Immunosuppressed Organ Transplant Patients Research Articles

BK Polyomavirus Activates the DNA Damage Response To Prolong S Phase.

BK polyomavirus (PyV) is a major source of kidney failure in transplant recipients. The standard treatment for patients with lytic BKPyV infection is to reduce immunosuppressive therapy, which increases the risk of graft rejection. PyVs are DNA viruses that rely upon host replication proteins for viral genome replication. A hallmark of PyV infection is activation of the DNA damage response (DDR) to prevent severe host and viral DNA damage that impairs viral production by an unknown mechanism. Therefore, we sought to better understand why BKPyV activates the DDR through the ATR and ATM pathways and how this prevents DNA damage and leads to increased viral production. When ATR was inhibited in BKPyV-infected primary kidney cells, severe DNA damage occurred due to premature Cdk1 activation, which resulted in mitosis of cells that were actively replicating host DNA in S phase. Conversely, ATM was required for efficient entry into S phase and to prevent normal mitotic entry after G2 phase. The synergistic activation of these DDR kinases promoted and maintained BKPyV-mediated S phase to enhance viral production. In contrast to BKPyV infection, DDR inhibition did not disrupt cell cycle control in uninfected cells. This suggests that DDR inhibitors may be used to specifically target BKPyV-infected cells.IMPORTANCE BK polyomavirus (BKPyV) is an emerging pathogen that reactivates in immunosuppressed organ transplant patients. We wanted to understand why BKPyV-induced activation of the DNA damage response (DDR) enhances viral titers and prevents host DNA damage. Here, we show that the virus activates the DNA damage response in order to keep the infected cells in S phase to replicate the viral DNA. The source of DNA damage was due to actively replicating cells with uncondensed chromosomes entering directly into mitosis when the DDR was inhibited in BKPyV-infected cells. This study clarifies the previously enigmatic role of the DDR during BKPyV infection by demonstrating that the virus activates the DDR to maintain the cells in S phase in order to promote viral replication and that disruption of this cell cycle arrest can lead to catastrophic DNA damage for the host.

Differentially Methylated Regions in T Cells Identify Kidney Transplant Patients at Risk for De Novo Skin Cancer

Cutaneous squamous cell carcinoma (cSCC) occurs 65–200 times more in immunosuppressed organ transplant patients than in the general population. T cells, which are targeted by the given immunosuppressive drugs, are involved in anti-tumor immune surveillance and are functionally regulated by DNA methylation. Prior to kidney transplantation, we aim to discover differentially methylated regions (DMRs) in T cells involved in de novo post-transplant cSCC development. We matched 27 kidney transplant patients with a future de novo cSCC after transplantation to 27 kidney transplant patients without cSCC and studied genome-wide DNA methylation of T cells prior to transplantation. From 11 out of the 27 cSCC patients, the DNA methylation of T cells after transplantation was also examined to assess stability of the observed differences in DNA methylation. Raw methylation values obtained with the 450k array were confirmed with pyrosequencing. We found 16 DMRs between patients with a future cSCC and those who do not develop this complication after transplantation. The majority of the DMRs were located in regulatory genomic regions such as flanking bivalent transcription start sites and bivalent enhancer regions, and most of the DMRs contained CpG islands. Examples of genes annotated to the DMRs are ZNF577, coding for a zinc-finger protein, and FLOT1, coding for a protein involved in T cell migration. The longitudinal analysis revealed that DNA methylation of 9 DMRs changed significantly after transplantation. DNA methylation of 5 out of 16 DMRs was relatively stable, with a variation in beta-value lower than 0.05 for at least 50% of the CpG sites within that region. This is the first study demonstrating that DNA methylation of T cells from patients with a future de novo post-transplant cSCC is different from patients without cSCC. These results were obtained before transplantation, a clinically relevant time point for cSCC risk assessment. Several DNA methylation profiles remained relatively stable after transplantation, concluding that these are minimally affected by the transplantation and possibly have a lasting effect on post-transplant cSCC development.

Differentially methylated regions in T cells identify kidney transplant patients at risk for de novo skin cancer

BackgroundCutaneous squamous cell carcinoma (cSCC) occurs 65–200 times more in immunosuppressed organ transplant patients than in the general population. T cells, which are targeted by the given immunosuppressive drugs, are involved in anti-tumor immune surveillance and are functionally regulated by DNA methylation. Prior to kidney transplantation, we aim to discover differentially methylated regions (DMRs) in T cells involved in de novo post-transplant cSCC development.MethodsWe matched 27 kidney transplant patients with a future de novo cSCC after transplantation to 27 kidney transplant patients without cSCC and studied genome-wide DNA methylation of T cells prior to transplantation. From 11 out of the 27 cSCC patients, the DNA methylation of T cells after transplantation was also examined to assess stability of the observed differences in DNA methylation. Raw methylation values obtained with the 450k array were confirmed with pyrosequencing.ResultsWe found 16 DMRs between patients with a future cSCC and those who do not develop this complication after transplantation. The majority of the DMRs were located in regulatory genomic regions such as flanking bivalent transcription start sites and bivalent enhancer regions, and most of the DMRs contained CpG islands. Examples of genes annotated to the DMRs are ZNF577, coding for a zinc-finger protein, and FLOT1, coding for a protein involved in T cell migration. The longitudinal analysis revealed that DNA methylation of 9 DMRs changed significantly after transplantation. DNA methylation of 5 out of 16 DMRs was relatively stable, with a variation in beta-value lower than 0.05 for at least 50% of the CpG sites within that region.ConclusionsThis is the first study demonstrating that DNA methylation of T cells from patients with a future de novo post-transplant cSCC is different from patients without cSCC. These results were obtained before transplantation, a clinically relevant time point for cSCC risk assessment. Several DNA methylation profiles remained relatively stable after transplantation, concluding that these are minimally affected by the transplantation and possibly have a lasting effect on post-transplant cSCC development.

Ridge augmentation in an organ transplant patient

With the continuing progress in medicine, the number of successful organ transplantations has continued to increase, a fact that also concerns dentists and implantologists. Implantology after organ transplantation remains controversial due to the patient's immunocompromised situation and the corresponding risk of infection. Only a few studies on this topic have been reported, with all of them showing the dental implant success rates in transplant patients to be similar to those in healthy subjects. However, immunosuppression has been identified as a contraindication to bone augmentation. Consequently, there is still a lack of knowledge regarding pre-implantology bone grafting procedures. The following case report describes the use of ridge augmentation and extended bilateral sinus lift procedures in a liver transplant patient. The patient was treated with an implant-supported fixed prosthesis in the upper jaw and was followed up for a total of 28 months after implant insertion. According to the findings presented, pre-implantology augmentation procedures may be performed successfully in immunosuppressed organ transplant patients. Stable peri-implant conditions were shown over a period of more than 2 years. Nevertheless, further investigations are needed to define a safe treatment protocol for these high-risk patients.

Hepatitis e Vaccine: Current Status and Future Prospects

HEV, a positive ssRNA and nonenveloped virus, is endemic in many developing countries and one of the most frequent causes of acute hepatitis after fecal–oral transmission. Pregnant women are at particular risk for a fatal course of disease, including maternal and fetal mortality. Recent reports indicate that HEV genotype 3, possibly related to zoonotic transmission, may cause chronic hepatitis in some immunosuppressed organ transplant patients. Various approaches have been conducted to develop HEV vaccines, but only one candidate, a recombinant HEV (rHEV) vaccine generated from Spodoptera frugiperda-9 cells by baculoviruses expressing the HEV capsid antigen, has reached clinical Phase I and II trials so far. These trials suggest that the rHEV vaccine is safe and can prevent clinically overt acute hepatitis E in high-risk populations. We herein review the different approaches in HEV-vaccine development and critically discuss the current status and future directions of the rHEV vaccine used in clinical trials.

The Control of Anti-Donor Immune Responses by Regulatory T Cells in Organ Transplant Patients

The role of regulatory T cells in the induction and maintenance of transplant tolerance has been widely investigated in experimental animal models. Their involvement in the regulation of allogeneic immune reactivity in immunosuppressed organ transplant patients, however, remains unclear. Measurements of regulatory T cells after clinical organ transplantation may contribute to understanding their role in anti-donor immune responses. Several studies have investigated the frequency and/or immune regulatory function of peripheral regulatory T-cell populations, such as, the CD4 +CD25 + regulatory T cells or the CD8 +CD28 − suppressor T cells, in clinically stable organ transplant patients and patients with acute or chronic rejection. This review summarizes these studies and discusses the correlations found between the number and function of regulatory T cells and the immunological state of the patient. This knowledge is warranted for a better understanding of the control of allogeneic immune responses by regulatory T cells. Subsequently, monitoring regulatory T cells may help us to identify patients in whom the anti-donor reactivity is actively suppressed.

Linezolid-Related Pancytopenia in Organ-Transplant Patients: Report of Two Cases

Linezolid is a recent oral antibiotic used in drug-resistant Gram-positive cocci infection. We herein report on the first two cases of linezolid-related pancytopenia in organ-transplant patients. Both patients had methicillineresistant Staphylococcus aureus infections. Pancytopenia, i.e. aregenerative anemia, neutropenia and thrombopenia, developed 3 weeks and 5 weeks after initiating linezolid therapy at a conventional dosage (600 mg bid). There were no other confounding causes of pancytopenia, which resolved promptly after withdrawing linezolid. Because of the potential hazards of pancytopenia in immunosuppressed organ-transplant patients, we advocate the cautious use of linezolid for transplant patients.

Prevalence of human papillomavirus in skin tumors from repair deficient xeroderma pigmentosum patients

The predisposition to skin cancers in childhood is the hallmark of xeroderma pigmentosum (XP), a rare autosomal recessive disorder, deficient in DNA repair and hypersensitive to ultraviolet irradiation. Human papillomavirus (HPVs), are common infections of the skin which are often found associated to benign lesions and non-melanoma skin cancers (NMSC), mainly squamous cell carcinomas (SCC) and basal cell carcinomas (BCC). Our study is the first to analyse 40 SCCs, 27 BCCs and nine normal skin biopsies from XP patients for HPV DNA which are found more frequently in SCCs (20/40) than in BCCs (4/27) or normal skin (2/9). The HPV spectrum includes 22 different epidermodysplasia verruciformis (EV) HPV types, which predominate in SCCs (48%) compared to BCCs (15%) and normal skin (22%). Our data, showing an association between EV HPV and SCCs from young XP patients is comparable to that found for NMSC from adult immunosuppressed organ transplant patients and raises the question of the importance of HPV infection in skin carcinogenesis.

High Prevalence of Cutaneous Human Papillomavirus DNA on the Top of Skin Tumors but not in “Stripped” Biopsies from the Same Tumors

Genomes of human papillomaviruses (HPV) are common in biopsies from non-melanoma skin cancers but are also found on healthy skin and it is possible that HPV positivity in tumor biopsies by PCR may merely reflect contamination of the lesion surface. To investigate this issue, 229 immunocompetent patients were tested for HPV DNA in swab samples collected on top of skin tumors and in biopsies of the same tumors, obtained after stripping with tape to remove superficial layers. HPV DNA was detected on top of 69% (159 of 229) of the lesions, and in 12% (28 of 229) of the stripped biopsies (p<0.001). The difference was seen for all four types of tumors studied. Seborrheic keratosis had 79% (34 of 43) HPV positivity on top of lesions versus 19% (eight of 43) in biopsies; actinic keratosis had 83% (38 of 46) HPV positivity on top versus 11% (five of 46) in biopsies; basal cell carcinoma had 63% (69 of 109) on top versus 8% (nine of 109) in biopsies and squamous cell carcinoma had 58% (18 of 31) on top versus 19% (six of 31) in biopsies. HPV DNA is common in superficial layers of lesions, but is not necessarily present throughout tumors.

Emerging role of γδ T-cells in health and disease

The majority of T lymphocytes in the peripheral blood bear the αβ type of T-cell receptor (TCR) and less than 5% of circulating T lymphocytes bear the γδ type of TCR. The αβ and γδ T-cells contribute differently to the host immune defense. The immunologic function of γδ T-cell in humans is gradually unraveling. Pathologic studies have shown a relatively high proportion of γδ T-cells in the gastrointestinal mucosa, skin, and splenic red pulp where they appear to have an important immunologic function against pathogens attempting to enter body through the mucosal surfaces and possibly the skin. More data are emerging about the role of γδ T-cells in the course of infectious diseases and in the pathogenesis of autoimmunity. The possible role of these cells in immunologic surveillance against cancer has been inferred from their preferential expansion in certain malignancies. In parallel to the low frequency of these cells in normal lymphocytes, lymphomas bearing γδ type of T-cell receptors on cell surface are rare. These include hepatosplenic and non-hepatosplenic (including those involving the skin and those involving nasal cavity and upper aero digestive tract) and the rare non-B-cell cases of lymphomas seen in the immunosuppressed organ transplant patients. The limited available clinical data about γδ T-cell lymphomas suggest that these lymphomas tend to have an aggressive course particularly the hepatosplenic form with poor response to multi-agent chemotherapy and short median survival.

The diagnostic value of high resolution ultrasound in non-melanoma skin cancer

The predisposition to skin cancers in childhood is the hallmark of xeroderma pigmentosum (XP), a rare autosomal recessive disorder, deficient in DNA repair and hypersensitive to ultraviolet irradiation. Human papillomavirus (HPVs), are common infections of the skin which are often found associated to benign lesions and non-melanoma skin cancers (NMSC), mainly squamous cell carcinomas (SCC) and basal cell carcinomas (BCC). Our study is the first to analyse 40 SCCs, 27 BCCs and nine normal skin biopsies from XP patients for HPV DNA which are found more frequently in SCCs (20/40) than in BCCs (4/27) or normal skin (2/9). The HPV spectrum includes 22 different epidermodysplasia verruciformis (EV) HPV types, which predominate in SCCs (48%) compared to BCCs (15%) and normal skin (22%). Our data, showing an association between EV HPV and SCCs from young XP patients is comparable to that found for NMSC from adult immunosuppressed organ transplant patients and raises the question of the importance of HPV infection in skin carcinogenesis.

Detection of human herpesvirus-8 DNA in Kaposi’s sarcomas from iatrogenically immunosuppressed patients

Background: Kaposi’s sarcoma (KS) accounts for more than 5% of malignancies in immunosuppressed organ transplant patients (OKS). A new herpesvirus (HHV-8) was identified with high prevalence in biopsy specimens of AIDS-KS, endemic KS, and classic KS and in OKS. KS has also been associated with other underlying diseases in patients treated with corticosteroids, but this subset of KS has been reported to contain HHV-8 in only a few case reports. Objective: In this larger study, we determined the prevalence of HHV-8 in seven patients of Jewish origin in whom KS developed during immunosuppressive therapy for different primary diseases (ISKS). Methods: The study included HHV-8 DNA detection by polymerase chain reaction (PCR) coupled with Southern blot and sequence analysis as well as by in situ hybridization. Results: HHV-8 sequences were detected by PCR with confirmation by Southern blot and sequence analysis in 100% of the ISKS samples. Direct sequencing revealed several previously unknown base changes within the 208 bp region from open reading frame 26 (ORF26 208 ) of HHV-8 in ISKS. Conclusion: Ours is the largest known study describing the presence of HHV-8 in iatrogenic KS from immunosuppressed nontransplant patients and provides data of previously unknown sequence variations within the ORF26 of HHV-8 DNA. (J Am Acad Dermatol 1998;38:429-37.)

Maturation of antibody avidity after primary human cytomegalovirus infection is delayed in immunosuppressed solid organ transplant patients.

An IgG antibody avidity assay which uses urea to modify a commercial enzyme-linked immunosorbent assay (ELISA) has been investigated for its ability to distinguish primary human cytomegalovirus (CMV) from recurrent or long-term infection. Twenty-four immunosuppressed solid organ transplant patients were studied. The avidity indices for IgG to CMV were low for 12 out of 13 patients with primary infection (mean 18%), high for all 11 patients with long-term infection (mean 85%), and the 1 patient with primary infection showing an intermediate avidity index (51%) was found to have acquired passively large amounts of CMV immunoglobulin, presumably of high avidity, during therapy. From the results, low and high avidity indices were defined as lying between 0-34% and 60-100%, respectively, and it was thus clear that the avidity assay can discriminate between primary and recurrent or long-term CMV infection. The avidity indices of eight of the immunosuppressed organ transplant patients with primary infection were followed in serial serum samples over time and IgG antibody to CMV was found to take at least a year to mature to high avidity in contrast to the 2-6 months expected for normal subjects. This finding provides evidence that immunosuppression has subtle, hitherto unsuspected, effects on humoral immunity to CMV in addition to the well-known depression of cell-mediated responses. It is concluded that this reliable avidity assay will be of importance in the diagnosis of CMV infection and in elucidating the pathogenesis of CMV-induced disease in organ transplant recipients.