Early Blood Stream Infections after BMT are Associated with Cytokine Dysregulation and Poor Overall Survival

Impact of intensified contact precautions while treating hematopoietic stem cell transplantation recipients during aplasia

BACKGROUND

Bacterial infections are a major complication for patients undergoing allogeneic hematopoietic stem cell transplantation (HCT). Therefore, protective isolation is considered crucial to prevent nosocomial infections in this population. Here, the impact of intensified contact precautions on environmental contamination and the occurrence of bloodstream infections (BSI) in patients on a HCT unit were compared between two contact precaution measures.

METHODS

A 2-year retrospective observational study was performed. In the first year, strict contact precaution measures were applied (i.e., protective isolation, the use of sterile personal protective equipment (PPE) by healthcare workers and visitors and sterilization of linen and objects that entered the patient's room). After one year, contact precautions were reduced (i.e., no use of sterile PPE, no sterilization of linen and objects that entered the patient's room). Environmental contamination in randomly selected patient rooms was monitored by sampling six standardized environmental sites in the respective patient treatment units. In a before-and-after study, the number of BSI episodes of those patients, who were accommodated in the monitored rooms was compared.

RESULTS

In total, 181 treatment units were monitored. No significant difference in the contamination of anterooms and patient's rooms between both groups was found. A total of 168 patients were followed for the occurrence of BSI during the entire study period (before: 84 patients, after: 84 patients). The total count of patients with BSI episodes showed a higher incidence in the period with reduced contact precautions (30/84 vs. 17/84, p = 0.039). The cause of this increasing number of BSI can be traced back to BSI episodes with common commensal bacteria (17/84 vs. 5/84, p = 0.011).

CONCLUSIONS

The implementation of maximal barrier measures did not reduce the bacterial contamination of the patients' environment. The impact on the patients' outcomes remain controversial. Further research is needed to investigate the impact of infection prevention measures on the clinical outcome of patients undergoing HCT.

Glucocorticoids inhibit human hematopoietic stem cell differentiation toward a common ILC precursor

BACKGROUND

Innate lymphoid cells (ILCs) comprise cytotoxic natural killer (NK) cells and helper ILCs (hILCs). Human hILC development is less characterized as compared with that of NK cells, although all ILCs are developmentally related. It has been reported that the immunosuppressive drugs glucocorticoids (GCs) regulate ILC function, but whether they control ILC differentiation from hematopoietic stem cells (HSCs) is unknown.

OBJECTIVES

This study sought to analyze the effect of GCs on ILC development from HSCs.

METHODS

This study exploited an in vitro system to generate and expand from peripheral blood HSCs a multipotent CD56⁺ ILC precursor able to differentiate into NK cells, ILC1s, and ILC3s. We also analyzed ex vivo, at different time points, the peripheral blood of recipients of allogeneic HSC transplantation who were or were not treated with GCs and compared ILC subset reconstitution.

RESULTS

Invitro, GCs favor the generation of NK cells from myeloid precursors, while they strongly impair lymphoid development. In support of these data, recipients of HSC transplantation who had been treated with GCs display a lower number of circulating hILCs, including the ILC precursor (ILCP) previously identified as a systemic substrate for tissue ILC differentiation.

CONCLUSIONS

GCs impair the development of the CD117⁺ ILCP from CD34⁺ HSCs, while they do not affect the further steps of ILCP differentiation toward NK cells and hILC subsets. This reflects an association of GC treatment with a marked reduction of circulating hILCs in the recipients of HSC transplantation.

Risk of infectious complications in adult patients after allogeneic hematopoietic stem cell transplantation depending on the site of central venous catheter insertion-multicenter prospective observational study, from the IDWP EBMT and Nurses Group of EBMT

The current guidelines for prevention of infections in hematopoietic stem cell transplantation (HSCT) do not specify which central venous catheter (CVC) insertion site should be preferred in allogeneic HSCT recipients-internal jugular vein (IJV) or subclavian vein (SCV). We designed a multicenter prospective observational study comparing the risk of infectious and non-infectious complications between the two most common sites of CVC insertion (IJV and SCV) in allogeneic HSCT. There were in total 232 consecutive patients (86 IJV and 146 SCV) who underwent adult allogeneic HSCT reported from 11 centers in 8 countries. The center independent analysis of central line associated/related blood stream infections with ECDC criteria has shown statistically significant difference favoring SCV (23% IJV vs 13% SCV (OR 2.03 (1.01-4.06), p = 0.047)). The differences in CLABSI per 1000 days of CVC use favored SCV over IJV (7.93/1000 days IJV vs 2.79/1000 days SCV, p = 0.002). The frequency of all non-infectious complications was similar in both arms-13% IJV and 12% SCV (OR 1.1 (0.5-2.5), p = 0.8). This multicenter prospective study showed statistically significant lower confirmed number of CLABSI per 1000 days of CVC use without higher risk of noninfectious complications related to the subclavian insertion site in allogeneic HSCT recipients.

A Pilot Study of Human Milk to Reduce Intestinal Inflammation After Bone Marrow Transplant

OBJECTIVE

Human milk administration in the early peritransplant period would lower intestinal inflammation after bone marrow transplant (BMT).

MATERIALS AND METHODS

Children 0-5 years undergoing BMT received either a ready-to-feed human milk preparation designed for these children (Prolacta Bioscience, Duarte, CA) or standard formula. Babies breastfeeding at the time of BMT were also enrolled on the human milk arm. Human milk was administered from day -3 until day +14 after BMT. Metagenomic shotgun sequencing and metabolomics of stool, plasma cytokines, and regenerating islet-derived 3α (REG3α) levels were measured at enrollment and day +14. Human leukocyte antigen-DR isotype (HLA-DR), CD38, and CD69 expression on T cells were evaluated at day +21.

RESULTS

Forty-six children were enrolled, 32 received human milk (donor milk n = 23, breastfeeding babies n = 9), and 14 were controls who received standard feeds supervised by a BMT dietician. Twenty-four patients received at least 60% of goal human milk and were evaluable. Plasma interleukin (IL)-8 (p = 0.04), IL-10 (p = 0.02), and REG3α (p = 0.03) were decreased in the human milk cohort. Peripheral blood CD69⁺ CD8⁺ T cells were higher in controls (p = 0.01). Species abundance of Adenovirus (p = 0.00034), Escherichia coli (p = 0.0017), Cryptosporidium parvum (p = 0.0006), Dialister invisus (p = 0.01), and Pseudomonas aeruginosa (p = 0.05) from stool was higher in controls. Stool alanine, tyrosine, methionine, and the ratio of fecal alanine to choline and phosphocholine were higher in controls (p < 0.05). No difference was observed in stool propionate and butyrate levels as measures of short-chain fatty acids between the two cohorts.

CONCLUSIONS

Administration of human milk resulted in decreased markers of intestinal inflammation and could be a valuable adjunct for patients after BMT.

Modulation of B Cells and Homing Marker on NK Cells Through Extracorporeal Photopheresis in Patients With Steroid-Refractory/Resistant Graft-Vs.-Host Disease Without Hampering Anti-viral/Anti-leukemic Effects

Graft-vs.-host disease (GvHD), a severe complication of allogeneic hematopoietic stem cell transplantation, significantly affects the post-transplant morbidity and mortality. Systemic steroids remain the gold standard for the initial management of GvHD. However, up to 60% of patients will not sufficiently respond to steroids. Extracorporeal photopheresis (ECP), a cell-based immunotherapy, has shown good clinical results in such steroid-refractory/resistant GvHD patients. Given its immunomodulatory, but not global immunosuppressive and steroid-sparing capacity, ECP constitutes an attractive option. In the case of GvHD, the balance of immune cells is destroyed: effector cells are not any longer efficiently controlled by regulatory cells. ECP therapy may restore this balance. However, the precise mechanism and the impact of ECP on anti-viral/anti-leukemic function remain unclear. In this study, 839 ECP treatments were performed on patients with acute GvHD (aGvHD) and chronic GvHD (cGvHD). A comprehensive analysis of effector and regulatory cells in patients under ECP therapy included multi-parametric flow cytometry and tetramer staining, Luminex^TM-based cytokine, interferon-γ enzyme-linked immunospot, and chromium-51 release assays. Gene profiling of myeloid-derived suppressor cells (MDSCs) was performed by microarray analysis. Immunologically, modulations of effector and regulatory cells as well as proinflammatory cytokines were observed under ECP treatment: (1) GvHD-relevant cell subsets like CD62L⁺ NK cells and newly defined CD19^hiCD20^hi B cells were modulated, but (2) quantity and quality of anti-viral/anti-leukemic effector cells were preserved. (3) The development of MDSCs was promoted and switched from an inactivated subset (CD33^-CD11b⁺) to an activated subset (CD33⁺CD11b⁺). (4) The frequency of Foxp3⁺CD4⁺ regulatory T cells (Tregs) and CD24⁺CD38^hi regulatory B cells was considerably increased in aGvHD patients, and Foxp3⁺CD8⁺ Tregs in cGvHD patients. (5) Proinflammatory cytokines like IL-1β, IL-6, IL-8, and TNF-α were significantly reduced. In summary, ECP constitutes an effective immunomodulatory therapy for patients with steroid-refractory/resistant GvHD without impairment of anti-viral/leukemia effects.