A putative Leishmania DNA polymerase theta protects the parasite against oxidative damage.

Leishmania infantum is a protozoan parasite that is phagocytized by human macrophages. The host macrophages kill the parasite by generating oxidative compounds that induce DNA damage. We have identified, purified and biochemically characterized a DNA polymerase θ from L. infantum (LiPolθ), demonstrating that it is a DNA-dependent DNA polymerase involved in translesion synthesis of 8oxoG, abasic sites and thymine glycol lesions. Stably transfected L. infantum parasites expressing LiPolθ were significantly more resistant to oxidative and interstrand cross-linking agents, e.g. hydrogen peroxide, cisplatin and mitomycin C. Moreover, LiPolθ-overexpressing parasites showed an increased infectivity toward its natural macrophage host. Therefore, we propose that LiPolθ is a translesion synthesis polymerase involved in parasite DNA damage tolerance, to confer resistance against macrophage aggression.

Chagasic patients are able to respond against a viral antigen from influenza virus.

BACKGROUND: Trypanosoma cruzi, the etiological agent of Chagas' disease, is an obligate intracellular parasite which induces a CD8+ T cell immune response with secretion of cytokines and release of cytotoxic granules. Although an immune-suppressive effect of T. cruzi on the acute phase of the disease has been described, little is known about the capacity of CD8+ T cell from chronic chagasic patients to respond to a non-T. cruzi microbial antigen. METHODS: In the present paper, the frequency, phenotype and the functional activity of the CD8+ T cells specific from Flu-MP*, an influenza virus epitope, were determined in 13 chagasic patients and 5 healthy donors. RESULTS: The results show that Flu-MP* peptide specific CD8+ T cells were found with similar frequencies in both groups. In addition, Flu-MP* specific CD8+ T cells were distributed in the early or intermediate/late differentiation stages without showing enrichment of a specific sub-population. The mentioned Flu-MP* specific CD8+ T cells from chagasic patients were predominately TEM (CCR7- CD62L-), producing IL-2, IFNγ, CD107a/b and perforin, and did not present significant differences when compared with those from healthy donors. CONCLUSIONS: Our results support the hypothesis that there is no CD8+ T cell nonspecific immune-suppression during chronic Chagas disease infection. Nonetheless, other viral antigens must be studied in order to confirm our findings.

Patient and Treatment Factors Associated With Improved Local Control and Survival in Oligometastatic Bone Disease: Results From a Large Single-Institution Experience Using Stereotactic Body Radiation Therapy.

PURPOSE: Limited data exist to guide optimal patient selection and treatment of bone metastases with curative intent despite the increasing application of stereotactic body radiation therapy (SBRT) for oligometastatic (OM) disease control and reirradiation (Re-RT). METHODS AND MATERIALS: Clinical characteristics for 434 patients consecutively treated with bone SBRT at a single institution from March 2011 to June 2020 were analyzed by OM, spine, and nonspine bone using Cox regression to determine association with local control (LC), progression-free survival (PFS), and overall survival (OS), and the Kaplan-Meier method to estimate PFS and OS. RESULTS: Most patients had prostate (39%) or breast/lung (21%) cancer and 1 to 3 lesions (96%), with 651 lesions (spine 63%) treated for Re-RT (12%) or OMD (88%), including synchronous (10%), metachronous (28%), repeat (27%), or induced (23%) states as defined by The European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer criteria. Biologically effective dose (BED10) ≥50 (hazard ratio, 0.68; 95% confidence interval, 0.48-0.96; P < .03) predicted improved LC among OM lesions and planning target volume (PTV) ≥150 cc (hazard ratio, 1.94; 95% confidence interval, 1.02-3.70; P < .04) predicted worse LC for nonspine bone. Prostate histology, performance status (PS) 0 to 1, and metastasis-free interval ≥2 year predicted improved PFS and OS (P < .05). Metachronous, synchronous, or repeat OM had higher PFS and OS (P ≤ .001) than induced OM. With median follow-up 25.7 months, 1- and 2-year PFS was 63% and 47% for OM and 36% and 25% for Re-RT; 1- and 2-year OS was 87% and 73% for OM and 58% and 43% for Re-RT. Acute toxicities included grade 1 to 2 pain flare (9%) and fatigue (14%). Late toxicities included fracture (1%) for OM and myelopathy (2.5%) or nerve pain (1.2%) for Re-RT. CONCLUSIONS: BED10 ≥50 for OM and PTV <150 cc for nonspine bone lesions was associated with improved LC. Prostate histology, PS 0 to 1, metastasis-free interval ≥2 years, and metachronous, synchronous, or repeat presentations per The European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer criteria predicted improved PFS and OS among OM patients treated with bone SBRT.

A DEVH-box RNA Helicase from Leishmania braziliensis is Associated to mRNA Cytoplasmic Granules.

RNA helicases are ubiquitous enzymes that participate in almost all aspects of RNA processing, including RNA and RNA-protein complex remodelling. In trypanosomatids, which post-transcriptionally regulate gene expression, the formation of different kinds of ribonucleoprotein granules under stress conditions modulates the parasite's RNA metabolism. This paper describes the isolation of a putative DEVH-box RNA helicase produced by promastigotes of Leishmania braziliensis. Using a Cy3-labelled dT30 oligo, FISH showed the localization of this protein to mRNA granules under starvation stress conditions. The central region of the protein was shown to be responsible for this behaviour.