Inhibition by CsA and FK506 of the in vitro proliferative response of gamma delta T cells on stimulation with anti-TCR delta monoclonal antibody

Anti-inflammatory and antioxidative actions of tacrolimus (FK506) on human microglial HMC3 cell line

Microglial cells are indispensable for the normal development and functioning of neurons in the central nervous system, where they play a crucial role in maintaining brain homeostasis by surveilling the microenvironment for signs of injury or stress and responding accordingly. However, in neurodegenerative diseases, the density and phenotypes of microglial cells undergo changes, leading to chronic activation and inflammation. Shifting the focus from neurons to microglia in drug discovery for neurodegenerative diseases has become an important therapeutic target. This study was aimed to investigate the potential of Tacrolimus (FK506) an FDA-approved calcineurin inhibitor, to modulate the pathology of neurodegenerative diseases through anti-inflammatory and antioxidative effects on microglial activation. The human microglia clone 3 (HMC3) cells were exposed to 1 μg/mL LPS in the presence and absence of doses of FK506. Survival rates of cells were determined using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) method. Morphological evaluation of cells showed that FK506 restored the normal morphology of activated microglia. Furthermore, FK506 treatment increases the total antioxidant capacity and reduces the total oxidative capacity, indicating its potential antioxidant effects. Data from ELISA and RT-PCR analyses showed that LPS abolished its promoting effects on the release of proinflammatory IL-1β and IL-6 cytokines in HMC3 cells, reflecting the anti-inflammatory effect of FK506. These findings support the idea that FK506 could be a promising therapeutic agent for neurodegenerative diseases by modulating microglial activation and reducing inflammation and oxidative stress.

Cytomegalovirus and cancer after kidney transplantation: Role of the human leukocyte antigen system?

BACKGROUND

The role of cytomegalovirus (CMV) in cancer development after transplantation remains uncertain. We aimed to determine the association between donor and recipient CMV serological status and the risk of cancer development after kidney transplantation.

METHODS

Using data from the Australian and New Zealand Dialysis and Transplant (ANZDATA) Registry, we assessed the association between CMV donor/recipient (D/R) serological status and the risk of solid organ cancers in primary adult deceased-donor kidney transplant patients between 1990 and 2012.

RESULTS

Of 8140 recipients, a total of 895 (11%) recipients developed incident cancers during a follow-up time of 51 555 person-years. Human leukocyte antigen (HLA) mismatches was an effect modifier between CMV serological status and cancer (P=.03 for interaction). In recipients who have received 0-2 HLA-ABDR mismatched kidneys, the adjusted hazard ratios for cancer incidence among those with CMV D-/R-, CMV D-/R+, and CMV D+/R- were 0.47 (95% confidence interval [CI]: 0.24-0.91), 1.42 (95% CI: 0.97-2.07), and 1.02 (95% CI: 0.67-1.57), respectively compared with the reference of CMV D+/R+. A similar association was not observed in those with >2 HLA-ABDR mismatches.

CONCLUSION

CMV D-/R- status was associated with a reduced risk of cancer in kidney transplant recipients who have received well-matched renal allografts, suggesting a potential role of HLA matching in cancer development.

Interplay of T-cell receptor and interleukin-2 signalling in Vγ2Vδ2 T-cell cytotoxicity

Human peripheral blood Vγ2Vδ2 T cells are important for host defence and tumour immunity. Their unusual T-cell receptor (TCR) recognizes small molecule phosphoantigens; stimulated cells produce inflammatory cytokines and are potently cytotoxic for a variety of tumours. However, molecular mechanisms linking phosphoantigen stimulation and cytotoxicity are incompletely understood. We know that isopentenyl pyrophosphate (IPP) activates mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/Erk) and phosphoinositide 3-kinase (PI-3K)/Akt pathways; specific inhibition of Erk or Akt significantly impairs the functional response to IPP. We now show that interleukin-2 also activates MEK/Erk and PI-3K/Akt pathways but on its own, fails to induce cytokine expression or cytotoxicity. Hence, MEK/Erk and PI-3K/Akt activation are necessary but not sufficient to induce effector responses in Vγ2Vδ2 T cells and a TCR-dependent signal is still required for tumour cell killing. Cyclosporin A, an inhibitor of calcineurin, blocked calcium-dependent nuclear translocation of nuclear factor of activated T cell (NFAT) and significantly reduced IPP-induced cytokine production, degranulation and cytotoxicity. The IPP-induced calcium mobilization and NFAT translocation were necessary to activate Vγ2Vδ2 effector functions; interleukin-2, acting on the MEK/Erk pathway, regulated the strength of these responses. The TCR has a specific role in Vγ2Vδ2 T-cell killing of tumour cells, which is distinct from its role in triggering cellular proliferation in response to phosphoantigens.

Characterization of a newly discovered T-cell receptor beta-chain heterodimer expressed on a CD8+ bone marrow subpopulation that promotes allogeneic stem cell engraftment

The facilitating cell is a rare CD8+ bone marrow subpopulation that can enhance allogeneic hematopoietic stem cell engraftment across complete major histocompatibility complex barriers without inducing acute graft-versus-host disease. Here we describe a CD3epsilon-associated complex on the facilitating cell surface that consists of the T-cell receptor beta-chain disulfide-linked to a previously unknown 33-kilodalton glycoprotein. Provisionally called FCp33, this glycoprotein does not represent any of the known protein chains or surrogates associated with CD3-T-cell receptor beta. Expression of this CD3-T-cell receptor beta-FCp33 complex directly correlates with the facilitating cell's functional ability to enhance allogeneic stem cell engraftment in vivo.

Post-transplant epididymitis and orchitis following Listeria monocytogenes septicaemia

We report the occurrence of epididymitis and orchitis 1 week after the onset of Listeriosis in an 11-month-old boy receiving an orthotopic liver transplantation for biliary atresia. Immunologic implications of Listeria monocytogenes-induced testicular inflammation are discussed, and the potential role of immunosuppression with tacrolimus is also discussed.