The Ins and Outs of Autophagy and Metabolism in Hematopoietic and Leukemic Stem Cells: Food for Thought

Discovered over fifty years ago, autophagy is a double-edged blade. On one hand, it regulates cellular energy sources by “cannibalization” of its own cellular components, feeding on proteins and other unused cytoplasmic factors. On the other, it is a recycling process that removes dangerous waste from the cytoplasm keeping the cell clean and healthy. Failure of the autophagic machinery is translated in dysfunction of the immune response, in aging, and in the progression of pathologies such as Parkinson disease, diabetes, and cancer. Further investigation identified autophagy with a protective role in specific types of cancer, whereas in other cases it can promote tumorigenesis. Evidence shows that treatment with chemotherapeutics can upregulate autophagy in order to maintain a stable intracellular environment promoting drug resistance and cell survival. Leukemia, a blood derived cancer, represents one of the malignancies in which autophagy is responsible for drug treatment failure. Inhibition of autophagy is becoming a strategic target for leukemic stem cell (LSC) eradication. Interestingly, the latest findings demonstrate that LSCs show higher levels of mitochondrial metabolism compared to normal stem cells. With this review, we aim to explore the links between autophagy and metabolism in the hematopoietic system, with special focus on primitive LSCs

Antimicrobial properties of chitosan from different developmental stages of the bioconverter insect Hermetia illucens

Growing antimicrobial resistance has prompted researchers to identify new natural molecules with antimicrobial potential. In this perspective, attention has been focused on biopolymers that could also be functional in the medical field. Chitin is the second most abundant biopolymer on Earth and with its deacetylated derivative, chitosan, has several applications in biomedical and pharmaceutical fields. Currently, the main source of chitin is the crustacean exoskeleton, but the growing demand for these polymers on the market has led to search for alternative sources. Among these, insects, and in particular the bioconverter Hermetia illucens, is one of the most bred. Chitin can be extracted from larvae, pupal exuviae and dead adults of H. illucens, by applying chemical methods, and converted into chitosan. Fourier-transformed infrared spectroscopy confirmed the identity of the chitosan produced from H. illucens and its structural similarity to commercial polymer. Recently, studies showed that chitosan has intrinsic antimicrobial activity. This is the first research that investigated the antibacterial activity of chitosan produced from the three developmental stages of H. illucens through qualitative and quantitative analysis, agar diffusion tests and microdilution assays, respectively. Our results showed the antimicrobial capacity of chitosan of H. illucens, opening new perspectives for its use in the biological area

Preliminary investigation on the effect of insect-based chitosan on preservation of coated fresh cherry tomatoes

: Chitosan was produced from Hermetia illucens pupal exuviae by heterogeneous and homogeneous deacetylation. Tomato fruits (Solanum lycopersicum), that are one of the most grown and consumed food throughout the world, were coated with 0.5 and 1% chitosan, applied by dipping or spraying, and stored at room temperature or 4 °C, for a storage period of 30 days. Statistical analysis give different results depending on the analysed parameters: heterogeneous chitosan, indeed, had a better effect than the homogenous one in maintaining more stable physico-chemical parameters, while the homogenous chitosan improved the total phenols, flavonoids and antioxidant activity. Chitosan coatings applied by spraying were more effective in all the analyses. Chitosan derived from H. illucens always performed similarly to the commercial chitosan. However, a general better performance of insect-derived chitosan on the concentration of phenolics and flavonoids, and the antioxidant activity was observed as compared to the commercial one. Chitosan coating has already been successfully used for preservation of fresh fruits, as alternative to synthetic polymers, but this is the first investigation of chitosan produced from an insect for this application. These preliminary results are encouraging regarding the validation of the insect H. illucens as a source of chitosan

Inhibition of mitochondrial folate metabolism drives differentiation through mTORC1-mediated purine sensing

Supporting cell proliferation through nucleotide biosynthesis is an essential requirement for cancer cells. Hence, inhibition of folate-mediated one carbon (1C) metabolism, which is required for nucleotide synthesis, has been successfully exploited in anti-cancer therapy. Here, we reveal that mitochondrial folate metabolism is upregulated in patient-derived leukaemic stem cells (LSCs). We demonstrate that inhibition of mitochondrial 1C metabolism through impairment of de novo purine synthesis has a cytostatic effect on chronic myeloid leukaemia (CML) cells. Consequently, changes in purine nucleotide levels lead to activation of AMPK signalling and suppression of mTORC1 activity. Notably, suppression of mitochondrial 1C metabolism increases expression of erythroid differentiation markers. Moreover, we find that increased differentiation occurs independently of AMPK signalling and can be reversed through reconstitution of purine levels and reactivation of mTORC1. Of clinical relevance, we identify that combination of 1C metabolism inhibition with imatinib, a frontline treatment for CML patients, decreases the number of therapy-resistant CML LSCs in a patient-derived xenograft model. Our results highlight a role for folate metabolism and purine sensing in stem cell fate decisions and leukaemogenesis

ULK1 inhibition promotes oxidative stress–induced differentiation and sensitizes leukemic stem cells to targeted therapy

Inhibition of autophagy has been proposed as a potential therapy for individuals with cancer. However, current lysosomotropic autophagy inhibitors have demonstrated limited efficacy in clinical trials. Therefore, validation of novel specific autophagy inhibitors using robust preclinical models is critical. In chronic myeloid leukemia (CML), minimal residual disease is maintained by persistent leukemic stem cells (LSCs), which drive tyrosine kinase inhibitor (TKI) resistance and patient relapse. Here, we show that deletion of autophagy-inducing kinase ULK1 (unc-51–like autophagy activating kinase 1) reduces growth of cell line and patient-derived xenografted CML cells in mouse models. Using primitive cells, isolated from individuals with CML, we demonstrate that pharmacological inhibition of ULK1 selectively targets CML LSCs ex vivo and in vivo, when combined with TKI treatment. The enhanced TKI sensitivity after ULK1-mediated autophagy inhibition is driven by increased mitochondrial respiration and loss of quiescence and points to oxidative stress–induced differentiation of CML LSCs, proposing an alternative strategy for treating patients with CML

Risk Factors Associated with Adverse Fetal Outcomes in Pregnancies Affected by Coronavirus Disease 2019 (COVID-19): A Secondary Analysis of the WAPM study on COVID-19

To evaluate the strength of association between maternal and pregnancy characteristics and the risk of adverse perinatal outcomes in pregnancies with laboratory confirmed COVID-19. Secondary analysis of a multinational, cohort study on all consecutive pregnant women with laboratory-confirmed COVID-19 from February 1, 2020 to April 30, 2020 from 73 centers from 22 different countries. A confirmed case of COVID-19 was defined as a positive result on real-time reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay of nasal and pharyngeal swab specimens. The primary outcome was a composite adverse fetal outcome, defined as the presence of either abortion (pregnancy loss before 22 weeks of gestations), stillbirth (intrauterine fetal death after 22 weeks of gestation), neonatal death (death of a live-born infant within the first 28 days of life), and perinatal death (either stillbirth or neonatal death). Logistic regression analysis was performed to evaluate parameters independently associated with the primary outcome. Logistic regression was reported as odds ratio (OR) with 95% confidence interval (CI). Mean gestational age at diagnosis was 30.6\ub19.5 weeks, with 8.0% of women being diagnosed in the first, 22.2% in the second and 69.8% in the third trimester of pregnancy. There were six miscarriage (2.3%), six intrauterine device (IUD) (2.3) and 5 (2.0%) neonatal deaths, with an overall rate of perinatal death of 4.2% (11/265), thus resulting into 17 cases experiencing and 226 not experiencing composite adverse fetal outcome. Neither stillbirths nor neonatal deaths had congenital anomalies found at antenatal or postnatal evaluation. Furthermore, none of the cases experiencing IUD had signs of impending demise at arterial or venous Doppler. Neonatal deaths were all considered as prematurity-related adverse events. Of the 250 live-born neonates, one (0.4%) was found positive at RT-PCR pharyngeal swabs performed after delivery. The mother was tested positive during the third trimester of pregnancy. The newborn was asymptomatic and had negative RT-PCR test after 14 days of life. At logistic regression analysis, gestational age at diagnosis (OR: 0.85, 95% CI 0.8-0.9 per week increase; p<0.001), birthweight (OR: 1.17, 95% CI 1.09-1.12.7 per 100 g decrease; p=0.012) and maternal ventilatory support, including either need for oxygen or CPAP (OR: 4.12, 95% CI 2.3-7.9; p=0.001) were independently associated with composite adverse fetal outcome. Early gestational age at infection, maternal ventilatory supports and low birthweight are the main determinants of adverse perinatal outcomes in fetuses with maternal COVID-19 infection. Conversely, the risk of vertical transmission seems negligible

Leukaemia exposure alters the transcriptional profile and function of BCR::ABL1 negative macrophages in the bone marrow niche

Macrophages are fundamental cells of the innate immune system that support normal haematopoiesis and play roles in both anti-cancer immunity and tumour progression. Here we use a chimeric mouse model of chronic myeloid leukaemia (CML) and human bone marrow (BM) derived macrophages to study the impact of the dysregulated BM microenvironment on bystander macrophages. Utilising single-cell RNA sequencing (scRNA-seq) of Philadelphia chromosome (Ph) negative macrophages we reveal unique subpopulations of immature macrophages residing in the CML BM microenvironment. CML exposed macrophages separate from their normal counterparts by reduced expression of the surface marker CD36, which significantly reduces clearance of apoptotic cells. We uncover aberrant production of CML-secreted factors, including the immune modulatory protein lactotransferrin (LTF), that suppresses efferocytosis, phagocytosis, and CD36 surface expression in BM macrophages, indicating that the elevated secretion of LTF is, at least partially responsible for the supressed clearance function of Ph- macrophages