Patterns of C-reactive protein release following allogeneic stem cell transplantation are correlated with leukemic relapse

Connecting secretome to hematopoietic stem cell phenotype shifts in an engineered bone marrow niche

Hematopoietic stem cells (HSCs) primarily reside in the bone marrow, where they receive external cues from their local microenvironment. The complex milieu of biophysical cues, cellular components and cell-secreted factors regulates the process by which HSC produce the blood and immune system. We previously showed direct coculture of primary murine hematopoietic stem and progenitor cells with a population of marrow-derived mesenchymal stromal and progenitor cells (MSPCs) in a methacrylamide-functionalized gelatin (GelMA) hydrogel improves hematopoietic progenitor maintenance. However, the mechanism by which MSPCs influenced HSC fate decisions remained unknown. Herein, we report the use of proteomic analysis to correlate HSC phenotype to a broad candidate pool of 200 soluble factors produced by combined mesenchymal and hematopoietic progeny. Partial least squares regression (PLSR), along with an iterative filter method, identified TGFβ-1, MMP-3, c-RP and TROY as positively correlated with HSC maintenance. Experimentally, we then observe exogenous stimulation of HSC monocultures in GelMA hydrogels with these combined cytokines increases the ratio of hematopoietic progenitors to committed progeny after a 7-day culture 7.52 ± 3.65-fold compared to non-stimulated monocultures. Findings suggest a cocktail of the downselected cytokines amplifies hematopoietic maintenance potential of HSCs beyond that of MSPC-secreted factors alone. This work integrates empirical and computation methods to identify cytokine combinations to improve HSC maintenance within an engineered HSC niche, suggesting a route toward identifying feeder-free culture platforms for HSC expansion. Insight Hematopoietic stem cells within an artificial niche receive maintenance cues in the form of soluble factors from hematopoietic and mesenchymal progeny. Applying a proteomic regression analysis, we identify a reduced set of soluble factors correlated to maintenance of a hematopoietic phenotype during culture in a biomaterial model of the bone marrow niche. We identify a minimum factor cocktail that promotes hematopoietic maintenance potential in a gelatin-based culture, regardless of the presence of mesenchymal feeder cells. By combining empirical and computational methods, we report an experimentally feasible number of factors from a large dataset, enabling exogenous integration of soluble factors into an engineered hematopoietic stem cell for enhanced maintenance potential of a quiescent stem cell population.

Associations between febrile neutropenia-related parameters and the risk of acute GVHD or non-relapse mortality after allogeneic hematopoietic stem cell transplantation

Infection and inflammation can induce acute graft-vs.-host disease (aGVHD). We hypothesized that febrile neutropenia early after allogeneic hematopoietic cell transplantation (HCT) would increase the risk of aGVHD and non-relapse mortality (NRM). We retrospectively evaluated the impact of fever, C-reactive protein (CRP) concentration and blood stream infection (BSI) early after HCT on the incidence of grade II-IV aGVHD and NRM in 227 patients. Within 7 days after HCT, 91 (40.1%) patients experienced fever for at least 2 days (early-FN group). BSI occurred in 27 (11.9%) patients and the maximum CRP concentration was 2.57 mg/dl in the median. In a multivariate analysis, early-FN (hazard ratio (HR) 1.81, P = 0.007) and older recipient age (HR 1.68, P = 0.019) were significantly associated with the incidence of grade II-IV aGVHD. High-CRP and BSI were not significant risk factors for grade II-IV aGVHD. On the other hand, high-CRP was significantly associated with the incidence of NRM (HR 2.67, P = 0.004) in a multivariate analysis. In conclusion, although fever, CRP elevation and BSI are considered to be closely related events, they had different effects on the incidence of aGVHD and NRM. The development of early-FN after HCT may predict the risk of aGVHD.

C-reactive protein (CRP) but not the related pentraxins serum amyloid P and PTX3 inhibits the proliferation and induces apoptosis of the leukemia cell line Mono Mac 6

Background

Pentraxins are a family of highly conserved secreted proteins that regulate the innate immune system, including monocytes and macrophages. C-reactive protein (CRP) is a plasma protein whose levels can rise to 1000 μg/ml from the normal <3 μg/ ml during inflammation.

Results

We find that CRP inhibits proliferation of the human myeloid leukemia cell line Mono Mac 6 with an IC50 of 75 μg/ ml by inducing apoptosis of these cells. The related proteins serum amyloid P (SAP) and pentraxin 3 (PTX3) do not inhibit Mono Mac 6 proliferation. CRP has no significant effect on the proliferation of other leukemia cell lines such as HL-60, Mono Mac 1, K562, U937, or THP-1, or the survival of normal peripheral blood cells. The effect of CRP appears to be dependent on the CRP receptor FcγRI, and is negatively regulated by a phosphatidylinositol −3-kinase pathway.

Conclusion

These data reveal differential signaling by pentraxins on immune cells, and suggest that CRP can regulate the proliferation of some myeloid leukemia cells.

Programmed Death 1 Expression on CD4+ T Cells Predicts Mortality after Allogeneic Stem Cell Transplantation

Excessive or persistent programmed death 1 (PD-1) expression on virus- or tumor-specific T cells during chronic viral infection or malignancy has been associated with impaired immune control. To assess the role of the PD-1 pathway in allogeneic stem cell transplantation (SCT), we examined PD-1 expression and maturation phenotype on T cells from 42 patients early (day 55 to 85) after cord blood (CB), matched unrelated donor, and matched related donor transplantation. Expression of PD-1 on CD4⁺ T cells was significantly elevated in all transplantation types, with the highest level observed in CB subjects. Elevated PD-1 expression on CD4⁺ T cells early after transplantation was observed in nonsurvivors (median, 40.2%; range, 15.1 to 86.1) compared with survivors (median, 23.6%; range, 8.4 to 55.2; P = .001), indicating its association with increased risk for mortality, especially with CB transplantations, where PD-1 was increased in nonsurvivors (median, 64.6%; range, 36.5 to 86.1) compared with survivors (median, 34.1%; range, 15.9 to 55.2; P = .01). Furthermore, T cell subset analysis revealed that PD-1 expression was further elevated on CD4⁺ T central memory in nonsurvivors (median, 49.8%; range, 15.1 to 83.4) compared with survivors (median, 24.8%; range, 8.9 to 71.3; P = .002) and on T effector memory cells in nonsurvivors (median, 69.1%; range, 24.7 to 92.6) compared with survivors (median, 43.7%; range, 13.9 to 96.5; P = .0003). Our findings suggest that elevation of PD-1 expression on CD4⁺ T cells is associated with mortality in CB and possibly all SCT recipients.

Possible implication of bacterial infection in acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

Graft-versus-host disease (GVHD) is still one of the major causes of morbidity and mortality in allogeneic hematopoietic stem cell transplantation (HSCT). In the pathogenesis of acute GVHD, it has been established that donor-derived T-cells activated in the recipient play a major role in GVHD in initiation and maintenance within an inflammatory cascade. To reduce the risk of GVHD, intensification of GVHD prophylaxis like T-cell depletion is effective, but it inevitably increases the risk of infectious diseases and abrogates beneficial graft-versus-leukemia effects. Although various cytokines are considered to play an important role in the pathogenesis of GVHD, GVHD initiation is such a complex process that cannot be prevented by means of single inflammatory cytokine inhibition. Thus, efficient methods to control the whole inflammatory milieu both on cellular and humoral view are needed. In this context, infectious diseases can theoretically contribute to an elevation of inflammatory cytokines after allogeneic HSCT and activation of various subtypes of immune effector cells, which might in summary lead to an aggravation of acute GVHD. The appropriate treatments or prophylaxis of bacterial infection during the early phase after allogeneic HSCT might be beneficial to reduce not only infectious-related but also GVHD-related mortality. Here, we aim to review the literature addressing the interactions of bacterial infections and GVHD after allogeneic HSCT.

Inflammatory markers in patients after hematopoietic stem cell transplantation

Infections are one of the most common complications after hematopoietic stem cell transplantation (HSCT). Diagnosis is established by analysis of clinical symptoms and results of diagnostic tests such as biochemical panels, microbiological cultures, and visual diagnostics. As the microbiological cultures yield positive results in only some patients and visual diagnostics might miss the infectious source, the diagnosis and proper treatment often depends on clinical assessment supported by laboratory test results. The most commonly used makers of inflammation include C-reactive protein and procalcitonin. However, these tests have serious limitations when used in patients after HSCT. The drugs used in conditioning, neutropenia, and graft-versus-host disease might influence the results of the tests and misguide the physician. In this review, we summarize the current knowledge on profiles of expression of basic markers of inflammation used in clinical practice in patients after HSCT.

The influence of pretransplantation conditioning on graft-vs.-leukemia effect in mice

OBJECTIVE

The therapeutic potential of allogeneic hematopoietic stem cell transplantation relies on the graft-vs.-leukemia (GVL) effect to eradicate residual tumor cells immunologically. The relationship of conditioning intensity to GVL effect was investigated.

MATERIALS AND METHODS

Lethally irradiated (either 900 or 1300 cGy) B6D2F1 (H-2(b/d)) recipients were transplanted from B6 (H-2(b)) donors. P815 or L1214 (H-2(d)) tumor cells were injected intravenously or subcutaneously on day 1 post-transplantation to generate a GVL model.

RESULTS

Tumors in allogeneic mice treated with 1300 cGy exhibited markedly delayed subcutaneous tumor growth in vivo as compared with mice treated with 900 cGy, while intravenous tumor growths were comparable between the two radiation doses. Serum levels of tumor necrosis factor-α or interferon-γ were similar and the percentages of donor T-cell proliferation or apoptosis early after hematopoietic stem cell transplantation were comparable. The numbers of CD8(+) T cells from recipients that received 1300 cGy were significantly elevated in skin and tumor tissues. CD62L(low) and CD44(high) CD8(+) T-cell fractions were also elevated in 1300 cGy. After the higher radiation dose, P815-specific interferon-γ responses of splenic CD8(+) T cells were markedly enhanced and the fractions of T cells of interferon-γ-producing T cells in tumor tissues but not in spleen were increased. The protein concentrations of chemokines in skin and tumor tissues were substantially elevated in 1300 cGy compared to 900 cGy.

CONCLUSIONS

The higher radiation dose (1300 vs. 900 cGy) resulted in significantly enhanced GVL effect against an extramedullary tumor and the alterations in effector T-cell trafficking into tumor tissue are the most likely mechanism.

Change in serum proteome during allogeneic hematopoietic stem cell transplantation and clinical significance of serum C-reactive protein and haptoglobin

Successful hematopoietic stem cell transplantation (HSCT) involves the restoration of hematopoietic function after engraftment, arising from the differentiation and proliferation of hematopoietic stem cells. Several factors could influence the course of allogeneic-HSCT (allo-HSCT). Therefore, knowledge of serum proteome changes during the allo-HSCT period might increase the efficacy of diagnosis and disease prevention efforts. This study conducted proteomic analyses to find proteins that were significantly altered in response to allo-HSCT. Sera from five representative patients who underwent allo-HSCT were analyzed by 2-dimensional gel electrophoresis and liquid chromatography tandem mass spectrometry, and were measured on a weekly basis before and after allo-HSCT in additional 78 patients. Fourteen protein spots showing changes in expression were further examined, and most proteins were identified as acute phase proteins (APPs). Studies of 78 additional patients confirmed that C-reactive protein (CRP) and haptoglobin undergo expression changes during allo-HSCT and thus may have the potential to serve as representative markers of clinical events after allo-HSCT. Maximal CRP level affected the development of major transplant-related complications (MTCs) and other problems such as fever of unknown origin. Particularly, an increase in CRP level 21 days after allo-HSCT was found to be an independent risk factor for MTC. Maximal haptoglobin and haptoglobin level 14 days after allo-HSCT were predictive of relapses in underlying hematologic disease. Our results indicated that CRP and haptoglobin were significantly expressed during allo-HSCT, and suggest that their level can be monitored after allo-HSCT to assess the risks of early transplant-related complications and relapse.

Pretreatment C-reactive protein is a predictor for outcomes after reduced-intensity allogeneic hematopoietic cell transplantation

We tested the independent prognostic impact of 2 commonly used biomarkers, C-reactive protein (CRP) and interleukin (IL)-6, on the outcomes of allogeneic hematopoietic cell transplantation (HCT). Consecutive patients who underwent a uniform reduced-intensity conditioning (RIC) regimen of fludarabine (Flu), melphalan (Mel), and alemtuzumab were evaluated retrospectively. Cryopreserved serum samples drawn before the RIC were available to measure CRP levels in 81 patients and IL-6 levels in 79 patients. Patients with CRP levels above the median of 18.5 mg/L had significantly more grade 3-4 hepatic toxicity (P=.01), longer HCT hospital stay (P=.005), more acute graft-versus-host disease (aGVHD) (P=.003), greater nonrelapse mortality (NRM) (P=.01), and inferior overall survival (OS; P=.02). Higher baseline CRP showed no significant correlation with grade 3-4 infectious toxicity (P=.09). In contrast to CRP, pre-HCT IL-6 levels above the median of 78.3 pg/mL did not confer a statistically significant increased risk of toxicity or mortality. An elevated HCT comorbidity index (HCT-CI) did not predict for any measure of HCT morbidity. After adjustment for disease status, comorbidity, performance status, and age, elevated CRP concentration remained predictive of NRM. These data require confirmation in non-T cell-depleted conditioning regimens. If validated, they suggest that preconditioning CRP holds promise for enhancing estimates of transplantation tolerance.

Preengraftment serum C-reactive protein (CRP) value may predict acute graft-versus-host disease and nonrelapse mortality after allogeneic hematopoietic stem cell transplantation

In a mouse model, inflammatory cytokines play a primary role in the development of acute graft-versus-host disease (aGVHD). Here, we retrospectively evaluated whether the preengraftment C-reactive protein (CRP) value, which is used as a surrogate marker of inflammation, could predict posttransplant complications including GVHD. Two hundred twenty-four adult patients (median age, 47 years; range: 18-68 years) underwent conventional stem cell transplantation (CST, n = 105) or reduced-intensity stem cell transplantation (RIST, n = 119). Patients were categorized according to the maximum CRP value during neutropenia: the "low-CRP" group (CRP < 15 mg/dL, n = 157) and the "high-CRP" group (CRP >or= 15 mg/dL, n = 67). The incidence of documented infections during neutropenia was higher in the high-CRP group (34% versus 17%, P = .004). When patients with proven infections were excluded, the CRP value was significantly lower after RIST than after CST (P = .017) or after related than after unrelated transplantation (P < .001). A multivariate analysis showed that male sex, unrelated donor, and HLA-mismatched donor were associated with high CRP values. The high-CRP group developed significantly more grade II-IV aGVHD (P = .01) and nonrelapse mortality (NRM) (P < .001), but less relapse (P = .02). The present findings suggest that the CRP value may reflect the net degree of tissue damage because of the conditioning regimen, infection, and allogeneic immune reactions, all of which lead to subsequent aGVHD and NRM.