1Division of Hematology, Department of Internal Medicine, Catholic Blood and Marrow Transplantation Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
2Division of Infectious diseases, Department of Internal Medicine, Catholic Blood and Marrow Transplantation Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
3Cancer Research Institute, The Catholic University of Korea, Seoul, Korea.
The expression of the
Using quantitative RT-PCR of mononuclear cells, we conducted pairwise comparison of
Compared to that in the healthy donor group,
We report differential expression of SOCS genes according to CMV viremia with acute GVHD occurrence after HSCT, suggesting that regulation of
Many patients acquire cytomegalovirus (CMV) viremia after allogeneic hematopoietic stem cell transplantation (HSCT). This sometimes results in overt CMV disease or fatal outcomes despite pre-emptive treatment. Human CMV is a ubiquitous human herpes virus associated with subclinical primary infections followed by life-long asymptomatic carriage, during which the innate and adaptive immune systems act together to control the virus . However, CMV diseases associated with severe symptoms are easily provoked in immune-suppressed patients like allogeneic HSCT recipients . Immune-suppression can lead to viremia of latent CMV in HSCT recipients, which may progress to overt CMV disease . CMV is closely associated with the immune response as well as with inflammatory factors; CMV viremia is also related to an enhanced secretion of cytokines that can render a patient unable to defend himself against pathogens. This pathway is tightly regulated to prevent excessive inflammatory damage in the host [4, 5].
Suppressors of cytokine signaling (SOCS) proteins are inhibitors of cytokine signaling pathways and key physiological regulators of both innate and adaptive immunity . In addition to regulating the activity of immune cells such as macrophages and dendritic cells, SOCS proteins are also essential for B- and T-cell development and differentiation. The SOCS and cytokine-inducible SRC homology 2 (SH2) protein (CIS) family is comprised of eight members (CIS and SOCS1-SOCS7). All family members have a central SH2 domain, an N-terminal domain of variable length and sequence, and a C-terminal 40-amino acid module called the SOCS box . In particular, the roles of SOCS1 and SOCS3 in toll-like receptor (TLR) responses, which recognize the CMV virus, have been extensively investigated [4, 6].
Recent studies have shown that
Therefore, we investigated the expression of
All experiments were performed with authorization of the Institutional Review Board (IRB) for Human Research at the Catholic University of Korea. Study patients were the recipients of allogeneic SCT that were initially diagnosed with one of the hematologic diseases designated by the World Health Organization (WHO). Heparinized blood samples were collected from the recipients at a time of high CMV DNAemia for those diagnosed with CMV viremia (CMV+ group) and at any time after transplantation for those without CMV viremia (CMV- group). In addition, blood samples were collected from the recipients before conditioning (pre-HSCT group) and healthy donors (healthy donor group) before harvesting hematopoietic stem cells.
Mononuclear cells were isolated by overlaying the heparinized blood samples on a Ficoll-Hypaque gradient (density, 1.077; Lymphoprep; Gibco-BRL, Carlsbad, CA, USA), followed by centrifugation at 400×g for 30 minutes. The buffy coats were harvested and washed twice with phosphate-buffered saline (pH 7.4).
We defined patients as positive for CMV viremia if they had a CMV DNA load ≥ 500 copies/mL, which is the lowest detectable level. Acute graft-versus-host disease (aGVHD) was assessed according to previously published criteria [14, 15] and patients with aGVHD grades II-IV were regarded as positive for aGVHD occurrence.
Previously, we demonstrated that
For the prophylaxis of CMV, acyclovir (10 mg/kg three times a day) was intravenously administered from the conditioning until neutrophil engraftment. Recipients were monitored for CMV DNA load twice a week using quantitative reverse-transcription PCR (qRT-PCR) using a LightCycler 2.0 Real-Time PCR system (Roche Diagnostics, Mannheim, Germany) from neutrophil engraftment to hospital discharge. Thereafter, they were monitored weekly to biweekly until the cessation of immunosuppressive agents. For CMV positive patients, we conducted a risk-adapted pre-emptive therapy to prevent CMV disease according to the treatment protocol of our institution .
In the present study, we performed qRT-PCR on the blood samples from all recipients and donors as described previously because no data were available regarding the reference levels of
All results are presented as the mean ± SE. Statistical analyses were performed with the Mann-Whitney
Blood samples from 107 recipients with acute myeloid leukemia (N=58), acute lymphoblastic leukemia (N=20), myelodysplastic syndrome (N=12), chronic myelogenous leukemia (N=4), severe aplastic anemia (N=9), and other hematologic diseases (N=4) were collected between 2009 and 2011. Recipients received allogeneic HSCT from HLA-matched siblings (N=51) and unrelated donors (N=56). They received myeloablative conditioning (N=71) and reduced-intensity conditioning (N=36) before allogeneic HSCT. Of them, 61 (57.0%) recipients had CMV viremia at blood sampling. The median CMV DNA load of the CMV+ group was 9,250 copies/mL (range, 675-2,144,711). An additional 17 and 55 blood samples were obtained from the recipients and healthy donors, respectively. Forty recipients (65.8%) with CMV viremia and 29 (63.0%) without CMV viremia were diagnosed with aGVHD. Other baseline and transplant-related clinical characteristics of recipients and donors enrolled in this study are summarized in Table 2.
The level of
Although the results of our study are based on data collected from patients treated using our institution's own approach for various hematologic malignancies, this trial has several limitations: small sample size and restriction on aGVHD. However, as a pilot study in an understudied field, we showed that the
Although many specific prophylactic or pre-emptive anti-viral therapies have been widely used , an optimal treatment for CMV diseases remains to be established. In particular, understanding the relationship between the immune network and CMV infection is an emerging challenge to the development of treatment methods for CMV diseases with promising immunotherapies [23, 24]. We herein showed that the
A previous report showed differential expression of
The SOCS family of proteins contains eight members, called SOCS1-7 and CIS, which are similar in their structure and function via the Janus kinase (JAK)/STAT pathway . Their negative feedback and signaling cascade functions use many different mechanisms, depending on the cell line studied. Therefore, cytokine induction by SOCS members tends to vary in different conditions . Of note, SOCS molecules may interact with other SOCS members to counter-regulate their function; thus, exploration of this cross-modulation is needed to understand the biology of CMV infection in allogeneic HSCT. Therefore, further investigations should be conducted to reveal the function of other SOCS members, including SOCS4, 5, 6, and 7, in the occurrence of CMV infection and GVHD in allogeneic HSCT. Taken together, our preliminary results provide a new platform for studying the association between CMV immunobiology and
We showed that SOCS genes were differentially expressed in human CMV viremia with acute GVHD occurrence after allogeneic HSCT, suggesting the possibility of modulation of