Christian Bryant

The relationship between obesity and hypoferraemia in adults: a systematic review

A growing number of studies suggest a potential link between obesity and altered iron metabolism. The purpose of this systematic review was to examine existing literature on iron status in obese populations. A comprehensive literature search was conducted. Included studies recruited participants ≥ 18 years with a body mass index ≥ 30 kg m−2 and provided descriptive statistics for haemoglobin or ferritin at a minimum. There were 25 studies meeting all eligibility criteria, of these 10 examined iron status in free‐living obese individuals and 15 reported baseline iron biomarkers from bariatric surgery candidates. Non‐obese comparison groups were used by 10 (40%) articles. In these, seven obese groups reported higher mean haemoglobin concentration; six reported significantly higher ferritin concentration; and four significantly lower transferrin saturation. Due to insufficient data, it was not possible to make conclusions regarding mean differences for soluble transferrin receptor (sTfR), hepcidin or C‐reactive protein. Existing evidence suggests a tendency for higher haemoglobin and ferritin concentration and lower transferrin saturation in obesity. Alternation of iron biomarkers in obese populations may be a result of obesity‐related inflammation and/or related comorbidities. Further research incorporating measurement of inflammatory cytokines, sTfR and hepcidin is required to confirm the impact of obesity on iron status.

Long-term survival in multiple myeloma is associated with a distinct immunological profile, which includes proliferative cytotoxic T-cell clones and a favourable Treg/Th17 balance

Despite improved outcomes in multiple myeloma (MM), a cure remains elusive. However, even before the current therapeutic era, 5% of patients survived >10 years and we propose that immune factors contribute to this longer survival. We identified patients attending our clinic, who had survived >10 years (n=20) and analysed their blood for the presence of T-cell clones, T-regulatory cells (Tregs) and T helper 17 (Th17) cells. These results were compared with MM patients with shorter follow-up and age-matched healthy control donors. The frequency of cytotoxic T-cell clonal expansions in patients with <10 years follow-up (MM patients) was 54% (n=144), whereas it was 100% (n=19/19) in the long-survivors (LTS-MM). T-cell clones from MM patients proliferated poorly in vitro, whereas those from LTS-MM patients proliferated readily (median proliferations 6.1% and 61.5%, respectively (P<0.0001)). In addition, we found significantly higher Th17 cells and lower Tregs in the LTS-MM group when compared with the MM group. These results indicate that long-term survival in MM is associated with a distinct immunological profile, which is consistent with decreased immune suppression.

Dendritic Cells as Pharmacological Tools for Cancer Immunotherapy

Although the earliest—rudimentary—attempts at exploiting the immune system for cancer therapy can be traced back to the late 18th Century, it was not until the past decade that cancer immunotherapeutics have truly entered mainstream clinical practice. Given their potential to stimulate both adaptive and innate antitumor immune responses, dendritic cells (DCs) have come under intense scrutiny in recent years as pharmacological tools for cancer immunotherapy. Conceptually, the clinical effectiveness of this form of active immunotherapy relies on the completion of three critical steps: 1) the DCs used as immunotherapeutic vehicles must properly activate the antitumor immune effector cells of the host, 2) these immune effector cells must be receptive to stimulation by the DCs and be competent to mediate their antitumor effects, which 3) requires overcoming the various immune-inhibitory mechanisms used by the tumor cells. In this review, following a brief overview of the pivotal milestones in the history of cancer immunotherapy, we will introduce the reader to the basic immunobiological and pharmacological principles of active cancer immunotherapy using DCs. We will then discuss how current research is trying to define the optimal parameters for each of the above steps to realize the full clinical potential of DC therapeutics. Given its high suitability for immune interventions, acute myeloid leukemia was chosen here to showcase the latest research trends driving the field of DC-based cancer immunotherapy.

Multiple myeloma causes clonal T-cell immunosenescence: identification of potential novel targets for promoting tumour immunity and implications for checkpoint blockade.

Tumour-induced dysfunction of cytotoxic T cells in patients with multiple myeloma (MM) may contribute to immune escape and be responsible for the lack of therapeutic efficacy of immune checkpoint blockade. We therefore investigated dysfunctional clonal T cells in MM and demonstrated immunosenescence but not exhaustion as a predominant feature. T-cell clones were detected in 75% of MM patients and their prognostic significance was revalidated in a new post-immunomodulatory drug cohort. The cells exhibited a senescent secretory effector phenotype: KLRG-1+/CD57+/CD160+/CD28−. Normal-for-age telomere lengths indicate that senescence is telomere independent and potentially reversible. p38-mitogen-activated protein kinase, p16 and p21 signalling pathways known to induce senescence were not elevated. Telomerase activity was found to be elevated and this may explain how normal telomere lengths are maintained in senescent cells. T-cell receptor signalling checkpoints were normal but elevated SMAD levels associated with T-cell inactivation were detected and may provide a potential target for the reversal of clonal T-cell dysfunction in MM. Low programmed death 1 and cytotoxic T-lymphocyte-associated antigen 4 expression detected on T-cell clones infers that these cells are not exhausted but suggests that there would be a suboptimal response to immune checkpoint blockade in MM. Our data suggest that other immunostimulatory strategies are required in MM.

Iron, hepcidin and inflammatory status of young healthy overweight and obese women in Australia

Background and Aims Evidence suggests obesity-related inflammation alters iron metabolism potentially increasing the risk of iron deficiency. This cross-sectional study aimed to investigate iron, hepcidin and inflammatory status in young, healthy overweight and obese women. Methods 114 young (18–25 years), healthy comorbidity-free women with a body mass index (BMI) ≥27.5 kg/m2 were recruited. Biochemical data were analysed using mean ± standard deviation or median (interquartile range) and multivariate modelling. Biochemical markers were also stratified according to varying degrees of overweight and obesity. Results Anaemia (haemoglobin <120 g/l) and iron deficiency (serum ferritin <15.0 µg/l) were prevalent in 10% and 17% of participants respectively. Mean/median soluble transferrin receptor was 1.61±0.44 mg/l; hepcidin 6.40 (7.85) ng/ml and C-reactive protein (CRP) 3.58 (5.81) mg/l. Multivariate modelling showed that BMI was a significant predictor of serum iron (coefficient = -0.379; standard error = 0.139; p = 0.008), transferrin saturation (coefficient = -0.588; standard error = 0.222; p = 0.009) and CRP (coefficient = 0.127; standard error = 0.024; p<0.001). Stratification of participants according to BMI showed those with ≥35.0 kg/m2 had significantly higher CRP (p<0.001) than those in lower BMI categories. Conclusions Increasing obesity was associated with minor disturbances in iron metabolism. However, overall outcomes indicated simple iron deficiency (hypoferritinaemia) was the primary iron-related abnormality with no apparent contribution of inflammation or hepcidin, even in those with BMI >35.0 kg/m2. This indicates that obesity alone may not be sufficient to induce clinically significant disturbances to iron metabolism as previously described. This may be attributed to the lack of comorbidity in this cohort.

A CD2 high-expressing stress-resistant human plasmacytoid dendritic-cell subset

Human plasmacytoid dendritic cells (pDCs) were considered to be a phenotypically and functionally homogeneous cell population; however, recent analyses indicate potential heterogeneity. This is of major interest, given their importance in the induction of anti‐viral responses and their role in creating immunologically permissive environments for human malignancies. For this reason, we investigated the possible presence of human pDC subsets in blood and bone marrow, using unbiased cell phenotype clustering and functional studies. This defined two major functionally distinct human pDC subsets, distinguished by differential expression of CD2. The CD2hi and CD2lo pDCs represent discontinuous subsets, each with hallmark pDC functionality, including interferon‐alpha production. The rarer CD2hi pDC subset demonstrated a significant survival advantage over CD2lo pDC during stress and upon exposure to glucocorticoids (GCs), which was associated with higher expression of the anti‐apoptotic molecule BCL2. The differential sensitivity of these two human pDC subsets to GCs is demonstrated in vivo by a relative increase in CD2hi pDC in multiple myeloma patients treated with GCs. Hence, the selective apoptosis of CD2lo pDC during stress represents a novel mechanism for the control of innate responses.

Impact of Diet and Weight Loss on Iron and Zinc Status in Overweight and Obese Young Women

Young overweight women are at risk of iron and zinc deficiency. This study assessed iron, zinc and inflammatory status during a 12-month weight loss trial in young women (18-25 y; BMI >=27.5 kg/m2) randomised to a higher-protein (HP: 32% protein; 12.2 mg/day iron; 11.7 mg/day zinc) or lower-protein (LP: 20%; 9.9 mg/day; 7.6 mg/day respectively) diet with contrasting haem iron and zinc content. In completers (HP: n=21; LP: n=15), HP participants showed higher median ferritin (52.0 vs 39.0 μg/L; p=0.021) and lower median soluble transferrin receptor-ferritin index (sTfR-F; 0.89 vs 1.05; p=0.024) although concentrations remained within normal range for both diets. Median C-reactive protein (CRP; HP: 3.54; LP: 4.63 mg/L) and hepcidin (HP: 5.70; LP: 8.25 ng/mL) were not elevated at baseline, and no longitudinal between-diet differences were observed for zinc and CRP. Compared to those with <5% weight loss, HP participants losing >=10% weight showed lower median sTfR-F (0.76 vs 1.03; p=0.019) at six months. Impact of >=10% weight loss on iron was more apparent in LP participants who exhibited greater mean serum iron (20.0 vs 13.5 μmol/L; p=0.002), transferrin saturation (29.8% vs 19.4%; p=0.001) and lower sTfR (1.24 vs 1.92 mg/L; p=0.034) at 12 months. Results show normal iron and zinc status can be maintained during 12 months of energy restriction. In the absence of elevated baseline inflammation and hepcidin, a more favourable iron profile in those with >=10% weight loss may reflect stronger compliance or the potential influence of iron regulatory mechanisms unrelated to inflammatory hepcidin reduction.

CMRF-56+ blood dendritic cells loaded with mRNA induce effective antigen-specific cytotoxic T-lymphocyte responses

ABSTRACT There are numerous transcriptional, proteomic and functional differences between monocyte-derived dendritic cells (Mo-DC) and primary blood dendritic cells (BDC). The CMRF-56 monoclonal antibody (mAb) recognizes a cell surface marker, which is upregulated on BDC following overnight culture. Given its unique ability to select a heterogeneous population of BDC, we engineered a human chimeric (h)CMRF-56 IgG4 mAb to isolate primary BDC for potential therapeutic vaccination. The ability to select multiple primary BDC subsets from patients and load them with in vitro transcribed (IVT) mRNA encoding tumor antigen might circumvent the issues limiting the efficacy of Mo-DC. After optimizing and validating the purification of hCMRF-56+ BDC, we showed that transfection of hCMRF-56+ BDC with mRNA resulted in efficient mRNA translation and antigen presentation by myeloid BDC subsets, while preserving superior DC functions compared to Mo-DC. Immune selected and transfected hCMRF-56+ BDC migrated very efficiently in vitro and as effectively as cytokine matured Mo-DC in vivo. Compared to Mo-DC, hCMRF-56+ BDC transfected with influenza matrix protein M1 displayed superior MHC peptide presentation and generated potent antigen specific CD8+ T-cell recall responses, while Wilms tumor 1 (WT1) transfected CMRF-56+ BDC generated effective primary autologous cytotoxic T-cell responses. The ability of the combined DC subsets within hCMRF-56+ BDC to present mRNA delivered tumor antigens merits phase I evaluation as a reproducible generic platform for the next generation of active DC immune therapies.

The T Cell in Myeloma

An active role for the immune system in controlling the malignant plasma cell clone in myeloma has been postulated for many years. The clinical states of monoclonal gammopathy of undetermined significance, plateau phase disease, and smoldering myeloma all suggest that a significant host-tumor interaction is taking place. The fundamental role of the cytotoxic T cell in tumor elimination and control has been exemplified by the dramatic efficacy of adoptive T-cell therapies in many hemopoietic malignancies. However, tumor-host cross-talk results in suppression of the endogenous cytotoxic T-cell response against the malignant plasma cell. Whereas patients with myeloma do not clinically exhibit a T-cell immunodeficiency state, with, for example, increased mycobacterial infections, a number of abnormalities of T-cell function are evident. The major abnormalities of T cells include clonal expansions and associated immunosenescence, alterations of regulatory T cells/T helper 17 cells (Treg/Th17 ratio) and acquired membrane abnormalities, due to trogocytosis, which result in acquired Treg cells. Dendritic cell dysfunction associated with impaired antigen processing and presentation caused by abnormalities of the bone marrow microenvironment plays an additional role. In this perspective, we examine the T-cell abnormalities in myeloma and postulate that, whereas cytotoxic T cells interacting with the tumor are dysfunctional, residual T cells still function adequately against external pathogens and thus protect patients from the infections normally associated with a generalized T-cell immunodeficiency state. The so-called 3 Es of host-tumor interaction (elimination, equilibrium, and escape) are clearly reflected in the immune landscape and clinical behavior of myeloma.

The Analysis of CD83 Expression on Human Immune Cells Identifies a Unique CD83+-Activated T Cell Population

CD83 is a member of the Ig gene superfamily, first identified in activated lymphocytes. Since then, CD83 has become an important marker for defining activated human dendritic cells (DC). Several potential CD83 mRNA isoforms have been described, including a soluble form detected in human serum, which may have an immunosuppressive function. To further understand the biology of CD83, we examined its expression in different human immune cell types before and after activation using a panel of mouse and human anti-human CD83 mAb. The mouse anti-human CD83 mAbs, HB15a and HB15e, and the human anti-human CD83 mAb, 3C12C, were selected to examine cytoplasmic and surface CD83 expression, based on their different binding characteristics. Glycosylation of CD83, the CD83 mRNA isoforms, and soluble CD83 released differed among blood DC, monocytes, and monocyte-derived DC, and other immune cell types. A small T cell population expressing surface CD83 was identified upon T cell stimulation and during allogeneic MLR. This subpopulation appeared specifically during viral Ag challenge. We did not observe human CD83 on unstimulated human natural regulatory T cells (Treg), in contrast to reports describing expression of CD83 on mouse Treg. CD83 expression was increased on CD4+, CD8+ T, and Treg cells in association with clinical acute graft-versus-host disease in allogeneic hematopoietic cell transplant recipients. The differential expression and function of CD83 on human immune cells reveal potential new roles for this molecule as a target of therapeutic manipulation in transplantation, inflammation, and autoimmune diseases.