The Viral KSHV Chemokine vMIP-II Inhibits the Migration of Naive and Activated Human NK Cells by Antagonizing Two Distinct Chemokine Receptors

Natural killer (NK) cells are innate immune cells able to rapidly kill virus-infected and tumor cells. Two NK cell populations are found in the blood; the majority (90%) expresses the CD16 receptor and also express the CD56 protein in intermediate levels (CD56^Dim CD16^Pos) while the remaining 10% are CD16 negative and express CD56 in high levels (CD56^Bright CD16^Neg). NK cells also reside in some tissues and traffic to various infected organs through the usage of different chemokines and chemokine receptors. Kaposi''s sarcoma-associated herpesvirus (KSHV) is a human virus that has developed numerous sophisticated and versatile strategies to escape the attack of immune cells such as NK cells. Here, we investigate whether the KSHV derived cytokine (vIL-6) and chemokines (vMIP-I, vMIP-II, vMIP-III) affect NK cell activity. Using transwell migration assays, KSHV infected cells, as well as fusion and recombinant proteins, we show that out of the four cytokine/chemokines encoded by KSHV, vMIP-II is the only one that binds to the majority of NK cells, affecting their migration. We demonstrate that vMIP-II binds to two different receptors, CX3CR1 and CCR5, expressed by naïve CD56^Dim CD16^Pos NK cells and activated NK cells, respectively. Furthermore, we show that the binding of vMIP-II to CX3CR1 and CCR5 blocks the binding of the natural ligands of these receptors, Fractalkine (Fck) and RANTES, respectively. Finally, we show that vMIP-II inhibits the migration of naïve and activated NK cells towards Fck and RANTES. Thus, we present here a novel mechanism in which KSHV uses a unique protein that antagonizes the activity of two distinct chemokine receptors to inhibit the migration of naïve and activated NK cells.     

A Transporter Interactome Is Essential for the Acquisition of Antimicrobial Resistance to Antibiotics

Awareness of the problem of antimicrobial resistance (AMR) has escalated and drug-resistant infections are named among the most urgent problems facing clinicians today. Our experiments here identify a transporter interactome and portray its essential function in acquisition of antimicrobial resistance. By exposing E. coli cells to consecutive increasing concentrations of the fluoroquinolone norfloxacin we generated in the laboratory highly resistant strains that carry multiple mutations, most of them identical to those identified in clinical isolates. With this experimental paradigm, we show that the MDTs function in a coordinated mode to provide an essential first-line defense mechanism, preventing the drug reaching lethal concentrations, until a number of stable efficient alterations occur that allow survival. Single-component efflux transporters remove the toxic compounds from the cytoplasm to the periplasmic space where TolC-dependent transporters expel them from the cell. We postulate a close interaction between the two types of transporters to prevent rapid leak of the hydrophobic substrates back into the cell. The findings change the prevalent concept that in Gram-negative bacteria a single multidrug transporter, AcrAB-TolC type, is responsible for the resistance. The concept of a functional interactome, the process of identification of its members, the elucidation of the nature of the interactions and its role in cell physiology will change the existing paradigms in the field. We anticipate that our work will have an impact on the present strategy searching for inhibitors of AcrAB-TolC as adjuvants of existing antibiotics and provide novel targets for this urgent undertaking.     

Enhanced plasmid-mediated bioaugmentation of RDX-contaminated matrices in column studies using donor strain Gordonia sp. KTR9

Journal of Industrial Microbiology & Biotechnology - Horizontal gene transfer (HGT) is the lateral movement of genetic material between organisms. The RDX explosive-degrading bacterium Gordonia...     

Cure of mice bearing a late-stage,highly metastatic,drug-resistant tumor by adoptive chemoimmunotherapy

We show here that in contrast to BALB/c mice bearing a late-stage, large MOPC-315 plasmacytoma, BALB/c mice bearing a late-stage, large RPC-5 plasmacytoma were not cured by cyclophosphamide therapy (15, 50, 100 or 200 mg/kg). However, most BALB/c mice bearing a late-stage RPC-5 tumor were cured by cyclophosphamide therapy (100 mg/kg) in conjunction with adoptive immunotherapy using tumor-infiltrated spleen cells (TISpC) that had been cultured with inactivated RPC-5 tumor cells plus polyethylene glycol 6000, even though this protocol was not effective for the therapy of mice bearing a barely palpable, early-stage RPC-5 tumor. Only a few of the mice that were cured of a late-stage RPC-5 tumor following adoptive chemoimmunotherapy (ACIT) were resistant to a subsequent challenge with RPC-5 tumor cells. However, the challenged mice that had developed progressively growing tumors could then be cured by cyclophosphamide alone when the tumor became large, even though this treatment was not curative for mice bearing a tumor of similar size but not previously treated by ACIT. Thus, the cure by ACIT of BALB/c mice bearing a lethal, late-stage RPC-5 tumor with extensive metastases provides a novel experimental tumor model for investigating the mechanisms by which a chemotherapeutic drug and adoptive cellular immunotherapy can cooperate in causing the complete regression of a large tumor load.Supported by research grant CA-30088 from the National Cancer Institute and IM-435 from the American Cancer Society. M. B. M. was supported by Career Development Award CA-01350 from the National Cancer InstituteThis work is a partial fulfillment of the requirements for the Ph.D. degree     

Human tumor cells, modified by a novel pressure/crosslinking methodology, promote autologous lymphocyte proliferation and modulate cytokine secretion

 Hydrostatic pressure (P) combined with membrane protein crosslinking (CL) by adenosine dialdehyde (AdA) can render tumor cells immunogenic. We have recently shown that PCL treatment of murine tumor cells augmented the presentation of MHC-restricted tumor-associated antigens and enhanced cell-mediated immunity. In cancer patients inoculated with autologous PCL-modified tumor cells, a significant delayed-type hypersensitivity response was elicited. Since the balance between cell-mediated immunity and humoral immunity is reciprocally controlled by immunoregulatory cytokines, we have examined the proliferative response and cytokine secretion pattern in cultures of human peripheral blood mononuclear cells (PBMC) stimulated by autologous PCL-modified and unmodified tumor cells. These tumor cells were obtained from freshly resected tumor tissue of 16 patients with colon (8), lung (4) and renal (4) carcinomas. The results demonstrated that PCL-modified tumor cells promoted an increase in PBMC proliferation in 5 out of 8 (63%), 1 out of 4 (25%) and 4 out of 4 (100%) colon, lung and renal cell carcinomas. Fourteen of the above cultures were also analyzed for the secretion of interleukin-10 and interferon-γ. Overall, a substantial decrease in IL-10 secretion was detected in 9 out of 14 (64%) cultures while a reciprocal increase in interferon-γ secretion was noted in 8 out of 14 (57%) cultures. Our results confirmed that PCL-modified human tumor cells of different etiologies can modulate the pattern of cytokines released from stimulated autologous lymphocytes. Such a procedure could prove valuable in the production of autologous tumor vaccines. Received: 8 January 1998 / Accepted: 9 April 1998     

Enhanced expansion of the thymic CD8+ cell subset as a potential mechanism for the generation of enhanced antitumor cytotoxicity by thymocytes from low-dose melphalan-treated MOPC-315 tumor bearers

Summary We have previously shown that thymocytes from low-dose melphalan (l-phenylalanine mustard)-treated MOPC-315-tumor-bearing mice (melphalan TuB) are able to generate an enhanced level of anti-MOPC-315 cytotoxicity, as compared to thymocytes from untreated MOPC-315-tumor-bearing mice or thymocytes from untreated or low-dose melphalan-treated normal mice, upon in vitro stimulation with MOPC-315 tumor cells in the presence of a low concentration of recombinant interleukin-2 (rIL-2). Here we show that the generation of enhanced anti-MOPC-315 cytotoxicity by melphalan TuB thymocytes depends on the ability of the thymocytes to proliferate. In addition, the ability of melphalan TuB thymocytes to generate an enhanced level of anti-MOPC-315 cytotoxicity correlated with their ability to proliferate more readily than thymocytes from untreated tumor-bearing mice and thymocytes from untreated or melphalan-treated normal mice in response to stimulation with MOPC-315 tumor cells plus a low concentration of rIL-2. Moreover, although fresh melphalan TuB thymocytes do not contain a higher percentage of phenotypically mature cells (i.e., CD4^–/CD8⁺ or CD4⁺/CD8^–) than do thymocytes from normal mice or untreated tumor-bearing mice, after a 5-day culture with both MOPC-315 tumor cells and a low concentration of rIL-2, cultures of thymocytes from melphalan TuB contained a much higher percentage of CD4^–/CD8⁺ (but not CD4⁺/CD8^–) cells than did cultures of thymocytes from the other two sources. Since CD4^–/CD8⁺ cells were previously shown to be responsible for the exertion of antitumor cytotoxicity by thymocytes stimulated with MOPC-315 in vitro, our results indicate that the enhanced antitumor cytotoxicity exerted by melphalan TuB thymocytes following in vitro stimulation with MOPC-315 tumor cells in the presence of a low concentration of rIL-2 is due, at least in part, to an expansion of the pool of CD4^–/CD8⁺ effector cells.Supported by research grant CA-35 761 from the National Cancer InstituteIn partial fulfillment of the requirements for the Doctor of Philosophy degreeSupported by career development award CA-01 350 from the National Cancer Institute