A Positive Prospective Trial of Antibiotic Therapy in Advanced Stage, Non-Bulky Indolent Lymphoma

Role of the gut microbiota in hematologic cancer

Hematologic neoplasms represent 6.5% of all cancers worldwide. They are characterized by the uncontrolled growth of hematopoietic and lymphoid cells and a decreased immune system efficacy. Pathological conditions in hematologic cancer could disrupt the balance of the gut microbiota, potentially promoting the proliferation of opportunistic pathogens. In this review, we highlight studies that analyzed and described the role of gut microbiota in different types of hematologic diseases. For instance, myeloma is often associated with Pseudomonas aeruginosa and Clostridium leptum, while in leukemias, Streptococcus is the most common genus, and Lachnospiraceae and Ruminococcaceae are less prevalent. Lymphoma exhibits a moderate reduction in microbiota diversity. Moreover, certain factors such as delivery mode, diet, and other environmental factors can alter the diversity of the microbiota, leading to dysbiosis. This dysbiosis may inhibit the immune response and increase susceptibility to cancer. A comprehensive analysis of microbiota-cancer interactions may be useful for disease management and provide valuable information on host-microbiota dynamics, as well as the possible use of microbiota as a distinguishable marker for cancer progression.

Host-microbe interactions and outcomes in multiple myeloma and hematopoietic stem cell transplantation

Microbiota are essential to normal immune development and there is growing recognition of its importance to human health and disease and deepening understanding of the complexity of host-microbe interactions in the human gut and other tissues. Commensal microbes not only can influence host immunity locally through impacts of bioactive microbial metabolites and direct interactions with epithelial cells and innate immune receptors but also can exert systemic immunomodulatory effects via impacts on host immune cells capable of trafficking beyond the gut. Emerging data suggest microbiota influence the development of multiple myeloma (MM), a malignancy of the immune system derived from immunoglobulin-producing bone marrow plasma cells, through the promotion of inflammation. Superior treatment outcomes for MM correlate with a higher abundance of commensal microbiota capable of influencing inflammatory responses through the production of butyrate. In patients with hematologic malignancies, higher levels of diversity of the gut microbiota correlate with superior outcomes after hematopoietic stem cell transplantation. Correlative data support the impact of commensal microbiota on survival, risk of infection, disease relapse, and graft-versus-host disease (GVHD) after transplant. In this review, we will discuss the current understanding of the role of host-microbe interactions and the inflammatory tumor microenvironment of multiple myeloma, discuss data describing the key role of microbiota in hematopoietic stem cell transplantation for treatment of hematologic malignancies, and highlight several possible concepts for interventions directed at the gut microbiota to influence treatment outcomes.

Infections and Follicular Lymphoma: is there a Link?

Several infectious agents appear to provide a proliferative signal -- “antigen-drive” – that could be implicated in the pathogenesis of various type of Non-Hodgkin Lymphoma (NHL). A classical model of the infection-driven lymphoproliferative disorder is Helicobacter pylori-induced gastric MALT lymphoma, where antibiotic therapy allows the eradication of both the infectious agent and the clonal B-cell expansion. Following the footsteps of this example, several retrospective studies have found a correlation with other pathogens and B-cell Lymphomas, adding new relevant information about pathogenesis and laying the groundwork for chemotherapy-free treatments.

Although no clear association has been found between infectious agents and Follicular Lymphoma (FL), a growing number of biological and clinical observations suggests the interaction of physiological and pathological microbial populations also in this subtype of lymphoma. In the last few years, epidemiological studies investigating the association of known risk factors and FL found a potential correlation with viral or bacterial infections; moreover, recent findings of the stimulation of FL clones support the importance of microbial exposure to lymphomagenesis and disease progression.

In the following review we make an attempt to find tangible evidence for a role of either physiological and pathological exogenous microbial species in the pathogenesis of FL, and try to integrate the findings coming from epidemiological, biological and interventional studies to define future novel treatment and prevention strategies for FL.