Prognostic Significance of Tumor-Associated Inflammation in Renal Cell Carcinoma

This study analyzed tumor-associated inflammation by assessing the expression of cyclophilin A (CypA) and TNF in samples of kidney tumors of various histological types. It was shown that different histological types of renal cell carcinoma differed by the expression of these proteins. Thus, the highest expression of CypA and TNF was observed in papillary and chromophobe kidney cancer, although no correlation with overall bacterial load was found for these tumors. In the case of clear cell renal cell carcinoma, the expression of proinflammatory factors was observed in only half of the cases and directly correlated with the presence of resident bacteria, serving as a favorable prognostic factor for the disease.

T Cell Receptor Chain Centricity: The Phenomenon and Potential Applications in Cancer Immunotherapy

T cells are crucial players in adaptive anti-cancer immunity. The gene modification of T cells with tumor antigen-specific T cell receptors (TCRs) was a milestone in personalized cancer immunotherapy. TCR is a heterodimer (either α/β or γ/δ) able to recognize a peptide antigen in a complex with self-MHC molecules. Although traditional concepts assume that an α- and β-chain contribute equally to antigen recognition, mounting data reveal that certain receptors possess chain centricity, i.e., one hemi-chain TCR dominates antigen recognition and dictates its specificity. Chain-centric TCRs are currently poorly understood in terms of their origin and the functional T cell subsets that express them. In addition, the ratio of α- and β-chain-centric TCRs, as well as the exact proportion of chain-centric TCRs in the native repertoire, is generally still unknown today. In this review, we provide a retrospective analysis of studies that evidence chain-centric TCRs, propose patterns of their generation, and discuss the potential applications of such receptors in T cell gene modification for adoptive cancer immunotherapy.

Recombinant Human Cyclophilin A in Combination with Adoptive T-cell Therapy Improves the Efficacy of Cancer Immunotherapy in Experimental Models in vivo

Adoptive T-cell therapy (ACT) is successfully applied in cancer treatment; however, its efficiency can be limited by a low viability, short persistence time, and loss of functional activity of T-cells after adoptive transfer. The search for novel immunomodulators that can improve the viability, expansion, and functions of T-cells after their infusion with the minimal side effects could contribute to the development of more efficient and safe ACT strategies. Recombinant human cyclophilin A (rhCypA) is of particular interest in this respect, as it exhibits pleiotropic immunomodulatory activity and stimulates both innate and adaptive anti-tumor immunity. Here, we evaluated the effect of rhCypA on the efficacy of ACT in the mouse EL4 lymphoma model. Lymphocytes from transgenic 1D1a mice with an inborn pool of EL4-specific T-cells were used as a source of tumor-specific T-cells for ACT. In models of immunocompetent and immunodeficient transgenic mice, the course (3 days) rhCypA administration was shown to significantly stimulate EL4 rejection and prolong the overall survival of tumor-bearing mice after adoptive transfer of lowered doses of transgenic 1D1a cells. Our studies showed that rhCypA significantly improved the efficacy of ACT by enhancing the effector functions of tumor-specific cytotoxic T-cells. These findings open up the prospects for the development of innovative strategies of adoptive T-cell immunotherapy for cancer using rhCypA as an alternative to existing cytokine therapies.

Physiological and Functional Effects of Dominant Active TCRα Expression in Transgenic Mice

A T cell receptor (TCR) consists of α- and β-chains. Accumulating evidence suggests that some TCRs possess chain centricity, i.e., either of the hemi-chains can dominate in antigen recognition and dictate the TCR’s specificity. The introduction of TCRα/β into naive lymphocytes generates antigen-specific T cells that are ready to perform their functions. Transgenesis of the dominant active TCRα creates transgenic animals with improved anti-tumor immune control, and adoptive immunotherapy with TCRα-transduced T cells provides resistance to infections. However, the potential detrimental effects of the dominant hemi-chain TCR’s expression in transgenic animals have not been well investigated. Here, we analyzed, in detail, the functional status of the immune system of recently generated 1D1a transgenic mice expressing the dominant active TCRα specific to the H2-Kb molecule. In their age dynamics, neither autoimmunity due to the random pairing of transgenic TCRα with endogenous TCRβ variants nor significant disturbances in systemic homeostasis were detected in these mice. Although the specific immune response was considerably enhanced in 1D1a mice, responses to third-party alloantigens were not compromised, indicating that the expression of dominant active TCRα did not limit immune reactivity in transgenic mice. Our data suggest that TCRα transgene expression could delay thymic involution and maintain TCRβ repertoire diversity in old transgenic mice. The detected changes in the systemic homeostasis in 1D1a transgenic mice, which are minor and primarily transient, may indicate variations in the ontogeny of wild-type and transgenic mouse lines.

Preparative Production and Purification of Recombinant Human Cyclophilin A

In this work, we developed the method of preparative production of recombinant human cyclophilin A (rhCypA) in Escherichia coli. The full-length cDNA encoding the gene of human CypA (CYPA) was amplified by RT-PCR from the total RNA of human T cell lymphoma Jurkat. The nucleotide sequence of CYPA was optimized to provide highly effective translation in E. coli. Recombinant CYPA DNA was cloned into the pET22b(+) vector, and the resulted expression plasmid was used to transform E. coli strain BL21(DE3)Gold. The recombinant producer strain of E. coli produced soluble rhCypA in the bacterial cytoplasm. The synthesis efficiency of rhCypA was up to 50% of the total cell protein allowing to produce rhCypA in the amount of 1 g per liter of the culture. We also developed the method for rhCypA purification, consisting of a single-step tandem anion exchange chromatography on DEAE- and Q-Sepharose columns. The protein purity was 95% according to electrophoresis (SDS-PAGE), and its contamination with endotoxin did not exceed 0.05 ng per 1 mg of the protein that met the requirements of European pharmacopoeia for injectable preparations. The produced recombinant protein exhibited functional features of native CypA, i.e., isomerase activity and chemokine activity as assessed by stimulation of migration of mouse bone marrow hematopoietic stem cells in vivo. The generated producer strain of E. coli is a super-producer and could be used for large-scale experimental studies of rhCypA and in its preclinical and clinical trials as a drug.

Formation of a Unique Population of CD8+ T Lymphocytes after Adoptive Transfer of Syngeneic Splenocytes to Mice with Lymphopenia

Under conditions of lymphopenia, T lymphocytes proliferate and acquire a surface activation phenotype, which in many respects is similar to the phenotype of true memory T cells. We investigated the phenotypic features of the CD8+ T-cell population formed from donor lymphocytes after adoptive transfer of syngeneic splenocytes to sublethally irradiated mice. This population expresses markers CD44, CD122, CD5, CD49d and the chemokine receptor CXCR3. Thus, for the first time, the phenomenon of the formation of a population of T cells with signs of suppressive CD8+ T lymphocytes and true memory cells was demonstrated.

Adoptive Immunotherapy Based on Chain-Centric TCRs in Treatment of Infectious Diseases

Complications after vaccination, lack of vaccines against certain infections, and the emergence of antibiotic-resistant microorganisms point to the need for alternative ways of protection and treatment of infectious diseases. Here, we proposed a therapeutic approach to control salmonellosis based on adoptive cell therapy. We showed that the T cell receptor (TCR) repertoire of salmonella-specific memory cells contains 20% of TCR variants with the dominant-active α-chain. Transduction of intact T lymphocytes with the dominant salmonella-specific TCRα led to their enhanced in vitro proliferation in response to salmonella. Adoptive transfer of transduced T cells resulted in a significant decrease in bacterial loads in mice infected with salmonella before or after the adoptive transfer. We demonstrated that adoptive immunotherapy based on T cells, transduced with dominant-specific TCRα could be successfully applied for treatment and prevention of infectious diseases and represent a useful addition to vaccination and existing therapeutic strategies.

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A regular TCR repertoire of memory T cells contains alpha-chain-centric TCRs

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Dominant-active TCRα, paired with random TCRβ, recognizes specific microbial antigens

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Adoptive immunotherapy could be applied for treatment of infections

Proteasomes in the brain of β2-microglobulin knockout mice

MHC class I molecules play an important role in synaptic plasticity of the mammalian nervous system. Proteolytic complexes (proteasomes) produce oligopeptides that are presented on cell surfaces in complexes with MHC class I molecules and regulate many cellular processes beside this. The goal of the present work was to study peculiarities in functioning of proteasomes and associated signaling pathways along with evaluation of NeuN and gFAP expression in different sections of the brain in mice with knockout of β2-microglobulin, a constituent of MHC class I molecules. It was found that the frontal cortex and the brainstem, structures with different ratio of NeuN and gFAP expression, are characterized by opposite changes in the proteasome pool under constant total proteasome levels in B2m-knockout mice in comparison with those in control animals. ChTL-activity as well as expression of LMP7 immune subunit and PA28 regulator of proteasomes was elevated in the cortex of B2m-knockout mice, while these indicators were decreased in the brainstem. The concentrations of the signaling molecules nNOS and HSP70 in B2m-knockout mice were increased in the cortex, while being decreased in the brainstem, and this indicates the possibility of control of expression of the LMP7 subunit and the regulator PA28 by these molecules. Changes in the proteasome pool observed in striatum of B2m-knockout mice are similar to those observed in the brainstem. At the same time, the cerebellum is characterized by a specific pattern of proteasome functioning in comparison with that in all other brain structures. In cerebellum the expression of immune subunits LMP7 and LMP2 and the regulator PA28 was increased, while expression of regulator PA700 was decreased. Deficiency of NeuN and gFAP was revealed in most brain compartments of B2m-knockout mice. Thus, increased expression of the above-mentioned immune subunits and the proteasome regulator PA28 in the cortex and cerebellum may compensate disturbances revealed in the brain structures and the absence of MHC class I molecules. Apparently, this promotes production of peptides necessary for cell-to-cell interactions and maintains nervous system plasticity in B2m-knockout mice.

[Proteasomes on thyroid tissue allotransplantation under induction of donor specific tolerance in rats]

The proteasomes in the liver of August rats (RT1C) were investigated 30 days after the allotransplantation of Wistar rat (RT1u) thyroid tissue under renal capsule with/without induction of donor specific tolerance by donor splenocyte intraportal administration. The level of the total proteasome pool, immune proteasomes containing the LMP2 and/or LMP7 subunits, proteasome 19S- and 11S-regulators was defined. The intact and sham-operated August rats were used as control groups. The level of all immune proteasome forms and 11S regulator increased while the level of the total proteasome pool and 19S regulator decreased in the liver of experimental animals compared to the control groups that indicated changes of liver functional state after transplantation. The 19S/11S ratio increased in the liver of non-tolerated rats compared to tolerated animals. In the liver of tolerated rats with survived transplants, the quantity of mononuclear cells, expressing the immune subunit LMP2, greatly increased in comparison with control and non-tolerated animals. Study of the survived transplants showed the increase of the ratio of LMP2/LMP7 immune subunits and 19S/11S regulators in them compared to the tissue replacing the rejected transplants. In the control intact thyroid tissue, the immune proteasomes were almost not revealed, while 19S/11S ratio was maximal. Thus, the development of the immune reaction or its suppression is accompanied by change of the balance between different proteasome forms. The immune subunit LMP7 and 11S regulator are connected with the response against donor tissue. On the contrary, the immune subunit LMP2 and 19S regulator are likely to be important for the immune tolerance development and survived tissue functioning. The low content of the immune proteasomes in the follicle cells was found by immunofluorescence assay. The formation of antigens for major histocompatibility complex class I molecules was impaired by low immune proteasome content that led to immunological tolerance to hormone-producing follicle cells.

Immune selection of tumor cells in TCR β-chain transgenic mice

The concept of immunological surveillance implies that immunogenic variants of tumor cells arising in the organism can be recognized by the immune system. Tumor progression is provided by somatic evolution of tumor cells under the pressure of the immune system. The loss of MHC Class I molecules on the surface of tumor cells is one of the most known outcomes of immune selection. This study developed a model of immune selection based on the immune response of TCR 1d1 single β-chain transgenic B10.D2(R101) (K(d)I(d)D(b)) mice to allogeneic EL4 (H-2(b)) thymoma cells. In wild-type B10.D2(R101) mice, immunization with EL4 cells induced a vigorous CTL response targeted to the H-2K(b) molecule and results in full rejection of the tumor cells. In contrast, transgenic mice developed a compromised proliferative response in mixed-lymphocyte response assays and were unable to reject transplanted allogeneic EL4 cells. During the immune response to EL4 cells, CD8(+) T-lymphocytes with endogenous β-chains accumulated predominantly in the spleen of transgenic mice and only a small part of the T-lymphocytes expressing transgenic β-chains became CD8(+)CD44(+)CD62L(-) effectors. Then, instead of a full elimination of tumor cells as in wild-type mice, a reproducible prolonged equilibrium phase and subsequent escape was observed in transgenic mice that resulted in death of 90% of the mice in 40-60 days after grafting. Prolonged exposure of tumor cells to the pressure of the immune system in transgenic mice in vivo resulted in a stable loss of H-2K(b) molecules on the EL4 cell surface. Genetic manipulation of the T-lymphocyte repertoire was sufficient to reproduce the classic pattern of interactions between tumor cells and the immune system, usually observed in reliable syngeneic models of anti-tumor immunity. This newly-developed model could be used in further studies of immunoregulatory circuits common for transplantational and anti-tumor immune responses.

Decrease in pool of T lymphocytes with surface phenotypes of effector and central memory cells under influence of TCR transgenic β-chain expression

Peripheral T lymphocytes can be subdivided into naïve and antigen-experienced T cells. The latter, in turn, are represented by effector and central memory cells that are identified by different profiles of activation markers expression, such as CD44 and CD62L in mice. These markers determine different traffic of T lymphocytes in the organism, but hardly reproduce real antigenic experience of a T lymphocyte. Mechanisms of homeostasis maintenance of T lymphocytes with different activation phenotypes remain largely unknown. To investigate impact of T cell receptor (TCR) transgenic chains on formation of T lymphocytes, their peripheral survival and activation surface phenotypes, we have generated the transgenic mouse strain expressing transgenic β-chain of TCR 1D1 (belonging to the Vβ6 family) on the genetic background B10.D2(R101). Intrathymic development of T cells in these transgenic mice is not impaired. The repertoire of peripheral T lymphocytes in these mice contains 70-80% of T cells expressing transgenic β-chain and 20-30% of T cells expressing endogenous β-chains. The ratio of peripheral CD4⁺CD8⁻ and CD4⁻CD8⁺ T lymphocytes remained unchanged in the transgenic animals, but the percent of T lymphocytes with the "naïve" phenotype CD44⁻CD62L⁺ was significantly increased, whereas the levels of effector memory CD44⁺CD62L⁻ and central memory CD44⁺CD62L⁺ T lymphocytes were markedly decreased in both subpopulations. On the contrary, T lymphocytes expressing endogenous β-chains had surface phenotype of activated T cells CD44⁺. Thus, for the first time we have shown that the pool of T lymphocytes with different activation phenotypes depends on the structure of T cell receptors.

MHC restriction and allogeneic immune responses

Discovery of major histocompatability complex (MHC) restriction helped in the understanding of how T-lymphocytes recognize antigens on bacteria, viruses, and tumor cells. It was initially accepted that MHC restriction was a consequence of "adaptive differentiation" in the thymus; during differentiation, the forming repertoire of T-lymphocytes "learned" a low affinity for self MHC molecules via positive selection. This view was later countered by discovery of artifacts in underlying studies and the fact that adaptive differentiation could not explain direct allogeneic and allorestricted recognition phenomena. Data from experiments with TCR transgenic animals, individual MHC/peptide complex expression, and recipients of xenogenic thymus glands yielded evidence of an ability to adapt to microenvironment and a low specificity of positive selection. These facts led to an alternative interpretation of MHC restriction explained, in part, by specificity of a pool of effector cells activated by primary immunization. Details of this phenomenon were defined in studies that noted differential primary structures of peptides that bound various allelic forms of MHC molecules. Here, the T-lymphocyte repertoire formed in the thymus was a result, in part, of random rearrangement of germinal sequences of TCR gene fragments. Such pre-selected repertoires were inherently capable of reacting with different allelic forms of MHC molecules. In contrast, MHC molecules were characterized by significant intraspecies polymorphisms; negative and positive selections were aimed at adaptation of a pre-selected repertoire to a specific microenvironment in an individual. Via elimination of autoreactive clones and sparing of a broad spectrum of specificity to potential pathogens, selection in the thymus could be considered a life-long allogeneic reaction of a pre-selected repertoire to self MHC molecules resulting in tolerance to "self," increased responsiveness to foreign MHC molecules, and cross-reactivity of the mature T-lymphocyte repertoire to individual foreign peptides plus self MHC.

Intrathymic selection: new insight into tumor immunology

Central tolerance to self-antigens is formed in the thymus where deletion of clones with high affinity to "self" takes place. Expression of peripheral antigens in the thymus has been implicated in T cell tolerance and autoimmunity. During the last years, it has been shown that medullary thymic epithelial cells (mTECs) are the unique cell type expressing a diverse range of tissue-specific antigens. Promiscuous gene expression is a cell autonomous property of thymic epithelial cells and is maintained during the entire period of thymic T cell output. The array of promiscuously expressed self-antigens was random and included well-known targets for cancer immunotherapy, such as alpha-fetoprotein, P1A, tyrosinase, and gp100. Gene expression in normal tissues may result in tolerance of high-avidity cytotoxic T lymphocyte (CTL), leaving behind low-avidity CTL that cannot provide effective immunity against tumors expressing the relevant target antigens. Thus, it may be evident that tumor vaccines that targeted the tumor-associated antigens should be inefficient due to the loss of high-avidity T cell clones capable to be stimulated. Stauss with colleagues have described a strategy to circumvent immunological tolerance that can be used to generate high-avidity CTL against self-proteins, including human tumor-associated antigens. In this strategy, the allorestricted repertoire of T cells from allogenic donor is used as a source of T cell clones with high avidity to tumor antigens of recipient for adoptive immunotherapy. Then, the T cell receptor (TCR) genes isolated from antigen-specific T cells can be exploited as generic therapeutic molecules for antigen-specific immunotherapy.

Avian adenovirus vector CELO-TK displays anticancer activity in human cancer cells and suppresses established murine melanoma tumors

Avian adenovirus CELO is a novel adenovirus vector system with the advantages of efficient production, high virion stability, and the absence of crossreactivity with Ad5-neutralizing antibodies. In this study, we evaluated the anticancer efficacy of a CELO vector encoding the herpes simplex virus type 1 thymidine kinase, a prodrug-activating therapeutic gene. Vectors carrying the gene for HSV-tk or EGFP under the control of the HCMV promoter in place of the "nonessential" region of the CELO genome were constructed. Anticancer activity of the CELO-TK vector was studied in vitro, in human and murine tumor cells in cell culture, and in vivo, in established subcutaneous murine B16 melanoma tumors in C57BL/6 mice. The CELO-TK vector mediated delivery of functional HSV-tk to tumor cell lines in cell culture. Comparison of the CELO-TK vector to a first-generation human adenovirus type 5 vector Ad5-TK in cultured H1299 cells showed equal levels of functional activity at increasing multiplicities of infection with CELO-based vector. CELO vectors allowed for transduction and expression of EGFP and HSV-tk genes in subcutaneous melanoma tumors in C57BL/6 mice. Intratumoral injections of CELO-TK followed by ganciclovir administration resulted in suppression of tumor growth and significantly increased the median of survival. The results of the study demonstrated the efficacy of CELO vector as a vehicle for the delivery of prodrug-activating genes such as HSV-tk to tumor cells in vitro and in vivo.

Recombinant avian adenovirus CELO expressing the human interleukin-2: characterization in vitro, in ovo and in vivo

In our study, a recombinant adenovirus based on the avian adenovirus CELO genome, has been constructed that contains the human interleukin-2 gene. We have shown the production of biologically active recombinant interleukin-2 in vitro (LMH and 293 cells) and in ovo (chicken embryos) infected with recombinant virus CELO-IL2. An increase in the median survival time of C57BL/6 mice carrying B16 melanoma tumors has been demonstrated after multiple intra-tumors injections of the recombinant adenovirus CELO-IL2.

Peptides of a major histocompatibility complex class I (Kb) molecule cause prolongation of skin graft survival and induce specific down-regulatory T cells demonstrable in the mixed lymphocyte reaction

Six individual peptides of the major histocompatibility complex (MHC) class I molecule H-2Kb were synthesized. Intravenous injection of peptide 6 into mice prolonged the survival of Kb (BL/6 or B10.MBR) skin grafts on allogeneic R101 and B10.AKM mice, respectively. This was specific, as control skin grafts from Kk (B10.BR) or Kd (DBA/2) donors, respectively, were rejected at the same time in both control and peptide-treated mice. The optimal doses for peptide 6, which is from the alpha 2 domain, were defined. The test system was the inhibition of proliferation in vitro of naive lymph node cells by syngeneic mitomycin c-treated spleen cells from R101 mice preimmunized with irradiated stimulator splenocytes of Kb (BL/6) origin. Down-regulation was specific, as proliferation in response to third-party allogeneic stimulator Kk (B10.BR) splenocytes was not inhibited. Of the six peptides of H-2Kb tested, potent down-regulatory cells were induced by peptides 2 (alpha 1 domain) and 5 and 6 (alpha 2 domain). The greatest down-regulatory activity was obtained by giving peptide 2 to mice that had already been immunized against H-2Kb by injecting EL4 cells. Under the same conditions, injecting peptide 2 did not induce any cytotoxic T cells. In contrast, specific cytotoxic lymphocytes (CTL) were induced when cells from primed mice were incubated for 4 days with heated stimulator cells from BL/6 mice. The data suggest that peptides from MHC class I molecules activate precursors of down-regulatory T cells, but not of CTL, and this may explain their ability to prolong skin allograft survival.

Immunosuppressive factor from liver induces apoptosis in thymoma EL-4 cells but not normal MHC class II-specific T lymphocytes

An endogenously produced immunosuppressive factor (ISFnp, immunosuppressive factor-neutral protein), inducing a decrease in viability of thymoma EL-4 cells in vitro, was isolated from murine liver using ion exchange, gel filtration and hydrogen-bonding chromatography. Polyclonal rabbit antibodies against this factor were developed and attached to periodate-activated Sepharose CL-6B. The immunoaffine sorbent obtained significantly depleted the biological activity of ISFnp from tested fractions. The factor shows liver-specific location, an M(r) of about 70-80 kDa and consists of 2 subunits (40 and 42 kDa) as determined by SDS-PAGE and Western blotting. ISFnp induced DNA degradation in EL-4 cells similar to the cleavage of DNA onto olygonucleosomal fragments in dexamethasone-treated thymocytes. This DNA degradation preceded lysis of thymoma cells, suggesting an induction of apoptosis in ISFnp-treated EL-4 cells. Addition of the factor into primary mixed lymphocyte culture (MLC) strongly inhibited proliferative response but failed to induce any decrease in the ability of normal MHC class II-specific alloreactive cells to respond in the secondary MLC. Moreover, addition of ISFnp into primary MLC on the peak of proliferative response resulted in augmentation of secondary responses of primed cells as compared with the same quantities of primed cells from untreated cultures. These results suggest a possible role of liver both in deletion of transformed clones of T lymphocytes and formation of allospecific memory T cells.