Monocyte dysfunction in patients with multiple myeloma and lymphoplasmacytic disorders is related to serum paraprotein levels

Inflammation and infection in plasma cell disorders: how pathogens shape the fate of patients

The role of infection and chronic inflammation in plasma cell disorders (PCD) has been well-described. Despite not being a diagnostic criterion, infection is a common complication of most PCD and represents a significant cause of morbidity and mortality in this population. As immune-based therapeutic agents are being increasingly used in multiple myeloma, it is important to recognize their impact on the epidemiology of infections and to identify preventive measures to improve outcomes. This review outlines the multiple factors attributed to the high infectious risk in PCD (e.g. the underlying disease status, patient age and comorbidities, and myeloma-directed treatment), with the aim of highlighting future prophylactic and preventive strategies that could be implemented in the clinic. Beyond this, infection and pathogens as an entity are believed to also influence disease biology from initiation to response to treatment and progression through a complex interplay involving pathogen exposure, chronic inflammation, and immune response. This review will outline both the direct and indirect role played by oncogenic pathogens in PCD, highlight the requirement for large-scale studies to decipher the precise implication of the microbiome and direct pathogens in the natural history of myeloma and its precursor disease states, and understand how, in turn, pathogens shape plasma cell biology.

Classical monocytes maintain ex vivo glycolytic metabolism and early but not later inflammatory responses in older adults

BACKGROUND

Inflammaging is a condition of chronic low-grade inflammation due to the aging process and is associated with a variety of chronic diseases. Monocytes are innate immune cells which contribute to inflammation and are dysregulated during aging, demonstrated reduced phagocytosis, increased inflammation, and alterations in subset proportions. Metabolism is known to determine immune cell function, with quiescent and anti-inflammatory cells primarily relying on fatty acid oxidation, while activated and inflammatory cells primarily rely on glycolysis. We have previously shown an age-related decrease in mitochondrial respiratory capacity in monocytes, so we hypothesized here that a compensatory shift toward glycolysis would occur which would also exacerbate inflammation.

RESULTS

Using Seahorse assays, we profiled glycolysis in classical monocytes isolated from older (60-80 yr) and younger (18-35 yr) adults. Aging did not affect parameters of basal glycolysis in the glycolysis stress test, nor did it alter glycolytic activation early (2 h) or later (24 h) post-LPS stimulation. Cytokine gene expression was unchanged between aged and young subjects at 2 h post-LPS but was reduced in older subjects at 24 h post-LPS either significantly (IL1B) or near-significantly (IL6, IL10).

CONCLUSIONS

Aging appears not to affect glycolytic metabolism ex vivo in classical monocytes, but may reduce cytokine expression at later timepoints. Studies examining monocytes stimulated with age-altered circulating factors or with other pattern recognition receptor agonists may shed further light on monocyte metabolism as a determinant of immunosenescence and inflammaging.

Low frequency of CD3+CD4+CD161+ T cells correlates with the occurrence of infections in refractory/relapsed multiple myeloma patients receiving lenalidomide plus low-dose dexamethasone treatment

The aim of this study was to explore the predictive implications of the composition of immune cell populations prior to lenalidomide plus high-dose dexamethasone (Len-Dex) initiation for the occurrence of infections. We prospectively examined immune cell populations in peripheral blood taken at baseline of lenalidomide plus low-dose dexamethasone (Len-dex) therapy and reviewed clinical and microbiology records in 90 patients with refractory/relapsed multiple myeloma (RRMM). Risk factors for infection were analyzed using logistic regression. During a median of 11 cycles of Len-dex treatment, 52 (57.8%) patients experienced at least 1 infection episode. Of a total of 92 episodes of infection, 58 (63%) episodes were clinically defined, 29 (31.5%) episodes were microbiologically defined, and 5 (5.4%) episodes were fever of unknown origin. Severe episodes were more frequently observed during the first 3 cycles. After adjusting for risk factors for infection based on univariate analyses, multivariate analyses showed that lower Hb (< 10 g/dL) was a clinically independent factor associated with occurrence of infections. Lower frequency (P = 0.044) and absolute count (P = 0.014) of circulating CD3⁺CD4⁺CD161⁺ cells prior to Len-dex treatment were also associated with the occurrence of infection, especially during the first 3 cycles of Len-dex therapy. In addition to several clinical predictive factors, we found that CD3⁺CD4⁺CD161⁺ cells may provide additional information for predicting the occurrence of infection in the early period of Len-dex therapy.

Aging impairs mitochondrial respiratory capacity in classical monocytes

Aging is a critical healthcare concern, with age-related inflammation disposing individuals to a variety of diseases. Monocytes are affected by the aging process, with increased inflammation and impaired cellular functions such as phagocytosis. Mechanisms by which aging alters monocyte function are unknown, but recent research suggests that the balance of metabolic processes determine immune cell phenotype and function. Given the known association between aging and mitochondrial dysfunction in other tissues, we hypothesized that aging would impair mitochondrial function in monocytes. To test this, we isolated classical monocytes from young and older adults and tested mitochondrial function by a Seahorse assay. Aging reduced mitochondrial respiratory capacity and spare capacity in monocytes. Mitochondrial dysfunction is a potential mechanism by which aging alters monocyte phenotype and may impair inflammatory functions, especially in low-glucose environments where oxidative metabolism is necessary to meet energy demands.

Pretreatment Lymphopenia, Poor Performance Status, and Early Courses of Therapy Are Risk Factors for Severe Bacterial Infection in Patients with Multiple Myeloma during Treatment with Bortezomib-based Regimens

The aim of this study was to identify the risk factors associated with severe bacterial infection (SBI) in multiple myeloma (MM) patients during treatment with bortezomib-based regimens. A total of 98 patients with MM were evaluated during 427 treatment courses. SBI occurred in 57.1% (56/98) of the patients and during 19.0% (81/427) of the treatment courses. In the multivariate analysis for the factors associated with the development of SBI in each treatment course, poor performance status (Eastern Cooperative Oncology Group ≥ 2, P < 0.001), early course of therapy (≤ 2 courses, P < 0.001), and pretreatment lymphopenia (absolute lymphocyte count < 1.0 × 10(9)/L, P = 0.043) were confirmed as independent risk factors. The probability of developing SBI were 5.1%, 14.9%, 23.9% and 59.5% in courses with 0, 1, 2, and 3 risk factors, respectively (P < 0.001). In conclusion, we identified three pretreatment risk factors associated with SBI in each course of bortezomib treatment. Therefore, MM patients with these risk factors should be more closely monitored for the development of SBI during bortezomib-based treatment.

Changing treatment paradigms for patients with plasma cell myeloma: impact upon immune determinants of infection

Plasma cell myeloma (PCM) is increasing in prevalence in older age groups and infective complications are a leading cause of mortality. Patients with PCM are at increased risk of severe infections, having deficits in many arms of the immune system due to disease and treatment-related factors. Treatment of PCM has evolved over time with significant impacts on immune function resulting in changing rates and pattern of infection. Recently, there has been a paradigm shift in the treatment of PCM with the use of immunomodulatory drugs and proteasome inhibitors becoming the standard of care. These drugs have wide-ranging effects on the immune system but their impact on infection risk and aetiology remain unclear. The aims of this review are to discuss the impact of patient, disease and treatment factors on immune function over time for patients with PCM and to correlate immune deficits with the incidence and aetiology of infections seen clinically in these patients. Preventative measures and the need for clinically relevant tools to enable infective profiling of patients with PCM are discussed.

Cell-dependent influence on the phagocytosis induced by non-ionic contrast medium injection

Iodinated contrast media (CM) can inhibit phagocytosis. To better understand the importance of this effect upon the elementary defence mechanism, the aim of the study was to compare the in vivo effect of non-ionic CM on the engulfing ability of peripheral blood phagocytic cells from patients undergoing CM-enhanced CT. Neutrophil granulocytes and monocytes from patients' peripheral blood obtained before and 30 min after CM injection were incubated with fluorescent-labelled Escherichia coli bacteria. Both the percentage of cells that engulfed bacteria and the phagocytic activity per cell has been determined by flow cytometry. We found that phagocytosis was greater in neutrophils than in monocytes. CM decreased the percentage of monocytes phagocyting bacteria, both at 4 degrees C (20.3%+/-3.3% versus 16.1%+/-2.0%; p<0.03) and at 37 degrees C (51.6%+/-4.1% versus 47.5%+/-2.6%; p>0.05), and increased the percentage of neutrophils at 4 degrees C (11.8%+/-2.1% versus 14.3%+/-2.2%; p<0.002) and at 37 degrees C (83.1%+/-3.6% versus 85.1%+/-3.2%; p>0.05). The phagocytic activity decreased significantly at 37 degrees C in monocytes (p<0.02), and was not affected in neutrophils. CM injection has different effects on both the percentage of phagocytosing cells and the phagocytic activity in monocytes and neutrophils. The inhibitory effect on monocyte phagocytosis seems to be compensated by neutrophils.

Autologous stem-cell transplantation restores the functional properties of CD14+CD16+ monocytes in patients with myeloma and lymphoma

The CD14+CD16+ monocytes appear to be important to immune defense against infection, as these cells are very potent with respect to tumor necrosis factor (TNF) production, phagocytosis, and antigen presentation. Myeloablative high-dose chemotherapy (HDT) and subsequent autologous stem-cell transplantation (ASCT) are being used increasingly for therapy of hematological malignancies, but the pronounced immunosuppression renders the patients prone to infection. To determine the functional properties of CD14+CD16+ monocytes under these conditions, 15 patients with lymphoma or myeloma were examined. Before HDT, the ratio of CD14+CD16+ cells to the population of the classical CD14++ monocytes was 0.28 +/- 0.12; this ratio changed during the course of HDT and ASCT in favor of the CD14+CD16+ monocytes to a maximum of 12.4 +/- 7.8 (P<0.001) on day 3.5 +/- 1.6 after transplanation (Tx) and returned to 0.11 +/- 0.07 (P<0.001) after engraftment on day 11.3 +/- 2.2. Although the absolute number of classical CD14++ monocytes declined to less than 1/microl at the nadir, the number of CD14+CD16+monocytes fell from 29.7 +/- 9.8/microl to 4.5 +/- 3.0/microl at the nadir and increased to 13.8 +/- 9.8/microl at the day of discharge from the hospital. Flow cytometric analysis of phagocytosis of fluorescein isothiocyanate (FITC)-labeled Escherichia coli showed that 30 +/- 10% CD14+CD16+ monocytes of patients were FITC-positive before Tx, and at engrafment, the percentage of FITC-positive cells had doubled to 60 +/- 6% (healthy controls, 41+/-7%). When determining generation of reactive oxygen species after E. coli ingestion, the CD14+CD16+ monocytes showed a decreased response before Tx (32+/-12% positve cells), which increased to 53 +/- 24% after ASCT. The median fluorescence intensity of human leukocyte antigen (HLA)-DR expression on the CD14+CD16+ monocytes increased from 11 +/- 6 before Tx to 17 +/- 11 after Tx, and the production of TNF after lipopolysaccharide showed no remarkable difference (46+/-13 vs. 49+/-14 channels). At the same time, expression of TNF and of HLA-DR showed a dramatic decrease in the CD14++ monocytes. Taken together after stem-cell Tx, the function of the CD14++ monocytes is impaired, and the functional properties of CD14+CD16+ monocytes recover, indicating that these cells may be important for defense against infections post-ASCT.