Browsing by Autor "Luis Felipe Mamani"

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Acute promyelocytic leukemia incidence in Andean highlanders with the NFKB1 haplotype (rs230511)
(Elsevier BV, 2025) Ricardo Amaru; Victor R. Gordeuk; Julieta Luna; Edgar Teddy Quispe Soto; Silvia Mancilla; Javier Valencia; Luis Felipe Mamani; Daniela Patón; Ariel Amaru
Abstract Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML), characterized by the oncogenic fusion protein PML-RARα, which results from the t(15;17) chromosomal translocation. APL accounts for approximately 4-10% of AML cases worldwide. The median age at diagnosis falls around the fifth decade of life, with a slight male predominance (PMID: 39682277). The PML-RARα fusion protein plays an essential role in the pathogenesis of APL by enhancing hypoxia-inducible factor (HIF)-driven transcriptional activity. PML-RARα acts as a transcriptional co-activator of HIF-α, amplifying HIF-mediated transcription independently of PML protein inhibition. This activation is unique to APL-specific fusion proteins; it is absent in other AML subtypes. The interaction of PML-RARα and HIF factors significantly influences disease progression and relapse. (PMID: 24711541). Transcriptomic analyses of APL cells reveal enrichment of NF-κB signaling pathways among differentially expressed genes, particularly those involved in cancer pathways. This suggests that NFKB1 contributes to the proliferative and survival signaling in APL cells (Villiers W, Nat. Commun, 2023). However, PML-RARα disrupts NF-κB activity by inhibiting phosphorylation and DNA binding of the NF-κB p65 subunit, suppressing NF-κB target gene expression. This disruption contributes to leukemogenesis through impaired differentiation and altered transcriptional regulation (Ahmed A, Sci.rep, March 2017). The incidence of APL varies across geographic regions and ethnic groups. Higher frequencies have been observed in Latin American populations compared to North America and Europe. These disparities suggest that genetic and environmental factors contribute to differences in disease distribution and outcomes (PMID: 12935956) and currently, there are no published data directly comparing APL incidence between populations living at sea level and those residing at high altitudes. We investigated the proportion of AML cases diagnosed as APL in Bolivian Andean highlanders residing at 4000 m, a population characterized by elevated HIF-α expression and a predominant NFKB1 haplotype rs230511 (95%) that results in a non-functional NFKB1 protein. We then compared the proportion of APL cases from Bolivian populations living at 2000m and 400 m. We analyzed 1,273 AML diagnoses from January 2000 to June 2025, grouped by altitude of residence: 406 at 4,000 m (mean age 37 years), 412 at 2,000 m (mean age 41 years), and 455 at 400 m (mean age 28 years). The overall mean age at AML diagnosis was 35 ± 25 years, with a male predominance of 54%. Among the total AML cases, 140 (11.0%) were identified as APL. We compared the proportion of AML cases classified as APL across three altitudes: at 4,000 m, 38 of 406 AML cases (9.4%) were APL; at 2,000 m, 46 of 412 cases (11.2%); and at 400 m, 56 of 455 cases (12.3%). There was a trend toward a lower proportion of APL cases at 4,000 m compared to 2,000 m and 400 m, although this difference was not statistically significant (P = 0.17). The age distribution of APL cases was as follows: 1-17 years, 44 cases (31.4%); 18-39 years, 59 cases (41.7%); 40–59 years, 30 cases (21.4%); and ≥60 years, 7 cases (5.0%). The age of AML patients was significantly lower at 400 m compared to the higher altitudes, whereas the proportion of males did not differ significantly by altitude. ConclusionsThe APL tends to decrease with increasing altitude, consistent with genetic adaptations in high-altitude Andean populations (~4000 m) involving increased HIF activity and a specific NFKB1 haplotypeThe 25-year incidence of APL was significantly lower in the La Paz population at 4000 m compared to populations at lower elevations (P &lt; 0.020).Individuals younger than 40 years are disproportionately affected, representing 73.1% of APL cases. The increased incidence in younger age groups does not vary by altitude, suggesting that genetic factors may predominantly drive this demographic pattern.Investigating genetic adaptations in high-altitude populations could offer novel insights into APL pathobiology and therapeutic strategies.
Erythroid Leukemia Is Increased at High Altitude (4000 m)
(Elsevier BV, 2024) Ricardo Amaru; Maria Julieta Luna Leyza; Luis Felipe Mamani; Silvia Mancilla; Daniela Patón; Juan Carlos Valencia; Mireya Carrasco; Ariel Amaru
Acute erythroid leukemia (AEL) also known as pure erythroid leukemia (PEL) from the 2016 WHO update (PMID: 35264503; Wang, Am J Hematol. 2017; 92: 292-296) is a rare and unique subtype of acute myeloid leukemia (AML). It is characterized by immature erythroid precursors predominance with a high frequency of gains and amplifications involving EPOR/JAK2 (PMID: 35839275) and phosphorylation of ERK1/2 by inhibiting Fli-1 Promoter Activity (Min Mo, Catalysts, 2022. 13.1:84). AEL accounts for 1% of AML cases and can evolve from prior myelodysplastic syndrome or develop de novo, it is typically observed in adults with a median age ranging 66-68 years, and of dismal prognosis (&lt;6 months overall median survival) (PMID: 36323674). Its distinction attributes to erythroblastic proliferation (&gt;80%), pancytopenia, and extensive bone marrow involvement by proerythroblasts (≥30%). Common immunophenotype markers include CD105, CD34, CD71, CD36, CD235 (Wang, Am J Hematol. 2017). Moreover, it has been reported that hypoxia influences the development of erythroleukemia through various mechanisms, including promoting erythroid differentiation, inducing hemoglobin production, defining cell heterogeneity, regulating erythropoiesis, and influencing the bone marrow microenvironment (PMID: 33675821; 17255519). Regardingly, an overexpression of HIFs is related with a bad prognosis in AML (PMID: 25687039), HIF-1α is involved in cancer early stages, whereas HIF-2α in the later stages (PMID: 29753878). HIF-2a expression plays an important role in regulating proliferation in erythroleukemia cells under hypoxia (PMID: 26898802). Thus, we aimed to search for the hematologic and immunophenotypic characteristics of AEL cases among all AML diagnoses at high altitude. We retrospectively analyzed cases of AML diagnosed in Bolivia from the period of May 2019 to April 2024 considering the different altitudes 4000m (n=68), 2000m (n=62), and 400m (n=71), and gathered a comprehensive account of hematologic, bone marrow morphology, and immunophenotypic features. Among AML cases (n=201), 13 cases of AEL were identified which corresponded to 6.5 %. Interestingly, AEL cases at 4000 m accounted for 13.2 % (female 2, male 7, median age 54 years), and this was significantly higher (p=0.02) when compared to cases at 2000 m representing 3.2 % (female 1, male 1, median age 75 years) or at 400 m with 2.8 % (female 2, median age 52 years). Hematologic indices displayed mean Hb 7.3 g/dl, WBC: 11515/ul and Plt: 127154/ul. Bone marrow findings reflected &gt; 80% of prominent erythroid precursors with large irregular nuclei, dispersed chromatin, 1 to 3 elongated nucleoli, deeply basophilic cytoplasm, and an intense mitotic activity. Immunophenotypic features revealed CD34, CD71, CD105, CD36 and CD235 regarding erythroid clonality. AEL incidence is increased at high altitude, reflects intriguingly morphology and hematological characteristics. This increase may be due to the increase in HIF and Epo at high altitude, since the barometric pressure (462 mmHg) and the oxygen level in the air (14%) at high altitude are low. So, further studies elucidating the genetic mechanism involved are of interest.
Phenotypic Variations Related to Hypoxic Responses Among Andean Highlanders Living at Different Altitudes (400m, 4000m, 5000m)
(Elsevier BV, 2022) Ricardo Amaru; Emerson Cayo; Teddy Quispe; Juan Carlos Valencia; Daniela Patón; Luis Felipe Mamani; Julieta Luna
Introduction Adaptation to high altitude poses selective evolutionary changes involving multiple and challenging adaptive responses, and one of them deals with the low pressure of oxygen. Native Bolivian Andeans have lived at an average of 3000-5000 m for about 14,000 years, and have developed different erythroid phenotypes compared to other populations living at high altitude (PMID 30781443; PMID 25342802). Although Andeans have developed genetic adaptations related to erythropoiesis regulation (Blood, ASH 2316, 2018) they still undergone with polycythemic states, and those of clinical relevance are often Chronic Mountain Sickness erythrocytosis (CMS-E), secondary erythrocytosis (SE) and polycythemia vera (PV) (Rev Hematol Mex. 2016 Jan;17(1):8-20). Either adaptation or erythrocytosis condition entails important changes in hemoglobin, SpO2, P50 and lactate, so evaluating significant changes among Andeans living at different altitudes as well as the modifications between erythrocytosis patients and healthy highlanders became of interest. Material and method We collected venous blood samples from Bolivian native Andeans born at 4000 m (n=124) but living at 3 different altitudes (400 m, 4000 m, 5000 m), aside from Europeans (n=11) residing at 4000 m. Complete blood count, venous blood gas, and oxygen saturation studies were performed. P50 was measured by using a formula described by Lichtman. Likewise, a differential diagnosis regarding healthy inhabitants and polycythemia patients was performed. Results In healthy Andean inhabitants in different altitudes, the Hb levels increased at increasing altitude (p:0.001), meanwhile SpO2 (p:0.001) and P50 (p:0.001) decreased. No lactate variations among them were observed (Table 1). European subjects at 4000 m in relation to Andean inhabitants at the same altitude displayed higher Hb levels (p: 0.01), without variations in SpO2 and P50, but a significant increased lactate (p: 0.001) (Table 1). When comparing healthy subjects and patients with erythrocytosis (CMS-E, SE, PV) at 4000 m, the latter displayed higher Hb levels (p:0.001), decreased SpO2 (p:0.001), no variations in P50, and increased lactate in CMS-E and SE patients (p:0.01) (Table 2). Similarly, patients with erythrocytosis (CMS-E, SE) at 5000 m, related to healthy subjects at the same altitude, reflected increased Hb (p:0.001), decreased SpO2 (p:0.01), P50 without variations, and increased lactate (p:0.01) (Table 2). Conclusions Native Andeans from Bolivia born at 4000 m but living at different altitudes have variations regarding hematological phenotypes, decreased P50 shifts the hemoglobin dissociation curve to left. Patients with erythrocytosis have distinct phenotypes in relation to healthy subjects characterized by decreased saturation and increased lactate. Higher Hb levels and increased lactate in Europeans living at 4000 m probably due to the different residing time at high altitude, since native Andean inhabited high-altitude regions for many years. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal
Transferrin and Erythropoietin Increased Levels Correlate with Thrombosis at High Altitude
(Elsevier BV, 2023) Ricardo Amaru; Luis Felipe Mamani; Emma Mancilla; Daniela Patón; Juan Carlos Valencia; Ariel Amaru; Mireya Carrasco
Living at high altitude involves great interest because of the challenging multiple adaptive responses to a hypoxic environment. Native Bolivian Andeans have lived at an altitude of 4000 m in The Andes mountains for about 14,000 years exposed to a low atmospheric pressure (453 mmHg) and low oxygen concentration (12,7%). It was described Andeans adaptation to high altitude is mainly related to cardiovascular issues (PMID: 29100088), with a low significantly genetic selection in HIF pathway components responsible of erythropoiesis regulation (PMID: 36980912), so that they have adapted to exist with increased hemoglobin concentrations. Thus, Andeans can be prevalent to undergone hematological and thromboembolic disorders. Thrombotic events have been reported to be increased at high altitude, and this recently associated to increased transferrin (Tf) (PMID: 36040436), likewise to increased erythropoietin (Epo) (Amaru, RevMed 2022). Increased Tf were described to be induced by both iron deficiency and hypoxia via HIF (PMID: 9242677). In addition, iron deficiency was postulated to inhibit the function of prolyl hydroxylase 2 (PHD2) in the hydroxylation of HIF-2, necessary for recognition and degradation by VHL (PMID:22304911). Under normal conditions, Tf is bound to fibrinogen at a molar ratio of 4:1, leading to plasma Tf sequestration by fibrinogen and leaving little Tf free in the circulation. While at hypoxia conditions, abnormally upregulated Tf potentiates thrombin, factor XIIa and inhibits antithrombin, inducing hypercoagulability (PMID:36040436). Similarly, increased HIF1a at high altitude increases Tf promoting the transferrin gene expression, which contains HIF-1α binding sites in its enhancer region (PMID:36844187). HIF is a DNA-binding transcription factor for activating expression of Epo gene (PMID:32561149). Epo, in turn, is increased due to the hyperegulation of HIF as expected at low atmospheric pressure environments. Epo activates the hypoxia-inducible factor that leads to Epo synthesis to stimulate red blood cell production, which also increases the demand for iron to synthesize hemoglobin (PMID:21078592). This, added to a decreased iron and increased HIF 1a, gives rise to a hyperregulation of Tf. Epo has been described to have prothrombotic properties and be related to thrombotic events (PMID:10779449; Amaru, RevMed 2022). In this sense, to further observe a correlation of transferrin and erythropoietin increased levels with the risk of thrombotic events at high altitude, we studied patients with erythrocytosis, anemia and polycythemia vera. We analyzed clinical, lab tests and epidemiological data of 920 patients with Chronic Mountain Sickness erythrocytosis (CMS-e) (n=560), anemia (n=372), and Polycythemia Vera (PV) (n=20), all Bolivian Andeans born and residing at 4000 m. Considering at this altitude normal hemoglobin concentrations vary from 14-17 g/dl in women and 15-18 g/dl in men, erythrocytosis condition comprises Hb levels &gt;18 g/dl in women and &gt;19 g/dl in men (Amaru et al, Rev Hematol Mex, 2016); similarly, it embraces Hb &lt;12 g/dl for women and &lt;13 g/dl for men in anemias (PMID: 23317073). Positive JAK F617V tests were corroborated in PV patients. Iron deficiency correlation considered serum ferritin &lt;30 ug/L and MCV &lt;80 fL (Clark et al, Nutrition, 2008). Eco-doppler study records confirmed the occurrence of thrombotic events. Data analysis was performed through Excel 16.29.1 and SPSS program, Chi-squared, Fishers and Pearson tests were done. We observed significative increased Tf levels in erythrocytosis, anemia, and PV patients mainly on those presenting iron levels deficiency. Epo was highly increased in erythrocytosis patients with iron deficiency. These results correlated with the incidence of thrombotic events in erythrocytosis (CMS-e) and anemia patients with iron deficiency. Age was also relevant in both groups. (Table 1). The increase of Epo levels correlated with thrombosis in erythrocytosis and PV patients with iron deficiency (Table 1). Transferrin and Erythropoietin increased levels at high altitude correlated with thrombosis in Chronic Mountain Sickness erythrocytosis and iron deficiency anemia patients. However, Increased Tf did not correlate with thrombosis in PV patients at high altitude. Our data confirm that increased Tf and Epo have prothrombogenic properties in CMS-e, iron deficiency anemia patients at high altitude.