus ◽  
Donald Metcalf ◽  
Emanuela Handman ◽  
Robyn Starr ◽  
...  
Keyword(s):  
T Cells ◽  
Leishmania Major ◽  
Lymphoid Cells ◽  
Cytokine Signaling ◽  
Lymphocyte Function ◽  
Wild Type ◽  
Cell Responses ◽  
Resistance To Infection ◽  
And Function ◽  
Th2 Differentiation

ABSTRACT Suppressors of cytokine signaling (SOCSs) are key regulators of cytokine-induced responses in hematopoietic as well as nonhematopoietic cells. SOCS1 and SOCS3 have been shown to modulate T-cell responses, whereas the roles of other SOCS family members in the regulation of lymphocyte function are less clear. Here, we report the generation of mice with a targeted disruption of the Socs5 gene. Socs5 −/− mice were born in a normal Mendelian ratio and were healthy and fertile. We found that SOCS5 is expressed in primary B and T cells in wild-type mice. However, no abnormalities in the lymphocyte compartment were seen in SOCS5-deficient mice. We examined antigen- and cytokine-induced proliferative responses in B and T cells in the absence of SOCS5 and found no deviations from the responses seen in wild-type cells. Because SOCS5 has been implicated in Th1 differentiation, we also investigated the importance of SOCS5 in T helper cell responses. Unexpectedly, SOCS5-deficient CD4 T cells showed no abnormalities in Th1/Th2 differentiation and Socs5 −/− mice showed normal resistance to infection with Leishmania major. Therefore, although SOCS5 is expressed in primary B and T cells, it appears to be dispensable for the regulation of lymphocyte function.

Effective Prevention of Acute Graft-Verses-Host Disease by Targeting PKC Alpha and PKC Theta in Mice

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1898-1898
Author(s):  
Kelley M.K. Haarberg ◽  
Crystina Bronk ◽  
Dapeng Wang ◽  
Amer Beg ◽  
Xue-Zhong Yu
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Acute Gvhd ◽  
T Cell Signaling ◽  
Effector Cells ◽  
T Effector Cells ◽  
Immunologic Synapse

Abstract Abstract 1898 Protein kinase C theta (PKCθ), a T cell signaling molecule, has been implicated as a therapeutic target for several autoimmune diseases as well as graft-versus-host disease (GVHD). PKCθ plays a vital role in stabilization of the immunologic synapse between T effector cells and antigen presenting cells (APC), but has been shown to be excluded from the immunologic synapse in T regulatory cells (T reg). PKCθ inhibition reduces the alloreactivity of donor T cells responsible for induction of GVHD while preserving graft-versus-leukemia (GVL) responses. The roles of PKCθ and the potential compensatory alpha isoform (PKCα) are not clearly defined with regard to alloresponses or T cell mediated responses in GVHD. In this context, we measured PKCθ and PKCα/θ gene deficient T cell activation upon TCR-ligation in vitro using [3H]-TdR incorporation and CSFE labeling assays. T cells from PKCθ and PKCα/θ gene deficient donor mice were utilized in vivo in a pre-clinical allogenic murine model of myeloablative bone marrow transplantation (BMT). The development of GVHD was monitored in recipient mice with or without injection of A20-luciferase cells to observe the progression of GVL in vivo. Combined blockade of PKCα and PKCθ causes a significant decrease in T cell proliferation compared to blocking PKCθ alone in vitro. Deficiency in PKCα and PKCθ had no effect on immune reconstitution following irradiation and BMT in vivo. Even with a high transplant load of 5×106 CD4+ and CD8+ T cells, PKCα/θ deficient (PKCα/θ−/−) T cells failed to induce acute GVHD. Our data suggest that the ability of double deficient T cells to induce GVHD was further reduced than PKCθ-deficient T cells. Additionally, a greater number and percentage of B220+ B cells and FoxP3+ T regs were isolated from the spleens of PKCα/θ−/− T cell recipient mice 120 after BMT than were isolated from wild type (WT) or PKCθ−/− T cell recipients. Fewer CD4+ or CD8+ T effector cells were isolated from the spleens of PKCα/θ−/− T cell recipient mice 120 after BMT than were isolated from wild type or PKCθ−/− T cell recipients. Importantly, the activity of B cells isolated from PKCα/θ−/− T cell recipient mice 120 after BMT was greater on a per cell basis, while the activity of T effector cells isolated from these mice was greatly reduced compared to WT or PKCθ−/− T cell recipients. While not absent, GVL was reduced in PKCα/θ−/− T cell recipient mice when compared to WT or PKCθ−/− T cell recipients. This work demonstrates the requirement of PKCα and θ for optimal activation and function of T cells in vitro. These experiments highlight a potential compensatory role for PKCα in the absence of PKCθ in T cell signaling and activation. Combined deficiency of PKCα and θ prevents induction of acute GVHD while improving the maintenance of splenic cellularity in PKCα/θ T cell recipient mice. Additionally, PKCα/θ dual deficient T cell transplant shifts the splenic balance toward a greater number and percentage of T reg and B cells and away from T effector cells following BMT. The reduced and sub-optimally active T effector cells isolated from PKCα/θ−/− T cell recipient mice in combination with reduced GVL stresses the importance of PKCα and θ molecules and their roles in T cell activity in the context of both GVHD and GVL. Dual deficiency of PKCα/θ is associated with a decline of T effector function that is optimal for the amelioration of GVHD, but is perhaps too reduced to substantially maintain effective GVL. Modulation of PKCα and θ signaling presents a valid avenue of investigation as a therapeutic option for GVHD. Disclosures: No relevant conflicts of interest to declare.

BK Virus Reactivation After Double Umbilical Cord Blood Transplantation in Adults Correlates with Tregs and Delayed Reconstitution of CD4+ and CD8+ T Effector Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4174-4174
Author(s):  
Gowri Satyanarayana ◽  
Sarah Hammond ◽  
Haesook T Kim ◽  
Sean McDonough ◽  
Julia Brown ◽  
...  
Keyword(s):  
T Cells ◽  
Cord Blood ◽  
Immune Reconstitution ◽  
Hemorrhagic Cystitis ◽  
Cord Blood Transplantation ◽  
Bk Virus ◽  
Cellular Mechanisms ◽  
Effector Cells ◽  
T Effector Cells ◽  
Blood Transplantation

Abstract Abstract 4174 Umbilical cord blood transplantation (UCBT) in adults is associated with impaired immune function and increased infection-related morbidity and mortality due to lack of antigen experienced cells and delayed immune reconstitution. BK virus (BKV) is a human polyomavirus that remains latent in renal epithelial cells and can be reactivated after hematopoietic stem cell transplantation (HSCT), leading to hemorrhagic cystitis. Data regarding BKV reactivation and its association with immune reconstitution after UCBT is lacking. We evaluated the status, cellular mechanisms, and clinical implications of immune reconstitution on BK viremia in adults with hematologic malignancies undergoing double unit cord blood transplantation. Thirty-two patients with a median age of 50 years with hematopoietic malignancies were treated with reduced intensity conditioning (Flu/Mel/rATG) followed by infusion of two sequential UCB grafts and GvHD prophylaxis with tacrolimus and sirolimus. The grafts were at least a 4/6 match with each other and the recipient. The results are based on 27 evaluable patients. Assessments were done prior to transplant and at 1, 2, 3, 6 and 12 months after UCBT. After UCBT, 15 patients had detectable serum BKV DNA, median 2.6×104 copies/ml (range, 2.5×102–7.9×106) with a median time to viremia of 40 days (range, 26–733). The cumulative probability of developing BK viremia by day 100 was 0.52 (95% CI, 0.33–0.71). In 9 of the 15 patients with detectable serum BKV DNA, urinary BKV PCR was also performed. All 9 tested patients had detectable urinary BKV and developed clinical symptoms ranging from dysuria to hemorrhagic cystitis. To determine whether development of BK viremia was related to the immunological status, we analyzed detection of serum BKV DNA in conjunction with parameters of immune reconstitution. At 6 and 12 months after transplantation development of BK viremia displayed a statistically significant inverse correlation with CD4+ and CD8+ T cells (p<0.05). Development of BK viremia at these time intervals also inversely correlated with CD4+CD45RO+ and CD8+CD45RO+ T cells (p<0.05), consistent with a potentially significant role of these effector populations in preventing and/or clearing BKV. Conversely, simultaneoulsy, there was a significant positive correlation of BK viremia with T regulatory cell numbers (p<0.05) suggesting that cellular mechanisms of Treg-mediated immune suppression were directly involved in regulating this clinical outcome. At 3 months after UCBT there was a significant positive correlation (p<0.05) between BK viremia and T cell receptor excision circles (TRECs), which are expressed in recent thymic emigrant T cells. BK viremia was not dependent on any other immune cell populations including CD20+ B cells, CD16+CD56+ NK cells and CD14+ monocytes. Furthermore, prevention and/or clearance of BK viremia was not dependent on naïve cell numbers as determined by lack of correlation between BK viremia -or absence thereof- with CD4+CD45RA+ T cells and CD8+CD45RA+ T cells. These observations were in complete contrast to our previous findings regarding CMV-specific immunity, which revealed that prevention and/or clearance of CMV viremia depend on reconstitution of thymopoiesis and increase of TRECs and naïve CD4+CD45RA+ cells. In addition, we found no correlation between development of CMV viremia and BK viremia in UCBT recipients. Our results indicate that reactivation of BK virus occurs with high frequency in adult UCBT recipients and is related to the inability of TREC positive cells to control BK viremia, the impaired and delayed reconstitution of CD4+ and CD8+ T effector cells, and the suppressive function of Treg. Furthermore, our results indicate that distinct immunological mechanisms govern CMV-specific and BK-specific anti-viral responses after UCBT. Disclosures: No relevant conflicts of interest to declare.

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