Influence of Human Bone Marrow Mesenchymal Stem Cells Secretome from Acute Myeloid Leukemia Patients on the Proliferation and Death of K562 and K562-Lucena Leukemia Cell Lineages.

Leukemias are among the most prevalent types of cancer worldwide. Bone marrow mesenchymal stem cells (MSCs) participate in the development of a suitable niche for hematopoietic stem cells, and are involved in the development of diseases such as leukemias, to a yet unknown extent. Here we described the effect of secretome of bone marrow MSCs obtained from healthy donors and from patients with acute myeloid leukemia (AML) on leukemic cell lineages, sensitive (K562) or resistant (K562-Lucena) to chemotherapy drugs. Cell proliferation, viability and death were evaluated, together with cell cycle, cytokine production and gene expression of ABC transporters and cyclins. The secretome of healthy MSCs decreased proliferation and viability of both K562 and K562-Lucena cells; moreover, an increase in apoptosis and necrosis rates was observed, together with the activation of caspase 3/7, cell cycle arrest in G0/G1 phase and changes in expression of several ABC proteins and cyclins D1 and D2. These effects were not observed using the secretome of MSCs derived from AML patients. In conclusion, the secretome of healthy MSCs have the capacity to inhibit the development of leukemia cells, at least in the studied conditions. However, MSCs from AML patients seem to have lost this capacity, and could therefore contribute to the development of leukemia.

Predictors of Survival, Treatment Modalities, and Clinical Outcomes of Diffuse Large B-Cell Lymphoma in Patients Older Than 70 Years Still an Unmet Medical Need in 2024 Based on Real-World Evidence.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) especially affects the older population. Old (≥60 years) and very old age (≥80 years) DLBCL patients often present high-risk molecular alterations, lower tolerability to conventional immunochemotherapy, and poor clinical outcomes. In this scenario, attenuated therapeutic strategies, such as the R-MiniCHOP and R-MiniCHOP of the elderly regimens, have emerged for this particularly fragile population. However, the responses, clinical outcomes, and toxicities of these regimens currently remain poorly understood, mainly because these individuals are not usually included in controlled clinical trials. METHODS: This retrospective, observational, and single-center real-world study included 185 DLBCL, NOS patients older than 70 years treated at the largest oncology center in Latin America from 2009 to 2020. We aimed to assess the outcomes, determine survival predictors, and compare responses and toxicities between three different primary therapeutic strategies, including the conventional R-CHOP regimen and the attenuated R-MiniCHOP and R-MiniCHOP of the elderly protocols. RESULTS: The median age at diagnosis was 75 years (70-97 years), and 58.9% were female. Comorbidities were prevalent, including 19.5% with immobility, 28.1% with malnutrition, and 24.8% with polypharmacy. Advanced clinical stage was observed in 72.4%, 48.6% had bulky disease ≥7 cm, 63.2% had B-symptoms, and 67.0% presented intermediate-high/high-risk IPI. With a median follow-up of 6.3 years, the estimated 5-year OS and PFS were 50.2% and 44.6%, respectively. The R-MiniCHOP of the elderly regimen had a lower ORR (p = 0.040); however, patients in this group had higher rates of unfavorable clinical and laboratory findings, including hypoalbuminemia (p = 0.001), IPI ≥ 3 (p = 0.013), and NCCN-IPI ≥ 3 (p = 0.002). Although associated with higher rates of severe neutropenia (p = 0.003), the R-CHOP regimen promoted increased OS (p = 0.003) and PFS (p = 0.005) in comparison to the attenuated protocols. Additionally, age ≥ 75 years, high levels of LDH, B-symptoms, advanced clinical stage (III/IV), neutrophilia, and low lymphocyte/monocyte ratio were identified as poor prognostic factors in this cohort. CONCLUSIONS: In this large and real-life Latin American cohort, we demonstrated that patients with DLBCL, NOS older than 70 years still do not have satisfactory clinical outcomes in 2024, with half of cases not reaching 5 years of life expectancy after diagnosis. Although the conventional R-CHOP offers response and survival advantages over attenuated regimens, its myelotoxicity is not negligible. Therefore, the outcomes reported and the prognostic factors here identified may assist clinicians in the appropriate selection of therapeutic strategies adapted to the risk for old and very old DLBCL patients.

Effect of adjuvant probiotic therapy (Lactobacillus reuteri) in the treatment of periodontitis associated with diabetes mellitus: clinical, controlled, and randomized study.

OBJECTIVES: Subgingival instrumentation (SI) with probiotics may be a proposal for the treatment of periodontitis (P), for patients with type 2 diabetes mellitus (T2DM). The Lactobacillus reuteri probiotic as an adjunctive therapy in the treatment of P associated with T2DM was evaluated. MATERIALS AND METHODS: Forty diabetic participants diagnosed with P (stage III and IV, grade B) were randomized into SI + Placebo (n = 20): subgingival instrumentation plus placebo lozenges and SI + Probi (n = 20): subgingival instrumentation plus probiotics. Probing depth (PD), gingival recession (GR), clinical attachment level (CAL), plaque index (PI), bleeding on probing (BoP), and PISA index were performed at baseline and 30, 90, and 180 days. Cytokine concentration in the gingival crevicular fluid, subgingival biofilm sample, and LDL and HDL subfractions were evaluated. RESULTS: In the deep pockets, PD in SI + Probi showed increased values (p = 0.02) compared to SI + Placebo at 90 days. For CAL, SI + Probi showed increased values compared to SI + Placebo, with a significant difference at 30 days (p = 0.03), 90 days (p = 0.02), and 180 days (p = 0.04). At #PD ≥ 7 mm, SI + Probi had a more frequent number of sites (p = 0.03) compared to SI + Placebo only at baseline. For the PISA, SI + Probi showed a significant difference (p = 0.04) compared to SI + Placebo at 90 days. For cytokines, SI + Probi showed higher quantification than SI + Placebo for IL-10 (p < 0.001) at 90 days, IL-12 (p = 0.010) at 90 days, IL-1ß (p = 0.035) at 90 days, and IL-8 (p = 0.003) at baseline. SI + Placebo showed higher quantification of IL-1ß (p = 0.041) compared to SI + Probi only at 30 days. There was a reduction in all microbial complexes. SI + Probi improved LDL size (246.7 nm vs 260.4 nm; p < 0.001), while large HDL subfractions were reduced aft 180 days of treatment (24.0% vs 20.3%; p = 0.022) when compared with SI + Placebo; this response was dependent of probiotics (1.0 mg/dL vs - 6.2 mg/dL; p = 0.002). CONCLUSION: Subgingival instrumentation improved the clinical periodontal parameters in patients with T2DM. The use of L. reuteri probiotics had no additional effects compared with the placebo; however, there was a positive effect on the lipoprotein subfraction. CLINICAL RELEVANCE: Scientific rationale for study: subgingival instrumentation with probiotics may be a proposal for the treatment of periodontitis (P), especially for patients with type 2 diabetes mellitus (T2DM). PRINCIPAL FINDINGS: the use of L. reuteri probiotics had no additional effects compared with the placebo; however, there was a positive effect on the lipoprotein subfraction.  Practical implications: L. reuteri as an adjunct to subgingival instrumentation may have significant therapeutic implications in dyslipidemia.

Up-Front ASCT Overcomes the Survival Benefit Provided by HDAC-Based Induction Regimens in Mantle Cell Lymphoma: Data from a Real-Life and Long-Term Cohort.

BACKGROUND: Mantle cell lymphoma (MCL) is a rare malignancy with heterogeneous behavior. Despite the therapeutic advances recently achieved, MCL remains incurable. Currently, the standard of care for young and fit patients involves induction immunochemotherapy followed by up-front autologous stem cell transplantation (ASCT). However, the role of more intensive induction regimens, such as those based on high doses of cytarabine (HDAC), remains controversial in the management of ASCT-eligible patients. METHODS: This retrospective, observational, and single-center study involved 165 MCL patients treated at the largest oncology center in Latin America from 2010 to 2022. We aimed to assess outcomes, determine survival predictors, and compare responses between different primary therapeutic strategies, with a focus on assessing the impact of HDAC-based regimens on outcomes in ASCT-eligible patients. RESULTS: The median age at diagnosis was 65 years (38-89 years), and 73.9% were male. More than 90% of the cases had a classic nodal form (cnMCL), 76.4% had BM infiltration, and 56.4% presented splenomegaly. Bulky ≥ 7 cm, B-symptoms, ECOG ≥ 2, and advanced-stage III/IV were observed in 32.7%, 64.8%, 32.1%, and 95.8%, respectively. Sixty-four percent of patients were categorized as having high-risk MIPI. With a median follow-up of 71.1 months, the estimated 2-year OS and EFS were 64.1% and 31.8%, respectively. Patients treated with (R)-HDAC-based regimens had a higher ORR (85.9% vs. 65.7%, p = 0.007) compared to those receiving (R)-CHOP, as well as lower POD-24 rates (61.9% vs. 80.4%, p = 0.043) and lower mortality (43.9% vs. 68.6%, p = 0.004). However, intensified induction regimens with (R)-HDAC were not associated with a real OS benefit in MCL patients undergoing up-front consolidation with ASCT (2-year OS: 88.7% vs. 78.8%, p = 0.289). Up-front ASCT was independently associated with increased OS (p < 0.001), EFS (p = 0.005), and lower POD-24 rates (p < 0.001) in MCL. Additionally, CNS infiltration, TLS, hypoalbuminemia, and the absence of remission after induction were predictors of poor OS. CONCLUSIONS: In the largest Latin American cohort of MCL patients, we confirmed the OS benefit promoted by up-front consolidation with ASCT in young and fit patients, regardless of the intensity of the immunochemotherapy regimen used in the pre-ASCT induction. Although HDAC-based regimens were not associated with an unequivocal increase in OS for ASCT-eligible patients, it was associated with higher ORR and lower rates of early relapses for the whole cohort.

Angioimmunoblastic T-cell lymphoma and correlated neoplasms with T-cell follicular helper phenotype: from molecular mechanisms to therapeutic advances.

Angioimmunoblastic T-cell lymphoma (AITL) is the second most frequent subtype of mature T-cell lymphoma (MTCL) in the Western world. It derives from the monoclonal proliferation of T-follicular helper (TFH) cells and is characterized by an exacerbated inflammatory response and immune dysregulation, with predisposition to autoimmunity phenomena and recurrent infections. Its genesis is based on a multistep integrative model, where age-related and initiator mutations involve epigenetic regulatory genes, such as TET-2 and DNMT3A. Subsequently, driver-mutations, such as RhoA G17V and IDH-2 R172K/S promote the expansion of clonal TFH-cells ("second-hit"), that finally begin to secrete cytokines and chemokines, such as IL-6, IL-21, CXCL-13 and VEGF, modulating a network of complex relationships between TFH-cells and a defective tumor microenvironment (TME), characterized by expansion of follicular dendritic cells (FDC), vessels and EBV-positive immunoblasts. This unique pathogenesis leads to peculiar clinical manifestations, generating the so-called "immunodysplastic syndrome", typical of AITL. Its differential diagnosis is broad, involving viral infections, collagenosis and adverse drug reactions, which led many authors to use the term "many-faced lymphoma" when referring to AITL. Although great advances in its biological knowledge have been obtained in the last two decades, its treatment is still an unmet medical need, with highly reserved clinical outcomes. Outside the setting of clinical trials, AITL patients are still treated with multidrug therapy based on anthracyclines (CHOP-like), followed by up-front consolidation with autologous stem cell transplantation (ASCT). In this setting, the estimated 5-year overall survival (OS) is around 30-40%. New drugs, such as hypomethylating agents (HMAs) and histone deacetylase inhibitors (HDAi), have been used for relapsed/refractory (R/R) disease with promising results. Such agents have their use based on a biological rationale, have significant potential to improve the outcomes of patients with AITL and may represent a paradigm shift in the therapeutic approach to this lymphoma in the near future.

Tumor mutation burden involving epigenetic regulatory genes and the RhoA GTPase predicts overall survival in nodal mature T-cell lymphomas.

Nodal mature T-cell lymphomas (nMTCL) comprises a heterogeneous group of rare malignancies with aggressive biological behavior and poor prognosis. Epigenetic phenomena, including mutations in genes that control DNA methylation and histone deacetylation, in addition to inactivating mutations in the RhoA GTPase, play a central role in its pathogenesis and constitute potential new targets for therapeutic intervention. Tumor mutational burden (TMB) reflects the process of clonal evolution, predicts response to anti-cancer therapies and has emerged as a prognostic biomarker in several solid neoplasms; however, its potential prognostic impact remains unknown in nMTCL. In this study, we conducted Sanger sequencing of formalin-fixed paraffin-embedded (FFPE) diagnostic tumor samples using a target-panel to search for recurrent mutations involving the IDH-1/IDH-2, TET-2, DNMT3A and RhoA genes in 59 cases of nMTCL. For the first time, we demonstrated that high-TMB, defined by the presence of ≥ two mutations involving the aforementioned genes, was associated with decreased overall survival in nMTCL patients treated with CHOP-like regimens. Additionally, high-TMB was correlated with bulky disease, lower overall response rate, and higher mortality. Future studies using larger cohorts may validate our preliminary results that indicate TMB as a potential molecular biomarker associated with adverse prognosis in nMTCL.

High-dose extended-field radiotherapy plus chemotherapy improved survival in extranodal NK/T-cell lymphoma in a real-life setting: results from the multicenter T-Cell Brazil Project.

Extranodal natural-killer/T-cell lymphoma (ENKTL) is a rare and aggressive Epstein-Barr virus related mature T-cell and natural-killer malignancy. Although highly prevalent in South America, few studies covering data from this geographic location have been published. Therefore, this study aims to report clinical characteristics, prognostic factors, and outcomes in a multicenter cohort of ENKTL patients from Brazil. This retrospective, observational and multicenter study included 98 ENKTL patients treated during two decades in Brazil. Data were extracted from the T-Cell Brazil Project database. In our cohort, 59/98 patients (60.2%) were male, with a median age of 50 years. Sixty-two patients (63.3%) had B-symptoms, 26/98 (26.5%) had Eastern Cooperative Oncology Group scale ≥ 2; 16/98 (16.3%) presented extranasal disease and 34.7% (34/98) were advanced-stage (Ann Arbor/Cotswolds III/IV). The median follow-up for the whole cohort was 49 months, with an estimated 2-year overall survival (OS) and progression-free survival (PFS) of 51.1% and 17.7%, respectively. In early-stage disease (IE/IIE), the median OS was 21.8 months for patients treated with concurrent radiotherapy plus chemotherapy (CCRT-VIPD [etoposide/vp-16, ifosfamide, cisplatin and dexamethasone), 16.2 months for sequential chemoradiotherapy (SCRT) followed by asparaginase-based regimens, and 56.7 months for SCRT followed by CHOP-like (cyclophosphamide, doxorrubicin, vincristine and prednisone) treatments, p = 0.211. CCRT was associated with higher rates of early-mortality, hematological toxicity, and mucositis. Median OS was 8.2 months for patients with advanced-stage disease receiving regimens containing asparaginase compared to 3.2 months for anthracycline-based therapy, p = 0.851. Chemo-radiotherapy (CRT) regimens demonstrated better OS (p = 0.001) and PFS (p = 0.007) than chemotherapy alone. Multivariate analysis revealed anemia, relapsed/refractory (R/R) disease and radiotherapy omission as poor outcome predictors for OS. Lymphopenia and radiotherapy omission adversely affected PFS. Concerning progression of disease within 24-months (POD-24), clinical stage III/IV was a poor outcome predictor. In this real-life Brazilian cohort, ENKTL presented dismal outcomes. Radiation therapy was an independent factor for increased OS and PFS, but CCRT regimens were associated with higher toxicities. Polychemotherapy based on anti-multi drug resistant agents was not associated with survival benefit in either early or advanced-stage disease in our patient cohort.

The role of whole-brain radiotherapy (WBRT) in primary central nervous system lymphoma: is it an alternative to ASCT for consolidation following HD-methotrexate based induction in low-income settings?

BACKGROUND: Primary central nervous system lymphoma (PCNSL) is a rare and aggressive malignancy. Although potentially curable, its prognosis remains dismal. Its treatment is based on high-doses of methotrexate (HD-MTX) and rituximab, followed by consolidation therapy with whole-brain radiotherapy (WBRT) or autologous stem cell transplantation (ASCT). Currently, there is no consensus about the best consolidation strategy, but better outcomes with ASCT are obtained with conditioning regimens based on thiotepa, a high-cost drug with restricted use in resource-constrained settings. Latin American data on clinical outcomes, prognostic factors, and therapeutic management in PCNSL are virtually unknown. METHODS: This is a retrospective, observational, and single-center study involving 47-Brazilian patients with PCNSL. We aim to assess outcomes, determine predictors of survival, and compare responses, as well as toxicities in patients consolidated with chemotherapy alone versus chemotherapy plus WBRT. RESULTS: The median age at diagnosis was 59 years (24-88 years), and 53.1% were male. LDH ≥ UVN occurred in 44.7%, ECOG ≥ 2 in 67.6%, and 34.1% had multifocal disease. Hemiparesis was the main clinical presentation, observed in 55.3%, 51.0% had intermediate-/high-risk IELSG prognostic score, and 57.6% had an ABC-like phenotype by IHC. With a median follow-up of 24.4 months, estimated 5-year OS and PFS were 45.5% and 36.4%, respectively. Among 40 patients treated with HD-MTX-based induction, estimated 2-year OS was 85.8% for those consolidated with WBRT plus HIDAC versus only 41.5% for those consolidated with HIDAC alone (p < 0.001). Hematologic and non-hematologic toxicities were not significant, and severe cognitive impairment occurred in only 6.3% (3/47) of cases, all of them treated with WBRT. Age < 60 years, Hb ≥ 120 g/L and WBRT consolidation were associated with increased OS, however, LDH ≥ UVN, hypoalbuminemia, ECOG ≥ 2, Karnofsky PS < 70 and intermediate-/high-risk Barcelona score were associated with decreased OS. CONCLUSION: Combined consolidation therapy (CCT) based on WBRT plus HIDAC was associated with increased OS in PCNSL compared to isolated consolidation therapy (ICT) based on HIDAC alone. Here, severe late neurotoxicity was uncommon with this approach. These data suggest that WBRT may be an effective and safe alternative to ASCT for consolidation therapy in PCNSL, particularly in resource-constrained settings, where access to thiotepa for pre-ASCT conditioning is not universal.

Up-front Therapy With CHOP Plus Etoposide in Brazilian nodal PTCL Patients: Increased Toxicity and No Survival Benefit Compared to CHOP Regimen-Results of a Real-Life Study From a Middle-Income Country.

BACKGROUND: Nodal peripheral T-cell lymphoma (nPTCL) constitute a heterogeneous group of neoplasms with aggressive behavior and poor-survival. They are more prevalent in Latin America and Asia, although data from Brazil are scarce. Its primary therapy is still controversial and ineffective. Therefore, we aim to describe clinical-epidemiological characteristics, outcomes, predictors factors for survival and compare the results of patients treated with CHOP and CHOEP regimens. METHODS: Retrospective, observational and single-center study involving 124 nPTCL patients from Brazil treated from 2000 to 2019. RESULTS: With a median follow-up of 23.7 months, the estimated 2-year overall survival (OS) and progression-free survival (PFS) were 59.2% and 37.3%, respectively. The median age was 48.5 years and 57.3% (71/124) were male, 81.5% (101/124) had B-symptoms, 88.7% (110/124) had advanced disease (stage III/IV) and 58.1% (72/124) presented International Prognostic Index (IPI) score ≥3, reflecting a real-life cohort. ORR to first-line therapy was 58.9%, 37.9% (N = 47) received CHOP-21 and 35.5% (N = 44) were treated with CHOEP-21; 30.1% (37/124) underwent to consolidation with involved field radiotherapy (IF-RT) and 32.3% (40/124) were consolidated with autologous hematopoietic stem cell transplantation (ASCT). The overall response rate (ORR) was similar for CHOP-21 (76.6%) and CHOEP-21 (65.9%), P = .259. Refractory disease was less frequent in the CHOEP-21 group (4.5% vs. 21.2%, P = .018). However, few patients were able to complete 6-cycles of CHOEP-21 (31.8%) than to CHOP-21 (61.7%), P = .003. Delays ≥2 weeks among the cycles of chemotherapy were more frequent for patients receiving CHOEP-21 (43.1% vs. 10.6%), P = .0004, as well as the toxicities, including G3-4 neutropenia (88% vs. 57%, P = .001), febrile neutropenia (70% vs. 38%, P = .003) and G3-4 thrombocytopenia (63% vs. 27%, P = .0007). The 2-year OS was higher for CHOP (78.7%) than CHOEP group (61.4%), P = .05, as well as 2-year PFS (69.7% vs. 25.0%, P < .0001). In multivariate analysis, high LDH (HR 3.38, P = .007) was associated with decreased OS. CR at first line (HR: 0.09, P < .001) and consolidation with ASCT (HR: 0.08, P = .015) were predictors of increased OS. CONCLUSION: In the largest cohort of nPTCL from Latin America, patients had poor survival and high rate of chemo-resistance. In our cohort, the addition of etoposide to the CHOP-21 backbone showed no survival benefit and was associated with high-toxicity and frequent treatment interruptions. Normal LDH values, obtaintion of CR and consolidation with ASCT were independent factors associated with better outcomes.

Effects of Oxysterols on Immune Cells and Related Diseases.

Oxysterols are the products of cholesterol oxidation. They have a wide range of effects on several cells, organs, and systems in the body. Oxysterols also have an influence on the physiology of the immune system, from immune cell maturation and migration to innate and humoral immune responses. In this regard, oxysterols have been involved in several diseases that have an immune component, from autoimmune and neurodegenerative diseases to inflammatory diseases, atherosclerosis, and cancer. Here, we review data on the participation of oxysterols, mainly 25-hydroxycholesterol and 7α,25-dihydroxycholesterol, in the immune system and related diseases. The effects of these oxysterols and main oxysterol receptors, LXR and EBI2, in cells of the immune system (B cells, T cells, macrophages, dendritic cells, oligodendrocytes, and astrocytes), and in immune-related diseases, such as neurodegenerative diseases, intestinal diseases, cancer, respiratory diseases, and atherosclerosis, are discussed.

"H" is not for hydroxychloroquine-"H" is for heparin: lack of efficacy of hydroxychloroquine and the role of heparin in COVID-19-preliminary data of a prospective and interventional study from Brazil.

BACKGROUND: COVID-19 pandemic is the major public health problem in the world actually. It's associated with high morbidity and mortality. To date, no therapeutic measure has a curative potential. Hydroxychloroquine (HCQ) is a drug with immunomodulatory properties that has demonstrated antiviral efficacy in in vitro experiments, with conflicting results in in vivo studies. METHODS: A single-center, prospective and interventional study, that evaluates the impact on mortality of the HCQ use in 154 patients hospitalized with COVID-19 in a Brazilian public hospital. The study also aims to determine prognostic factors that predict mortality, ICU admission and endotracheal intubation in this population. RESULTS: 154 patients diagnosed with COVID-19 confirmed by RT-PCR and hospitalized were included. There was a male predominance (87/154, 56.5%), median age 60 years and 88% (136/154) had comorbidities. Among these, 76% (117/154) were admitted to the ICU and 29.2% (45/154) experienced EOT. The OMR was 51.3% (79/154). There was no difference in mortality between patients treated with HCQ (N = 95) and non-HCQ (N = 59) (44.1% × 55.8%, p = 0.758). In univariate analysis, age ≥ 60 years (HR 3.62, p < 0.001), need for mechanical ventilation (HR 2.17, p = 0.001), ≥ 2 comorbidities (HR 1.83, p = 0.049), SAH (HR: 1.56, p = 0.054) were predictors of mortality, as well as no use of prophylactic or therapeutic heparin (HR 3.60, p = 0.02). Multivariate analysis identified admission to the ICU (HR 8.98, p = 0.002) and advanced age (HR 3.37, p < 0.01) as independent predictors of mortality, although, use of heparin (HR 0.25, p = 0.001) was independently associated with a favorable outcome. CONCLUSION: This study confirmed the absence of a benefit associated with the use of HCQ in Brazilian patients hospitalized with COVID-19. However, prophylactic or therapeutic heparin was an independent predictor for reducing mortality in this population.

Oxysterols and mesenchymal stem cell biology.

Mesenchymal stem cells have the ability to differentiate into several cell types when exposed to determined substances, including oxysterols. Oxysterols are cholesterol products derived from its auto-oxidation by reactive species or from enzymatic action. They are present in the body in low quantities under physiological conditions and exhibit several physiological and pharmacological actions according to both the types of oxysterol and tissue. Some of them are cytotoxic while others have been shown to promote cell differentiation through the action on several different receptors, such as nuclear LXR receptors and Smoothened receptor ligands. Here, we review the main pathways by which oxysterols have been associated with cell differentiation and death of mesenchymal stem cells.

Paraoxonase Role in Human Neurodegenerative Diseases.

The human body has biological redox systems capable of preventing or mitigating the damage caused by increased oxidative stress throughout life. One of them are the paraoxonase (PON) enzymes. The PONs genetic cluster is made up of three members (PON1, PON2, PON3) that share a structural homology, located adjacent to chromosome seven. The most studied enzyme is PON1, which is associated with high density lipoprotein (HDL), having paraoxonase, arylesterase and lactonase activities. Due to these characteristics, the enzyme PON1 has been associated with the development of neurodegenerative diseases. Here we update the knowledge about the association of PON enzymes and their polymorphisms and the development of multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and Parkinson's disease (PD).

Ferroptosis Mechanisms Involved in Neurodegenerative Diseases.

Ferroptosis is a type of cell death that was described less than a decade ago. It is caused by the excess of free intracellular iron that leads to lipid (hydro) peroxidation. Iron is essential as a redox metal in several physiological functions. The brain is one of the organs known to be affected by iron homeostatic balance disruption. Since the 1960s, increased concentration of iron in the central nervous system has been associated with oxidative stress, oxidation of proteins and lipids, and cell death. Here, we review the main mechanisms involved in the process of ferroptosis such as lipid peroxidation, glutathione peroxidase 4 enzyme activity, and iron metabolism. Moreover, the association of ferroptosis with the pathophysiology of some neurodegenerative diseases, namely Alzheimer's, Parkinson's, and Huntington's diseases, has also been addressed.

Paraoxonases (PON) 1, 2, and 3 Polymorphisms and PON-1 Activities in Patients with Sickle Cell Disease.

(1) Background: Oxidative stress, chronic inflammation, vasoocclusion, and free iron are all features present in sickle cell disease. Paraoxonases (PON) are a family (PON-1, PON-2, PON-3) of antioxidant enzymes with anti-inflammatory action. Here, for the first time, we described PON-1 activities and PON-1, PON-2, PON-3 polymorphisms in patients with sickle cell disease, homozygous for HbSS, compared with healthy controls. (2) Methods: The groups were matched for age and gender. PON-1 activities (arylesterase and paraoxonase) were determined by enzymatic hydrolysis of phenylcetate and paraoxon, respectively. Polymorphisms were determined by Restriction Fragment Length Polymorphism- Polymerase Chain Reaction (RFLP-PCR). (3) Results: Plasma cholesterol and fractions, ApoA1 and ApoB levels were all decreased in sickle cell disease patients, while anti-oxidized low-density lipoprotein (LDL) antibodies and C-reactive protein were increased. Serum arylesterase activity was lower in sickle cell disease patients when compared with healthy controls. In patients, paraoxonase activity was higher in those with PON-1 RR Q192R polymorphism. In these patients, the increase of serum iron and ferritin levels and transferrin saturation were less pronounced than those observed in patients with QQ or QR polymorphism. No differences were observed with PON-1 L55M, and PON-2 and PON-3 polymorphisms. Multivariate regression analysis showed that transferrin and ferritin concentrations correlated with arylesterase and paraoxonase activities. (4) Conclusions: Both transferrin and ferritin were the main predictors of decreased arylesterase and paraoxonase activities in patients with sickle cell disease. LDL oxidation increased, and RR PON-1 Q192R polymorphism is likely to be a protective factor against oxidative damage in these patients.

Paraoxonases Activities and Polymorphisms in Elderly and Old-Age Diseases: An Overview.

Aging is defined as the accumulation of progressive organ dysfunction. There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. With increasing age, susceptibility to the development of diseases related to lipid peroxidation and tissue injury increases, due to chronic inflammatory processes, and production of reactive oxygen species (ROS) and free radicals. The paraoxonase (PON) gene family is composed of three members (PON1, PON2, PON3) that share considerable structural homology and are located adjacently on chromosome 7 in humans. The most studied member product is PON1, a protein associated with high-density lipoprotein with paraoxonase/esterase activity. Nevertheless, all the three proteins prevent oxidative stress. The major aim of this review is to highlight the importance of the role of PON enzymes in the aging process, and in the development of the main diseases present in the elderly: cardiovascular disease, diabetes mellitus, neurodegenerative diseases, and cancer.

7-Ketocholesterol Promotes Oxiapoptophagy in Bone Marrow Mesenchymal Stem Cell from Patients with Acute Myeloid Leukemia.

7-Ketocholesterol (7-KC) is a cholesterol oxidation product with several biological functions. 7-KC has the capacity to cause cell death depending on the concentration and specific cell type. Mesenchymal stem cells (MSCs) are multipotent cells with the ability to differentiate into various types of cells, such as osteoblasts and adipocytes, among others. MSCs contribute to the development of a suitable niche for hematopoietic stem cells, and are involved in the development of diseases, such as leukemia, to a yet unknown extent. Here, we describe the effect of 7-KC on the death of bone marrow MSCs from patients with acute myeloid leukemia (LMSCs). LMSCs were less susceptible to the death-promoting effect of 7-KC than other cell types. 7-KC exposure triggered the extrinsic pathway of apoptosis with an increase in activated caspase-8 and caspase-3 activity. Mechanisms other than caspase-dependent pathways were involved. 7-KC increased ROS generation by LMSCs, which was related to decreased cell viability. 7-KC also led to disruption of the cytoskeleton of LMSCs, increased the number of cells in S phase, and decreased the number of cells in the G1/S transition. Autophagosome accumulation was also observed. 7-KC downregulated the SHh protein in LMSCs but did not change the expression of SMO. In conclusion, oxiapoptophagy (OXIdative stress + APOPTOsis + autophagy) seems to be activated by 7-KC in LMSCs. More studies are needed to better understand the role of 7-KC in the death of LMSCs and the possible effects on the SHh pathway.

Hepcidin: Homeostasis and Diseases Related to Iron Metabolism.

Iron is an essential metal for cell survival that is regulated by the peptide hormone hepcidin. However, its influence on certain diseases is directly related to iron metabolism or secondary to underlying diseases. Genetic alterations influence the serum hepcidin concentration, which can lead to an iron overload in tissues, as observed in haemochromatosis, in which serum hepcidin or defective hepcidin synthesis is observed. Another genetic imbalance of iron is iron-refractory anaemia, in which serum concentrations of hepcidin are increased, precluding the flow and efflux of extra- and intracellular iron. During the pathogenesis of certain diseases, the resulting oxidative stress, as well as the increase in inflammatory cytokines, influences the transcription of the HAMP gene to generate a secondary anaemia due to the increase in the serum concentration of hepcidin. To date, there is no available drug to inhibit or enhance hepcidin transcription, mostly due to the cytotoxicity described in the in vitro models. The proposed therapeutic targets are still in the early stages of clinical trials. Some candidates are promising, such as heparin derivatives and minihepcidins. This review describes the main pathways of systemic and genetic regulation of hepcidin, as well as its influence on the disorders related to iron metabolism.