Which way for drug-mediated immunosuppression?

Multi-Omics Analysis of the Expression and Prognosis for FKBP Gene Family in Renal Cancer

Background

The FK506-binding protein (FKBP) is a family of intracellular receptors that can bind specifically to the immunosuppressant FK506 and rapamycin. Although FKBPs play crucial roles in biological processes and carcinogenesis, their prognostic value and molecular mechanism in clear cell renal cell carcinoma (ccRCC) remain unclear.

Methods

Using pan-cancer data from The Cancer Genome Atlas (TCGA) and public databases, we analyzed the expression and correlation of FKBPs in 33 tumor types. Survival and Cox regression analyses were employed to explore the prognostic value of FKBPs. The relationship with tumor microenvironment and stemness indices was taken into account to evaluate the function of FKBPs. We constructed a risk score model to predict the prognosis of patients with ccRCC. The receiver operating characteristic (ROC) curve was performed to further test the prognostic ability of our model. Nomogram, joint effects analysis, and clinical relevance were performed to assist the clinician. Gene set enrichment analysis (GSEA) and cell line experiments were performed to investigate the function and molecular mechanisms of FKBPs in patients with ccRCC. Paired clinical specimens and multi-omics analysis were used to further validate and explore the factors affecting gene expression in ccRCC patients.

Results

The expression levels of FKBP10 and FKBP11 were higher in ccRCC tissues than in normal tissues. The alteration in expression may be because of the degree of DNA methylation. Increased expression levels of FKBP10 and FKBP11 were associated with worse overall survival (OS). More importantly, GSEA revealed that FKBP10 is mainly involved in cell metabolism and autophagy, whereas FKBP11 is mainly associated with immune-related biological processes and autophagy. Cell Counting Kit 8 (CCK-8) and Transwell assays revealed that knockdown of FKBP10 and FKBP11 inhibits proliferation, migration, and invasion of the ccRCC cell line.

Conclusion

FKBP10 and FKBP11 play important roles in ccRCC phenotypes and are potential prognostic markers as well as new therapeutic targets for patients with ccRCC.

FKBP11 promotes cell proliferation and tumorigenesis via p53-related pathways in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is one of the causes of cancer-related death worldwide. The abnormal proliferation ability of OSCC has become one of the major reasons for its poor prognosis. FK-506 binding protein 11 (FKBP11) is abnormally expressed in malignant tumors and affects many biological processes. The purpose of this study is to investigate the effect of FKBP11 on cell proliferation in OSCC and explore the possible regulatory mechanism. The expression of FKBP11 was detected by western blotting (WB) and/or real-time PCR in OSCC and paracancerous normal tissues in tongue squamous cell carcinoma (TSCC) cell lines, revealing high expression in OSCC and CAL-27 cells. Furthermore, FKBP11 knockdown inhibited the proliferation of CAL-27 cells by CCK-8 and colony formation assays. G₂/M arrest and induction of apoptosis were observed using flow cytometry, Hoechst 33258 and Calcein-AM/PI staining, accompanied by changes in some cell cycle- and apoptosis-related proteins, including CDK1, Cyclin B1, p21, p27, p53, Bax, Bcl-2 and Caspase-3. Additionally, the expression of these proteins can be reversed by the use of pifithrin-α (PFT-α), a p53 inhibitor. An in vivo xenograft model further confirmed that FKBP11 enhanced OSCC progression. In conclusion, FKBP11 could promote cell proliferation by regulating G₂/M phase and apoptosis via the p53/p21/p27 and p53/Bcl-2/Bax pathways, respectively, which suggests that it may be a new candidate target for the treatment of OSCC.

Targeting Protein Folding: A Novel Approach for the Treatment of Pathogenic Bacteria

Infectious diseases are a major cause of morbidity and mortality worldwide, exacerbated by increasing antibiotic resistance in many bacterial species. The development of drugs with new modes of action is essential. A leading strategy is antivirulence, with the aim to target bacterial proteins that are important in disease causation and progression but do not affect growth, resulting in reduced selective pressure for resistance. Immunophilins, a superfamily of peptidyl-prolyl cis-trans isomerase (PPIase) enzymes have been shown to be important for virulence in a broad-spectrum of pathogenic bacteria. This Perspective will provide an overview of the recent advances made in understanding the role of each immunophilin family, cyclophilins, FK506 binding proteins (FKBPs), and parvulins in bacteria. Inhibitor design and medicinal chemistry strategies for development of novel drugs against bacterial FKBPs will be discussed. Furthermore, drugs against human cyclophilins and parvulins will be reviewed in their current indication as antiviral and anticancer therapies.

Characterization of three FK506-binding proteins in the entomopathogenic fungus Beauveria bassiana

FK506 binding proteins (FKBPs) participate in regulation of diverse biological processes. However, the role of these proteins in insect-pathogenic fungi is far from well understood. To investigate the functions of FKBPs in Beauveria bassiana, a widely used entomopathogenic fungus for control of insect pests, we identify three putative FKBP genes, Bbfkbp12, Bbfkbp15, and Bbfkbp50, in the fungus. Gene-disruption experiments show that loss of Bbfkbp12 results in a significant increase of resistance of B. bassiana against the immunosuppressive compounds FK506 and rapamycin, while loss of Bbfkbp50 leads to the resistance to the ergosterol synthesis inhibitor lovastatin. Transcription assays of calcineurin (CaN)- and mTOR (mammalian target of rapamycin)-downstream target genes confirm that BbFKBP12 is the target of both FK506 and rapamycin, associated with CaN- and mTOR-signal pathways in B. bassiana. GFP-tagging of the proteins shows that BbFKBP12 and BbFKBP15 localize in cytoplasm while BbFKBP50 in nucleus. Our results provide useful information for the study of functions of CaN- and mTOR-mediated signaling, and ergosterol synthesis in the entomopathogenic fungi.

In Silico Analysis of Conformational Changes Induced by Normal and Mutation of Macrophage Infectivity Potentiator Catalytic Residues and its Interactions with Rapamycin

The Legionella pneumophila (Lp), human pathogen, causes severe and often fatal Legionnaires' disease, produces a major virulence factor, termed 'macrophage infectivity potentiator protein' (Mip), that is necessary for optimal multiplication of the bacteria within human alveolar macrophages. Mip exhibits peptidyl prolyl cis-trans isomerase (PPIase) activity, which can be inhibited by rapamycin and FK506. It was previously shown that substitutions at the catalytic residues, aspartate-142 position replaced to leucine-142 and tyrosine-185 position replaced to alanine-185 strongly reduces the PPIase activity of Mip proteins. Therefore, we aim to develop an in silico mutagenesis model for both important catalytic residues, validated the stability of the mutated model. Further, we have docked the known inhibitor rapamycin with Lp Mip (native) and mutants (D142L and Y185A) to analyze the conformational and binding mode. Electrostatic contributions and van der Waals interactions are the major driving forces for rapamycin binding and largely responsible for the binding differences between the Lp Mip (native and mutated) proteins.

In silico analysis of conformational changes induced by normal and mutation of macrophage infectivity potentiator catalytic residues and its interactions with Rapamycin

The Legionella pneumophila (Lp), human pathogen causes severe and often fatal Legionnaires' disease, produces a major virulence factor, termed 'macrophage infectivity potentiator protein' (Mip), that is necessary for optimal multiplication of the bacteria within human alveolar macrophages. Mip exhibits peptidyl prolyl cistrans isomerase (PPIase) activity, which can be inhibited by Rapamycin and FK506. Mutation of Mip protein on catalytic residues at Aspartate-142 position replaced to Leucine-142 and Tyrosine-185 position replaced to Alanine-185 that strongly reduces the PPIase activity. Therefore, we aim to develop an in-silico mutagenesis model for both important catalytic residues, validated the stability of the mutated model. Further, we have docked to the known inhibitor rapamycin with Lp Mip (native) and mutants (D142L and Y185A) to analyze the conformational and binding model. For electrostatic contributions and VanderWaals interactions are the major driving force for rapamycin binding and largely responsible for the binding differences between the Lp Mip (native and mutated) proteins.

Inhibition of Orai1-mediated Ca(2+) entry is a key mechanism of the antiproliferative action of sirolimus in human arterial smooth muscle

Sirolimus (rapamycin) is used in drug-eluting stent strategies and proved clearly superior in this application compared with other immunomodulators such as pimecrolimus. The molecular basis of this action of sirolimus in the vascular system is still incompletely understood. Measurements of cell proliferation in human coronary artery smooth muscle cells (hCASM) demonstrated a higher antiproliferative activity of sirolimus compared with pimecrolimus. Although sirolimus lacks inhibitory effects on calcineurin, nuclear factor of activated T-cell activation in hCASM was suppressed to a similar extent by both drugs at 10 μM. Sirolimus, but not pimecrolimus, inhibited agonist-induced and store-operated Ca(2+) entry as well as cAMP response element binding protein (CREB) phosphorylation in human arterial smooth muscle, suggesting the existence of an as-yet unrecognized inhibitory effect of sirolimus on Ca(2+) signaling and Ca(2+)-dependent gene transcription. Electrophysiological experiments revealed that only sirolimus but not pimecrolimus significantly blocked the classical stromal interaction molecule/Orai-mediated, store-operated Ca(2+) current reconstituted in human embryonic kidney cells (HEK293). A link between Orai function and proliferation was confirmed by dominant-negative knockout of Orai in hCASM. Analysis of the effects of sirolimus on cell proliferation and CREB activation in an in vitro model of arterial intervention using human aorta corroborated the ability of sirolimus to suppress stent implantation-induced CREB activation in human arteries. We suggest inhibition of store-operated Ca(2+) entry based on Orai channels and the resulting suppression of Ca(2+) transcription coupling as a key mechanism underlying the antiproliferative activity of sirolimus in human arteries. This mechanism of action is specific for sirolimus and not a general feature of drugs interacting with FK506-binding proteins.

Switchable elastin-like polypeptides that respond to chemical inducers of dimerization

Elastin-like polypeptides (ELPs) are protein polymers that reversibly phase separate in response to increased temperature, pressure, concentration, ionic strength, and molecular weight. If it were possible to engineer their phase separation to respond to specific molecular substrates, ELP fusion proteins might be engineered as biosensors, smart biomaterials, diagnostic imaging agents, and targeted therapies. What has been lacking is a strategy to design ELPs to respond to specific substrates. To address this deficiency, we report that ELP fusion proteins phase separate in response to chemical inducers of dimerization (CID). The rationale is that ELP phase separation depends on molecular weight, concentration, and local hydrophobicity; therefore, processes that affect these properties, including noncovalent dimerization, can be tuned to produce isothermal phase separation. To test this hypothesis, constructs were evaluated consisting of an immunophilin: human FK-506 binding protein 12 (FKBP) attached to an ELP. Under stoichiometric binding of a CID, the fusion protein homodimerizes and triggers phase separation. This dimerization is reversible upon saturation with excess CID or competitive binding of a small lipophilic macrolide to FKBP. By modulating the ELP molecular weight, phase separation was tuned for isothermal response to CID at physiological ionic strength and temperature (37 °C). To interpret the relationship between transition temperature and equilibrium binding constants, an empirical mathematical model was employed. To the best of our knowledge, this report is the first demonstration of reversible ELP switching in response to controlled dimerization. Due to its simplicity, this strategy may be useful to design ELP fusion proteins that respond to specific dimeric biological entities.

Incidence, risk factors, and preventative management of skin cancers in organ transplant recipients: a review of single- and multicenter retrospective studies from 2006 to 2010

BACKGROUND

Organ transplant recipients (OTRs) taking immunosuppressants are at high risk of skin cancer, which is the most common malignant condition in OTRs, so dermatologic surveillance is important for OTRs.

OBJECTIVES

To characterize the most common skin cancers arising from chronic immunosuppression in OTRs.

METHODS

A PubMed search for retrospective single- and multicenter studies reporting skin cancer incidence from 2006 to 2010 was undertaken. Data regarding each study's immunosuppressive regimen, affected skin cancer cohort, and associated risk factors were extracted.

RESULTS

Thirty-six articles that met our inclusion criteria reported incidences of nonmelanoma skin cancer (NMSC), Kaposi's sarcoma, melanoma, and Merkel cell carcinoma. NMSC was the most commonly reported cancer of all skin cancers after transplantation. Common risk factors were sex, age, sunlight exposure, and immunosuppressive agent-related (duration, type).

CONCLUSION

Sun education programs and frequent screenings in organ transplant clinics have provided the best preventative strategies after transplantation, although the characteristics of the immunosuppressive regimen also play an important role. Thus, the adjuvant strategy of modifying immunosuppression may be effective when confronting severe transplant-associated skin cancer. Although the decision-making process for curbing levels of immunosuppression is difficult, further long-term, randomized controlled studies should assess the effect of using less immunosuppressant medication while preserving graft function.

Evolving concepts in the selection of immunosuppression regimen for liver transplant recipients

The introduction of calcineurin inhibitor (CNI) based immunosuppression has revolutionized the field of liver transplantation by dramatically reducing the incidence of acute cellular rejection and prolonging patient and allograft survival. However, the introduction of CNIs has also come at the price of increased patient morbidity, particularly with regard to the well-known nephrotoxic effects of the medications. In an effort to minimize the adverse effects, immunosuppression regimen have evolved to include the use of various induction agents and purine synthesis inhibitors to limit the dose of CNI necessary to achieve low acute cellular rejection rates. Careful assessments of risks and benefits are needed as these newer agents have their own side effect profiles. In addition, the impact of newer immunosuppression regimen on hepatitis C (HCV) recurrence has not been completely elucidated. This review will provide an overview of the most common immunosuppression regimen used in liver transplantation and discuss their impact on acute cellular rejection, patient and allograft survival, and HCV recurrence.

FKBP family proteins as promising new biomarkers for cancer

FK506-binding proteins (FKBPs) belong to the immunophilin family and bind immunosuppressive drugs, such as FK506 and rapamycin. These proteins, through interactions with steroid hormone receptors, kinases, or other cellular factors, play important roles in various physiological processes and, more interestingly, in pathological processes in mammals. Accumulating evidence has implicated some FKBP members in a variety of processes, such as the cell cycle and survival and apoptotic signaling pathways, particularly in cancers. After the deregulation of their expression was observed in cancer tissues, it became increasingly clear that FKBP members played an important role in tumorigenesis and the response to chemotherapies and radiotherapies and that FKBP members could act as oncogenes or tumor suppressors depending on the tissue type. A wealth of data from in vitro and clinical studies is paving the way for novel, promising roles of FKBPs as diagnostic, prognostic or therapy-monitoring cancer biomarkers.

Generation of Epstein-Barr virus-specific cytotoxic T lymphocytes resistant to the immunosuppressive drug tacrolimus (FK506)

Adoptive transfer of autologous Epstein-Barr virus-specific cytotoxic T lymphocytes (EBV-CTLs) to solid organ transplant (SOT) recipients has been shown safe and effective for the treatment of EBV-associated posttransplantation lymphoproliferative disorders (PTLDs). SOT recipients, however, require the continuous administration of immunosuppressive drugs to prevent graft rejection, and these agents may significantly limit the long-term persistence of transferred EBV-CTLs, precluding their use as prophylaxis. Tacrolimus (FK506) is one of the most widely used immunosuppressive agents in SOT recipients, and its immunosuppressive effects are largely dependent on its interaction with the 12-kDa FK506-binding protein (FKBP12). We have knocked down the expression of FKBP12 in EBV-CTLs using a specific small interfering RNA (siRNA) stably expressed from a retroviral vector and found that FKBP12-silenced EBV-CTLs are FK506 resistant. These cells continue to expand in the presence of the drug without measurable impairment of their antigen specificity or cytotoxic activity. We confirmed their FK506 resistance and anti-PTLD activity in vivo using a xenogenic mouse model, suggesting that the proposed strategy may be of value to enhance EBV-specific immune surveillance in patients at high risk of PTLD after transplantation.

A comprehensive review of immunosuppression used for liver transplantation

Since liver transplantation was approved for the treatment of end stage liver disease, calcineurin inhibitors (CNI's) have played a critical role in the preservation of allograft function. Unfortunately, these medications cause a variety of Side effects such as diabetes, hypertension and nephrotoxicity which in turn result in significant morbidity and reduced quality of life. A variety of newer immunosuppressants have been evaluated over the last decade in an attempt to either substitute for CNI's or use with reduced dose CNI's while still preserving allograft function However, current data does not recommend complete cessation of CNI's due to unacceptably high rates of allograft rejection. As these medications have their own unique adverse effects, a careful assessment on their risks and benefits is essential, particularly when additive or synergistic effects with CNI's may occur. Furthermore, the impact of these newer medications on the risk of hepatitis C recurrence and progression remains to be elucidated. Controlled trials are urgently required to assist transplant physicians with choosing the optimum immunosuppressive regimen for their patients. This review will discuss commonly used immunosuppressants prescribed in liver transplantation, emerging therapties and where appropriate, the impact of these medications on the recurrence of hepatitis C after liver transplantation.

Immunosuppression in liver transplantation: beyond calcineurin inhibitors

Although calcineurin inhibitors (CNIs) remain the mainstay of immunosuppression in liver transplantation (LTX), their long-term toxicity significantly contributes to morbidity and mortality. The elucidation of mechanisms of alloimmunity and leukocyte migration have provided novel targets for immunosuppression development. The toxicities of these agents differ from that of the CNI and act additively or synergistically. CNI avoidance protocols in LTX have not been achieved routinely; however, pilot trials have begun to delineate the limitations and promises of such approaches. CNI-sparing protocols appear to be much more promising in balancing the early need for minimizing rejection while tapering doses and minimizing long-term toxicity.

Interleukin 6 and interferon-gamma gene expression in lung transplant recipients with refractory acute cellular rejection: implications for monitoring and inhibition by treatment with aerosolized cyclosporine

BACKGROUND

The purpose of this study was to correlate cytokine gene expression from bronchoalveolar lavage (BAL) cells and peripheral blood lymphocytes (PBL) with graft histology in recipients with persistent acute rejection treated with aerosolized cyclosporine (ACsA).

METHODS

We measured mRNA for interleukin (IL) 6, interferon (IFN)-gamma, and IL-10 in recipients (1) without rejection (n=13), (2) with acute rejection that responded to pulsed methylprednisolone (n=7), and (3) with "refractory" acute rejection that failed to respond to conventional immunosuppression (n=17). In the latter group, ACsA was initiated.

RESULTS

BAL cell IL-6 and IFN-gamma were highest in recipients with refractory rejection compared with recipients with steroid-responsive rejection and recipients with no rejection. Improvement in rejection histology occurred in 15 of 17 recipients who were treated with ACsA. IL-6 and IFN-gamma mRNA levels from BAL cells decreased during treatment with ACsA (median IL-6:actin ratio: before treatment, 0.40 vs. after treatment, 0.003, P=0.001; IFN-gamma:actin ratio: before treatment, 0.32 vs. after treatment, 0.04, P=0.001). PBL IL-6 and IFN-gamma mRNA expression also decreased during ACsA treatment after 180 days. Expression of IL-10 mRNA from BAL and PBL did not change during ACsA treatment (0.0 vs. 0.03 and 0.0 vs. 0.02, respectively).

CONCLUSIONS

IL-6 and IFN-gamma mRNA expression from BAL cells was highest in those recipients with refractory histologic acute rejection. ACsA was associated with decreased IFN-gamma and IL-6 gene expression in BAL cells and PBL.

Mycophenolate mofetil. A review of its pharmacodynamic and pharmacokinetic properties and clinical efficacy in renal transplantation

Mycophenolate mofetil is an ester prodrug of the active immunosuppressant mycophenolic acid. It is a noncompetitive, selective and reversible inhibitor of inosine monophosphate dehydrogenase, an important enzyme in the de novo synthesis of guanosine nucleotides in T and B lymphocytes. Mycophenolate mofetil and/or mycophenolic acid inhibit the proliferation of lymphocytes and the production of antibodies induced by a variety of mitogens and antigens. Mycophenolate mofetil is also active in several animal models of transplantation and has produced effects in animals that indicate that it may inhibit the chronic rejection process. Mycophenolate mofetil has been compared with azathioprine or placebo in 3 large, randomised, double-blind, multicentre trials as part of combination immunosuppression therapy with cyclosporin and corticosteroids. Compared with either placebo or azathioprine (1 to 2 mg/kg/day or 100 to 150 mg/day), mycophenolate mofetil 2 or 3 g/day was associated with a significantly lower proportion of patients experiencing acute rejection or treatment failure during the first 6 months after transplantation. Mycophenolate mofetil also tended to be associated with a lower proportion of patients who required a full course of antirejection therapy. However, the proportion of patients who died or who had graft loss was similar between all of the treatment groups. There are currently no data regarding the effects of mycophenolate mofetil on long term patient or graft survival, which are important clinical outcomes in assessing its place in the management of renal transplantation. Clinical trials are also needed to evaluate mycophenolate mofetil in specific patient populations (e.g. repeat renal transplant patients or highly sensitised patients), to determine its efficacy in alternative immunosuppressive protocols and to investigate its use in the transplantation of other solid organs. In summary, mycophenolate mofetil appears to be an attractive new agent in the prevention of graft rejection in renal transplant recipients that has shown superior efficacy to azathioprine. Although long term clinical outcome data are required, mycophenolate is a potentially important advance in transplant immunosuppression.