Red/processed meat consumption and non-cancer-related outcomes in humans: umbrella review.

The associations of red/processed meat consumption and cancer-related health outcomes have been well discussed. The umbrella review aimed to summarise the associations of red/processed meat consumption and various non-cancer-related outcomes in humans. We systematically searched the systematic reviews and meta-analyses of associations between red/processed meat intake and health outcomes from PubMed, Embase, Web of Science and the Cochrane Library databases. The umbrella review has been registered in PROSPERO (CRD 42021218568). A total of 40 meta-analyses were included. High consumption of red meat, particularly processed meat, was associated with a higher risk of all-cause mortality, CVD and metabolic outcomes. Dose-response analysis revealed that an additional 100 g/d red meat intake was positively associated with a 17 % increased risk of type 2 diabetes mellitus (T2DM), 15 % increased risk of CHD, 14 % of hypertension and 12 % of stroke. The highest dose-response/50 g increase in processed meat consumption at 95 % confident levels was 1·37, 95 % CI (1·22, 1·55) for T2DM, 1·27, 95 % CI (1·09, 1·49) for CHD, 1·17, 95 % CI (1·02, 1·34) for stroke, 1·15, 95 % CI (1·11, 1·19) for all-cause mortality and 1·08, 95 % CI (1·02, 1·14) for heart failure. In addition, red/processed meat intake was associated with several other health-related outcomes. Red and processed meat consumption seems to be more harmful than beneficial to human health in this umbrella review. It is necessary to take the impacts of red/processed meat consumption on non-cancer-related outcomes into consideration when developing new dietary guidelines, which will be of great public health importance. However, more additional randomised controlled trials are warranted to clarify the causality.

Association between the weight-adjusted waist index and stroke: a cross-sectional study.

BACKGROUND: The weight-adjusted waist index (WWI) is a new measure of obesity, and this study aimed to determine the association between the WWI and stroke. METHODS: Using the National Health and Nutrition Examination Survey (NHANES) 2011-2020 dataset, cross-sectional data from 23,389 participants were analysed. The correlation between the WWI and stroke was investigated through multivariate logistic regression and smoothing curve fitting. Subgroup analysis and interaction tests were also carried out. RESULTS: The research involved 23,389 participants, of whom 893 (3.82%) had a stroke. The fully adjusted model revealed a positive correlation between the WWI and stroke [1.25 (1.05, 1.48)]. Individuals who were in the highest quartile of WWI exhibited a 62% higher likelihood of experiencing a stroke than those in the lowest quartile [1.62 (1.06, 2.48)]. Subgroup analysis and interaction tests revealed that this positive correlation was similar in different population settings (all P for interaction > 0.05). CONCLUSION: A higher WWI was associated with a higher prevalence of stroke. The results of this study underscore the value of the WWI in stroke prevention and management.

Efficacy and safety of preoperative chewing gum for undergoing elective surgery: A meta-analysis of randomised controlled trials.

AIMS AND OBJECTIVES: This meta-analysis aimed to investigate the safety and feasibility of preoperative chewing gum in adult patients undergoing elective surgery. BACKGROUND: Postoperative chewing gum has been shown to be safe and effective for most surgeries, while the safety and efficacy of preoperative chewing gum are still controversial. DESIGN: A meta-analysis of randomised controlled trials was performed. NO PATIENT OR PUBLIC CONTRIBUTION: This was a meta-analysis involving no people or animals. METHODS: The literature search was performed in 9 databases from inception to July 2022. Randomised controlled trials that compared the safety and efficacy of preoperative chewing gum and preoperative chewing no gum in adult patients undergoing elective surgery were included. The study was reported in compliance with PRISMA statement. TRIAL REGISTRATION: PROSPERO CRD42022330223. RESULTS: Fourteen trials involving 1433 adult patients who undergo elective surgery were pooled in this meta-analysis. The results showed that preoperative chewing gum group resulted in no significant difference in gastric pH (p = .13) and gastric fluid volume (p = .25) compared with non-gum-chewing group. In comparison with the non-gum-chewing group, the gum-chewing group was associated with shorter preoperative thirst score (p = .02), lower incidence of postoperative nausea (p = .0004), lower incidence of postoperative sore throat, lower incidence of postoperative hoarseness, lower postoperative pain score, shorter first postoperative anal exhaust time (p < .00001), shorter first postoperative defecation time (p < .00001) and shorter hospital days (p = .02). CONCLUSIONS: Preoperative chewing gum was associated with lower discomforts and complication rates, without increasing gastric pH and gastric fluid volume. This strategy may be an innovative, feasible and safe choice for elective surgery in adults. RELEVANCE TO CLINICAL PRACTICE: This study's results could be used as an evidence for the implementation of preoperative chewing gum in perioperative care for adult patients undergoing elective surgery.

Meta-analysis of alcohol consumption and venous thromboembolism.

BACKGROUND: The associations of alcohol consumption and venous thromboembolism (VTE) have been investigated widely, but the conclusions were inconsistent. OBJECTIVE: To summarize the relationship of alcohol consumption and VTE. METHODS: This study has been registered in PROSPERO (ID: CRD42020164567). We searched the PubMed, Embase, Web of Science and the Cochrane Library databases from inception to September 2019 and reviewed the reference list of relevant articles to identify studies assessing the association between alcohol consumption and risk of VTE. RESULTS: Fourteen cohorts and four case-control studies were included in the meta-analysis. Compared with non-drinkers, the risk of VTE was decreased (RR: 0.93; 95% confidence interval [CI] 0.88-0.99) for alcohol drinkers. The pooled RRs of VTE were 0.91 (95% CI 0.84-0.99) for low to moderate alcohol intake (0.1-14.0 drinks/week) and 0.91 (95% CI 0.78-1.06) for high alcohol intake (>14.0 drinks/week) compared with non-drinker. Subgroup analysis showed liquor intake might slightly increase the risk of VTE (1.01; 95% CI 0.85-1.21) although the difference was not significant. CONCLUSIONS: Alcohol consumption in low to moderate was associated with a lower risk of VTE. However, precautions are needed when providing personal drinking advice considering the potential harm of alcohol. Further studies are warranted to determine whether moderate alcohol consumption has a causal role in VTE.

Emerging trends and focus of human gastrointestinal microbiome research from 2010-2021: a visualized study.

BACKGROUND: The gastrointestinal microbiome is an important component of the human body and is closely related to human health and disease. This study describes the hotspots of the human gastrointestinal microbiome research and its evolution in the past decade, evaluates the scientific cooperation network, and finally predicts the field's future development trend using bibliometric analysis and a visualized study. METHODS: We searched the original articles from January 2010 to February 2021 in the Scopus database using the term "gastrointestinal microbiome" and its synonyms. CiteSpace was used to construct country and author co-occurrence map; conduct journal, citation cocitation analysis, and reference co-citation knowledge map; and form a keywords co-occurrence map, a clustering knowledge map, timeline view of keywords, and burst term map. RESULT: A total of 4444 documents published from January 2010 to February 2021 were analysed. In approximately the past decade, the number of articles on the human gastrointestinal microbiome has increased rapidly, and the research topics focus on different populations, research methods, and detection methods. All countries and regions in the world, led by the US, are studying the human gastrointestinal microbiome, and many research teams with close cooperation have been formed. The research has been published extensively in microbiology journals and clinical medicine journals, and the highly cited articles mainly describe the relationship between gastrointestinal microorganisms and human health and disease. Regarding the research emphasis, researchers' exploration of the human gastrointestinal microbiome (2011-2013) was at a relatively macro and superficial stage and sought to determine how the gastrointestinal microbiome relates to humans. From 2014 to 2017, increasingly more studies were conducted to determine the interaction between human gastrointestinal flora and various organs and systems. In addition, researchers (2018-2021) focused on the gastrointestinal microbial community and the diversity of certain types of microbes. CONCLUSION: Over time, the scope of the research on the clinical uses of the gastrointestinal microbiome gradually increased, and the contents were gradually deepened and developed towards a more precise level. The study of the human gastrointestinal microbiome is an ongoing research hotspot and contributes to human health.

[Analysis of prescription regularity of traditional Chinese medicine for colorectal cancer based on data mining].

The tumor prescriptions contained in Dictionary of Tumor Formulas, Compendium of Good Tumor Formulas, Chinese Pharmacopoeia, Ministry of Health Drug Standards for Chinese Medicine Formulas and National Compilation of Standards for Proprietary Chinese Medicines were selected and organized to construct a database for tumor prescriptions, and the data mining techniques were applied to investigate the prescription regularity of colorectal cancer prescriptions. The formula data were extracted after screening in strict accordance with the inclusion and exclusion criteria, and were then analyzed with Microsoft Excel 2010 for frequency statistics, Apriori block provided by SPSS Clementine 12.0 software for correlation rule analysis, and arules and arulesViz packages in R 4.0.2 software for correlation rule visualization. In addition, SPSS 18.0 software was used for cluster analysis and factor analysis, in which cluster analysis was performed by Ochiai algorithm with bicategorical variables in systematic clustering method and factor analysis was performed mainly with principal component analysis. A total of 285 prescriptions were included in the statistical analysis, and the frequency statistics showed that 43 herbs had been used more than 16 times. The association rules analysis showed that 26 high-frequency me-dicine pair rules were obtained, and the association rules for those dispelling evil spirits, strengthening the body, resolving stasis, dispelling dampness, etc. were visualized. In the cluster analysis, we generated a dendrogram from which 7 groups of traditional Chinese medicines with homogeneity were extracted. 10 common factors were obtained in the factor analysis. The types of herbal medicines involved in the colorectal cancer prescription included anti-cancer antidotes, strengthening and tonifying medicines, blood-regulating medicines, and expectorant medicines, corresponding to the treatment for eliminating evil spirits, strengthening, resolving stasis, and expectorating dampness. The prescriptions for anti-cancer detoxification were normally based on the pairs composed of Scutellaria barbata-Hedyotis diffusa and Sophora flavescens, Sargentodoxa cuneata, S. barbata, often combined with stasis relieving drug and dampness eliminating drug, reflecting the characteristics of treatment for both toxicity and stasis, dampness and toxicity simultaneously. The prescriptions for strengthening the righteousness and tonifying the deficiency were composed of Astragalus membranaceus and Atractylodes macrocephala mainly, exerting the effect of benefiting Qi, strengthening the spleen and drying dampness, tonifying kidney and essence, tonifying blood and invigorating blood. Meanwhile, anti-cancer detoxification medicines shall be reduced as much as possible. The compatibility of the medicines for the intestinal tract reflected the principle of using the right medicine for the right condition and eliminating evil spirits or strengthening the body, as appropriate.

Genetically modified pigs are protected from classical swine fever virus.

Classical swine fever (CSF) caused by classical swine fever virus (CSFV) is one of the most detrimental diseases, and leads to significant economic losses in the swine industry. Despite efforts by many government authorities to stamp out the disease from national pig populations, the disease remains widespread. Here, antiviral small hairpin RNAs (shRNAs) were selected and then inserted at the porcine Rosa26 (pRosa26) locus via a CRISPR/Cas9-mediated knock-in strategy. Finally, anti-CSFV transgenic (TG) pigs were produced by somatic nuclear transfer (SCNT). Notably, in vitro and in vivo viral challenge assays further demonstrated that these TG pigs could effectively limit the replication of CSFV and reduce CSFV-associated clinical signs and mortality, and disease resistance could be stably transmitted to the F1-generation. Altogether, our work demonstrated that RNA interference (RNAi) technology combining CRISPR/Cas9 technology offered the possibility to produce TG animal with improved resistance to viral infection. The use of these TG pigs can reduce CSF-related economic losses and this antiviral strategy may be useful for future antiviral research.

Meta-Analysis of Efficacy of Sijunzi Decoction Combined with Enteral Nutrition for the Treatment of Gastric Cancer.

Objective: Whether to conduct Sijunzi decoction combined with enteral nutrition (SJZD/EN) in patients with gastric cancer (GC) remains controversial. This study was aimed to systematically analyze the efficacy and safety of SJZD/EN in patients with gastric cancer.Methods: We performed searches in PubMed, MEDLINE, EMBASE, Cochrane Library, Web of Science, Chinese National Knowledge Infrastructure (CNKI), Chinese Scientific Journal Database (VIP), Wanfang database, and Chinese Biomedicine Literature Database (SinoMed) to identify relevant literature comparing SJZD/EN with conventional EN for GC patients. The analysis was carried out with RevMan 5.3.Results: A total of 10 randomized controlled trials (688 patients) were included. Meta-analysis showed a significantly shorter time to flatus (t/h) (MD, -9.45; 95% CI, -10.76 to -8.13; p < 0.00001), a shorter length of hospital stay (t/d) (MD, -5.22; 95% CI, -7.46 to -2.99; p < 0.00001), and a lower incidence of postoperative complications (%) (OR, 0.14; 95% CI, 0.03-0.64; p = 0.01) in the SJZD/EN group than the EN group. Compared with the EN, the SJZD/EN group had a higher level of albumin(g/L) (MD, 2.59; 95% CI, 1.90-3.28; p < 0.00001), prealbumin (mg/L) (MD, 36.81; 95% CI, 13.41-60.20; p = 0.002), transferrin (g/L) (MD, 0.19; 95% CI, 0.10-0.28; p < 0.0001), immunoglobulin G (g/L) (MD, 2.61; 95% CI, 2.12-3.09; p < 0.00001), immunoglobulin A (g/L) (MD, 0.38; 95% CI, 0.31-0.45, p < 0.00001), immunoglobulin M (g/L) (MD, 0.31; 95% CI, 0.22-0.41; p < 0.00001), CD3+ (%) (MD, 6.73; 95% CI, 3.48-9.98; p < 0.0001), CD4+ (%) (MD, 4.32; 95% CI, 3.30-5.33; p < 0.00001), and CD4+/CD8+ (MD, 0.20; 95% CI, 0.11-0.28; p < 0.00001).Conclusions: Sijunzi decoction combined with enteral nutrition appears to have efficacy and safety for gastric cancer.

Efficient Similarity Point Set Registration by Transformation Decomposition.

Point set registration is one of the basic problems in computer vision. When the overlap ratio between point sets is small or the relative transformation is large, local methods cannot guarantee the accuracy. However, the time complexity of the branch and bound (BnB) optimization used in most existing global methods is exponential in the dimensionality of parameter space. Therefore, seven-Degrees of Freedom (7-DoF) similarity transformation is a big challenge for BnB. In this paper, a novel rotation and scale invariant feature is introduced to decouple the optimization of translation, rotation, and scale in similarity point set registration, so that BnB optimization can be done in two lower dimensional spaces. With the transformation decomposition, the translation is first estimated and then the rotation is optimized by maximizing a robust objective function defined on consensus set. Finally, the scale is estimated according to the potential correspondences in the obtained consensus set. Experiments on synthetic data and clinical data show that our method is approximately two orders of magnitude faster than the state-of-the-art global method and more accurate than a typical local method. When the outlier ratio with respect to the inliers is up to 1.0, our method still achieves accurate registration.

Long-term Follow-up of Patients Treated with Percutaneous Radiofrequency Thermocoagulation via the Foramen Rotundum for Isolated Maxillary Nerve Idiopathic Trigeminal Neuralgia.

OBJECTIVE: The purpose of this study is to evaluate the effectiveness and safety of percutaneous radiofrequency thermocoagulation (PRT) via the foramen rotundum (FR) for the treatment of isolated maxillary (V2) idiopathic trigeminal neuralgia (ITN) and assess the appropriate puncture angle through the anterior coronoid process to reach the FR. METHODS: Between January 2011 and October 2016, 87 patients with V2 ITN refractory to conservative treatment were treated by computed tomography (CT)-guided PRT via the FR at our institution. The outcome of pain relief was assessed by the visual analog scale (VAS) and Barrow Neurological Institute (BNI) pain grade and grouped as complete pain relief (BNI grades I-III) or unsuccessful pain relief (BNI grades IV-V). Recurrence and complications were also monitored and recorded. The puncture angle for this novel approach was assessed based on intraoperative CT images. RESULTS: Of the 87 treated patients, 85 (97.7%) achieved complete pain relief, and two patients (2.3%) experienced unsuccessful pain relief immediately after operation. During the mean follow-up period of 44.3 months, 15 patients (17.2%) experienced recurring pain. No severe complications occurred, except for hypoesthesia restricted to the V2 distribution in all patients (100%) and facial hematoma in 10 patients (11.5%). The mean puncture angle to reach the FR was 33.6° ± 5.7° toward the sagittal plane. DISCUSSION: CT-guided PRT via the FR for refractory isolated V2 ITN is effective and safe and could be a rational therapy for patients with V2 ITN.

CT-guided minimally invasive treatment for an extensive spinal epidural abscess: a case report and literature review.

PURPOSE: We present a case involving an extensive epidural abscess that was successfully treated with computed tomography (CT)-guided percutaneous needle drainage and systemic antibiotic therapy. METHODS: A 44-year-old woman with a history of spine injection procedures complained of severe backache and progressive radiating pain in her right lower extremity followed by sensory deficits in her right lower limb. A laboratory examination revealed leukocytosis and hyperglycemia. Magnetic resonance imaging of the lumbar region revealed an extremely large posterior spinal epidural abscess (SEA) extending from L2 to S2. Because the patient did not respond to intravenous antibiotics alone, she underwent CT-guided percutaneous needle drainage and irrigation. RESULTS: Staphylococcus aureus was detected in the purulent material from this abscess. Her clinical symptoms were dramatically and immediately relieved after this procedure. She achieved complete neurological recovery after 2 months of antibiotic therapy. CONCLUSION: CT-guided percutaneous needle drainage and irrigation may be a rational treatment choice for patients with SEA with the exception of patients with a chronic abscess, an anterior abscess or discitis.

Detection of Kobe-type and Otsu-type Babesia microti in wild rodents in China's Yunnan province.

Babesiosis is an emerging tick-transmitted zoonosis prevalent in large parts of the world. This study was designed to determine the rates of Babesia microti infection among small rodents in Yunnan province, where human cases of babesiosis have been reported. Currently, distribution of Babesia in its endemic regions is largely unknown. In this study, we cataloged 1672 small wild rodents, comprising 4 orders, from nine areas in western Yunnan province between 2009 and 2011. Babesia microti DNA was detected by polymerase chain reaction in 4·3% (72/1672) of the rodents analyzed. The most frequently infected rodent species included Apodemus chevrieri and Niviventer fulvescens. Rodents from forests and shrublands had significantly higher Babesia infection rates. Genetic comparisons revealed that Babesia was most similar to the Kobe- and Otsu-type strains identified in Japan. A variety of rodent species might be involved in the enzootic maintenance and transmission of B. microti, supporting the need for further serological investigations in humans.

Interactions of porcine circovirus 2 with its hosts.

Porcine circovirus 2 (PCV2) can cause porcine circovirus diseases and porcine circovirus-associated diseases (PCVD/PCVAD), which are widely presented in swine-producing countries. Since the discovery of this virus, considerable efforts have been devoted to understanding this pathogen and its interactions with its host. Here, we review the current state of knowledge on interactions between host cell factors and PCV2 with respect to viral proliferation, virus-induced cell apoptosis and autophagy, and host antiviral defenses during PCV2 infection. We also review mouse model systems for PCV2 infection.

Effect of atovastatin treatment on porcine circovirus 2 infection in BALB/c mice.

The HMG-CoA reductase (HMGCR) pathway is an important metabolic route, which is not only present in almost every organism, but also involves virus infection. It has recently been shown that expression levels of IFN-responsive genes were significantly increased in HMGCR-downregulated cells and HMGCR inhibitor-treated cells. The aim of this study was to determine whether inhibition of HMGCR by atovastatin would significantly affect Porcine circovirus type 2 (PCV2) infection and immunological reaction in BALB/c mice. The results showed atovastatin significantly stimulated PCV2 replication in vivo. Immunological reaction in atovastatin-treated mice was also significantly enhanced during PCV2 infection. Atovastatin also enhanced PCV2-induced illness in mice. The results of this study will provide new insight into the role of atovastatin in PCV2 infection.

A case of alopecia areata after rabies vaccination: unreported adverse effect?

Alopecia areata (AA) is an autoimmune-related disorder characterized by non-scarring hair loss in children. We report the case of a child who had AA after the fifth dose of rabies vaccine and summarized various potential mechanisms of vaccination induced AA. This case indicates that rabies vaccine might be a predisposition of AA by causing immune dysregulation.

Artificial intelligence generated content (AIGC) in medicine: A narrative review.

Recently, artificial intelligence generated content (AIGC) has been receiving increased attention and is growing exponentially. AIGC is generated based on the intentional information extracted from human-provided instructions by generative artificial intelligence (AI) models. AIGC quickly and automatically generates large amounts of high-quality content. Currently, there is a shortage of medical resources and complex medical procedures in medicine. Due to its characteristics, AIGC can help alleviate these problems. As a result, the application of AIGC in medicine has gained increased attention in recent years. Therefore, this paper provides a comprehensive review on the recent state of studies involving AIGC in medicine. First, we present an overview of AIGC. Furthermore, based on recent studies, the application of AIGC in medicine is reviewed from two aspects: medical image processing and medical text generation. The basic generative AI models, tasks, target organs, datasets and contribution of studies are considered and summarized. Finally, we also discuss the limitations and challenges faced by AIGC and propose possible solutions with relevant studies. We hope this review can help readers understand the potential of AIGC in medicine and obtain some innovative ideas in this field.

Full-body pose reconstruction and correction in virtual reality for rehabilitation training.

Existing statistical data indicates that an increasing number of people now require rehabilitation to restore compromised physical mobility. During the rehabilitation process, physical therapists evaluate and guide the movements of patients, aiding them in a more effective recovery of rehabilitation and preventing secondary injuries. However, the immutability of mobility and the expensive price of rehabilitation training hinder some patients from timely access to rehabilitation. Utilizing virtual reality for rehabilitation training might offer a potential alleviation to these issues. However, prevalent pose reconstruction algorithms in rehabilitation primarily rely on images, limiting their applicability to virtual reality. Furthermore, existing pose evaluation and correction methods in the field of rehabilitation focus on providing clinical metrics for doctors, and failed to offer patients efficient movement guidance. In this paper, a virtual reality-based rehabilitation training method is proposed. The sparse motion signals from virtual reality devices, specifically head-mounted displays hand controllers, is used to reconstruct full body poses. Subsequently, the reconstructed poses and the standard poses are fed into a natural language processing model, which contrasts the difference between the two poses and provides effective pose correction guidance in the form of natural language. Quantitative and qualitative results indicate that the proposed method can accurately reconstruct full body poses from sparse motion signals in real-time. By referencing standard poses, the model generates professional motion correction guidance text. This approach facilitates virtual reality-based rehabilitation training, reducing the cost of rehabilitation training and enhancing the efficiency of self-rehabilitation training.

Opportunities in Assessing and Regulating Organohalogen Flame Retardants (OFRs) as a Class in Consumer Products.

BACKGROUND: In 2015, the U.S. Consumer Product Safety Commission (CPSC) received and then, in 2017, granted a petition under the Federal Hazardous Substances Act to declare certain groups of consumer products as banned hazardous substances if they contain nonpolymeric, additive organohalogen flame retardants (OFRs). The petitioners asked the CPSC to regulate OFRs as a single chemical class with similar health effects. The CPSC later sponsored a National Academy of Sciences, Engineering, and Medicine (NASEM) report in 2019, which ultimately identified 161 OFRs and grouped them into 14 subclasses based on chemical structural similarity. In 2021, a follow-up discussion was held among a group of scientists from both inside and outside of the CPSC for current research on OFRs and to promote collaboration that could increase public awareness of CPSC work and support the class-based approach for the CPSC's required risk assessment of OFRs. OBJECTIVES: Given the extensive data collected to date, there is a need to synthesize what is known about OFR and how class-based regulations have previously managed this information. This commentary discusses both OFR exposure and OFR toxicity and fills some gaps for OFR exposure that were not within the scope of the NASEM report. The objective of this commentary is therefore to provide an overview of the OFR research presented at SOT 2021, explore opportunities and challenges associated with OFR risk assessment, and inform CPSC's work on an OFR class-based approach. DISCUSSION: A class-based approach for regulating OFRs can be successful. Expanding the use of read-across and the use of New Approach Methodologies (NAMs) in assessing and regulating existing chemicals was considered as a necessary part of the class-based process. Recommendations for OFR class-based risk assessment include the need to balance fire and chemical safety and to protect vulnerable populations, including children and pregnant women. The authors also suggest the CPSC should consider global, federal, and state OFR regulations. The lack of data or lack of concordance in toxicity data could present significant hurdles for some OFR subclasses. The potential for cumulative risks within or between subclasses, OFR mixtures, and metabolites common to more than one OFR all add extra complexity for class-based risk assessment. This commentary discusses scientific and regulatory challenges for a class-based approach suggested by NASEM. This commentary is offered as a resource for anyone performing class-based assessments and to provide potential collaboration opportunities for OFR stakeholders. https://doi.org/10.1289/EHP12725.

Receptor activator of nuclear factor κB ligand (RANKL) protein expression by B lymphocytes contributes to ovariectomy-induced bone loss.

Production of the cytokine receptor activator of NFκB ligand (RANKL) by lymphocytes has been proposed as a mechanism by which sex steroid deficiency causes bone loss. However, there have been no studies that functionally link RANKL expression in lymphocytes with bone loss in this condition. Herein, we examined whether RANKL expression in either B or T lymphocytes contributes to ovariectomy-induced bone loss in mice. Mice harboring a conditional RANKL allele were crossed with CD19-Cre or Lck-Cre mice to delete RANKL in B or T lymphocytes, respectively. Deletion of RANKL from either cell type had no impact on bone mass in estrogen-replete mice up to 7 months of age. However, mice lacking RANKL in B lymphocytes were partially protected from the bone loss caused by ovariectomy. This protection occurred in cancellous, but not cortical, bone and was associated with a failure to increase osteoclast numbers in the conditional knock-out mice. Deletion of RANKL from T lymphocytes had no impact on ovariectomy-induced bone loss. These results demonstrate that lymphocyte RANKL is not involved in basal bone remodeling, but B cell RANKL does contribute to the increase in osteoclasts and cancellous bone loss that occurs after loss of estrogen.