A Role for Human DNA Polymerase λ in Alternative Lengthening of Telomeres

Telomerase negative cancer cell types use the Alternative Lengthening of Telomeres (ALT) pathway to elongate telomeres ends. Here, we show that silencing human DNA polymerase (Pol λ) in ALT cells represses ALT activity and induces telomeric stress. In addition, replication stress in the absence of Pol λ, strongly affects the survival of ALT cells. In vitro, Pol λ can promote annealing of even a single G-rich telomeric repeat to its complementary strand and use it to prime DNA synthesis. The noncoding telomeric repeat containing RNA TERRA and replication protein A negatively regulate this activity, while the Protection of Telomeres protein 1 (POT1)/TPP1 heterodimer stimulates Pol λ. Pol λ associates with telomeres and colocalizes with TPP1 in cells. In summary, our data suggest a role of Pol λ in the maintenance of telomeres by the ALT mechanism.

Tissue-Specific Immunopathology in Fatal COVID-19

Rationale: In life-threatening coronavirus disease (COVID-19), corticosteroids reduce mortality, suggesting that immune responses have a causal role in death. Whether this deleterious inflammation is primarily a direct reaction to the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or an independent immunopathologic process is unknown.

Objectives: To determine SARS-CoV-2 organotropism and organ-specific inflammatory responses and the relationships among viral presence, inflammation, and organ injury.

Methods: Tissue was acquired from 11 detailed postmortem examinations. SARS-CoV-2 organotropism was mapped by using multiplex PCR and sequencing, with cellular resolution achieved by in situ viral S (spike) protein detection. Histologic evidence of inflammation was quantified from 37 anatomic sites, and the pulmonary immune response was characterized by using multiplex immunofluorescence.

Measurements and Main Results: Multiple aberrant immune responses in fatal COVID-19 were found, principally involving the lung and reticuloendothelial system, and these were not clearly topologically associated with the virus. Inflammation and organ dysfunction did not map to the tissue and cellular distribution of SARS-CoV-2 RNA and protein between or within tissues. An arteritis was identified in the lung, which was further characterized as a monocyte/myeloid-rich vasculitis, and occurred together with an influx of macrophage/monocyte-lineage cells into the pulmonary parenchyma. In addition, stereotyped abnormal reticuloendothelial responses, including excessive reactive plasmacytosis and iron-laden macrophages, were present and dissociated from viral presence in lymphoid tissues.

Conclusions: Tissue-specific immunopathology occurs in COVID-19, implicating a significant component of the immune-mediated, virus-independent immunopathologic process as a primary mechanism in severe disease. Our data highlight novel immunopathologic mechanisms and validate ongoing and future efforts to therapeutically target aberrant macrophage and plasma-cell responses as well as promote pathogen tolerance in COVID-19.

Monocyte-derived macrophages promote breast cancer bone metastasis outgrowth

Bone metastasis is the major cause of death in breast cancer. The lack of effective treatment suggests that disease mechanisms are still largely unknown. As a key component of the tumor microenvironment, macrophages promote tumor progression and metastasis. In this study, we found that macrophages are abundant in human and mouse breast cancer bone metastases. Macrophage ablation significantly inhibited bone metastasis growth. Lineage tracking experiments indicated that these macrophages largely derive from Ly6C+CCR2+ inflammatory monocytes. Ablation of the chemokine receptor, CCR2, significantly inhibited bone metastasis outgrowth and prolonged survival. Immunophenotyping identified that bone metastasis-associated macrophages express high levels of CD204 and IL4R. Furthermore, monocyte/macrophage-restricted IL4R ablation significantly inhibited bone metastasis growth, and IL4R null mutant monocytes failed to promote bone metastasis outgrowth. Together, this study identified a subset of monocyte-derived macrophages that promote breast cancer bone metastasis in an IL4R-dependent manner. This suggests that IL4R and macrophage inhibition can have potential therapeutic benefit against breast cancer bone disease.

Prenatal diagnosis and outcome of partial agenesis and hypoplasia of the corpus callosum

OBJECTIVE

To present antenatal sonographic findings and outcome of fetuses with hypoplasia or partial agenesis of the corpus callosum.

METHODS

The database of our ultrasound laboratory was searched retrospectively for cases of hypoplasia or partial agenesis of the corpus callosum suspected at antenatal neurosonography between 1998 and 2008 and confirmed by pathology or postnatal neuroimaging. In surviving infants, clinical follow-up had been arranged to assess neurodevelopmental outcome.

RESULTS

Nineteen fetuses with callosal underdevelopment were identified at a median gestational age of 22 (range, 21-33) weeks and confirmed at follow-up, including 14 with partial agenesis and five with hypoplasia. Among the 14 fetuses with partial agenesis, there were additional brain findings in 10, including two with absent cavum septi pellucidi, four with mild isolated ventriculomegaly and four with cerebellar abnormalities, two of which also had ventriculomegaly. Pregnancy was terminated electively in seven of the cases with partial agenesis and there was one neonatal death. Among the six surviving infants, neurodevelopmental outcome was appropriate for age in three at follow up, including two cases with isolated partial agenesis of the corpus callosum. Among the five fetuses with prenatally diagnosed callosal hypoplasia, additional anomalies were present in four. Two cases were terminated electively and three were alive at the time of writing, with a median age of 3 years. Among them, apparently normal neurological development was observed in only one case.

CONCLUSIONS

An antenatal diagnosis of callosal underdevelopment is possible by expert sonography. There is often association with other major anomalies. However, even in fetuses with apparently isolated findings, the prognosis is uncertain.

[Request for psychiatric admission: data from eight general hospital psychiatric wards in Lombardy]

OBJECTIVE

To describe requests of admissions to eight General Hospital Psychiatric Wards (SPDC) in Lombardy, Italy, during November 1995.

DESIGN

Descriptive prospective multicenter study.

SETTING

SPDCs of Busto Arsizio (VA), Calcinate (BG), Desio (MI), Magenta (MI), Merate (LC), Milano San Paolo I, Pavia, Treviglio (BG). The global catchment area sums up to 11% of the whole regional area, and to 18% of the population.

MAIN OUTCOME MEASURES

We used a previously developed flow chart with two major key points: who decided to go to the hospital? Did a doctor confirm this initiative? Main sociodemographic characteristics, ICD10 diagnosis and previous psychiatric admissions were collected for each admission.

RESULTS

Admissions were 315, patients 246. In 9.5% of cases patients asked for admission without any medical advice. In one third of cases the ward psychiatrist was the first doctor to visit the patient. Compulsive admissions (TSO) were 45 (14.3%), although patient's initiative lacked in 55.6% of cases. A referral from Outpatient Departments (CPS) was present in 28.2%. First-ever admitted were 63 (25.6%): 20.7% sent by CPS, 16% by GPs, 11% by other non psychiatric wards.

CONCLUSIONS

Although Goldberg & Huxley's model described General Hospital Psychiatric Wards as the last level of intervention, our data show that Italian SPDCs work as "front lines" services: less than one admission out of two were referred by a psychiatrist. Problems raised by "self-referred" patients are conspicuous and an evaluation of the filtering function of CPSs seems necessary. In this regard, a comparison with different modalities of Department organization could be useful.

Receiver-operator characteristic curves for the ultrasonographic prediction of small-for-gestational-age fetuses in low-risk pregnancies

OBJECTIVE

Our purpose was to assess the accuracy of third-trimester ultrasonographic biometry in the diagnosis of small-for-gestational-age fetuses in a low-risk obstetric population.

STUDY DESIGN

A total of 1000 low-risk pregnancies were prospectively examined at 31 weeks' gestation. The diagnostic accuracy of the fetal abdominal circumference and estimated fetal weight according to 24 formulas in the literature were evaluated by the use of receiver-operator characteristic curves.

RESULTS

The incidence of a birth weight <10th percentile was 8.2%. The diagnostic accuracies of abdominal circumference and estimated fetal weight were remarkably similar. None of the 24 formulas performed significantly better than the measurement of the abdominal circumference. At a specificity of 90%, 46% of infants with a birth weight <10th percentile and five of six cases with adverse perinatal outcomes were predicted.

CONCLUSION

In a low-risk obstetric population third-trimester ultrasonographic biometry has limited value in predicting small-for-gestational-age fetuses, and estimation of fetal weight does not carry an advantage over measurement of the abdominal circumference. The optimal cutoff value remains uncertain. However, by accepting a 10% false-positive rate, half of small-for-gestational-age fetuses and most perinatal complications could be recognized.