AMPKα1 negatively regulates osteoclastogenesis and mitigates pathological bone loss

Osteoclasts are specialized cells responsible for bone resorption, a highly energy-demanding process. Focus on osteoclast metabolism could be a key for the treatment of osteolytic diseases including osteoporosis. In this context, AMP-activated protein kinase α1 (AMPKα1), an energy sensor highly expressed in osteoclasts, participates in the metabolic reconfiguration during osteoclast differentiation and activation. This study aimed to elucidate the role of AMPKα1 during osteoclastogenesis in vitro and its impact in bone loss in vivo. Using LysMcre/0AMPK⍺1f/f animals and LysMcre/0 as control, we evaluated how AMPKα1 interferes with osteoclastogenesis and bone resorption activity in vitro. We found that AMPKα1 is highly expressed in the early stages of osteoclastogenesis. Genetic deletion of AMPKα1 leads to increased gene expression of osteoclast differentiation and fusion markers. In addition, LysMcre/0AMPK⍺1f/f mice had an increased number and size of differentiated osteoclast. Accordingly, AMPKα1 negatively regulates bone resorption in vitro, as evidenced by the area of bone resorption in LysMcre/0AMPK⍺1f/f osteoclasts. Our data further demonstrated that AMPKα1 regulates mitochondrial fusion and fission markers upregulating Mfn2 and downregulating DRP1 (dynamics-related protein 1) and that Ctskcre/0AMPK⍺1f/f osteoclasts lead to an increase in the number of mitochondria in AMPK⍺1-deficient osteoclast. In our in vivo study, femurs from Ctskcre/0AMPK⍺1f/f animals exhibited bone loss associated with the increased number of osteoclasts, and there was no difference between Sham and ovariectomized group. Our data suggest that AMPKα1 acts as a negative regulator of osteoclastogenesis, and the depletion of AMPKα1 in osteoclast leads to a bone loss state similar to that observed after ovariectomy.

POS1196 COVID-19 VACCINE WILLINGNESS IN RA? RESULTS FROM THE RA LOUVAIN BRUSSELS COHORT

Background:

Over 2 million deaths from the COVID-19 disease have been reported in the world. Since no antiviral treatment is available, the vaccination is the most important option to fight the SARS-CoV-2 infection. Patients living with rheumatoid arthritis (RA) affecting the immune system or under immunosuppressive agent will be considered as a high risk population and will start the vaccination shortly. But many patients could decline the vaccine for several reasons including safety concerns.

Objectives:

The aim of this study is to evaluate the proportion of patients with RA who are favourable to COVID-19 vaccination, to know the reasons to decline and to analyse the characteristics of these patients.

Methods:

We included patients with RA from the UCLouvain Brussels cohort who met the ACR/EULAR 2010 classification criteria. A simple and standard questionnaire was distributed to patients who attended rheumatology out patient and day care clinic from 14 december 20 to 14 januari 21. All patient and RA characteristics (Age, gender, education, smoking habits, disease duration, ACPA, RF, DAS28-CRP, HAQ and therapies) were collected at the same time.

Results:

Data from 460 eligible RA patients were analyzed. The average age of the population is 58.21 years. 72% of the patients are women. 21% are smokers and 65% are positive for anti-citrullinated protein antibody (ACPA) with a mean DAS28-CRP of 2.39 and a mean HAQ of 0.821.

281 patients (61%) indicated they would receive the vaccine as soon as it is available. For the 179 patients (39%) who decline, the reasons for not having vaccine were no trust in the vaccine at this time (53%), fear of side effects (28%), opposition to vaccine (4%), previous SARS-CoV-2 infection (2%) and unknown (5%),

Interestingly, there were differences among RA patients not willing to receive the vaccine. Patient under the age of 50, women, low education grade, smokers, presence of RF/ACPA and treatment with a bioDMARD were less willing to receive the vaccine. No differences were observed for RA disease duration, HAQ and DAS28-CRP (see Table 1).

Table 1.

Characteristics of RA population and correlation between groups.

TOTALn=460VACCIN-YESn=281 (61%)VACCIN-NOn=179 (39%)Age, mn58,21 +/-0,7160,37 ± 0,900454,82 ± 1,090p=0.0001*Group Age <30 yrs25 (5%)15 (5%)10 (6%)Group Age =31-50 yrs112 (24%)53 (19%)59 (33%)Group Age =51-70 yrs209 (45%)127 (45%)82 (46%)Group Age > 70 yrs114 (25%)86 (31%)28 (16%)p=0.0003**Gender, F/M, %-F332/128(F-72%)193/88(F-69%)139/40(F-78%)p=0.043**Educ0-163 (15%)27 (11%)36 (22%)Educ2-3349 (85%)222 (89%)127 (78%)p=0.003**RA Disease duration yrs, mn14,77 +/-0,5115,24 +/-0,6914,04 +/-0,73Smokers: YES/NO/Ex-Smokers, %-YES85/248/79 (21%)42/156/52 (17%)43/92/27 (27%)p=0.018**RF YES/NO, %243/137 (64%)133/94 (59%)110/43 (72%)p=0.009**ACPA YES/NO, %244/132 (65%)127/93 (58%)117/39 (75%)p=0.001**HAQ, mn0,814+/-0,0390,797+/-0,0510,838+/-0,061DAS28-CRP, mn2,39+/-0,052,35+/-0,072,44+/-0,09GC, YES/NO, %360/86 (19%)217/55 (20%)143/31 (18%)csDMARDs (MTX), YES/NO, %124/322 (72%)72/200 (74%)52/122 (70%)BioDMARDs, NO/YES, %151/295 (66%)107/165 (61%)44/130 (75%)p=0.003**

(*) - Unpaired t Test; (**) - Fisher’s exact test

Conclusion:

In our RA cohort, the rates of willingness to receive the vaccine are promising. Dedicated education and outreach efforts should be developed, especially in some RA subpopulation.

Disclosure of Interests:

None declared.

Influence of HLA-DR antigens on lymphocyte response to Mycobacterium tuberculosis culture filtrate antigens and mitogens in pulmonary tuberculosis

SETTING

Influence of HLA-DR antigens and lymphocyte responses in pulmonary TB patients.

OBJECTIVE

To elucidate the role of HLA-DR genes/gene products on lymphocyte responses to Mycobacterium tuberculosis antigens and mitogens, the present study was carried out in pulmonary tuberculosis during active and cured stage of the disease.

DESIGN

Serological determination of HLA-DR antigens was carried out in 50 active TB patients, 44 cured TB patients and 58 normal healthy control subjects. The influence of HLA-DR antigens on peripheral blood lymphocyte responses to M. tuberculosis culture filtrate antigens and mitogens such as phytohaemagglutinin (PHA) and concanavalin-A (Con-A) was studied in the patients as well as normal healthy control subjects.

RESULTS

Of all the DR antigens studied, patients (active TB and cured TB) with DR2 antigen showed an increased lymphocyte response (stimulation index) to a higher dose of antigenic (10 micrograms/ml) stimulation. A significantly lower lymphocyte response to antigen and mitogens was seen in HLA-DR3 positive normal healthy subjects than non-DR3 (DR3 negative) subjects.

CONCLUSION

The present study suggests that HLA-DR genes/gene products may be playing an immunoregulatory role in eliciting an immune response against M. tuberculosis antigens and mitogens induced lymphocyte response in pulmonary TB patients and normal healthy subjects.

Lymphocytotoxic antibodies & immunity in pulmonary tuberculosis

To understand whether the presence of cold reactive lymphocytotoxic antibodies (LCA) (reactive at 15 degrees C) in the system has any effect on immunity to tuberculosis lymphocytotoxic antibodies to adherent cells (enriched-B cells) and non-adherent cells were studied in active-TB (n = 42) and inactive-TB (cured) patients (n = 49) and healthy controls (n = 32). The plasma samples of inactive-TB patients showed higher percentage of positivity for lymphocytotoxic antibodies (36.7%) than the active-TB patients (21.4%) and control subjects (18.8%). No significant difference on antibody and lymphocyte response against Mycobacterium tuberculosis culture filtrate antigens was observed between LCA positive and LCA negative active-TB patients and normal healthy controls. Further, determination of HLA-DR phenotype of the patients and control subjects showed that individuals positive for lymphocytotoxic antibodies were more among HLA-DR2 positive and DR7 positive active-TB patients and control subjects than non-DR2 and non-DR7 subjects. The present study suggests that the cold reactive lymphocytotoxic antibodies may be against B-lymphocytes and persistent for a longer time. HLA-DR2 and -DR7 may be associated with the occurrence of LCA activity. Further, the presence of LCA has no immunoregulatory role on immunity to tuberculosis.

Influence of HLA-DR2 phenotype on humoral immunity & lymphocyte response to Mycobacterium tuberculosis culture filtrate antigens in pulmonary tuberculosis

Association of HLA-DR2 genes/gene products has been shown with pulmonary tuberculosis (PTB) patients in India. In the present study, the influence of HLA-DR2 and non-DR2 genes/gene products on immunity to tuberculosis has been studied. Plasma samples of -DR2 positive patients (active and inactive TB) showed a higher antibody titre to Mycobacterium tuberculosis culture filtrate antigens than non-DR2 (-DR2 negative) patients. Immunoblot analysis revealed a trend towards an increased percentage of DR2 positive patients recognizing 38, 32/34 and 30/31 kDa antigens of M. tuberculosis than DR2 negative patients. A low spontaneous lymphoproliferative response (without antigen stimulation) was seen in HLA-DR2 positive active TB patients than HLA-DR2 negative patients. However, the antigen stimulated lymphocyte response was higher in the -DR2 positive patients (active and inactive TB) when compared to non-DR2 patients. Further, an inversional correlation between antibody titre and spontaneous as well as antigen induced lymphocyte response (measured by 3H thymidine uptake and expressed as counts per minute) was seen in HLA-DR2 positive active PTB patients than non-DR2 patients. The present study suggests that HLA-DR2 genes/gene products may be associated with a regulatory role in the mechanism of disease susceptibility to tuberculosis. The genes while augmenting the humoral immune response, they suppress the spontaneous and antigen induced lymphocyte response in -DR2 positive patients with active disease.

HLA antigen profile in pulmonary tuberculosis patients & their spouses

HLA-A, -B, -DR and -DQ antigen profile was studied in pulmonary tuberculosis patients (n = 209) and their spouses (family contacts; n = 50) and healthy volunteers (n = 72). An increased frequency of HLA-A-10, B7, B15, DR2 and DQ1 was seen in the pulmonary-TB (PTB) patients when compared to the total control subjects (n = 122). However, a significant increase was seen only with HLA-DR2 (P < 0.001; Pc < 0.01; Relative Risk 2.3) and -DQ1 (P < 0.005; Pc < 0.015; Relative Risk 2.8). Among the spouses and the corresponding patients, a similar increase of HLA-DR2 was seen. A decreased frequency of HLA-A19, B8, B17, B35, DR5 and DR6 were seen in PTB as compared to control groups. The present study suggested that HLA-DR2 and DQ1 genes/gene products may be associated with the susceptibility to tuberculosis either alone or in combination with other HLA or non-HLA genes.

HLA-DR2 phenotype and plasma lysozyme, beta-glucuronidase and acid phosphatase levels in pulmonary tuberculosis

SETTING

Tuberculosis Research Centre, Indian Council of Medical Research, Madras, India.

OBJECTIVE

To elucidate the role of HLA-Class II genes/gene products on phagocyte enzymes such as lysozyme, beta-glucuronidase and acid phosphatase in the plasma of pulmonary tuberculosis patients.

DESIGN

Serological determination of HLA-DR and -DQ antigens was carried out in 54 active and 84 inactive pulmonary tuberculosis (quiescent) patients and 36 healthy control subjects. The levels of lysozyme, beta-glucuronidase and acid phosphatase were measured in the plasma of tuberculosis patients and control subjects.

RESULTS

Increased lysozyme levels were observed in active pulmonary tuberculosis patients. beta-glucuronidase activity was higher in inactive-TB than in active-TB patients and control subjects. HLA-DR2 positive patients showed a lower lysozyme level than -DR2 negative patients.

CONCLUSION

Increase in the plasma lysozyme level in active TB reveals the active stage of the disease. Further, increase in the activity of beta-glucuronidase in inactive-TB patients reveals the quiescent stage of the disease. The low level of lysozyme in HLA-DR2 positive patients may also be one of the possible factors involved in susceptibility to tuberculosis.

Influence of HLA-DR and -DO phenotypes on tuberculin reactive status in pulmonary tuberculosis patients

SETTING

HLA and tuberculin status in pulmonary tuberculosis patients. Tuberculosis Research Centre, Indian Council of Medical Research, Madras, India.

OBJECTIVE

To elucidate the role of HLA-class-II genes/gene products on tuberculin reactivity in pulmonary tuberculosis patients.

DESIGN

Serological determination of HLA-DR and -DQ antigens was carried out in 62 healthy control subjects and 146 pulmonary tuberculosis patients. The tuberculin reaction pattern of pulmonary tuberculosis patients to PPD was studied and the role of HLA-DR and -DQ antigens (class-II gene products) on tuberculin reaction was analysed.

RESULTS

HLA-DR and -DQ antigens did not influence high, medium and low tuberculin reaction dramatically in active pulmonary tuberculosis patients. However, a heterozygous combination of various HLA-DR antigens influenced the tuberculin reaction.

CONCLUSION

The HLA-genetic make up (heterozygous combination) of the individual may influence the tuberculin reaction pattern in pulmonary tuberculosis.

Feasibility of involving literate tribal youths in tuberculosis case-finding in a tribal area in Tamil Nadu

SETTING

Tribal area in South India with a population of 96,000, where the tuberculosis case-finding activity was very poor.

OBJECTIVES

To investigate the feasibility of (1) involving literate (who can read and write) tribal youth volunteers for detecting cases of pulmonary tuberculosis (PT) in their respective hamlets; and (2) antituberculosis drug delivery to sputum-positive patients at their homes by village health nurses (VHNs).

DESIGN

One volunteer from each of 61 hamlets was selected and trained in the detection of subjects with chest symptoms, sputum collection and transportation to the Primary Health Centre for smear examination. All smear-positive patients were treated with 2RHZ/6TH and the drugs were supplied by VHNs fortnightly at their homes.

RESULTS

During a period of 1 year (1992-93), the total population screened was 9383 persons; of these 5755 were aged 15 years and above. A total of 338 symptomatic subjects were identified; 12 sputum-positive cases were detected and started on treatment. Antituberculosis drugs were supplied by VHNs to patients for the first 9 months of the study and by literate youths for the next 3 months. Spot drug checks revealed that 11 of the 12 patients were regular in drug consumption.

CONCLUSION

It is feasible to train literate tribal youth volunteers within a short time to detect subjects with chest symptoms in the community and thereby cases of pulmonary tuberculosis. They can serve as an excellent model for community participation in difficult areas.