Both activating and inhibitory Fc gamma receptors mediate rituximab-induced trogocytosis of CD20 in mice

Antigenic modulation by trogocytosis during anti-CD20 mAb treatment with rituximab (RTX) leads to loss of CD20 and therefore can compromise therapy. During trogocytosis, effector cells, such as macrophages, remove CD20 from the surface of antibody-coated cells in an Fc receptor-dependent manner. Importantly, Fcγ receptors (FcγRs) are also crucial in the anti-tumor effects of RTX by inducing antibody dependent cell-mediated cytotoxicity (ADCC). Here we studied the role of FcγR during RTX-induced trogocytosis of CD20 in an intraperitoneal tumor model with EL4-CD20 cells. We found marked RTX-induced trogocytosis of CD20 in FcγRI- or FcγRIII-deficient mice, similar to wild type mice, demonstrating a redundancy for activating FcγR in trogocytosis. Interestingly, in FcRγ-chain-deficient mice, trogocytosis was still apparent, indicating that the inhibitory receptor FcγRIIB alone can also mediate trogocytosis. These data were confirmed by in vitro analysis with blocking antibodies. Decreasing the amount of RTX in vivo resulted in less trogocytosis of CD20, supporting clinical studies with lower RTX dose. Importantly, we show that cells which undergo in vivo trogocytosis can still be killed ex vivo by ADCC but not by complement-mediated cytotoxicity (CDC), underscoring the clinical relevance of trogocytosis. Taken together, our study provides more insights into the mechanism and consequences of RTX-induced trogocytosis of CD20.     

2p15-p16.1 microdeletion syndrome: molecular characterization and association of the OTX1 and XPO1 genes with autism spectrum disorders

Reports of unrelated individuals with autism spectrum disorder (ASD) and similar clinical features having overlapping de novo interstitial deletions at 2p15-p16.1 suggest that this region harbors a gene(s) important to the development of autism. We molecularly characterized two such deletions, selecting two genes in this region, exportin 1 (XPO1) and orthodenticle homolog 1 (OTX1) for association studies in three North American cohorts (Autism Spectrum Disorder - Canadian American Research Consortium (ASD-CARC), New York, and Autism Genetic Resource Exchange (AGRE)) and one Italian cohort (Società Italiana per la Ricerca e la Formazione sull'Autismo (SIRFA)) of families with ASD. In XPO1, rs6735330 was associated with autism in all four cohorts (P<0.05), being significant in ASD-CARC cohorts (P-value following false discovery rate correction for multiple testing (P(FDR))=1.29 × 10(-5)), the AGRE cohort (P(FDR)=0.0011) and the combined families (P(FDR)=2.34 × 10(-9)). Similarly, in OTX1, rs2018650 and rs13000344 were associated with autism in ASD-CARC cohorts (P(FDR)=8.65 × 10(-7) and 6.07 × 10(5), respectively), AGRE cohort (P(FDR)=0.0034 and 0.015, respectively) and the combined families (P(FDR)=2.34 × 10(-9) and 0.00017, respectively); associations were marginal or insignificant in the New York and SIRFA cohorts. A significant association (P(FDR)=2.63 × 10(-11)) was found for the rs2018650G-rs13000344C haplotype. The above three SNPs were associated with severity of social interaction and verbal communication deficits and repetitive behaviors (P-values <0.01). No additional deletions were identified following screening of 798 ASD individuals. Our results indicate that deletion 2p15-p16.1 is not commonly associated with idiopathic ASD, but represents a novel contiguous gene syndrome associated with a constellation of phenotypic features (autism, intellectual disability, craniofacial/CNS dysmorphology), and that XPO1 and OXT1 may contribute to ASD in 2p15-p16.1 deletion cases and non-deletion cases of ASD mapping to this chromosome region.     

A study of DNA damage recognition and repair gene polymorphisms in relation to cancer predisposition and G2 chromosomal radiosensitivity

The previously reported association of the APEX Asp148Glu single nucleotide polymorphism (SNP) with cancer, and the suggestion of associations of the XRCC3 Thr241Met and hOGG1 Ser326Cys SNP sites with G(2) chromosomal radiosensitivity were investigated in a new study of 30 childhood and young adult cancer survivors, their 30 partners, and 55 offspring. An additional SNP, hOGG1 Arg46Gln was also analyzed. Data on G(2) chromosomal radiosensitivity was available on 29 of the families including 53 offspring. No significant associations of genotype with cancer or G(2) chromosomal radiosensitivity were observed.     

Dual Role of Interleukin-10 in Murine Lyme Disease: Regulation of Arthritis Severity and Host Defense

In the murine model of Lyme disease, C3H/He mice exhibit severe arthritis while C57BL/6N mice exhibit mild lesions when infected with Borrelia burgdorferi. Joint tissues from these two strains of mice harbor similar concentrations of B. burgdorferi, suggesting that the difference in disease severity reflects differences in the magnitude of the inflammatory response to B. burgdorferi lipoproteins. Stimulation of bone marrow macrophages from C3H/HeN mice with the B. burgdorferi lipoprotein OspA resulted in higher-level production of the inflammatory mediators tumor necrosis factor alpha, nitric oxide, and interleukin-6 (IL-6) than that of macrophages from C57BL/6N mice. In contrast, macrophages from C57BL/6N mice consistently produced larger amounts of the anti-inflammatory cytokine IL-10 than did C3H/HeN macrophages. Addition of recombinant IL-10 suppressed the production of inflammatory mediators by macrophages from both strains. IL-10 was found to modulate B. burgdorferi-induced inflammation in vivo, since C57BL/6J mice deficient in IL-10 (IL-10-/-) developed more severe arthritis than wild-type C57BL/6J mice. The increase in arthritis severity was associated with a 10-fold decrease in the number of B. burgdorferi organisms present in ankle tissues from IL-10-/- mice. These findings suggest that in C57BL/6 mice, IL-10-dependent regulation of arthritis severity occurs at the expense of effective control of bacterial numbers.     

Gastrocnemius specific force is increased in elderly males following a 12-month physical training programme

The aim of the present investigation was to determine whether muscle force per physiological cross sectional area (PCSA) of the lateral gastrocnemius (GL) of elderly males increased following a 12-month physical training programme. Eleven elderly males were assigned to a 12-month training programme (TRN mean age 72.7 ± 3.3 years, mean ± SD) and eight elderly males were allocated to a control group (CTRL, 73.9 ± 4.0 years) who maintained their habitual physical activity levels. In vivo measurements of muscle architecture, muscle volume (VOL), achilles tendon moment arm length and plantarflexor torque were used to estimate GL PCSA (VOL/fascicle length) and specific force (GL fascicle force/GL PCSA). Maximal GL fascicle force was calculated accounting for agonist muscle activation and antagonist co-activation. Following training GL fascicle force increased by 31% (P < 0.01), which was not entirely accounted for by a 17% increase in PCSA (from 27.2 ± 5.9 to 31.8 ± 6.2 cm², P < 0.05). Specific force increased significantly from 8.9 ± 1.9 to 11.2 ± 3.0 N cm⁻² (P < 0.05). Pennation angle, but not fascicle length, increased by 12% with training (P < 0.05). The CTRL group showed no change in muscle size, strength or architecture over the 12-month period. In conclusion, with the level of agonist and antagonist muscle activity accounted for a 12-month strength training programme resulted in an increase in both PCSA and specific force in elderly males.     

Lymphotoxin-α and galectin-2 SNPs are not associated with myocardial infarction in two different German populations

Recent data provided strong evidence for the association of single nucleotide polymorphisms (SNPs) in the lymphotoxin-alpha (LTA) and galectin-2 (LGALS2) genes with myocardial infarction (MI) in a Japanese population. For populations of other genetic background, the relevance of these polymorphisms in the pathogenesis of MI remains controversial. We aimed to define the role of LTA and LGALS2 SNPs in two German MI populations with markedly different ascertainment strategies. Two different MI populations were studied. In the first population, MI patients were ascertained by a strong family history of MI (n = 1214). Controls were unrelated disease-free participants of the study (n = 1080). The second population included patients suffering from sporadic (nonfamilial) MI from the German KORA register (n = 607). The control group consisted of participants of the WHO MONICA survey in Germany (n = 1492). TaqMan assays were used to determine the genotypes of 4 SNPs in the LTA genomic region and 1 SNP in the LGALS2 gene. Single SNPs in both genomic regions as well as haplotypes in the LTA genomic region were tested for association in various models of inheritance. No association with MI could be found for any of the examined SNPs in the LTA genomic region and LGALS2 gene, or for haplotypes spanning the LTA genomic region. In two MI populations of European descent with markedly different ascertainment strategies, we were not able to identify a significant association of SNPs in the LTA genomic region or the LGALS2 gene with MI. These variants are unlikely to play a significant role in populations of European origin.     

Obesity and regional fat distribution in Kenyan populations: Impact of ethnicity and urbanization

Background: Obesity is increasing rapidly in Africa, and may not be associated with the same changes in body composition among different ethnic groups in Africa.

Objective: To assess abdominal visceral and subcutaneous fat thickness, prevalence of obesity, and differences in body composition in rural and urban Kenya.

Subjects and methods: In a cross-sectional study carried out among Luo, Kamba and Maasai in rural and urban Kenya, abdominal visceral and subcutaneous fat thicknesses were measured by ultrasonography. Height and weight, waist, mid-upper arm circumferences, and triceps skinfold thickness were measured. Body mass index (BMI), arm fat area (AFA) and arm muscle area (AMA) were calculated.

Results: Among 1430 individuals (58.3% females) aged 17–68 years, abdominal visceral and subcutaneous fat, BMI, AFA and waist circumference (WC) increased with age, and were highest in the Maasai and in the urban population. AMA was only higher with increasing age among males. The prevalence of overweight (BMI ≥ 25) (39.8% vs. 15.8%) and obesity (BMI ≥ 30) (15.5% vs. 5.1%) was highest in the urban vs. rural population.

Conclusion: Abdominal visceral and subcutaneous fat thickness was higher with urban residency. A high prevalence of overweight and obesity was found. The Maasai had the highest overall fat accumulation.     

Investigation of the human serotonin 6 (5‐HT6) receptor gene in bipolar affective disorder and schizophrenia

Serotonin (5‐hydroxytryptamine, 5‐HT) is a neurotransmitter that mediates a wide range of central nervous functions by activating multiple 5‐HT receptor subtypes. A possible irregularity of serotonergic neurotransmission has been implicated in a variety of neuropsychiatric diseases. In the present study, we performed a systematic mutation scan of the complete coding region and splice junctions of the 5‐HT₆ receptor gene to explore the contribution of this gene to the development of bipolar affective disorder and schizophrenia. Investigating 137 unrelated individuals (including 45 bipolar affective patients, 46 schizophrenic patients, and 46 unrelated controls), we identified six single base substitutions (126G/T, 267C/T, 873+30C/T, 873+128A/C, 1128G/C, 1376T/G). Comparing frequencies between patients and controls, we observed a significant overrepresentation of the 267C allele among bipolar patients (P=0.023 not corrected for multiple testing). This finding was followed up in an independent sample of 105 bipolar family trios using a family‐based association design. Fifty‐one transmissions could be examined. In 30 cases allele 267C and in 21 cases allele 267T were transmitted to the affected offspring. Although this result was far from statistical significance (transmission disequilibrium test=1.59, P=0.208), the limited number of possible transmissions may have prevented detection of smaller effects. Our preliminary data suggest that bipolar affective disorder may be associated with variation in the 5‐HT₆ gene. It will be important to extend the present analysis to larger samples. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:217–221, 2000. © 2000 Wiley‐Liss, Inc.     

Perioperative high-dose-rate brachytherapy in locally advanced and recurrent gynecologic cancer: Initial results of a phase II trial

BACKGROUND: This study was undertaken to determine the feasibility of perioperative high-dose-rate brachytherapy (PHDRB) as an adjunct to salvage surgery in primary advanced or recurrent gynecologic cancer. METHODS: Twenty-five patients with either locally advanced (n = 4) or recurrent (n = 21) gynecologic cancer suitable for salvage surgery were included. Unirradiated patients were treated with preoperative chemoradiation followed by salvage surgery and PHDRB (R0 and R1 resections receiving 16 or 24 Gy, respectively). Previously irradiated patients were treated with salvage surgery and PHDRB alone with 32 or 40 Gy for R0 or R1 resections, respectively. RESULTS: Resections were categorized as R0 in 9 patients (36.0%) and R1 in 16 (64.0%). Four previously irradiated patients suffered fatal pelvic bleeding between 8 and 13 months after surgery and PHDRB. After a median follow-up of 20 months (3-55+), the 4-year actuarial local and pelvic controls were 88.1% and 80.8%, respectively. The 4-year distant metastases-free survival was 40.9%. Four-year actuarial overall survival was 34.0%, with a median survival of 27.1 months (95% confidence interval: 17.5-36.8). CONCLUSIONS: Local and pelvic control results are excellent for this very high-risk-disease population. PHDRB dose in previously irradiated patients has been shifted to the closest lower level due to unacceptable vascular toxicity.