Opportunistic pathogen Porphyromonas gingivalis targets the LC3B-ceramide complex and mediates lethal mitophagy resistance in oral tumors.

Mechanisms by which Porphyromonas gingivalis (P. gingivalis) infection enhances oral tumor growth or resistance to cell death remain elusive. Here, we determined that P. gingivalis infection mediates therapeutic resistance via inhibiting lethal mitophagy in cancer cells and tumors. Mechanistically, P. gingivalis targets the LC3B-ceramide complex by associating with LC3B via bacterial major fimbriae (FimA) protein, preventing ceramide-dependent mitophagy in response to various therapeutic agents. Moreover, ceramide-mediated mitophagy is induced by Annexin A2 (ANXA2)-ceramide association involving the E142 residue of ANXA2. Inhibition of ANXA2-ceramide-LC3B complex formation by wild-type P. gingivalis prevented ceramide-dependent mitophagy. Moreover, a FimA-deletion mutant P. gingivalis variant had no inhibitory effects on ceramide-dependent mitophagy. Further, 16S rRNA sequencing of oral tumors indicated that P. gingivalis infection altered the microbiome of the tumor macroenvironment in response to ceramide analog treatment in mice. Thus, these data provide a mechanism describing the pro-survival roles of P. gingivalis in oral tumors.

Delays Starting Postoperative Radiotherapy Among Head and Neck Cancer Patients: A Systematic Review and Meta-analysis.

OBJECTIVE: Initiating postoperative radiotherapy (PORT) within 6 weeks (42 days) of surgery is the first and only Commission on Cancer (CoC) approved quality metric for head and neck squamous cell carcinoma (HNSCC). No study has systematically reviewed nor synthesized the literature to establish national benchmarks for delays in starting PORT. DATA SOURCES: Following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, we performed a systematic review of PubMed, Scopus, and CINAHL. REVIEW METHODS: Studies that described time-to-PORT or PORT delays in patients with HNSCC treated in the United States after 2003 were included. Meta-analysis of proportions and continuous measures was performed on nonoverlapping datasets to examine the pooled frequency of PORT delays and time-to-PORT. RESULTS: Thirty-six studies were included in the systematic review and 14 in the meta-analysis. Most studies utilized single-institution (n = 17; 47.2%) or cancer registry (n = 16; 44.4%) data. Twenty-five studies (69.4%) defined PORT delay as >6 weeks after surgery (the definition utilized by the CoC and National Comprehensive Cancer Network Guidelines), whereas 4 (11.1%) defined PORT delay as a time interval other than >6 weeks, and 7 (19.4%) characterized time-to-PORT without defining delay. Meta-analysis revealed that 48.6% (95% confidence interval [CI], 41.4-55.9) of patients started PORT > 6 weeks after surgery. Median and mean time-to-PORT were 45.8 (95% CI, 42.4-51.4 days) and 47.4 days (95% CI, 43.4-51.4 days), respectively. CONCLUSION: Delays in initiating guideline-adherent PORT occur in approximately half of patients with HNSCC. These meta-analytic data can be used to set national benchmarks and assess progress in reducing delays.

Alterations of lipid-mediated mitophagy result in aging-dependent sensorimotor defects.

The metabolic consequences of mitophagy alterations due to age-related stress in healthy aging brains versus neurodegeneration remain unknown. Here, we demonstrate that ceramide synthase 1 (CerS1) is transported to the outer mitochondrial membrane by the p17/PERMIT transporter that recognizes mislocalized mitochondrial ribosomes (mitoribosomes) via 39-FLRN-42 residues, inducing ceramide-mediated mitophagy. P17/PERMIT-CerS1-mediated mitophagy attenuated the argininosuccinate/fumarate/malate axis and induced d-glucose and fructose accumulation in neurons in culture and brain tissues (primarily in the cerebellum) of wild-type mice in vivo. These metabolic changes in response to sodium-selenite were nullified in the cerebellum of CerS1to/to (catalytically inactive for C18-ceramide production CerS1 mutant), PARKIN-/- or p17/PERMIT-/- mice that have dysfunctional mitophagy. Whereas sodium selenite induced mitophagy in the cerebellum and improved motor-neuron deficits in aged wild-type mice, exogenous fumarate or malate prevented mitophagy. Attenuating ceramide-mediated mitophagy enhanced damaged mitochondria accumulation and age-dependent sensorimotor abnormalities in p17/PERMIT-/- mice. Reinstituting mitophagy using a ceramide analog drug with selenium conjugate, LCL768, restored mitophagy and reduced malate/fumarate metabolism, improving sensorimotor deficits in old p17/PERMIT-/- mice. Thus, these data describe the metabolic consequences of alterations to p17/PERMIT/ceramide-mediated mitophagy associated with the loss of mitochondrial quality control in neurons and provide therapeutic options to overcome age-dependent sensorimotor deficits and related disorders like amyotrophic lateral sclerosis (ALS).

Crosstalk between pro-survival sphingolipid metabolism and complement signaling induces inflammasome-mediated tumor metastasis.

Crosstalk between metabolic and signaling events that induce tumor metastasis remains elusive. Here, we determine how oncogenic sphingosine 1-phosphate (S1P) metabolism induces intracellular C3 complement activation to enhance migration/metastasis. We demonstrate that increased S1P metabolism activates C3 complement processing through S1P receptor 1 (S1PR1). S1P/S1PR1-activated intracellular C3b-α'2 is associated with PPIL1 through glutamic acid 156 (E156) and aspartic acid 111 (D111) residues, resulting in NLRP3/inflammasome induction. Inactivation mutations of S1PR1 to prevent S1P signaling or mutations of C3b-α'2 to prevent its association with PPIL1 attenuate inflammasome activation and reduce lung colonization/metastasis in mice. Also, activation of the S1PR1/C3/PPIL1/NLRP3 axis is highly associated with human metastatic melanoma tissues and patient-derived xenografts. Moreover, targeting S1PR1/C3/PPIL1/NLRP3 signaling using molecular, genetic, and pharmacologic tools prevents lung colonization/metastasis of various murine cancer cell lines using WT and C3a-receptor1 knockout (C3aR1-/-) mice. These data provide strategies for treating high-grade/metastatic tumors by targeting the S1PR1/C3/inflammasome axis.

S1P/S1PR1 signaling differentially regulates the allogeneic response of CD4 and CD8 T cells by modulating mitochondrial fission.

Graft-versus-host disease (GVHD) significantly contributes to patient morbidity and mortality after allogeneic hematopoietic cell transplantation (allo-HSCT). Sphingosine-1-phosphate (S1P) signaling is involved in the biogenetic processes of different immune cells. In the current study, we demonstrated that recipient sphingosine kinase 1 (Sphk1), but not Sphk2, was required for optimal S1PR1-dependent donor T-cell allogeneic responses by secreting S1P. Using genetic and pharmacologic approaches, we demonstrated that inhibition of Sphk1 or S1PR1 substantially attenuated acute GVHD (aGVHD) while retaining the graft-versus-leukemia (GVL) effect. At the cellular level, the Sphk1/S1P/S1PR1 pathway differentially modulated the alloreactivity of CD4+ and CD8+ T cells; it facilitated T-cell differentiation into Th1/Th17 cells but not Tregs and promoted CD4+ T-cell infiltration into GVHD target organs but was dispensable for the CTL activity of allogeneic CD8+ T cells. At the molecular level, the Sphk1/S1P/S1PR1 pathway augmented mitochondrial fission and increased mitochondrial mass in allogeneic CD4+ but not CD8+ T cells by activating the AMPK/AKT/mTOR/Drp1 pathway, providing a mechanistic basis for GVL maintenance when S1P signaling was inhibited. For translational purposes, we detected the regulatory efficacy of pharmacologic inhibitors of Sphk1 and S1PR1 in GVHD induced by human T cells in a xenograft model. Our study provides novel mechanistic insight into how the Sphk1/S1P/S1PR1 pathway modulates T-cell alloreactivity and validates Sphk1 or S1PR1 as a therapeutic target for the prevention of GVHD and leukemia relapse. This novel strategy may be readily translated into the clinic to benefit patients with hematologic malignancies and disorders.

Ceramide synthase 6 impacts T-cell allogeneic response and graft-versus-host disease through regulating N-RAS/ERK pathway.

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective immunotherapy for various hematologic malignancies, predominantly through potent graft-versus-leukemia (GVL) effect. However, the mortality after allo-HCT is because of relapse of primary malignancy and followed by graft-vs-host-disease (GVHD) as a major cause of transplant-related mortality. Hence, strategies to limit GVHD while preserving the GVL effect are highly desirable. Ceramide, which serves a central role in sphingolipid metabolism, is generated by ceramide synthases (CerS1-6). In this study, we found that genetic or pharmacologic targeting of CerS6 prevented and reversed chronic GVHD (cGVHD). Furthermore, specific inhibition of CerS6 with ST1072 significantly ameliorated acute GVHD (aGVHD) while preserving the GVL effect, which differed from FTY720 that attenuated aGVHD but impaired GVL activity. At the cellular level, blockade of CerS6 restrained donor T cells from migrating into GVHD target organs and preferentially reduced activation of donor CD4 T cells. At the molecular level, CerS6 was required for optimal TCR signaling, CD3/PKCθ co-localization, and subsequent N-RAS activation and ERK signaling, especially on CD4+ T cells. The current study provides rationale and means for targeting CerS6 to control GVHD and leukemia relapse, which would enhance the efficacy of allo-HCT as an immunotherapy for hematologic malignancies in the clinic.

Alterations of lipid metabolism provide serologic biomarkers for the detection of asymptomatic versus symptomatic COVID-19 patients.

COVID-19 pandemic exerts a health care emergency around the world. The illness severity is heterogeneous. It is mostly unknown why some individuals who are positive for SARS-CoV-2 antibodies stay asymptomatic while others show moderate to severe disease symptoms. Reliable biomarkers for early detection of the disease are urgently needed to attenuate the virus's spread and help make early treatment decisions. Bioactive sphingolipids play a crucial role in the regulation of viral infections and pro-inflammatory responses involved in the severity of COVID-19. However, any roles of sphingolipids in COVID-19 development or detection remain unknown. In this study, lipidomics measurement of serum sphingolipids demonstrated that reduced sphingosine levels are highly associated with the development of symptomatic COVID-19 in the majority (99.24%) SARS-CoV-2-infected patients compared to asymptomatic counterparts. The majority of asymptomatic individuals (73%) exhibited increased acid ceramidase (AC) in their serum, measured by Western blotting, consistent with elevated sphingosine levels compared to SARS-CoV-2 antibody negative controls. AC protein was also reduced in almost all of the symptomatic patients' serum, linked to reduced sphingosine levels, measured in longitudinal acute or convalescent COVID-19 samples. Thus, reduced sphingosine levels provide a sensitive and selective serologic biomarker for the early identification of asymptomatic versus symptomatic COVID-19 patients.

Aging-dependent mitochondrial dysfunction mediated by ceramide signaling inhibits antitumor T cell response.

We lack a mechanistic understanding of aging-mediated changes in mitochondrial bioenergetics and lipid metabolism that affect T cell function. The bioactive sphingolipid ceramide, induced by aging stress, mediates mitophagy and cell death; however, the aging-related roles of ceramide metabolism in regulating T cell function remain unknown. Here, we show that activated T cells isolated from aging mice have elevated C14/C16 ceramide accumulation in mitochondria, generated by ceramide synthase 6, leading to mitophagy/mitochondrial dysfunction. Mechanistically, aging-dependent mitochondrial ceramide inhibits protein kinase A, leading to mitophagy in activated T cells. This aging/ceramide-dependent mitophagy attenuates the antitumor functions of T cells in vitro and in vivo. Also, inhibition of ceramide metabolism or PKA activation by genetic and pharmacologic means prevents mitophagy and restores the central memory phenotype in aging T cells. Thus, these studies help explain the mechanisms behind aging-related dysregulation of T cells' antitumor activity, which can be restored by inhibiting ceramide-dependent mitophagy.

Consanguinity rates among Syrian refugees in Lebanon: a study on genetic awareness.

Consanguineous marriage is a deeply rooted tradition in the Arab world. Such marriages are linked to higher rates of recessive genetic diseases. During the Syrian conflict, which started in 2011, around one million Syrian individuals became refugees in Lebanon. This study assessed the consanguinity rates among Syrian refugees living in Lebanon up to three successive consanguineous generations, and examined refugees' awareness of the possible consequences of consanguineous marriage and their attitudes towards consanguinity. Their knowledge of, and access to, premarital screening was also assessed. The study was conducted between January and May 2018. Several study sites representing refugees' distribution within the country were chosen. The study sample included 1008 interviewees from different families. Of those interviewed, 51.9% were in a consanguineous marriage. Interestingly, 23.9% were the product of consanguineous marriages themselves, and 17.9% were consanguineous for three successive generations. The interviewees generally knew about premarital screening, but the majority (61.9%) had not had the screening. The high rates of consanguinity in these Syrian refugees call for immediate action, including raising genetic awareness and providing appropriate genetic counselling. Despite the respondents' familiarity with premarital screening, there was a low rate of uptake of the test, underscoring the importance of providing better education to these refugees.

Measles and mumps outbreaks in Lebanon: trends and links.

BACKGROUND: Lebanon has experienced several measles and mumps outbreaks in the past 20 years. In this article, a case-based surveillance of both measles and mumps outbreaks in Lebanon was carried out in an attempt to outline factors contributing to the failure of elimination plans and to provide potential solutions. The relationship between the outbreaks of both diseases was described and explored. METHODS: A retrospective descriptive study of confirmed cases of measles and mumps in Lebanon between 2003 and 2018 collected from the Lebanese Ministry of Public Health Epidemiological Surveillance Unit public database was carried out. The information collected was graphically represented taking into consideration dates of reported cases, age groups affected, and vaccination status. RESULTS: The mean number of measles cases was 150.25 cases/year in the 1-4 years age group, 87 cases/year in individuals aging between 5 and 14, and 63.68 cases/year in those > 14 years old. In the latter group, only 18.05% were unvaccinated. The mean number of mumps cases was 30.4 cases/year in the < 4 year age group and 53.8 cases/year in the 10-19 years age group. During the study period, every spike in measles cases was followed by a similar spike in mumps. 9.66% of measles cases occurred in individuals who received at least 2 doses of the vaccine, 52.26% in the unvaccinated, and 38% in those whose vaccination status was undetermined. CONCLUSIONS: Measles in Lebanon is a disease of the pediatric population, but adults remain at risk. Outbreaks of mumps followed those of measles and were mainly among adolescents. Presence of a large number of Syrian refugees in the country may further complicate the situation. Vaccination activities need to be intensified.

Effect of vitamin D replacement on indexes of insulin resistance in overweight elderly individuals: a randomized controlled trial.

BACKGROUND: It is unclear whether and at what dose vitamin D supplementation affects insulin resistance (IR). OBJECTIVE: We sought to investigate whether vitamin D at doses higher than currently recommended decreases indexes of IR in an ambulatory population of overweight elderly subjects. DESIGN: This double-blind, randomized, controlled multicenter trial enrolled 257 elderly overweight individuals aged ≥65 y with baseline 25-hydroxyvitamin D [25(OH)D] concentrations between 10 and 30 ng/mL. All subjects received 1000 mg calcium citrate/d, with vitamin D administered weekly at an equivalent dose of 600 or 3750 IU/d. The homeostasis model assessment (HOMA) of IR index at 1 y was the primary outcome. We also assessed the McAuley index. RESULTS: In total, 222 subjects (55% women) with a mean ± SD age and body mass index (BMI; in kg/m(2)) of 71 ± 4 y and 30 ± 4, respectively, completed the study. Subjects' baseline characteristics, including IR indexes, were similar across groups: 69% had prediabetes, 54% had hypertension (47% were taking antihypertensive medications), and 60% had hyperlipidemia, nearly half of whom were receiving lipid-lowering drugs. At 1 y, mean ± SD serum 25(OH)D increased from 20 ± 7 to 26 ± 7 ng/mL in the low-dose arm (P < 0.0001) and from 21 ± 8 to 36 ± 10 ng/mL in the high-dose arm (P < 0.001). Median HOMA-IR indexes did not change compared with baseline concentrations and were similar in the high- [2.2 (IQR: 1.5, 2.9)] and low-dose [2.3 (IQR: 1.6, 3.3] treatment groups. Adjusted analyses showed that HOMA-IR was predicted by the baseline HOMA index and BMI but not by vitamin D dose, baseline serum 25(OH)D, or change in 25(OH)D. CONCLUSION: Vitamin D3 at 3750 IU/d did not improve HOMA-IR compared with the Institute of Medicine Recommended Dietary Allowance of 600 IU/d in elderly overweight individuals. This trial was registered at clinicaltrials.gov as NCT01315366.