Persistent stimulation with Mycobacterium tuberculosis antigen impairs the proliferation and transcriptional program of hematopoietic cells in bone marrow

When inflammatory stressors dramatically change, disease phenotypes may transform between autoimmune hematopoietic failure and myeloid neoplasms

Aplastic anemia (AA) and hypoplastic myelodysplastic syndrome are paradigms of autoimmune hematopoietic failure (AHF). Myelodysplastic syndrome and acute myeloid leukemia are unequivocal myeloid neoplasms (MNs). Currently, AA is also known to be a clonal hematological disease. Genetic aberrations typically observed in MNs are detected in approximately one-third of AA patients. In AA patients harboring MN-related genetic aberrations, a poor response to immunosuppressive therapy (IST) and an increased risk of transformation to MNs occurring either naturally or after IST are predicted. Approximately 10%-15% of patients with severe AA transform the disease phenotype to MNs following IST, and in some patients, leukemic transformation emerges during or shortly after IST. Phenotypic transformations between AHF and MNs can occur reciprocally. A fraction of advanced MN patients experience an aplastic crisis during which leukemic blasts are repressed. The switch that shapes the disease phenotype is a change in the strength of extramedullary inflammation. Both AHF and MNs have an immune-active bone marrow (BM) environment (BME). In AHF patients, an inflamed BME can be evoked by infiltrated immune cells targeting neoplastic molecules, which contributes to the BM-specific autoimmune impairment. Autoimmune responses in AHF may represent an antileukemic mechanism, and inflammatory stressors strengthen antileukemic immunity, at least in a significant proportion of patients who have MN-related genetic aberrations. During active inflammatory episodes, normal and leukemic hematopoieses are suppressed, which leads to the occurrence of aplastic cytopenia and leukemic cell regression. The successful treatment of underlying infections mitigates inflammatory stress-related antileukemic activities and promotes the penetration of leukemic hematopoiesis. The effect of IST is similar to that of treating underlying infections. Investigating inflammatory stress-powered antileukemic immunity is highly important in theoretical studies and clinical practice, especially given the wide application of immune-activating agents and immune checkpoint inhibitors in the treatment of hematological neoplasms.

Possible Mechanisms of Lymphopenia in Severe Tuberculosis

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis). In lymphopenia, T cells are typically characterized by progressive loss and a decrease in their count results. Lymphopenia can hinder immune responses and lead to systemic immunosuppression, which is strongly associated with mortality. Lymphopenia is a significant immunological abnormality in the majority of patients with severe and advanced TB, and its severity is linked to disease outcomes. However, the underlying mechanism remains unclear. Currently, the research on the pathogenesis of lymphopenia during M. tuberculosis infection mainly focuses on how it affects lymphocyte production, survival, or tissue redistribution. This includes impairing hematopoiesis, inhibiting T-cell proliferation, and inducing lymphocyte apoptosis. In this study, we have compiled the latest research on the possible mechanisms that may cause lymphopenia during M. tuberculosis infection. Lymphopenia may have serious consequences in severe TB patients. Additionally, we discuss in detail potential intervention strategies to prevent lymphopenia, which could help understand TB immunopathogenesis and achieve the goal of preventing and treating severe TB.

Leukemic transformation during anti-tuberculosis treatment in aplastic anemia-paroxysmal nocturnal hemoglobinuria syndrome: A case report and review of literature

BACKGROUND

Accumulating evidence demonstrates that autoimmune hematopoietic failure and myeloid neoplasms have an intrinsic relationship with regard to clonal hematopoiesis and disease evolution. In approximately 10%-15% of patients with severe aplastic anemia (SAA), the disease phenotype is transformed into myeloid neoplasms following antithymocyte globulin plus cyclosporine-based immunosuppressive therapy. In some of these patients, myeloid neoplasms appear during or shortly after immunosuppressive therapy. Leukemic transformation in SAA patients during anti-tuberculosis treatment has not been reported.

CASE SUMMARY

A middle-aged Chinese female had a 6-year history of non-SAA and a 2-year history of paroxysmal nocturnal hemoglobinuria (PNH). With aggravation of systemic inflammatory symptoms, severe pancytopenia developed, and her hemoglobinuria disappeared. Laboratory findings in cytological, immunological and cytogenetic analyses of bone marrow samples met the diagnostic criteria for "SAA." Definitive diagnosis of disseminated tuberculosis was made in the search for infectious niches. Remarkable improvement in hematological parameters was achieved within 1 mo of anti-tuberculosis treatment, and complete hematological remission was achieved within 4 mo of treatment. Frustratingly, the hematological response lasted for only 3 mo, and pancytopenia reemerged. At this time, cytological findings (increased bone marrow cellularity and an increased percentage of myeloblasts that accounted for 16.0% of all nucleated hematopoietic cells), immunological findings (increased percentage of cluster of differentiation 34+ cells that accounted for 12.28% of all nucleated hematopoietic cells) and molecular biological findings (identification of somatic mutations in nucleophosmin-1 and casitas B-lineage lymphoma genes) revealed that "SAA" had transformed into acute myeloid leukemia with mutated nucleophosmin-1. The transformation process suggested that the leukemic clones were preexistent but were suppressed in the PNH and SAA stages, as development of symptomatic myeloid neoplasm through acquisition and accumulation of novel oncogenic mutations is unlikely in an interval of only 7 mo. Aggravation of inflammatory stressors due to disseminated tuberculosis likely contributed to the repression of normal and leukemic hematopoiesis, and the relief of inflammatory stressors due to anti-tuberculosis treatment contributed to penetration of neoplastic hematopoiesis. The concealed leukemic clones in the SAA and PNH stages raise the possibility of an inflammatory stress-fueled antileukemic mechanism.

CONCLUSION

Aggravated inflammatory stressors can repress normal and leukemic hematopoiesis, and relieved inflammatory stressors can facilitate penetration of neoplastic hematopoiesis.

Tuberculosis-induced aplastic crisis and atypical lymphocyte expansion in advanced myelodysplastic syndrome: A case report and review of literature

BACKGROUND

Myelodysplastic syndrome (MDS) is caused by malignant proliferation and ineffective hematopoiesis. Oncogenic somatic mutations and increased apoptosis, necroptosis and pyroptosis lead to the accumulation of earlier hematopoietic progenitors and impaired productivity of mature blood cells. An increased percentage of myeloblasts and the presence of unfavorable somatic mutations are signs of leukemic hematopoiesis and indicators of entrance into an advanced stage. Bone marrow cellularity and myeloblasts usually increase with disease progression. However, aplastic crisis occasionally occurs in advanced MDS.

CASE SUMMARY

A 72-year-old male patient was definitively diagnosed with MDS with excess blasts-1 (MDS-EB-1) based on an increase in the percentages of myeloblasts and cluster of differentiation (CD)34+ hematopoietic progenitors and the identification of myeloid neoplasm-associated somatic mutations in bone marrow samples. The patient was treated with hypomethylation therapy and was able to maintain a steady disease state for 2 years. In the treatment process, the advanced MDS patient experienced an episode of progressive pancytopenia and bone marrow aplasia. During the aplastic crisis, the bone marrow was infiltrated with sparsely distributed atypical lymphocytes. Surprisingly, the leukemic cells disappeared. Immunological analysis revealed that the atypical lymphocytes expressed a high frequency of CD3, CD5, CD8, CD16, CD56 and CD57, suggesting the activation of autoimmune cytotoxic T-lymphocytes and natural killer (NK)/NKT cells that suppressed both normal and leukemic hematopoiesis. Elevated serum levels of inflammatory cytokines, including interleukin (IL)-6, interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α), confirmed the deranged type I immune responses. This morphological and immunological signature led to the diagnosis of severe aplastic anemia secondary to large granule lymphocyte leukemia. Disseminated tuberculosis was suspected upon radiological examinations in the search for an inflammatory niche. Antituberculosis treatment led to reversion of the aplastic crisis, disappearance of the atypical lymphocytes, increased marrow cellularity and 2 mo of hematological remission, providing strong evidence that disseminated tuberculosis was responsible for the development of the aplastic crisis, the regression of leukemic cells and the activation of CD56+ atypical lymphocytes. Reinstitution of hypomethylation therapy in the following 19 mo allowed the patient to maintain a steady disease state. However, the patient transformed the disease phenotype into acute myeloid leukemia and eventually died of disease progression and an overwhelming infectious episode.

CONCLUSION

Disseminated tuberculosis can induce CD56+ lymphocyte infiltration in the bone marrow and in turn suppress both normal and leukemic hematopoiesis, resulting in the development of aplastic crisis and leukemic cell regression.

Severe persistent mycobacteria antigen stimulation causes lymphopenia through impairing hematopoiesis

Miliary tubersculosis (TB), an acute systemic blood disseminated tuberculosis mainly caused by Mycobacterium tuberculosis (M. tuberculosis), can cause signs of lymphopenia in clinical patients. To investigate whether/how persistent mycobacteria antigen stimulation impairs hematopoiesis and the therapeutic effect of interleukin-7 (IL-7), a mouse model of Mycobacterium Bovis Bacillus Calmette-Guérin (BCG) intravenous infection with/without an additional stimulation with M. tuberculosis multi-antigen cocktail containing ESAT6-CFP10 (EC) and Mtb10.4-HspX (MH) was established. Consistent with what happened in miliary TB, high dose of BCG intravenous infection with/without additional antigen stimulation caused lymphopenia in peripheral blood. In which, the levels of cytokines IFN-γ and TNF-α in serum increased, and consequently the expression levels of transcription factors Batf2 and IRF8 involved in myeloid differentiation were up-regulated, while the expression levels of transcription factors GATA2 and NOTCH1 involved in lymphoid commitment were down-regulated, and the proliferating activity of bone marrow (BM) lineage^- c-Kit⁺ (LK) cells decreased. Furthermore, recombinant Adeno-Associated Virus 2-mediated IL-7 (rAAV2-IL-7) treatment could significantly promote the elevation of BM lymphoid progenitors. It suggests that persistent mycobacteria antigen stimulation impaired lymphopoiesis of BM hematopoiesis, which could be restored by complement of IL-7.

The role of inflammation in hematopoiesis and bone marrow failure: What can we learn from mouse models?

Hematopoiesis is a remarkable system that plays an important role in not only immune cell function, but also in nutrient transport, hemostasis and wound healing among other functions. Under inflammatory conditions, steady-state hematopoiesis switches to emergency myelopoiesis to give rise to the effector cell types necessary to fight the acute insult. Sustained or aberrant exposure to inflammatory signals has detrimental effects on the hematopoietic system, leading to increased proliferation, DNA damage, different forms of cell death (i.e., apoptosis, pyroptosis and necroptosis) and bone marrow microenvironment modifications. Together, all these changes can cause premature loss of hematopoiesis function. Especially in individuals with inherited bone marrow failure syndromes or immune-mediated aplastic anemia, chronic inflammatory signals may thus aggravate cytopenias and accelerate disease progression. However, the understanding of the inflammation roles in bone marrow failure remains limited. In this review, we summarize the different mechanisms found in mouse models regarding to inflammatory bone marrow failure and discuss implications for future research and clinical practice.

Intravesical High Dose BCG Tokyo and Low Dose BCG Tokyo with GMCSF+IFN α Induce Systemic Immunity in a Murine Orthotopic Bladder Cancer Model

This study evaluates a short therapy schedule for bladder cancer using BCG Tokyo. BCG Tokyo was evaluated in vitro using bone marrow derived dendritic cells, neutrophils, RAW macrophages and the murine bladder cancer cell line, MB49PSA, and compared to other BCG strains. BCG Tokyo > BCG TICE at inducing cytokine production. In vivo, high dose (1 × 10⁷ colony forming units (cfu)) and low dose (1 × 10⁶ cfu) BCG Tokyo with and without cytokine genes (GMCSF + IFNα) were evaluated in C57BL/6J mice (n = 12–16 per group) with orthotopically implanted MB49PSA cells. Mice were treated with four instillations of cytokine gene therapy and BCG therapy. Both high dose BCG alone and low dose BCG combined with cytokine gene therapy were similarly effective. In the second part the responsive groups, mice (n = 27) were monitored by urinary PSA analysis for a further 7 weeks after therapy cessation. More mice were cured at day 84 than at day 42 confirming activation of the immune system. Cured mice resisted the re-challenge with subcutaneous tumors unlike naïve, age matched mice. Antigen specific T cells recognizing BCG, HY and PSA were identified. Thus, fewer intravesical instillations, with high dose BCG Tokyo or low dose BCG Tokyo with GMCSF + IFNα gene therapy, can induce effective systemic immunity.

Common Sources of Inflammation and Their Impact on Hematopoietic Stem Cell Biology

Purpose of Review

Inflammatory signals have emerged as critical regulators of hematopoietic stem cell (HSC) function. Specifically, HSCs are highly responsive to acute changes in systemic inflammation and this influences not only their division rate but also their lineage fate. Identifying how inflammation regulates HSCs and shapes the blood system is crucial to understanding the mechanisms underpinning these processes, as well as potential links between them.

Recent Findings

A widening array of physiologic and pathologic processes involving heightened inflammation are now recognized to critically affect HSC biology and blood lineage production. Conditions documented to affect HSC function include not only acute and chronic infections but also autoinflammatory conditions, irradiation injury, and physiologic states such as aging and obesity.

Summary

Recognizing the contexts during which inflammation affects primitive hematopoiesis is essential to improving our understanding of HSC biology and informing new therapeutic interventions against maladaptive hematopoiesis that occurs during inflammatory diseases, infections, and cancer-related disorders.

Calf thymus polypeptide improved hematopoiesis via regulating colony-stimulating factors in BALB/c mice with hematopoietic dysfunction

Calf thymus polypeptide (CTP) is prepared from calf thymus. It has a molecular mass of <10 kilodalton (kDa) and contains 17 types of amino acids. This study investigated the hematopoietic function-improvement effect of CTP in CHRF, K562, and bone marrow mononuclear cells; mice with immunosuppression; and with hematopoietic dysfunction. In mice with immunosuppression, CTP enhanced the cytotoxic activity of natural killer cells and the proliferation of lymphocytes and regulated the levels of immunoglobulins. It also enhanced the proliferation and differentiation of CHRF and K562 cells by upregulating the expression of proliferation- and differentiation-related proteins. In mice with hematopoietic dysfunction, CTP restored white blood cell, neutrophil, and hemoglobin proportions in the peripheral blood and enhanced the levels of B lymphocytes and hematopoietic stem cells and progenitor cells in the bone marrow. CTP effectively regulated the levels of hematopoiesis-related cytokines, such as granulocyte colony-stimulating factor (G-CSF), macrophage colony-stimulating factor (M-CSF), interleukin 2, and interferons-γ, and enhanced the expression of hematopoiesis-related proteins in both primary bone marrow cells and mice with hematopoietic dysfunction. These results indicate that CTP has hematopoietic function-improvement effect and this effect may be related to the modulation of colony-stimulating factors (CSFs) and related signaling pathways.

IL-2 Restores T-Cell Dysfunction Induced by Persistent Mycobacterium tuberculosis Antigen Stimulation

Tuberculosis (TB) is a chronic disease mainly caused by Mycobacterium tuberculosis. The function of T cells usually decreased and even exhausted in severe TB such as multiple drug resistant TB (MDR-TB), which might lead to the failure of treatment in return. The mechanism of T cell dysfunction in TB is still not clear. In this study we set up a mouse model of T cell dysfunction by persistent M. tuberculosis antigen stimulation and investigated the therapeutic role of interleukin 2 (IL-2) in it. C57BL/6 mice were primed with Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and boosted repeatedly with a combination of M. tuberculosis fusion proteins Mtb10.4-HspX (MH) plus ESAT6-Ag85B-MPT64 _<190-198>-Mtb8.4-Rv2626c (LT70) or MH plus ESAT6 and CFP10 with adjuvant of N, N'-dimethyl-N, N'-dioctadecylammonium bromide (DDA) plus polyinosinic-polycytidylic acid (Poly I:C). Following persistent antigen stimulation, the mice were treated with IL-2 and the therapeutic effects were analyzed. The results showed that compared with the mice that received transient antigen stimulation (boost twice), persistent antigen stimulation (boost more than 10 times) resulted in decrease of antigen specific IFN-γ and IL-2 production, reduction of memory CD8⁺ T cells, over-expression of immune checkpoint programmed cell death protein 1 (PD-1), and impaired the protective immunity against bacterial challenge. Treating the T cell functionally exhausted mice with IL-2 restored antigen-specific T cell responses and protective efficacy. In conclusion, persistent stimulation with M. tuberculosis antigens induced T cell dysfunction, which could be restored by complement of IL-2.