EZH2 Inhibition by DS3201 Triggers the Kaposi's Sarcoma-Associated Herpesvirus Lytic Cycle and Potentiates the Effects Induced by SAHA in Primary Effusion Lymphoma Cells.

Primary Effusion Lymphoma (PEL) cells carry Kaposi's sarcoma-associated herpesvirus (KSHV) in a latent state, except for a small number of cells in which the virus replicates to ensure its persistence into the infected host. However, the lytic cycle can be reactivated in vitro by exposing these lymphoma cells to various treatments, leading to cell lysis. To restrict viral antigen expression, KSHV induces repressive epigenetic changes, including DNA methylation and histone modifications. Among the latter, histone deacetylation and tri-methylation of Histone H3 lisyne-27 (H3K27me3) have been reported to play a role. Here, we found that the inhibition of H3K27 tri-methylation by valemetostat DS3201 (DS), a small molecule that inhibits Enhancer of Zeste Homolog 2 (EZH2) methyltransferase, induced the KSHV lytic cycle in PEL cells, and that this effect involved the activation of the wtp53-p21 axis and autophagic dysregulation. DS also potentiated the lytic cycle activation mediated by the Histone deacetylases (HDAC) inhibitor Suberoylanilide hydroxamic acid (SAHA) and reinforced its cytotoxic effect, suggesting that such a combination could be used to unbalance the latent/lytic cycle and further impair the survival of PEL cells.

PAX5 functions as a tumor suppressor by RB-E2F-mediated cell cycle arrest in Kaposi sarcoma-associated herpesvirus-infected primary effusion lymphoma.

Primary effusion lymphoma (PEL) is a malignant B-cell lymphoma attributable to Kaposi sarcoma-associated herpesvirus (KSHV) infection. PEL is characterized by invasive behavior, showing recurrent effusions in body cavities. The clinical outcome and typical prognosis in patients with PEL are poor and potentially lethal. Clarification of the pathogenesis in PEL is urgently needed in order to develop novel therapies. PEL cells generally lack B-cell surface markers, and we therefore hypothesized that the B-cell transcription factor, PAX5, would be down-regulated in PEL. The expression of PAX5 is detected from the pro-B to the mature B-cell stage and is indispensable for the differentiation of B-cells. PAX5 was silenced in PEL cells via its promoter methylation. Up-regulation of PAX5 induced several genes coding for B-cell surface marker mRNA, but not protein level. PAX5 inhibited cell growth via G1 cell cycle arrest. PAX5 bound to RB and increased its protein expression. RB/E2F-regulated genes were significantly down-regulated in microarray analysis and PCR experiments. To elucidate the in vivo role of PAX5, we examined the restoration of PAX5 in a PEL mouse model. The ascites volume and organ invasions were significantly suppressed by PAX5 restoration. Reduction of PAX5 has played a crucial role in the oncogenesis of PEL, and PAX5 is a tumor suppressor in PEL. Targeting PAX5 could represent a novel therapeutic strategy for patients with PEL.

LKB1 suppresses KSHV reactivation and promotes primary effusion lymphoma progression.

Viruses normally reprogram the host cell metabolic pathways as well as metabolic sensors to facilitate their persistence. The serine-threonine liver kinase B1 (LKB1) is a master upstream kinase of 5'-AMP-activated protein kinase (AMPK) that senses the energy status and therefore regulates the intracellular metabolic homeostasis. Previous studies showed that AMPK restricts Kaposi's sarcoma-associated herpesvirus (KSHV) lytic replication in endothelial cells during primary infection and promotes primary effusion lymphoma (PEL) cell survival. However, the role of LKB1 in KSHV lytic reactivation and KSHV-associated malignancies is unclear. In this study, we found that LKB1 is phosphorylated or activated in KSHV-positive PEL cells. Mechanistically, KSHV-encoded vCyclin mediated LKB1 activation in PEL cells, as vCyclin knockout ablated, while vCyclin overexpression enhanced LKB1 activation. Furthermore, knockdown of LKB1 inactivated AMPK and induced KSHV reactivation, as indicated by the increased expression of viral lytic genes and the increased virions in supernatants. Accordingly, AMPK inhibition by functional knockdown or a pharmacologic inhibitor, Compound C, promoted KSHV reactivation in PEL cells. Furthermore, inhibition of either LKB1 or AMPKα1 efficiently induced cell death by apoptosis of PEL cells both in vitro and in vivo. Together, these results identify LKB1 as a vulnerable target for PEL, which could be potentially exploited for treating other virus-associated diseases.IMPORTANCEKaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic virus associated with several human cancers, such as primary effusion lymphoma (PEL). Here, we showed that serine-threonine liver kinase B1 (LKB1), upstream of 5' AMP-activated protein kinase (AMPK), is activated by KSHV-encoded vCyclin and maintains KSHV latency in PEL cells. Inhibition of either LKB1 or AMPK enhances KSHV lytic replication from latency, which at least partially accounts for PEL cell death by apoptosis. Compound C, a potent AMPK inhibitor, induced KSHV reactivation and efficiently inhibited PEL progression in vivo. Thus, our work revealed that LKB1 is a potential therapeutic target for KSHV-associated cancers.

Pediatric Erythroid Sarcoma Diagnostically Confirmed by Identification of a Recurrent NFIA::CBFA2T3 Fusion.

Erythroid sarcoma (ES) is exceedingly rare in the pediatric population with only a handful of reports of de novo cases, mostly occurring in the central nervous system (CNS) or orbit. It is clinically and pathologically challenging and can masquerade as a nonhematopoietic small round blue cell tumor. Clinical presentation of ES without bone marrow involvement makes diagnosis particularly difficult. We describe a 22-month-old female with ES who presented with a 2-cm mass involving the left parotid region and CNS. The presence of crush/fixation artifact from the initial biopsy made definitive classification of this highly proliferative and malignant neoplasm challenging despite an extensive immunohistochemical workup. Molecular studies including RNA-sequencing revealed a NFIA::CBFA2T3 fusion. This fusion has been identified in several cases of de novo acute erythroid leukemia (AEL) and gene expression analysis comparing this case to other AELs revealed a similar transcriptional profile. Given the diagnostically challenging nature of this tumor, clinical RNA-sequencing was essential for establishing a diagnosis.

Marine-Derived Cytosine Arabinoside (Ara-C) Inhibits Biofilm Formation by Inhibiting PEL Operon Proteins (Pel A and Pel B) of Pseudomonas aeruginosa: An In Silico Approach.

Pseudomonas aeruginosa (P. aeruginosa) is a gram-negative biofilm-forming opportunistic human pathogen whose vital mechanism is biofilm formation for better survival. PelA and PelB proteins of the PEL operon are essential for bacterial-synthesized pellicle polysaccharide (PEL), which is a vital structural component of the biofilm. It helps in adherence of biofilm on the surface and maintenance of cell-to-cell interactions and with other matrix components. Here, in-silico molecular docking and simulation studies were performed against PelA and PelB using ten natural bioactive compounds, individually [podocarpic acids, ferruginol, scopadulcic acid B, pisiferic acid, metachromin A, Cytarabine (cytosine arabinoside; Ara-C), ursolic acid, oleanolic acid, maslinic acid, and betulinic acid], those have already been established as anti-infectious compounds. The results obtained from AutoDock and Glide-Schordinger stated that a marine-derived cytosine arabinoside (Ara-C) among the ten compounds binds active sites of PelA and PelB, exhibiting strong binding affinity [Trp224 (hydrogen), Ser219 (polar), Val234 (hydrophobic) for PelA; Leu365 and Glu389 (hydrogen), Gln366 (polar) for PelB] with high negative binding energy - 5.518 kcal/mol and - 6.056 kcal/mol, respectively. The molecular dynamic and simulation studies for 100 ns showed the MMGBSA binding energy scores are - 16.4 kcal/mol (Ara-C with PelA), and - 22.25 kcal/mol (Ara-C with PelB). Further, ADME/T studies indicate the IC50 values of AraC are 6.10 mM for PelA and 18.78 mM for PelB, which is a comparatively very low dose. The zero violation of Lipinski's Rule of Five further established that Ara-C is a good candidate for drug development. Thus, Ara-C could be considered a potent anti-biofilm compound against PEL operon-dependent biofilm formation of P. aeruginosa.

Molecular Features of HHV8 Monoclonal Microlymphoma Associated with Kaposi Sarcoma and Multicentric Castleman Disease in an HIV-Negative Patient.

Human herpesvirus 8 (HHV8)-associated diseases include Kaposi sarcoma (KS), multicentric Castleman disease (MCD), germinotropic lymphoproliferative disorder (GLPD), Kaposi sarcoma inflammatory cytokine syndrome (KICS), HHV8-positive diffuse large B-cell lymphoma (HHV8+ DLBCL), primary effusion lymphoma (PEL), and extra-cavitary PEL (ECPEL). We report the case of a human immunodeficiency virus (HIV)-negative male treated for cutaneous KS, who developed generalized lymphadenopathy, hepatosplenomegaly, pleural and abdominal effusions, renal insufficiency, and pancytopenia. The excised lymph node showed features of concomitant involvement by micro-KS and MCD, with aggregates of HHV8+, Epstein Barr virus (EBV)-negative, IgM+, and lambda+ plasmablasts reminiscent of microlymphoma. Molecular investigations revealed a somatically hypermutated (SHM) monoclonal rearrangement of the immunoglobulin heavy chain (IGH), accounting for 4% of the B-cell population of the lymph node. Mutational analyses identified a pathogenic variant of KMT2D and variants of unknown significance in KMT2D, FOXO1, ARID1A, and KMT2A. The patient died shortly after surgery. The histological features (HHV8+, EBV-, IgM+, Lambda+, MCD+), integrated with the molecular findings (monoclonal IGH, SHM+, KMT2D mutated), supported the diagnosis of a monoclonal HHV8+ microlymphoma, with features intermediate between an incipient HHV8+ DLBCL and an EBV-negative ECPEL highlighting the challenges in the accurate classification of HHV8-driven lymphoid proliferations.

Flip the switch: the role of FleQ in modulating the transition between the free-living and sessile mode of growth in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen causing chronic infections that are associated with the sessile/biofilm mode of growth rather than the free-living/planktonic mode of growth. The transcriptional regulator FleQ contributes to both modes of growth by functioning both as an activator and repressor and inversely regulating flagella genes associated with the planktonic mode of growth and genes contributing to the biofilm mode of growth. Here, we review findings that enhance our understanding of the molecular mechanism by which FleQ enables the transition between the two modes of growth. We also explore recent advances in the mechanism of action of FleQ to both activate and repress gene expression from a single promoter. Emphasis will be on the role of sigma factors, cyclic di-GMP, and the transcriptional regulator AmrZ in inversely regulating flagella and biofilm-associated genes and converting FleQ from a repressor to an activator.

5-AZA Upregulates SOCS3 and PTPN6/SHP1, Inhibiting STAT3 and Potentiating the Effects of AG490 against Primary Effusion Lymphoma Cells.

Epigenetic modifications, including aberrant DNA methylation occurring at the promoters of oncogenes and oncosuppressor genes and histone modifications, can contribute to carcinogenesis. Aberrant methylation mediated by histone methylatransferases, alongside histones, can affect methylation of proteins involved in the regulation of pro-survival pathways such as JAK/STAT and contribute to their activation. In this study, we used DNA or histone demethylating agents, 5-Azacytidine (5-AZA) or DS-3201 (valemetostat), respectively, to treat primary effusion lymphoma (PEL) cells, alone or in combination with AG490, a Signal transducer and activator of transcription 3 (STAT3) inhibitor. Cell viability was investigated by trypan blue assay and FACS analysis. The molecular changes induced by 5-AZA and/or AG490 treatments were investigated by Western blot analysis, while cytokine release by PEL cells treated by these drugs was evaluated by Luminex. Statistical analyses were performed with Graphpad Prism® software (version 9) and analyzed by Student's t test or a nonparametric one-way ANOVA test. The results obtained in this study suggest that 5-AZA upregulated molecules that inhibit STAT3 tyrosine phosphorylation, namely Suppressor of Cytokine Signaling 3 (SOCS3) and tyrosine-protein phosphatase non-receptor type (PTPN) 6/Src homology region 2 domain-containing phosphatase-1 (SHP-1), reducing STAT3 activation and downregulating several STAT3 pro-survival targets in PEL cells. As this lymphoma is highly dependent on the constitutive activation of STAT3, 5-AZA impaired PEL cell survival, and when used in combination with AG490 JAK2/STAT3 inhibitor, it potentiated its cytotoxic effect. Differently from 5-AZA, the inhibition of the EZH1/2 histone methyltransferase by DS-3201, reported to contribute to STAT3 activation in other cancers, slightly affected STAT3 phosphorylation or survival in PEL cells, either alone or in combination with AG490. This study suggests that 5-AZA, by upregulating the expression level of SOCS3 and PTPN6/SHP1, reduced STAT3 activation and improved the outcome of treatment targeting this transcription factor in PEL cells.

Prevalence and factors associated with the perception of perineal laceration: a cross-sectional study with data from the Nascer no Brasil Survey, 2011 and 2012 / Prevalencia y factores asociados a la percepción de laceración perineal: estudio transversal con datos de la Encuesta Nascer no Brasil, 2011 y 2012 / Prevalência e fatores associados à percepção da laceração perineal: estudo transversal com dados do Inquérito Nascer no Brasil, 2011 e 2012

Abstract Objective: To describe the prevalence of perineal laceration, based on the self-reported perception of postpartum women, and to analyze factors associated with its occurrence in Brazil. Methods: This was a cross-sectional study conducted with 23,894 postpartum women, excluding twin pregnancies, cesarean sections, and births with episiotomies, between 2011 and 2012. Prevalence ratios (PR) and 95% confidence intervals (95%CI) of association between the event and maternal, fetus/newborn, obstetric and clinical management characteristics were estimated in hierarchical Poisson regression models. Results: Out of 4,606 postpartum women, 49.5% (95%CI 46.1;42.9) self-reported perineal laceration. Being an adolescent (PR = 1.12; 95%CI 1.02;1.25), primipara (PR = 1.47; 95%CI 1.33;1.63), having had excessive gestational weight gain (PR = 1.17; 95%CI 1.07;1.29) and having undergone the Kristeller maneuver (PR = 1.18; 95%CI 1.08;1.29) increased the proportion of the outcome. Conclusion: The results found call for prenatal care and adjustments to childbirth care so as to be in accordance with current recommendations.

Resumen Objetivo: Describir la prevalencia de laceración perineal, a partir de la percepción autoinformada de puérperas, y analizar los factores asociados a su aparición en Brasil. Métodos: Estudio transversal entre 2011 y 2012, con 23.894 puérperas, excluyendo embarazos gemelares, cesáreas y partos con episiotomías. Se estimaron razones de prevalencia (RP) e intervalos de confianza del 95% (IC95%) de la asociación entre el evento y las características maternas, feto/recién nacido, obstétricas y de manejo clínico en modelos de regresión jerárquica de Poisson. Resultados: Entre 4.606 mujeres en posparto, el 49,5%(IC95%:46,1;42,9) informó laceración perineal. Ser adolescente (RP = 1,12; IC95% 1,02;1,25), primipara (RP = 1,47; IC95% 1,33;1,63), haber tenido aumento excesivo de peso gestacional (RP = 1,17; IC95% 1,07;1,29) y haber sido sometido a la maniobra de Kristeller (RP = 1,18; IC95% 1,08;1,29) aumentó la proporción de resultados. Conclusión: Los resultados encontrados requieren atención prenatal y ajustes en la atención del parto de acuerdo con las recomendaciones actuales.

Resumo Objetivo: Descrever a prevalência da laceração perineal segundo a percepção autorrelatada da puérpera, e analisar os fatores associados à sua ocorrência no Brasil. Métodos: Estudo transversal conduzido em 23.894 puérperas, excluindo-se gestações gemelares, cesarianas e partos com episiotomias entre 2011 e 2012. Razões de prevalência (RP) e intervalos de confiança de 95% (IC95%) da associação entre o evento e as características maternas, feto/recém-nato, obstétricas e manejo clínico foram estimadas em modelos de regressão de Poisson hierarquizados. Resultados: Entre 4.606 puérperas, 49,5% (IC95% 46,1;42,9) autorrelataram laceração perineal. Ser adolescente (RP = 1,12; IC95% 1,02;1,25), primípara (RP = 1,47; IC95% 1,33;1,63), ter tido ganho de peso gestacional excessivo (RP = 1,17; IC95% 1,07;1,29) e ter sido submetida à manobra de Kristeller (RP = 1,18; IC95% 1,08;1,29) elevaram a proporção do desfecho. Conclusão: Os resultados encontrados demandam atenção pré-natal e adequações na assistência ao parto conforme recomendações vigentes.

HSP110 Inhibition in Primary Effusion Lymphoma Cells: One Molecule, Many Pro-Survival Targets.

Heat shock proteins (HSPs) are highly expressed in cancer cells and represent a promising target in anti-cancer therapy. In this study, we investigated for the first time the expression of high-molecular-weight HSP110, belonging to the HSP70 family of proteins, in Primary Effusion Lymphoma (PEL) and explored its role in their survival. This is a rare lymphoma associated with KSHV, for which an effective therapy remains to be discovered. The results obtained from this study suggest that targeting HSP110 could be a very promising strategy against PEL, as its silencing induced lysosomal membrane permeabilization, the cleavage of BID, caspase 8 activation, downregulated c-Myc, and strongly impaired the HR and NHEJ DNA repair pathways, leading to apoptotic cell death. Since chemical inhibitors of this HSP are not commercially available yet, this study encourages a more intense search in this direction in order to discover a new potential treatment that is effective against this and likely other B cell lymphomas that are known to overexpress HSP110.

Modulation of Epstein-Barr-Virus (EBV)-Associated Cancers by Co-Infections.

The oncogenic and persistent Epstein Barr virus (EBV) is carried by more than 95% of the human adult population. While asymptomatic in most of these, EBV can cause a wide variety of malignancies of lymphoid or epithelial cell origin. Some of these are also associated with co-infections that either increase EBV-induced tumorigenesis or weaken its immune control. The respective pathogens include Kaposi-sarcoma-associated herpesvirus (KSHV), Plasmodium falciparum and human immunodeficiency virus (HIV). In this review, I will discuss the respective tumor entities and possible mechanisms by which co-infections increase the EBV-associated cancer burden. A better understanding of the underlying mechanisms could allow us to identify crucial features of EBV-associated malignancies and defects in their immune control. These could then be explored to develop therapies against the respective cancers by targeting EBV and/or the respective co-infections with pathogen-specific therapies or vaccinations.

Pseudomonas aeruginosa biofilm exopolysaccharides: assembly, function, and degradation.

The biofilm matrix is a fortress; sheltering bacteria in a protective and nourishing barrier that allows for growth and adaptation to various surroundings. A variety of different components are found within the matrix including water, lipids, proteins, extracellular DNA, RNA, membrane vesicles, phages, and exopolysaccharides. As part of its biofilm matrix, Pseudomonas aeruginosa is genetically capable of producing three chemically distinct exopolysaccharides - alginate, Pel, and Psl - each of which has a distinct role in biofilm formation and immune evasion during infection. The polymers are produced by highly conserved mechanisms of secretion, involving many proteins that span both the inner and outer bacterial membranes. Experimentally determined structures, predictive modelling of proteins whose structures are yet to be solved, and structural homology comparisons give us insight into the molecular mechanisms of these secretion systems, from polymer synthesis to modification and export. Here, we review recent advances that enhance our understanding of P. aeruginosa multiprotein exopolysaccharide biosynthetic complexes, and how the glycoside hydrolases/lyases within these systems have been commandeered for antimicrobial applications.

Clinical management of Kaposi sarcoma herpesvirus-associated diseases: an update on disease manifestations and treatment strategies.

INTRODUCTION: Kaposi sarcoma herpes virus (KSHV) is associated with several diseases including Kaposi sarcoma, a form of multicentric Castleman's disease, primary effusion lymphoma, and an inflammatory cytokine syndrome. These KSHV-associated diseases (KAD) can present with heterogenous signs and symptoms that are often associated with cytokine dysregulation that may result in multiorgan dysfunction. The inability to promptly diagnose and treat these conditions can result in long-term complications and mortality. AREAS COVERED: Existing epidemiological subtypes of existing KSHV-associated diseases, specifically Kaposi sarcoma as well as the incidence of several KSHV-associated disorders are described. We review the KSHV latent and lytic phases as they correlate with KSHV-associated diseases. Given the complicated presentations, we discuss the clinical manifestations, current diagnostic criteria, existing treatment algorithms for individual KAD, and when they occur concurrently. With emerging evidence on the virus and host interactions, we evaluate novel approaches for the treatment of KAD. An extensive literature search was conducted to support these findings. EXPERT OPINION: KSHV leads to complex and concurrent disease processes that are often underdiagnosed both in the United States and worldwide. New therapies that exist for many of these conditions focus on chemotherapy-sparing options that seek to target the underlying viral pathogenesis or immunotherapy strategies.

NFE2L2 and STAT3 Converge on Common Targets to Promote Survival of Primary Lymphoma Cells.

NFE2L2 and STAT3 are key pro-survival molecules, and thus, their targeting may represent a promising anti-cancer strategy. In this study, we found that a positive feedback loop occurred between them and provided evidence that their concomitant inhibition efficiently impaired the survival of PEL cells, a rare, aggressive B cell lymphoma associated with the gammaherpesvirus KSHV and often also EBV. At the molecular level, we found that NFE2L2 and STAT3 converged in the regulation of several pro-survival molecules and in the activation of processes essential for the adaption of lymphoma cells to stress. Among those, STAT3 and NFE2L2 promoted the activation of pathways such as MAPK3/1 and MTOR that positively regulate protein synthesis, sustained the antioxidant response, expression of molecules such as MYC, BIRC5, CCND1, and HSP, and allowed DDR execution. The findings of this study suggest that the concomitant inhibition of NFE2L2 and STAT3 may be considered a therapeutic option for the treatment of this lymphoma that poorly responds to chemotherapies.

Primary Effusion Lymphoma, Multicentric Castleman's Disease, and Kaposi's Sarcoma in an HHV-8 and HIV-Positive Patient: A Case Report.

Primary effusion lymphoma (PEL), Kaposi's sarcoma (KS), and multicentric Castleman's disease (MCD) is an uncommon group of diseases included in the same spectrum with related characteristics. The coexistence of all of them in the same individual is a rare occurrence. We present the case of a 25-year-old patient diagnosed with human immunodeficiency virus (HIV) and the development of all these related pathologies. Despite the use of intensive treatment according to the latest recommendations, the evolution was unfavorable. This case reflects the need for new therapies and research in this field.

HHV8-unrelated primary effusion lymphoma in a patient with HBV-related liver cirrhosis: A case successfully treated with rituximab and lenalidomide.

Human herpesvirus type 8 (HHV-8) unrelated primary effusion lymphoma (PEL) like lymphoma (PEL-LL) is an exceedingly rare non-Hodgkin lymphoma with no characteristic symptoms and consensus on the optimal treatment. This case report presents a 55-year-old man with prior HBV-related Child-Pugh B liver cirrhosis and developing activity-related dyspnea. A moderate amount of pleural effusion was identified without tumor masses, and cytological studies confirmed a diagnosis of PEL-LL. The patient received rituximab and lenalidomide, albeit with HBV infection, and is currently on maintenance therapy with resolving symptoms but without HBV reactivation. Hence, the R2 protocol (rituximab and lenalidomide) might be clinically effective and safe for PEL-LL patients with HBV infection and Child-Pugh B liver cirrhosis.

Improving the specific activity and stability of alkaline pectinase PEL3 through SpyTag/SpyCatcher cyclization.

OBJECTIVES: PEL3, an alkaline pectinase, exhibited the highest activity among documented alkaline pectate lyases reported in our early study. Unfortunately, undesired thermal stability hampering its industrial application. The purpose of this study is to enhance the performance of wild-type PEL3 (W-PEL3) based on SpyTag/SpyCatcher-mediated cyclization. RESULTS: The cyclized PEL3 (C-PEL3) was observed to fold correctly and generate a spatial conformation in a head-to-tail manner in E. coli. C-PEL3 exhibited comparable optimum pH and temperature to those of W-PEL3. Moreover, the catalytic activity of C-PEL3 increased by 23% compared to W-PEL3, and the kcat/Km of C-PEL3 was 1.5-fold greater than that of the W-PEL3. Importantly, C-PEL3 showed improved stability compared to W-PEL3. Firstly, C-PEL3 displayed a 65% increase in residual activity after treatment at 55 °C for 30 min. Secondly, C-PEL3 was prone to resist heat-induced protein aggregation. Thirdly, C-PEL3 exhibited metal ion stability. Circular dichroism analysis revealed that C-PEL3 was more capable of maintaining its secondary structures than W-PEL3 upon heat treatment. CONCLUSIONS: C-PEL3, the initial example of a circular pectinase through SpyTag/SpyCatcher cyclization, exhibits superior performance and represents a highly encouraging contender for industrial utilization.

HHV8 and EBV-negative primary effusion-based lymphoma: A case report of a new provisional entity and review of literature.

Key Clinical Message: HHV8- and EBV-negative primary effusion lymphoma is an extremely rare neoplasm involving body cavities without detectable tumor mass. It usually presents in elderly patients without known immunodeficiency. Compared to primary effusion lymphoma, it has a better prognosis.Primary effusion lymphoma (PEL) is a rare non-Hodgkin lymphoma confined exclusively to body cavities without detectable tumor masses. The term PEL-like is an entity similar to PEL in clinical presentation but without relation to human herpesvirus 8 (HHV8). We report a case of HHV8- and EBV-negative primary effusion-based lymphoma.

Manganese Acts as an Environmental Inhibitor of Pseudomonas aeruginosa Biofilm Development by Inducing Dispersion and Modulating c-di-GMP and Exopolysaccharide Production via RbdA.

The opportunistic human pathogen Pseudomonas aeruginosa causes chronic infections that involve multicellular aggregates called biofilms. Biofilm formation is modulated by the host environment and the presence of cues and/or signals, likely affecting the pool of the bacterial second messenger cyclic diguanylate monophosphate (c-di-GMP). The manganese ion Mn2+ is a divalent metal cation that is essential for pathogenic bacterial survival and replication during the infection in a host organism. In this study, we investigated how Mn2+ alters P. aeruginosa biofilm formation via the regulation of c-di-GMP levels. Exposure to Mn2+ was found to temporally enhance attachment but impair subsequent biofilm development, apparent by reduced biofilm biomass accumulation and lack of microcolony formation due to the induction of dispersion. Moreover, exposure to Mn2+ coincided with reduced production of the exopolysaccharides Psl and Pel, decreased transcriptional abundance of pel and psl, and decreased levels of c-di-GMP. To determine whether the effect of Mn2+ was linked to the activation of phosphodiesterases (PDEs), we screened several PDE mutants for Mn2+-dependent phenotypes (attachment and polysaccharide production) as well as PDE activity. The screen revealed that the PDE RbdA is activated by Mn2+ and is responsible for Mn2+-dependent attachment, inhibition of Psl production, and dispersion. Taken together, our findings suggest Mn2+ is an environmental inhibitor of P. aeruginosa biofilm development that acts through the PDE RbdA to modulate c-di-GMP levels, thereby impeding polysaccharide production and biofilm formation but enhancing dispersion. IMPORTANCE While diverse environmental conditions such as the availability of metal ions have been shown to affect biofilm development, little is known about the mechanism. Here, we demonstrate that Mn2+ affects Pseudomonas aeruginosa biofilm development by stimulating phosphodiesterase RbdA activity to reduce the signaling molecule c-di-GMP levels, thereby hindering polysaccharide production and biofilm formation but enhancing dispersion. Our findings demonstrate that Mn2+ acts as an environmental inhibitor of P. aeruginosa biofilms, further suggesting manganese to be a promising new antibiofilm factor.