Factors Associated with Israeli Arab Women Anxiety and Depression During the COVID-19 Pandemic

BACKGROUND

Reports have shown that women suffered from anxiety, stress, depression, and fatigue during the COVID-19 pandemic more than men. No study so far has examined the effect of the pandemic among the Arab minority in Israel.

OBJECTIVES

To examine the associations between levels of pandemic fatigue and stress of Israeli Arab women, and their anxiety and depression, along with their socio-demographic and socio-economic characteristics.

METHODS

A Cohen and Williamson questionnaire, which was based on a Likert scale, was distributed by the snowball method through social networks. Bivariate associations between the psycho-social and demographic characteristics and anxiety and depression were assessed using t-tests, chi-square tests, Z tests, and Pearson correlations. Multiple linear regressions were used to evaluate the associations with anxiety and depression, and the mediation model was examined with path analysis with bootstrapping.

RESULTS

Among 2294 Israeli Arab mothers who participated in the study, 63.7% were in the clinical range for anxiety, 67.4% for depression, and 57.5% for both anxiety and depression. Low economic status, pandemic fatigue, living in closed communities, and stress were related to anxiety and depression. Pandemic fatigue was positively related to stress, which was positively related to both anxiety and depression (standardized indirect effect = 0.137, SE = 0.014, 95%CI = 0.111, 0.164, p < .001; vs. 0.133, SE = 0.013, 95%CI = 0.108, 0.160, p < .001 respectively). The contribution of stress to anxiety and depression was significantly greater than that of pandemic fatigue (Z = 19.43 and Z = 18.04, p < .001, for anxiety and depression, respectively).

CONCLUSIONS

Demographic characteristics may put Arab women at a higher risk of anxiety and depression. Elevated stress alongside high fatigue may trigger mental health difficulties. The welfare of minorities should be addressed by policymakers in relation to their demographic needs.

Who is following me? Public attitude towards government tracing apps in the covid Era in Israel

Background

In the battle to decrease coronavirus infection and mortality, Israel has employed emergency tools, e.g., tracking civilians’ locations via their cellphones or activating the HaMagen app that identifies when a person is near someone who has been diagnosed with the virus. While the aim of these tools is to ensure the public’s health, they could harm human rights.

Objective

To examine the Israeli public’s attitudes towards enhancing public health during the pandemic while preserving privacy, by examining the relationship between trust in the healthcare system, threat perceptions, cellphone tracking, and HaMagen App.

Methods

Surveys (distributed by iPanel) was completed by 741 adults, aged ≥18.

Results

About half the respondents (47.1%) perceived cellphone tracking as harmful to privacy, yet one-quarter (24.4%) reported that this increases their sense of security. About half (48.4%) agreed/greatly agreed with the item whereby the government uses the gathered data for non-coronavirus purposes. Jewish respondents had more positive attitudes towards government tracking than Arab ones, yet the latter reported higher downloading of HaMagen. The findings indicate that threat perceptions and positive attitudes towards cellphone tracking were related to greater chances of downloading the app. Moreover, attitudes towards such tracking were mediated by the relationship between trust levels/threat perceptions and downloading the app, whereby the former was association with more positive attitudes towards cellphone tracking, which in turn was related to greater app downloading.

Conclusions and Recommendations

Trust plays a central role in people’s willingness to forgo their privacy for the good of public health. To enhance trust, messages must be suited to a range of communities, presented in a suitable language by local professionals.

Key messages

• Trust plays a central role in people’s willingness to forgo their privacy for the good of public health.

• Concern for public health must include ethical considerations.

Lessons from the epidemiological investigation efforts during the COVID-19 epidemic in Israel

Background

The COVID-19 pandemic caused a crisis in the Israeli healthcare system. The wave-like morbidity created an overload of epidemiological investigations, which led to delays and less than successful efforts to prevent infection. For this reason, Israel decided to mobilize the military for this purpose, creating a forced cooperation between the Ministry of Health (MOH) and the IDF, an expert in dealing with crises.

Aim

To examine the implications of the forced encounter between the IDF and the healthcare system, including both tensions and cooperation efforts.

Methods

Twenty in-depth interviews were carried out with MOH and IDF personnel in different roles at various levels towards the end of the second pandemic wave in Israel.

Findings

The findings present a dual picture of cooperation and mutual respect, side by side with contradictions and conflicts. The feeling that the IDF came in to ‘save the day’ placed the healthcare people in an inferior position. Clearly, there was no explicit plan for division of authority. It was clear to the healthcare staff that they have the authority as the professionals, and to the IDF people that they have it as the ‘saviors’ brought in for this purpose. The healthcare people did see the potential of the military force mobilized for this purpose, but felt they were asked for their opinion only initially, when the military personnel had to study the system. As soon as they became familiar with it, they were no longer asked for advice, and control was given to the IDF. The findings also show that the MOH’s qualitative professional approach often clashed with the IDF’s action-based approach.

Conclusions

The military was mobilized as a crisis expert in order to assist the healthcare system in managing said crisis, but in fact this assistance had many side effects. Managing expectations, division of authority and open, sharing communication may have been useful in preventing the conflicts and managing them.

Key messages

• It is important to be aware of the a-symmetrical power relations of the military-healthcare system interface in order to create effective work and true, coherent cooperation.

• Management of expectations, organized division of authority and open, sharing communication may have assisted in preventing the conflicts raised and managing them.

Longitudinal analysis of Israeli nurses’ perceptions, trust & emotions during the COVID-19 pandemic

Background

The nursing sector is the largest human resource in the healthcare system providing direct patient care. The Covid-19 pandemic has forced nursing teams into a sustained state of emergency, and with it, much uncertainty and risk taking.

Aims

Examining the emotions, risk and threat perceptions, trust in the healthcare system and compliance with Ministry of Health (MOH) regulations among nurses at two points in time during the COVID-19 pandemic in Israel.

Methods

Research questionnaires were distributed to nurses at the height of the pandemic’s first wave (March-May 2020). Among the respondents, 140 agreed to continue with the follow-up study. During the pandemic’s third wave (January 2021), the research questionnaire was re-sent to these respondents. Of these, 80 filled-in the second questionnaire.

Findings

Naturally, there was a higher level of experience among the nursing staffs in dealing with the virus in the second as compared to the first period in time. During the first wave, approximately a fifth of the participants (21%) reported that they had cared for patients who had been confirmed as having COVID-19, while during the third wave, most of the participants (66%) reported caring for people who had been confirmed as having contracted the virus. The findings demonstrate significantly lower levels of compliance with regulations and risk perception, and a significantly higher level of emotions in the third wave as compared to the first. However, there was no change in the level of trust in the healthcare system or in the pandemic-related threat perception.

Conclusions

The findings provide us with some information regarding the process the nursing staffs have undergone (and are still undergoing) in dealing with the pandemic, and may point at a ‘pandemic fatigue’ amongst them. This concept relates to progressively lower regulation compliance levels appearing over time, affected by the target population’s emotions, experiences and perceptions.

Key messages

• It is important to assist the nurses’ emotional regulation with the help of professionals in the organization, form colleagues’ support groups and ensure management recognition of the situation.

• Resilience-raising steps should be taken, for example by ensuring rest times and sufficient medical and protective equipment.

Factors associated with physicians' decision making during the first wave of the COVID-19 pandemic

Background

Frontline medical staff, combating the Covid-19 pandemic are forced to make clinical and behavioral decisions daily. Their decision-making process and the factors associated with it, are of utmost importance in preserving and supporting their own health and their patient's health.

Aims

Tto explore the factors associated with physicians' decision-making during the first wave of the COVID-19 pandemic in Israel

Methods

Cross- sectional data were collected among 200 physicians at the Israeli health care system between March and May 2020 via an online questionnaire. A multiple hierarchical regression was calculated to assess the contribution of the study variables to the physicians' decision making.

Results

Most physicians reported that they complied with hygiene guidelines at work, issued by the Israeli ministry of health (MOH), fully (42%) or very often (31%), and with the MOH COVID-19 behavior guidelines fully (27%), very often (34%), or in general (23%). According to the study

Results

trust, positive emotions, perception of COVID-19 threat, and risk perceptions were found significant and positive. In other words, higher trust, more positive emotions, and perceptions of greater threat and risk, were associated with higher compliance with the MOH guidelines and more cautious decision making.

Conclusions

While threat and risk perceptions may be inevitable during the pandemic, trust and positive emotions may act as protective factors, encouraging cautious decision making among physicians.

Key messages

Physicians' decision making is a complex process affected by their perceptions, emotions, and trust levels. High levels of trust and positive emotions may facilitate carful decision making.

Stress and perceived discrimination among Israeli Arabs: the mediation role of threat and trust

 

During pandemics, minorities may experience high stress levels, which could harm their health. This study explores stress among the Arab minority in Israel during the first wave of the COVID-19 outbreak, and its association with the population's perceived COVID-19 threat, trust in the healthcare system, adherence to guidelines, and perceived discrimination. The study analyzed a cross-sectional online survey of 626 Israeli Arabs. Most participants (65%) reported moderate levels of stress, and 10% reported severe levels. The Bedouin population reported significantly higher levels of stress compared to other minority groups. The participants also reported a high degree of perceived threat, a moderate-to-high level of discrimination, a moderate level of trust in the healthcare system, and very high adherence to guidelines. Structural equation modeling (SEM) revealed that the participants' perceived threat and trust mediated the association between their perceived discrimination and stress [indirect effect=0.13, SE = 0.03 CI = (0.08, 0.18)], whereby discrimination was negatively associated with trust (β=-0.52), which, in turn, was negatively associated with stress (β=-0.10). Furthermore, discrimination was positively associated with perceived threat (β = 0.21), which, in turn, was positively associated with stress (β = 0.35). Discrimination is an important social determinant of health - especially during health emergencies when trust in healthcare systems and perceived threats are crucial. Our findings could assist policymakers in developing fair policies, that are tailored to various population groups and that may reduce stress levels among minorities, thereby improving their mental and physical health.

Key messages

The results highlight the relationships between discrimination, trust, perceived threat and stress. To reduce minorities’ stress, it is vital to create a credible and fair atmosphere during pandemics.

Evaluating adherence to future COVID-19 vaccination among elderly population in Israel

Background

On March 2020, COVID-19 was declared a global pandemic. It was perceived as an elderly issue in face of the high morbidity and mortality rates among people over 60 years old. Instructions regarding protective and preventative conduct were issued by the Israeli ministry of health, with emphasis concerning the elderly population. This study aimed at examining the adherence for future Covid-19 vaccine and its predicting factors among the elderly population in Israel.

Methods

A cross-sectional online survey was conducted in April 2020 among 1,797 Israeli respondents, aged 60 and above, via social media. The questionnaire assessed intentions to being vaccinated against the COVID-19 virus, attitudes and subjective norms regarding the disease and instructions issued by the ministry of health, adhering to these instructions, perception of threat, trust in the healthcare system, negative emotions and social support.

Results

Levels of willingness to future vaccination were extremely high (92%). Multiple logistic regression analysis found gender, level of religiosity, socio-economic status, perception of threat, social support, trust in the healthcare system, negative emotions and subjective norms regarding social distancing, as predictors of probability for future adherence to the vaccine.

Conclusions

The study findings point to future intention, in a time when an atmosphere of uncertainty regarding COVID-19 and its consequences is prevalent around the world. The adherence predictors are in concurrence with elements of the Health Belief Model and the Theory of Reasoned Action. Identifying the factors that predict future willingness to be vaccinated, may assist in developing ways to promote vaccination adherence against COVID-19, as well as against other illnesses.

Key messages

The results emphasize the importance of creating a supportive environment and shaping health-promoting attitudes among the elderly, as well as balanced and reliable threat communication of epidemics.

Actual vaccination would depend on factors such as the pandemic severity at that time.

Predicting postpartum mothers' intention for vaccinating their infants

Background

Vaccines are administered for free in Israel. Yet, despite experts' agreement that vaccinations are important, some parents choose not to vaccinate their children - in part due to lack of trust in the health system. This study examines factors that predict mothers' intention to vaccinate their infants as per recommendations of the Israeli Ministry of Health.

Methods

The study included 344 women in a maternity ward of a hospital in northern Israel. After receiving approval from the Helsinki Commission, and with the mothers' consent, data were collected through a self-administrated questionnaire, from June to September 2019.

Results

Participants were aged 19-47 (M = 30.77), 96% were married, and 70% had 1-2 children. About 78% reported that their children had been vaccinated for hepatitis B upon birth and had received vitamin K by injection. About 20% did not know if their newborns had received the injection and vaccination, meaning that they probably did as part of the hospital routine. Only 1.5-3% of the mothers said they would vaccinate their child later or not at all. Overall, the mothers' intention to vaccinate their infants was high (4.33 on a 1-5 scale). A hierarchical linear regression model for predicting mothers' intentions to vaccinate their infants was significant, explaining 36% of the variance. Factors that predict mothers' intentions to vaccinate their infants as recommended include mothers' adherence to the pertussis vaccination administration during their pregnancy (P = 0.037), lower trust in non-medical factors (P &lt; 0.001), and positive attitudes (P &lt; 0.001), and subjective norms (P &lt; 0.001) regarding vaccinating their infants.

Conclusions

Mothers' adherence to vaccinations during pregnancy could help identify at-risk populations. Interventions for encouraging vaccinations should focus on information sources and levels of trust, as trust in authoritative sources could assist in shaping attitudes and create a supportive environment for vaccinations.

Key messages

Mothers' adherence to vaccinations during pregnancy could help identify at-risk populations. Lower trust in non-medical factors, positive attitudes, and subjective norms are important predictors of mothers' intention for vaccinating their newborns.

'I smoke and drink alcohol during pregnancy, but I'm a good enough mom': a mixed methods study

Background

Smoking and alcohol consumption during pregnancy is a major public health concern. The aims of this study were: 1) to examine smoking and alcohol consumption during pregnancy and to investigate their association with maternal attitudes and socio-demographic characteristics; 2) to explore maternal attitudes regarding smoking and alcohol consumption during pregnancy among pregnant and postpartum women in Israel.

Methods

This mixed methods study is comprised of a self-reported questionnaire for measuring attitudes and behaviors regarding smoking and alcohol consumption among 676 Jewish women, up to 9 months postpartum; and semi-structured interviews with 17 women who smoked cigarettes and/or consumed alcohol during their pregnancy.

Results

Sixty-four women (9.6%) reported drinking alcohol during pregnancy, and 30 (4.8%) reported smoking. Women with a fewer children (OR 2.25; 99% CI: 1.30, 3.92) and those whose attitudes supported alcohol avoidance (OR 0.52; 99.9% CI: 0.36, 0.74) consumed less alcohol while pregnant. Educated women (OR 0.31; 99% CI: 0.14- 0.71) and women with anti-smoking attitudes (OR 0.50; 99% CI: 0.30, 0.82) were more likely to avoid smoking during pregnancy. Qualitative analyses reveals three major themes: 1) 'A good enough mom': The mothers presented risk-management practices in line with the conflict between their perception of ideal motherhood and that of being an independent person; 2) 'Social acceptance of smoking and alcohol consumption during pregnancy': Social attitudes of spouses, family and friends; 3) 'Lack of reliable information' from healthcare professionals.

Conclusions

Women's attitudes have a significant impact on their decision to drink alcohol and/or smoke during pregnancy. These attitudes may be a result of their risk management practices and the social acceptance of risk behaviors during pregnancy, and information provided (or not) by healthcare professionals.

Key messages

The results highlight the importance of creating a supportive environment and shaping health promoting attitudes among pregnant women. Reliable information given by healthcare professionals regarding risk behaviors during pregnancy is needed.

It’s all about trust: Women's compliance with influenza and pertussis vaccinations during pregnancy

Background

Although vaccination against pertussis and seasonal influenza during pregnancy is the safest and most efficient strategy to protect mothers and infants from related morbidity and mortality, maternal vaccination is unfortunately suboptimal. The aim of the current study is to assess vaccination compliance during pregnancy and the factors associated with adherence with the relevant Ministry of Health recommendations.

Methods

The study included 344 women in a maternity ward of a hospital in northern Israel. After receiving approval from the Helsinki Commission and with the mothers' consent, data was collected through a self-administrated questionnaire from June to September 2019.

Results

Eighty-three percent of participants reported having been vaccinated against pertussis during pregnancy, and 44% reported having been vaccinated against influenza. The main reasons for not being vaccinated were distrust in vaccine efficiency, fear of vaccination during pregnancy, and lack of recommendations from health professionals. Multivariate logistic regressions analysis showed that compliance with influenza and pertussis vaccinations were significantly explained by women's attitudes (influenza: OR 2.88; 99% CI: 2.05, 4.05; pertussis: OR 4.77; 99% CI: 3.04, 7.47) and norms (influenza: OR 1.55; 95% CI: 1.15, 2.08; pertussis: OR 2.09; 99% CI: 1.46, 2.99). Process procedure for mediation reveals that the greater the level of trust in the healthcare system, the more positive the attitudes and subjective norms toward vaccination during pregnancy, and the greater the likelihood of complying with both vaccination requirements during pregnancy.

Conclusions

Efforts should focus on raising women's trust in the healthcare system as an important part of shaping attitudes and creating a supportive environment for vaccination.

Key messages

Trust in the healthcare system is associated with positive attitudes and norms, which in turn contribute to vaccination compliance. Explicit recommendations for vaccinations among pregnant women made by health professionals are needed, including reassurance of vaccine safety and effectiveness.

Risk behaviors among adolescents participating youth movements - The role of social norms and support

Background

Risk behaviors such as smoking, alcohol consumption, and drug use are prevalent among adolescents worldwide, and are a major concern due to their harmful effects. Scientific literature presents no agreement as to whether belonging to a youth movement is a risk factor or a protective factor for risk behaviors. The current analysis aimed at evaluating the role of participating in youth movements (i.e., protective or risk factor) in substance use among Israeli adolescents.

Methods

Based on the 2015 Health Behavior in School-aged Children Survey (HBSC), The current analysis included 2197 participants aged 16-18, who answered the questions addressing participating in youth movements and questions regarding their risk behaviors.

Results

Overall, 17% of respondents reported smoking cigarettes, 39% consuming alcohol, 14% getting drunk, and 6% using drugs in the past 30 days. Of those respondents, 27% were members or guides in youth movements. Multiple logistic regression analysis showed that members of youth movements were significantly more at risk for drug use (OR = 3.54, 95%CI: 1.41, 8.90), and guiding was significantly associated with higher risk for alcohol consumption (OR = 1.90, 95%CI: 1.24, 2.91) and drunkenness (OR = 2.39, 95%CI: 1.50, 3.81) among 16-year-old respondents. No association was found between participation in youth movements and risk behaviors among 17-18year-olds. Family support was found to be a protective factor for cigarette smoking (OR = 0.83, 95%CI: 0.72, 0.97) and drug use (OR = 0.70, 95%CI: 0.58, 0.86) among 16-year-olds. Social norms were associated with all four risk behaviors among all age groups, showing, as expected, that the greater the social pressure, the higher the risk for participation in risk behaviors.

Conclusions

Social and family influence play an important role in the prevention of risk behaviors among adolescents. Youth movement settings should be monitored to ensure they do not become a supportive environment for risk behaviors.

Key messages

Social and family influence are important in preventing risk behavior in adolescents. Youth movements should be monitored to ensure they do not become a supportive environment for risk behavior.

Mapping human risk of infection with Borrelia burgdorferi sensu lato, the agent of Lyme borreliosis, in a periurban forest in France

Lyme borreliosis is a major zoonosis in Europe, with estimates of over 26,000 cases per year in France alone. The etiological agents are spirochete bacteria that belong to the Borrelia burgdorferi sensu lato (s. l.) complex and are transmitted by hard ticks among a large range of vertebrate hosts. In Europe, the tick Ixodes ricinus is the main vector. In the absence of a vaccine and given the current difficulties to diagnose and treat chronic Lyme syndromes, there is urgent need for prevention. In this context, accurate information on the spatial patterns of risk of exposure to ticks is of prime importance for public health. The objective of our study was to provide a snapshot map of the risk of human infection with B. burgdorferi s. l. pathogens in a periurban forest at a high resolution, and to analyze the factors that contribute to variation in this risk. Field monitoring took place over three weeks in May 2011 in the suburban Sénart forest (3,200ha; southeast of Paris), which receives over 3 million people annually. We sampled ticks over the entire forest area (from 220 forest stands with a total area of 35,200m(2)) and quantified the density of questing nymphs (DON), the prevalence of infection among nymphs (NIP), and the density of infected nymphs (DIN), which is the most important predictor of the human risk of Lyme borreliosis. For each of these response variables, we explored the relative roles of weather (saturation deficit), hosts (abundance indices of ungulates and Tamias sibiricus, an introduced rodent species), vegetation and forest cover, superficial soil composition, and the distance to forest roads. In total, 19,546 questing nymphs were collected and the presence of B. burgdorferi s. l. was tested in 3,903 nymphs by qPCR. The mean DON was 5.6 nymphs per 10m(2) (standard deviation=10.4) with an average NIP of 10.1% (standard deviation=0.11). The highest DIN was 8.9 infected nymphs per 10m(2), with a mean of 0.59 (standard deviation=0.6). Our mapping and modeling revealed a strong heterogeneity of risk within the forest. The highest risk was found in the eastern part of the forest and localized patches in the northwestern part. Lyme borreliosis risk was positively associated with stands of deciduous trees (mainly oaks) and roe deer abundance. Contrary to expectations, DIN actually increased with distance from the point of introduction of T. sibiricus (i.e., DIN was higher in areas with potentially lower abundances of T. sibiricus). Thus, despite the fact that T. sibiricus is an important reservoir host for B. burgdorferi s. l., our study found that other explanatory factors played a more important role in determining the density of infected ticks. Precise mapping of the risk of exposure to Lyme borreliosis in a highly visited forest represents an important tool for targeting prevention and control measures, as well as making the general public and local health officials aware of the risks.

Osteoclast formation and bone resorption are inhibited by megakaryocytes

It has been previously reported that addition of megakaryocytes (MKs) to osteoblasts in vitro results in increased osteoblastic collagen and osteoprotegerin (OPG) production, suggesting a role for MKs in bone formation. To further investigate this role, we have studied the effects of MKs on osteoclast formation and activity. Human osteoclasts were generated from CD14 monocytes isolated from peripheral blood and cultured in the presence of M-CSF and sRANKL on dentine and calcium phosphate substrates. MKs were generated from CD34+ cells isolated from either human peripheral blood or cord blood and cultured in liquid medium for 6 days, after which time maturing MKs (CD61-positive cells) were isolated and added to monocyte cultures. After 6 and 9 days of culture, the number of osteoclasts identified morphologically and by TRAP staining was counted. Cells were removed and the area of resorption was identified by von Kossa staining and quantitatively assessed by image analysis. The addition of MKs to osteoclast cultures at day 0 inhibited the number of osteoclasts formed 1.9-fold (p>0.003), whereas addition at 3 days had no effect on osteoclast number. The presence of MKs inhibited resorption 8.7-fold when co-cultured with osteoclasts from day 0 (p>0.004), but only by 3.1-fold when co-cultured from day 3 (p>0.01). In dose-response experiments, it was found that 1-10% of MKs added to monocyte cultures elicited the greatest inhibition of resorption. Similar osteoclast cultures were treated with CD61-negative cells (non-MKs) to confirm that the inhibition of osteoclast formation and activity was specifically due to MKs. Experiments with a cell-impermeable membrane indicated that both cell to cell contact and release of soluble factor(s) were involved in mediating these effects. These results show that MKs inhibit osteoclast formation and activity. The most pronounced effects were seen when MKs and osteoclasts were co-cultured from day 0, suggesting that MKs act primarily on osteoclast precursors.

Dairy Management Practices Associated with Incidence Rate of Clinical Mastitis in Low Somatic Cell Score Herds in France

An epidemiological prospective study was carried out in French dairy herds with Holstein, Montbéliarde, or Normande cows and with low herd somatic cell scores. The objective was to identify dairy management practices associated with herd incidence rate of clinical mastitis. The studied herds were selected on a national basis, clinical cases were recorded through a standardized system, and a stable dairy management system existed. In the surveyed herds, mean milk yield was 7420 kg/cow per yr and mean milk somatic cell score was 2.04 (132,000 cells/mL). Overdispersion Poisson models were performed to investigate risk factors for mastitis incidence rate. From the final model, the herds with the following characteristics had lower incidence rates of clinical mastitis: 1) culling of cows with more than 3 cases of clinical mastitis within a lactation; 2) more than 2 person-years assigned to dairy herd management; 3) balanced concentrate in the cow basal diet. Moreover, herds with the following characteristics had higher incidence rates of clinical mastitis: 1) milking cows loose-housed in a straw yard; 2) no mastitis therapy performed when a single clot was observed in the milk; 3) clusters rinsed using water or soapy water after milking a cow with high somatic cell count; 4) 305-d milk yield >7435 kg; 5) herd located in the South region; 6) herd located in the North region; 7) cows with at least 1 nonfunctional quarter; and 8) premilking holding area with a slippery surface. The underlying mechanisms of some highlighted risk factors, such as milk production level and dietary management practices, should be investigated more thoroughly through international collaboration.

Megakaryocytes modulate osteoblast synthesis of type-l collagen, osteoprotegerin, and RANKL

We have previously reported evidence that megakaryocytes may play a role in bone remodeling, possibly by interactions with cells at the bone surface. To investigate the direct effects of megakaryocytes on osteoblasts, maturing megakaryocytes (CD61 positive cells) were isolated and added to cultures of human osteoblasts. Osteoblasts alone and osteoblasts treated with CD61-negative (non-megakaryocytic) cells were used as control cultures. After 48 h in culture, megakaryocytes were removed and osteoblasts immunolocalized for type-1 collagen, osteoprotegerin (OPG), and RANKL expression. Similar cultures were used for RNA extraction with mRNA for Col 1A1, OPG, and RANKL in osteoblasts measured quantitatively by RT-PCR. Osteoblasts cultured alone showed high levels of expression of collagen with 74% (+/-7) of cells staining positively. When cultured with megakaryocytes, the number of positively staining cells remained similar but the intensity of expression was increased 1.54-fold (P < 0.02). OPG was expressed by 32% (+/-6.3) of osteoblasts increasing to 51% (+/-5.5) when cultured in the presence of megakaryocytes (P < 0.01) with a 1.63-fold increase in intensity of expression (P < 0.01). In contrast, osteoblasts cultured with megakaryocytes showed suppression of RANKL expression; 35.6% (+/-5.8) of osteoblasts cultured alone stained positively decreasing to 24.3% (+/-5.3) with a 1.6-fold diminished intensity of expression (P < 0.02). Osteoblasts co-cultured with CD61-negative cells showed no differences in collagen, OPG, or RANKL expression levels compared to osteoblasts cultured alone. mRNA data supported these findings with a 3.1-fold increase in Col 1A1 expression in megakaryocyte-treated cultures compared to controls (P < 0.02). Low-level OPG mRNA expression increased 8.14-fold in osteoblasts cultured in the presence of megakaryocytes (P < 0.01), while RANKL expression was suppressed 3.3-fold (P < 0.02). These results demonstrate that in vitro, megakaryocytes have direct effects on osteoblastic production of factors affecting both bone formation and resorption. These data provide further evidence that megakaryocytes may play an important role in bone remodeling.

Synthesis of osteoprotegerin and RANKL by megakaryocytes is modulated by oestrogen

To investigate the mechanisms by which megakaryocytes (MKs) may influence bone remodelling, CD34(+) cells were cultured for 6, 9 and 12 d with or without 17beta-oestradiol (E) and immunolocalized for osteoprotegerin (OPG), receptor activator of nuclear factor (NF)-kappaB ligand (RANKL) and CD61. Specific protein expression was measured quantitatively by image analysis. Fluorescence-based immunocytochemistry was used to co-localize OPG and RANKL with CD61. OPG and RANKL mRNA was assessed in CD61(+) cells with or without E at 24 and 48 h. At 6 d, OPG and RANKL expression was unchanged by E treatment. At 9 d, the E-treated cultures with maturing MKs showed a 1.72-fold (P < 0.01) increase in OPG expression and a 1.8-fold (P < 0.01) reduction in RANKL. Maximal OPG expression was seen at 12 d with a threefold induction of expression (P < 0.001), whilst RANKL levels were further suppressed by 2.3-fold compared with controls (P < 0.001). CD61 co-localized with OPG and RANKL. mRNA data were consistent with that of protein, with a 90-fold induction in OPG expression and a 34-fold suppression of RANKL expression by E (P < 0.001). Thus, E stimulates megakaryocytopoiesis and modulates OPG and RANKL expression, providing evidence that MKs may play a role in bone remodelling and, in particular, in E-induced changes in osteoclastogenesis and bone resorption.

Joint erosion in rheumatoid arthritis: interactions between tumour necrosis factor alpha, interleukin 1, and receptor activator of nuclear factor kappaB ligand (RANKL) regulate osteoclasts

BACKGROUND

Osteoclasts, specialised bone resorbing cells regulated by RANKL and M-CSF, are implicated in rheumatoid joint erosion. Lymphocyte-monocyte interactions activate bone resorption, this being attributed to tumour necrosis factor alpha (TNFalpha) and interleukin 1 beta (IL1beta) enhanced osteoblast expression of RANKL. In animal studies, TNF potently increases osteoclast formation in the presence of RANKL. RANKL-independent osteoclastogenesis also occurs, though IL1 is required for resorptive function in most studies. These inflammatory cytokines have a pivotal role in rheumatoid arthritis,

OBJECTIVE

To study the interactions of TNFalpha and IL1beta with RANKL, particularly the time course of the interactions and the role of lymphocytes.

METHOD

Cultures of lymphocytes and monocytes (osteoclast precursors) or of purified CD14(+) cells alone (osteoclast precursors) were exposed to various combinations of TNFalpha, RANKL, and IL1beta or the inhibitors osteoprotegerin, IL1 receptor antagonist, or neutralising antibodies to RANKL or to IL1. Osteoclastogenesis and resorptive activity were assessed on microscopy of dentine slices.

RESULTS

TNFalpha potently increased osteoclast proliferation/differentiation in the presence of RANKL. This effect was greatest when RANKL was present before but not after exposure of osteoclast precursor cells to TNFalpha. The resorptive activity of osteoclasts generated by TNFalpha in the absence of RANKL was critically dependent upon IL1, which was expressed by lymphocyte-monocyte interaction.

CONCLUSION

TNFalpha potently enhances RANKL mediated osteoclast activity. Interactions between TNFalpha and IL1 also result in osteoclastic activity independently of RANKL. These findings will inform therapeutic approaches to the prevention of joint erosion in rheumatoid arthritis.

The effects of estrogen on osteoprotegerin, RANKL, and estrogen receptor expression in human osteoblasts

Estrogen is essential for bone growth and development and for the maintenance of bone health in adulthood. The cellular responses of osteoblasts and osteoclasts to estrogen are initiated via two high-affinity receptors (ERs). Osteoblasts synthesize RANKL (receptor activator of NF-kappaB ligand), necessary for osteoclast formation and function, and osteoprotegerin (OPG), its decoy receptor. To investigate the effects of estrogen on the expression of OPG, RANKL, and ERs in human osteoblasts, cells were cultured with physiological (10(-10) M) and high-dose (10(-7) M) 17beta-estradiol for 24 and 48 h. Proteins and corresponding mRNA levels were quantitatively determined by immunocytochemistry and RT-PCR. OPG expression was significantly increased three- and sevenfold at 24 h with 10(-10) M (P < 0.05) and 10(-7) M (P < 0.01) estradiol, respectively, compared to untreated cells. Similar but smaller increases were seen at 48 h (P < 0.05). Osteoblasts treated with estradiol demonstrated increased RANKL protein expression at 24 h (P < 0.05), but this was not maintained at 48 h. ERalpha expression was significantly increased by high-dose estradiol (P < 0.01) at 24 h and dose-dependently increased at 48 h (P < 0.01), while ERbeta was only increased at 24 h (P < 0.01). The estrogen-induced protein expression of ER, OPG, and RANKL was abrogated when cells were cultured in the presence of the estrogen antagonist ICI 182780. mRNA levels at 24 h demonstrated a significant suppression of RANKL with the low-dose but not the high dose. ERalpha mRNA but not ERbeta expression was up-regulated by estrogen. Our results suggest that estrogen may exert its anti-resorptive effects on bone, at least in part, by stimulating ER and OPG expression in osteoblasts.

Reduced bone formation in UK Gulf War veterans: a bone histomorphometric study

AIMS

Gulf War veterans report a high prevalence of musculoskeletal symptoms. The aim of this study was to establish whether there were abnormalities in bone turnover and remodelling in a group of symptomatic subjects who had served in the Gulf War.

METHODS

Iliac crest bone biopsies were obtained from 17 Gulf War veterans who were seeking litigation and compared with those of 13 age and sex matched healthy controls. Bone histomorphometry was performed using image analysis.

RESULTS

Cancellous bone area was significantly lower in Gulf War veterans than in control subjects (p = 0.027) and this was associated with a significantly reduced mineral apposition rate (p = 0.002), mean wall width (p < 0.0001), and bone formation rate at the tissue level (p < 0.0001).

CONCLUSIONS

These results demonstrate that in this group of Gulf War veterans there was a significant reduction in bone formation at both the cellular and tissue level and this was associated with a reduction in cancellous bone area. The cause of these abnormalities is unknown but might be related to potentially harmful exposures during service in the Gulf War or to changes in life style as a result of chronic ill health. The clinical relevance of the observed reduction in bone formation remains to be established.

Mechanisms by which high-dose estrogen therapy produces anabolic skeletal effects in postmenopausal women: role of locally produced growth factors

Conventional hormone replacement therapy acts primarily by preserving bone, but cannot restore lost bone in women with established osteoporosis. Studies in rodents have shown that high doses of estrogens have anabolic skeletal effects, and recent observations in a group of women treated long term with high doses of estrogen indicated that similar effects occur in humans. This study examines the hypothesis that locally produced growth factors, including transforming growth factor-beta (TGF-beta) and platelet-derived growth factors (PDGFs), are involved in mediating the anabolic effects of high-dose estrogen. Transiliac-crest bone biopsies were taken from ten women, aged 52-67 years (mean 58 years), who had been treated with high-dose estrogen for 15 years. Control samples were obtained from four age-matched postmenopausal women not receiving estrogen therapy. TGF-betas and PDGFs were analyzed for mRNA and protein expression by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. Results showed both TGF-beta1 and -beta2 mRNA, expressed as a ratio to GAPDH, were increased in the estrogen-treated group with an eightfold increase for TGF-beta1 (0.258 +/- 0.246 [mean +/- SD] vs. 0.032 +/- 0.053 in the control group, p = 0.02) and a twofold increase for TGF-beta2 (p = n.s.). TGF-beta3 analysis showed only negligible amounts in both groups. Protein expression levels for TGF-beta1, -beta2, -betaRI and -RII were higher in the estrogen-treated group than in controls, the most marked effects being seen for TGF-beta1. PDGF-A protein expression was also significantly higher in osteoblasts and osteocytes in women treated with estrogen, whereas PDGF-B showed only modest differences. The percentage of bone surface occupied by osteoclasts, as determined by tartrate-resistant acid phosphatase (TRAP) staining, was significantly reduced in the estrogen-treated group (p = 0.001). These results demonstrate that high-dose estrogen therapy is associated with increased TGF-beta, TGF-betaR, and PDGF synthesis and decreased osteoclast activity, consistent with the hypothesis that these growth factors may mediate the actions of estrogen in bone.

Colocalization of glucocorticoid and mineralocorticoid receptors in human bone

Osteoporosis is a poorly understood but common complication of glucocorticoid therapy. The actions of glucocorticoids are mediated via glucocorticoid receptors (GRs), but in vitro, glucocorticoids also can bind to mineralocorticoid receptors (MRs). It is not known if MR protein is present in human bone and little is known of GR isoform expression (GRalpha and GRbeta). GR and MR protein expression and possible sites of action were investigated in neonatal rib and adult iliac crest biopsy specimens using antibodies specific for MR, GRalpha, and GRalphabeta. Colocalization [MR GRalpha] [MR GRalphabeta] was performed using fluorescent-conjugated secondary antibodies. GRalpha, GRbeta, and MR show distinct but overlapping patterns of expression, suggesting important functions for each receptor type. Osteoclasts showed no staining for GRalpha but strong staining for GRalphabeta, indicating expression of GRbeta and a specific role in addition to antagonizing the transcriptional activity of GRalpha. MR also was observed in osteoclasts and colocalized with GRalphabeta. Coexpression of MR, GRalpha, and GRalphabeta was seen in osteoblasts. Reverse-transcription-polymerase chain reaction (RT-PCR) of cultured osteoblast RNA confirmed expression of both GRalpha and GRbeta. Osteocytes stained with MR, GRalpha, and GRalphabeta antibodies but to a lesser degree than osteoblasts. In the neonatal rib cartilage, staining for GRalpha, GRalphabeta, and MR was present in approximately one-half of the resting and hypertrophic chondrocytes and in most of proliferating chondrocytes and chondrocytes within the mineralizing matrix. Identification of MR raises the possibility that the physiological and pharmacologic effects of glucocorticoids on bone may be mediated via MR as well as GR and that GRalpha, GRbeta, and MR synergize to influence corticosteroid metabolism in human bone.

Estrogen receptors alpha and beta are differentially expressed in developing human bone

Estrogen plays an essential role in the development and maintenance of the skeleton; its effects are mediated via interactions with two estrogen receptor (ER) subtypes, alpha and beta. The aim of this study was to establish the cellular distribution of ERalpha and ERbeta in neonatal human rib bone. ERalpha and ERbeta immunoreactivity was seen in proliferative and prehypertrophic chondrocytes in the growth plate, with lower levels of expression in the late hypertrophic zone. Different patterns of expression of the two ERs were seen in bone. In cortical bone, intense staining for ERalpha was observed in osteoblasts and osteocytes adjacent to the periosteal-forming surface and in osteoclasts on the opposing resorbing surface. In cancellous bone, ERbeta was strongly expressed in both osteoblasts and osteocytes, whereas only low expression of ERalpha was seen in these areas. Nuclear and cytoplasmic staining for ERbeta was apparent in osteoclasts. These observations demonstrate distinct patterns of expression for the two ER subtypes in developing human bone and indicate functions in both the growth plate and mineralized bone. In the latter, ERalpha is predominantly expressed in cortical bone, whereas ERbeta shows higher levels of expression in cancellous bone.

Tie2 ligands angiopoietin-1 and angiopoietin-2 are coexpressed with vascular endothelial cell growth factor in growing human bone

Angiogenesis is essential for bone growth and repair. Recent studies have shown that the endothelial-specific mitogen vascular endothelial growth factor (VEGF) is a key regulator of vascular invasion into the growth plate in infant and adolescent animals. In order to identify mechanisms regulating VEGF-induced angiogenesis in growing bone, we have investigated the expression of the angiopoietins (Ang-1 and Ang-2) in human neonatal ribs. Ang-1 and Ang-2 exhibited similar patterns of staining in the growing rib. In the cartilage, expression of Ang-1 and Ang-2 increased with chondrocyte maturation. Ang-1, Ang-2, and VEGF were not detected in the resting zone except adjacent to vascular canals, and maximum expression was detected at the cartilage bone interface. In the cartilage, Ang-2 was more highly expressed than Ang-1 or VEGF, with staining observed in the proliferating, hypertrophic, and mineralized zones. In the bone, Ang-1, Ang-2, and VEGF were detected in modeling and remodeling sites. Ang-1 was detected in the majority of osteoblasts, osteoclasts, and in some marrow space cells. Ang-2 was expressed at variable levels by osteoblasts and osteoclasts in modeling and remodeling bone. VEGF was detected in cells at bone surfaces and in the marrow spaces. Strong staining for VEGF was observed in osteoblasts and osteoclasts in modeling and remodeling bone. In the perichondrium, Ang-1, Ang-2, and VEGF were most highly expressed adjacent to the hypertrophic zone and at sites of bone collar formation. In the periosteum, Ang-1, Ang-2, and VEGF expression colocalized with alkaline phosphatase expression. These observations provide the first evidence for the expression of the angiopoietins in growing human bone in vivo. The distribution of Ang-1, Ang-2, and VEGF indicate these factors may play key roles in the regulation of angiogenesis at sites of endochondral ossification, intramembranous ossification, and bone turnover in the growing human skeleton.

Megakaryocyte population in human bone marrow increases with estrogen treatment: a role in bone remodeling?

Skeletal effects of conventional hormone replacement therapy (HRT) are predominately antiresorptive, while high doses of estrogen have anabolic effects. The mechanisms mediating these effects are unclear but may involve cells in the bone marrow. We have investigated the in vivo effects of estrogen on the megakaryocyte (MK) population in bone marrow in 10 postmenopausal women before and after 2 years of conventional HRT, in 11 women after long-term, high-dose estradiol therapy, and in 2 premenopausal and 4 postmenopausal women who had received no previous estrogen treatment. Transiliac crest biopsies were halved and either decalcified and paraffin wax embedded for immunolocalization studies or dehydrated and embedded in LR White resin for histology. MKs were identified morphologically, and the bone marrow cell population and MK number quantified by cell counting in a defined area of view (1 mm(2)) from 5 randomly selected fields of bone marrow. Compared with pretreatment values, significantly higher MK numbers were found after conventional HRT treatment (before treatment, mean +/- SEM; 7.3 +/- 1.1 vs. after treatment, 18.0 +/- 1.6/5 mm(2); p < 0.0001), while the greatest MK number was associated with long-term, high-dose estradiol treatment (32.8 +/- 2.1/5 mm(2); p < 0.0001). Total bone marrow cell number did not differ significantly between groups. Immunolocalization studies revealed more intense estrogen receptor (ER)beta expression in MKs in the high-dose estradiol-treated group but similar levels of weak ERalpha staining in MKs in the control and high-dose estrogen-treated groups. Positive immunoreactivity for transforming growth factor (TGF)beta1, 2, and 3 and TGFbeta receptor I, II, and III was detected in MKs, with more intense staining being demonstrated in the high-dose estradiol-treated group, particularly for TGFbeta2 and TGFbetaRI and II. Our results demonstrate an increase in the MK population in bone marrow from women treated with estrogen. The ability of MKs to express ERs and synthesise TGFbeta, a potent mitogen in osteoblast differentiation, suggests that these cells may play a role in mediating estrogen-induced effects on bone.

Reduced bone formation after exposure to organophosphates

Bone histomorphometric analysis in 24 agricultural workers with chronic organophosphate exposure showed significantly lower bone formation at tissue and cellular level than in healthy controls.

Immunolocalisation of vascular endothelial growth factor (VEGF) in human neonatal growth plate cartilage

Angiogenesis is essential for the replacement of cartilage by bone during growth and repair. In order to obtain a better understanding of the mechanisms regulating vascular invasion at sites of endochondral ossification we have investigated the expression of the endothelial cell-specific mitogen, vascular endothelial growth factor (VEGF), by chondrocytes in human neonatal growth plates. VEGF was absent from chondrocytes in the resting zone and only weakly expressed by occasional chondrocytes in the proliferating region. In the hypertrophic zone the number of chondrocytes stained and the intensity of staining for VEGF increased with chondrocyte hypertrophy, maximum expression of VEGF being observed in chondrocytes in the lower hypertrophic and mineralised regions of the cartilage. These observations provide the first demonstration of the presence of VEGF in situ in developing human bone and are consistent with in vitro observations demonstrating the upregulation of proangiogenic growth factor production with increasing chondrocyte hypertrophy. The presence of numerous small blood vessels and vascular structures in the subchondral region where VEGF expression was maximal indicates that VEGF produced by hypertrophic chondrocytes may play a key role in the regulation of vascular invasion of the growth plate.

Tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) distribution in normal and pathological human bone

Degradation of skeletal connective tissue is regulated, at least in part, by the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinase (TIMPs), their natural inhibitors. The balance between MMPs and TIMPs may therefore be a determinant of normal bone turnover, and imbalance could thus lead to reduced organization of bone structure. To test this hypothesis, the cellular expression of MMPs and TIMP-1 was investigated by immunohistochemistry in human neonatal rib and osteophytic and heterotopic bone; these differ in their structure, with heterotopic bone showing the least and normal rib the most organized development. In all samples, high levels of MMPs were expressed. Collagenase and stromelysin-2 were detected in chondrocytes, osteoblasts, and osteoclasts, whereas gelatinase-B was confined to osteoclasts and mononuclear cells. Matrix-associated stromelysin-1 was present in fibrous tissue and osteoid. In contrast, the expression of TIMP-1 varied markedly between the three types of bone. In heterotopic bone only occasional low level TIMP-1 expression was detected in chondrocytes and osteoblasts. Osteophytic bone showed varying levels of TIMP-1, which was matrix-bound in fibrous tissue and cell-associated in osteoblasts, chondrocytes, and occasional mononuclear cells. In both types of bone, expression of TIMP-1 by osteoclasts was absent despite large numbers of these cells. Neonatal rib bone showed consistent expression of TIMP-1, particularly in chondrocytes, osteoblasts, and lining cells. In contrast to pathological bone, many osteoclasts were TIMP-1 positive. These results suggest that, in heterotopic and osteophytic bone, the low levels of TIMP-1, and in particular its absence in osteoclasts, may partly explain the more poorly organized bone formation in these pathological bone samples. Furthermore, TIMP-1 may play a role in the regulation of bone modeling and remodeling in normal developing human bone.

Bone remodeling and structure in postmenopausal women treated with long-term, high-dose estrogen therapy

Conventional hormone replacement therapy preserves bone mass predominantly by reducing bone turnover but does not exert significant anabolic skeletal effects. In contrast, high doses of estrogen have been shown to increase bone formation in animals and we have recently reported high bone mineral density values in women treated long-term with estradiol implant therapy. The aim of this study was to investigate the mechanisms by which high doses of estrogen may increase bone mass in postmenopausal women. Iliac crest biopsies were obtained from 12 women who had received long-term treatment with estradiol implants (at least 14 years), on demand, following hysterectomy and bilateral salpingo-oophorectomy. Indices of bone turnover, remodeling balance and cancellous bone structure were assessed by image analysis and compared with those of premenopausal women. Mean wall width was significantly higher in women treated with estradiol therapy than in premenopausal women (44. 8 +/- 4.8 vs 38.8 +/- 2.8 mm; mean +/- SD; p = 0.001) and eroded cavity area was significantly lower in the implant-treated women (3612 +/- 956 vs 5418 +/- 1404 mm(2); p = 0.001). Bone formation rate at tissue level and activation frequency were lower in the women treated with implants, although the differences were not statistically significant. Indices of cancellous bone structure were generally similar between the two groups. These results provide the first direct evidence that high-dose estrogen therapy produces anabolic skeletal effects in postmenopausal women and indicate that these are achieved by stimulation of osteoblastic activity.

Expression and distribution of transforming growth factor-beta isoforms and their signaling receptors in growing human bone

Transforming growth factors type beta (TGF-beta1, -beta2, and -beta3) are potent stimulators of bone formation and have been shown to regulate chondrocyte, osteoblast, and osteoclast formation and function. However, the distribution of the different isoforms and their signaling receptors in human bone in vivo has not previously been reported. Using samples of normal (neonatal rib) and pathological (osteophytic) developing human bone, we have investigated the expression of the different TGF-beta isoforms and their signaling receptors (TGF-betaRI and RII) at the messenger ribonucleic acid (mRNA) and protein levels by in situ hybridization and immunolocalization to establish the sites of TGF-beta production and their possible sites of action during human bone development in vivo. All three TGF-beta isoforms and the receptors were detected at sites of endochondral and intramembranous ossification. At sites of endochondral ossification, TGF-beta2 was detected in all zones of the cartilage, with the highest expression seen in the hypertrophic and mineralizing zones. TGF-beta3 was detected in proliferative and hypertrophic zone chondrocytes, while TGF-beta1 expression was restricted to the proliferative and upper hypertrophic zones. TGF-betaRI and RII exhibited similar distributions with maximum expression in the hypertrophic and mineralizing zones in the neonatal rib but in the resting/proliferative zone in the developing osteophyte. At sites of intramembranous ossification TGF-beta3 was the most widely distributed isoform and showed both matrix- and cell-associated staining. TGF-beta2 and -beta1 were expressed almost exclusively at sites of mineralization. These observations demonstrate that the different TGF-beta isoforms and their receptors exhibit distinct but overlapping patterns of expression, and support the hypothesis that they are involved in the regulation of endochondral and intramembranous ossification during human bone development in vivo.

Stromelysin-1 (MMP-3) and stromelysin-2 (MMP-10) expression in developing human bone: potential roles in skeletal development

Stromelysin, a member of the matrix metalloproteinase family, demonstrates wide substrate specificity with the ability to degrade proteoglycan, fibronectin, laminin, casein, and the nonhelical region of collagen. The two forms of stromelysin (SL), types 1 (MMP-3) and 2 (MMP-10), share 82% sequence homology, but exhibit differences in cellular synthesis and inducibility by cytokines and growth factors in vitro. However, the distribution of the two isoforms in bone has not been reported. We investigated the presence of SL-1 and SL-2 in human osteophytic and neonatal rib bone using immunohistochemistry and, combined with a new method of in situ zymography, determined the activity of the immunolocalized stromelysins. Latent SL-1 was strongly expressed in the extracellular matrix in fibrous tissue surrounding areas of endochondral ossification in osteophytes, and adjacent to the periosteum of fetal rib bone. Active SL-1 expression was detected in osteocytes and the matrix surrounding osteocytic lacunae. SL-2 showed intense cell-associated staining at sites of resorption in areas of endochondral ossification and in resorptive cells at the chondro-osseous junction, which correlated with enzyme activity detected by zymography. Within the rib, active SL-2 expression was localized in chondrocytes of the growth plate, whereas only occasional SL-1 signal was evident. Vascular areas showed strong SL-2 staining with some proteolytic activity. SL-2, but not SL-1, was strongly expressed in osteoclasts and most mononuclear cells within the marrow. At sites of bone formation both isoforms were expressed by osteoblasts with SL-1 also present in osteoid. These results demonstrate, for the first time, the differential expression of SL-1 and SL-2 in developing human bone, indicating specific roles for the two isoforms. In situ zymography demonstrates that SL-2 is produced in an active form with associated degradation, whereas SL-1, in a matrix-bound proenzyme form, may act as a reservoir for later activation.

Skeletal progenitor cells and ageing human populations

1. Stem and progenitor cells present within bone marrow give rise to colony forming units-fibroblastic (CFU-F) which can differentiate into fibroblastic, osteogenic, myogenic, adipogenic and reticular cells. The decrease in skeletal bone formation and rate of fracture repair observed with ageing and in osteoporosis has been suggested to be due to a decrease in numbers of these progenitors, but human studies are limited. 2. We have tested the potential to form CFU-F in a total of 99 patients undergoing corrective surgery (16 controls, 14-48 years of age) or hip arthroplasty for osteoarthritis (57 patients, 28-87 years of age) or osteoporosis (26 patients, 69-97 years of age). Total colony number, alkaline phosphatase-positive colony number and colony size were determined. 3. No decrease in colony forming efficiency under the culture conditions used was observed in all populations examined irrespective of age, disease or gender, as determined by the lack of correlation between colony formation and age. 3. Examination of colony sizes showed a significant reduction in colony size with age in osteoarthritis and in control populations indicating a change in cellular proliferative potential with age. 4. Examination of number and percentage of alkaline phosphatase-positive CFU-F showed a significant decrease in osteoporotic patients compared with controls and osteoarthritis patients, indicating altered differentiation potential. 5. These results suggest that the reduction in bone mass with ageing may be due to reduction of the proliferative capacity of progenitor cells or their responsiveness to biological factors leading to alteration in subsequent differentiation. The maintenance of CFU-F number and alkaline phosphatase activity in these osteoarthritis patients may, in part, explain the inverse relationship observed for the preservation of bone mass between generalized osteoarthritis and primary osteoporosis.

The expression of thyroid hormone receptors in human bone

The mechanism of action of thyroid hormones on bone is poorly understood. Thyroid hormones may act on bone cells either indirectly by increasing secretion of growth hormone (GH) and insulin-like growth factor-1 (IGF-1), or directly by influencing target genes via specific nuclear receptors. The presence of thyroid hormone receptors (TRs) has been demonstrated in human and rodent osteoblast-like cells and cell lines and recently in osteoclasts derived from an osteoclastoma in vitro. However, their presence in human bone in situ has not been reported. We have used specific polyclonal antibodies to TR-alpha 1, -alpha 2, and -beta 1 to investigate the expression of these receptors in sections of human osteophytes and heterotopic bone. Osteoblasts and osteoclasts were identified by alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP), respectively, whereas chondrocytes were identified morphologically. At sites of endochondral and intramembranous bone formation, TR-beta 1 and the splice variant -alpha 2 were widely expressed by proliferating, mature, and hypertrophic chondrocytes and also in cells within the fibrous tissue and at the bone forming surfaces, respectively. They were also detected in osteoblasts, osteoclasts, and a few osteocytes at sites of bone remodeling. In contrast, TR-alpha 1 was the least expressed and was present mainly in osteoblasts at remodeling sites and in a few mature and undifferentiated chondrocytes. Our results show, for the first time, the presence and distribution of TRs in human bone in situ and suggest that the skeletal actions of thyroid hormones may be mediated via these receptors. Further studies are required to define the role of the individual receptor isoforms in bone metabolism.

Distribution of matrix metalloproteinases and their inhibitor, TIMP-1, in developing human osteophytic bone

Connective tissues synthesise and secrete a family of matrix metalloproteinases (MMPs) which are capable of degrading most components of the extracellular matrix. Animal studies suggest that the MMPs play a role in bone turnover. Using specific polyclonal antisera, immunohistochemistry was used to determine the patterns of synthesis and distribution of collagenase (MMP-1), stromelysin (MMP-3), gelatinase A (MMP-2) and gelatinase B (MMP-9) and of the tissue inhibitor of metalloproteinases-1 (TIMP-1) within developing human osteophytic bone. The different MMPs and TIMP showed distinct patterns of localisation. Collagenase expression was seen at sites of vascular invasion, in osteoblasts synthesising new matrix and in some osteoclasts at sites of resorption. Chondrocytes demonstrated variable levels of collagenase and stromelysin expression throughout the proliferative and hypertrophic regions, stromelysin showing both cell-associated and strong matrix staining. Intense gelatinase B expression was observed at sites of bone resorption in osteoclasts and mononuclear cells. Gelatinase A was only weakly expressed in the fibrocartilage adjacent to areas of endochondral ossification. There was widespread but variable expression of TIMP-1 throughout the fibrous tissue, cartilage and bone. These results indicate that MMPs play a role in the development of human bone from cartilage and fibrous tissue and are likely to have multiple functions.

Effects of intrajejunal perfusion and chronic ingestion of Lactobacillus johnsonii strain La1 on serum concentrations and jejunal secretions of immunoglobulins and serum proteins in healthy humans

OBJECTIVES

Link-Amster reported an increase in serum IgA when healthy subjects ingested a fermented dairy product containing Lactobacillus johnsonii La1. We aimed to assess the effects of La1 on the jejunal secretions and serum concentrations of total and specific immunoglobulins and proteins.

METHODS

Twelve healthy volunteers ingested a fermented milk containing La1 or a control from day 1 till day 28, following a randomised double blind protocol. At days 0 and 28, the jejunum was successively perfused with a control solution and with a La1 suspension. The serum concentrations and jejunal secretions of albumin, orosomucoid, transferrin, alpha 2-macroglobulin, m-IgA, p-IgA, IgG, IgM, secretory component, and specific antibodies against La1 were assessed.

RESULTS

Serum concentrations of IgA slightly increased between d0 and d28 in the group receiving La1 (1.85 +/- 0.64 g/L vs 1.76 +/- 0.76; P = 0.02). The other parameters were not altered.

CONCLUSION

This study shows that the immunomodulating effects of La1 ingestion in man are not due to modification of jejunal protein permeability.

Distribution of platelet-derived growth factor (PDGF) A chain mRNA, protein, and PDGF-alpha receptor in rapidly forming human bone

Platelet-derived growth factors (PDGFs) are potent bone cell mitogens which stimulate the proliferation of osteoblastic cells, may also be involved in the regulation of osteoclastic bone resorption, and indirectly induce vascular endothelial cell proliferation and angiogenesis. In view of the established relationship between angiogenesis and osteogenesis, the production of PDGFs by both osteoblastic and vascular endothelial cells suggests that they may play a role in bone formation during skeletal development. We have used two human models of rapid bone formation, heterotopic bone and osteophytic bone, to investigate the expression of PDGF-A mRNA and protein and the PDGF-alpha receptor protein in vivo using in situ hybridization and immunohistochemistry. PDGF-A mRNA and protein were widely distributed throughout heterotopic and osteophytic bone. Within the cartilaginous tissue PDGF-A mRNA and protein were most strongly expressed by mature chondrocytes with decreased expression in the hypertrophic zone and almost no staining in the mineralizing and mineralized zones. PDGF mRNA and protein were also expressed in cells of small blood vessels within fibrous and cartilaginous tissue. In contrast, PDGF-alpha receptor expression was restricted to a minority of hypertrophic chondrocytes and sites of vascular invasion. Within the bone and fibrous tissue the growth factor and the receptor were widely distributed, being detected on most cells at sites of bone formation or in remodeling sites; no receptor was detected on osteoclasts. These data demonstrate the widespread expression of PDGF-A and its receptor in forming human bone and indicate that this growth factor may exert autocrine and paracrine effects to regulate osteogenesis during skeletal development.

Production of collagenase by human osteoblasts and osteoclasts in vivo

Studies in some animal species have demonstrated the production of metalloproteinases by bone cells, suggesting that they may play a role in bone modeling and remodeling. The aim of the present study was to investigate the expression of collagenase in human bone in situ, using heterotopic and osteophytic bone. Immunohistochemistry was performed on chilled sections of bone, using well characterized polyclonal antibodies to human collagenase. The heterotopic and osteophytic bone exhibited high turnover and both bone modeling and remodeling were evident. Collagenase expression by osteoblasts was demonstrated in cells synthesising matrix and in lining cells; the strongest signal was seen in areas of de novo matrix formation, where bridges of woven bone were being formed between areas of mineralized bone. Collagenase was also present in some osteoclasts associated with eroded bone surfaces and in some mononuclear cells that were present in resorption cavities and in the bone marrow. Our results provide the first demonstration, in situ, of collagenase in human bone and suggest that it may play a role in human bone modeling and remodeling. Production of collagenase by active osteoblasts and lining cells suggest that it may be involved both in matrix formation and activation of bone remodeling. The presence of collagenase in osteoclasts provides further evidence that metalloproteinases may play a role in bone resorption.

The synthesis of collagenase, gelatinase-A (72 kDa) and -B (95 kDa), and TIMP-1 and -2 by human osteoblasts from normal and arthritic bone

Bone resorption is a complex multistep process that involves removal of both the organic and mineral constituents of bone matrix by proteolytic enzymes synthesized by osteoblasts and osteoclasts. To further understand the role of matrix metalloproteinases (MMPs) and their specific inhibitors TIMPs (tissue inhibitor of metalloproteinases) in this process, human osteoblasts were obtained by sequential enzymatic digestion from samples of bone from normal donors and patients with various forms of arthritis; first passage cells were used in all experiments and cultured on a type I collagen substratum. Collagenase was detected by an ELISA in supernatants from unstimulated osteoblasts (range 12-730 ng/mL), although the levels did not appear to bear any relationship to the age or clinical status of the patient; treatment with parathyroid hormone (PTH; 2 units/mL) and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3, 10 ng/mL] had no added effect, but mononuclear cell conditioned medium (MCM; 5% v/v) and interleukin-1 alpha (IL-1 alpha; 1 ng/mL) both stimulated collagenase synthesis, in the case of MCM by two orders of magnitude. TIMP-1 was detected in unstimulated cultures by an ELISA (range 320-590 ng/mL), the mean level being three-fold greater than for collagenase and was stimulated by 1,25(OH)2D3 and MCM treatment. Degradation studies showed that, over a 120 h culture period, one third of the collagen substratum was degraded by unstimulated cells. PTH and 1,25(OH)2D3 had no effect on this endogenous level of lysis, but addition of MCM and IL-1 alpha resulted in a significant increase in collagen degradation.(ABSTRACT TRUNCATED AT 250 WORDS)

Rabbit calvarial osteoblasts in culture constitutively synthesize progelatinase-A, and TIMP-1 and TIMP-2

Defining the TIMPs (tissue inhibitors of metalloproteinases) produced by non-human bone cells is important because animal models and cells are used extensively for research on bone resorption, and because TIMP-2 can bind to and prevent activation of progelatinase-A. By zymography we show that rabbit calvarial osteoblasts in culture constitutively synthesize TIMP-2 in addition to TIMP-1 and progelatinase-A. Previously we found that human osteoblasts produced only low levels of TIMP-2 under any conditions. We also show that stimulated rabbit osteoblasts can degrade a type I collagen film even though both TIMPs are being synthesized.

Human osteoblasts in culture synthesize collagenase and other matrix metalloproteinases in response to osteotropic hormones and cytokines

Collagenase production by rodent osteoblasts in response to calciotropic hormones has led to the hypothesis that bone cells play a major role in bone resorption by degrading the surface osteoid layer, thereby exposing the underlying mineralized matrix to osteoclastic action. Many studies suggest, however, that this model might not apply to bone resorption in the human. Human osteoblasts have been shown to produce gelatinase-A (72 kDa) and TIMP-1 (tissue inhibitor of metalloproteinases), but previous investigators have been unable to demonstrate the synthesis of collagenase by human osteoblasts either constitutively or in response to bone resorptive agents. In the present study the ability of human osteoblasts to produce the matrix metalloproteinases (MMPs) collagenase, gelatinase and stromelysin, and their specific inhibitors TIMPs-1 and 2, was examined using highly sensitive and specific antisera and by zymography. Semi-quantitative histomorphometric data showed that cells cultured on either glass or a type I collagen substratum constitutively synthesized gelatinase-A and TIMP-1. On type I collagen, however, a small proportion of unstimulated cells produce both collagenase (7%) and gelatinase-B (95 kDa; 3%). Treatment of cells with either parathyroid hormone (PTH), 1,25-dihydroxy-vitamin D3 (1,25(OH)2D3), or partially purified mononuclear cell conditioned medium (MCM), stimulated the synthesis of collagenase, gelatinase-B and stromelysin; MCM was 2- to 3-fold more potent than either PTH or 1,25(OH)2D3. Zymography using SDS/PAGE on conditioned media from cells cultured on type I collagen films revealed the presence of active gelatinase-A and that MCM stimulated progelatinase-B synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)