Long-term implications of COVID-19 on bone health: pathophysiology and therapeutics

Bacillus coagulans ameliorates inflammatory bone loss in post-menopausal osteoporosis via modulating the "Gut-Immune-Bone" axis

Osteoporosis is a systemic skeletal disease that leads to lower bone mineral density and intensifies the risk of unexpected fractures. Recently, our group reported that numerical defect in the frequencies of Bregs along with their compromised tendency to produce IL-10 cytokine further aggravates inflammatory bone loss in post-menopausal osteoporosis (PMO). Dysbiosis induced mucosal injury and leaky gut are the predominant contributors involved in the progression of inflammatory diseases including PMO. Furthermore, several evidence suggest that gut microbial composition plays a crucial role in the development and differentiation of Bregs. Nevertheless, the potential role of dysbiotic gut microbiota (GM) and Bregs under estrogen deficient PMO conditions has never been deciphered. Here, we evaluated the role of GM in the onset and progression of PMO along with its role in modulating the anti-osteoporotic potential of Bregs. We found that enhancement in the endotoxin producing bacteria and concomitant reduction in the short chain fatty acids producing bacteria, both under pre-clinical and clinical osteoporotic condition augment inflammatory bone loss. This suggests that dysbiosis of GM potentially exacerbates bone deterioration under estrogen deficient PMO conditions. Remarkably, supplementation of probiotic Bacillus coagulans significantly improved the bone mineral density, bone strength, and bone microarchitecture by modulating the anti-osteoclastogenic, immunosuppressive and immunomodulatory potential of Bregs. The present study delves deeper into the role of immune homeostasis ("Breg-Treg-Th17" cell axis) and GM profile in the pathophysiology of PMO. Altogether, findings of the present study open novel therapeutic avenues, suggesting restoration of GM composition as one of the viable therapeutic options in mitigating inflammatory bone loss under PMO conditions via modulating the "Gut-Immune-Bone" axis.

Unravelling the pandemic: impaired bone metabolism and risk of SARS-CoV-2 infection

INTRODUCTION

While the impact of COVID-19 on bone metabolism has been extensively studied, the inverse relationship remains less understood. This study investigates whether impaired bone metabolism is associated with an increased risk of COVID-19 infection.

METHODS

We conducted a nested case-control study within a population-based cohort, incorporating Kaplan-Meier analysis (KMA) to assess time to infection (TTI) differences. Propensity score matching (1:2) was performed and validated through standardized mean differences (<0.10), variance ratio (=1), and McFadden's pseudo-R2 (=0), ensuring balanced covariates. Bone status was evaluated using a composite index (AOMI), which included five components: P1NP and CTX (bone turnover markers), total hip bone mineral density (BMD-TH), trabecular bone score (TBS), and integral volumetric BMD (IvBMD). Inflammation and insulin resistance (IR) were assessed by albumin-to-globulin ratio (AGR <1.50) and the TG/HDL ratio (>2.50 in women and >2.80 in men), respectively.

RESULTS

We analysed 294 COVID-19 cases and 528 controls. AOMI+ individuals had a higher prevalence of COVID-19 (41.5% vs. 33.2%; p = 0.031), an adverse lipid pattern ("A" profile: high ApoB, LDL and TC) and pronounced bone changes (higher P1NP and CTX, lower BMD-TH, TBS, and IvBMD). AOMI - individuals were more likely to have metabolic syndrome, displayed a different lipid profile ("B" profile: elevated TG, AIP, and TG/HDL ratio), fewer bone alterations, and lower COVID-19 prevalence. TG/HDL ratio was 1.66 ± 1 in "A" profile, while it was 2.85 ± 1.4 in "B" profile individuals (p = 0.0001). Age acted as an effect modifier, and lowest tercile significantly increased COVID-19 risk associated with AOMI+ [Mantel-Haenszel OR = 1.42 (95%CI: 1.08-1.9); p = 0.022]. KMA identified AOMI+ men and individuals of both sexes in lowest age tercile, as groups with shorter TTI: These younger individuals had high CTX (women), low TBS (men), and high ApoB (both). In multivariable analyses, plasma CTX levels negatively correlated with TTI (adjusted β= -0.325; p = 0.0001). AOMI+ status was associated with increased COVID-19 risk after controlling for confounders, including IR (adjusted OR = 1.51; 95%CI: 1.04-2.10; p = 0.027), although this association weakened when adjusting for AGR (95%CI: 0.99-2.28; p = 0.055). ANCOVA-estimated adjusted TBS means were lower in COVID-19 cases compared to controls (1.259 vs. 1.294; p = 0.013).

CONCLUSIONS

Impaired bone metabolism was found to be associated with increased COVID-19 risk, in a relationship potentially mediated by underlying inflammation. Elevated osteoclastic activity and a defined lipid profile with high ApoB, TC, LDL levels, played a crucial role in the results. Bone quality parameters more accurately captured COVID-19-related bone changes than BMD.

Unveiling the Oral Lesions, Dysgeusia and Osteonecrosis Related to COVID-19: A Comprehensive Systematic Review

Background/Objectives: The oral cavity has garnered increasing attention as a site for viral infection and related pathological manifestations in coronavirus disease-19. This article aims to provide a comprehensive overview of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2)-related oral manifestations, including taste disturbances, oral lesions and osteonecrosis. Methods: A search was conducted up to September 2024 according to PRISMA (Preferred Reporting Items for Systematic Reviews) guidelines using the databases PubMed and Scopus. All the observational, case-series, case-report and cross-sectional studies written in English on oral manifestations related to COVID-19 disease and long-COVID disease were included. All other types of studies and studies based on oral manifestation after COVID-19 vaccination and oral impairment due to lockdown were excluded. The risk of bias of included studies was assessed using the Joanna Briggs Appraisal checklist. Results: A total of 104 articles including 23 case-report, 15 case-series, 8 case-control, 18 cohort and 40 cross-sectional studies were selected. The results showed that patients with COVID-19 were found to have a significantly higher prevalence of xerostomia (45-74%) and dysgeusia (32-59%) compared to non-infected individuals. Regarding oral mucosal lesions, ulcers, candidiasis and herpes simplex infections were frequently observed. As for osteonecrosis, a significant number of patients with COVID-19-associated rhinomaxillary mucormycosis presented with maxillary osteonecrosis due to fungal infection, primarily mucormycosis. The methodological quality of most of the studies was moderate/high. Conclusions: COVID-19 has been associated with a range of oral manifestations. The complex interplay of viral infection, immune response, medication use and stress likely contributes to these oral complications. Early recognition and management of these oral manifestations are crucial for improving patient outcomes and developing targeted preventive and therapeutic strategies for COVID-19-related oral health issues.

Immunologic and inflammatory consequences of SARS-CoV-2 infection and its implications in renal disease

The emergence of the COVID-19 pandemic made it critical to understand the immune and inflammatory responses to the SARS-CoV-2 virus. It became increasingly recognized that the immune response was a key mediator of illness severity and that its mechanisms needed to be better understood. Early infection of both tissue and immune cells, such as macrophages, leading to pyroptosis-mediated inflammasome production in an organ system critical for systemic oxygenation likely plays a central role in the morbidity wrought by SARS-CoV-2. Delayed transcription of Type I and Type III interferons by SARS-CoV-2 may lead to early disinhibition of viral replication. Cytokines such as interleukin-1 (IL-1), IL-6, IL-12, and tumor necrosis factor α (TNFα), some of which may be produced through mechanisms involving nuclear factor kappa B (NF-κB), likely contribute to the hyperinflammatory state in patients with severe COVID-19. Lymphopenia, more apparent among natural killer (NK) cells, CD8+ T-cells, and B-cells, can contribute to disease severity and may reflect direct cytopathic effects of SARS-CoV-2 or end-organ sequestration. Direct infection and immune activation of endothelial cells by SARS-CoV-2 may be a critical mechanism through which end-organ systems are impacted. In this context, endovascular neutrophil extracellular trap (NET) formation and microthrombi development can be seen in the lungs and other critical organs throughout the body, such as the heart, gut, and brain. The kidney may be among the most impacted extrapulmonary organ by SARS-CoV-2 infection owing to a high concentration of ACE2 and exposure to systemic SARS-CoV-2. In the kidney, acute tubular injury, early myofibroblast activation, and collapsing glomerulopathy in select populations likely account for COVID-19-related AKI and CKD development. The development of COVID-19-associated nephropathy (COVAN), in particular, may be mediated through IL-6 and signal transducer and activator of transcription 3 (STAT3) signaling, suggesting a direct connection between the COVID-19-related immune response and the development of chronic disease. Chronic manifestations of COVID-19 also include systemic conditions like Multisystem Inflammatory Syndrome in Children (MIS-C) and Adults (MIS-A) and post-acute sequelae of COVID-19 (PASC), which may reflect a spectrum of clinical presentations of persistent immune dysregulation. The lessons learned and those undergoing continued study likely have broad implications for understanding viral infections' immunologic and inflammatory consequences beyond coronaviruses.

Is there an Increase in Total Hip Arthroplasty Due to Osteonecrosis of Femoral Head After Covid-19 Pandemic?: A Retrospective Study Among Patients in Central Karnataka, India

Introduction

Coronavirus disease 2019 (COVID-19) infection or corticosteroid usage during the COVID-19 pandemic as risk factors for avascular necrosis (AVN) of the femoral head (osteonecrosis of the femoral head/femoral head AVN [FHAVN]), as well as its link to clinical and radiological outcomes, are poorly understood. Osteonecrosis, which results from a disruption in vascular supply to the femoral head, is a prevalent cause of hip joint deterioration and one of the most common reasons for total hip arthroplasty (THA)/total hip replacement in India and other Asian countries. This study will aid in understanding the condition's epidemiology and statistically determining the risk of disease related with pandemic exposure.

Materials and Methods

This is a retrospective study of 100 hips diagnosed with osteonecrosis/osteoarthritis of the femoral head that underwent THA at a tertiary care center before and after the COVID-19 pandemic between February 2014 and February 2024.

Results

Late stages of FHAVN, when the diagnosis requiring THA, following the pandemic have increased exponentially. It has also switched from affecting the middle-aged to the younger age groups. Furthermore, the bilaterality necessitating THA has increased considerably. There is a clear shift in the presentation of this disabling illness, as well as the need for THA, which otherwise is rarely carried out on younger people. Furthermore, data on how much corticosteroids were used in the treatment is disturbingly scant, and how it may have contributed to this ailment in India is still questionable.

Conclusion

The COVID-19 pandemic could be the most serious threat, causing late-stages FHAVN (stages 3 and 4 of the Ficat and Arlet classification), in an accelerated manner, necessitating THA and overburdening existing medical care.

Incidence and Outcomes of Vertebral Compression Fracture Among Patients Infected with COVID-19

Background/Objectives: Early studies have suggested that the SARS-CoV-2 virus has a deleterious effect on bone mineral density and may increase the risk of pathological fractures. This study characterized vertebral compression fractures in patients with and without a prior diagnosis of COVID-19. Methods: Using a nationwide claims database, this retrospective study used ICD-10 billing codes to identify patients with a diagnosis of vertebral compression fracture from January 2020 to April 2022. Two cohorts were created based on whether the patients had a concurrent diagnosis of COVID-19. Patient demographics, comorbidities, and outcome measures were characterized by descriptive analysis. Results: In total, 413,425 patients met the inclusion criteria. Among them, a total of 23,148 patients (5.60%) had a diagnosis of COVID-19 at the time of their compression fracture. Among the COVID-19 patients, the incidences of vertebral compression fracture were 0.42% in 2020 and 0.33% in 2021, in comparison to the historical average yearly incidence of 0.17% across all patients. The patients with COVID-19 at the time of compression fracture diagnosis had a higher rate of vitamin D deficiency (OR: 1.25) and a lower rate of routine healing (OR: 0.61). The patients without COVID-19 were more likely to be osteoporotic (OR: 0.88), experience additional compression fractures (OR: 0.38), and have kyphoplasty or vertebroplasty (OR: 0.73). Conclusions: Despite lower rates of osteoporosis, patients with a concomitant COVID-19 diagnosis exhibited a higher incidence of compression fractures. Although more research is needed, these results support increasing bone health surveillance in patients with a history of COVID-19 infection.

Syndrome of inappropriate antidiuresis/hyponatremia in COVID-19

Hyponatremia is the most frequent electrolyte alteration among hospitalized patients and it has been reported in 20-40% of patients with SARS-CoV-2 (COVID-19) infection. Multiple causes of hyponatremia have been hypothesized in these patients. The syndrome of inappropriate antidiuresis (SIAD) has been considered one of the main reasons leading to hyponatremia in this condition. SIAD can be secondary to cytokines release, in particular IL-6. Positive pressure ventilation can be another cause of hyponatremia due to SIAD. Other possible etiologies of hyponatremia in COVID-19 patients can be related to secondary hypocortisolism, nausea, vomiting, heart and kidney damage. Similar to many other clinical conditions, there is strong evidence that hyponatremia is associated with a worse prognosis also in patients with COVID-19 infection. In particular, hyponatremia has been identified as an independent risk of ICU transfer, need of non-invasive ventilation and death. Hyponatremia in COVID-19 patients is in principle acute and symptomatic and should be treated as such, according to the published guidelines. Therefore, patients should be initially treated with i.v. hypertonic saline (3% NaCl) infusion and serum [Na+] should be frequently monitored, in order to remain within a safe rate of correction. There is evidence showing that serum [Na+] correction is associated with a better outcome in different pathologies, including COVID-19 infection.

A Pilot Case-Control Study of Muscle and Bone Health Status in Patients Who Have Recovered From COVID-19 Infection

BACKGROUND

Coronavirus disease 2019 (COVID-19), resulting from the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), affects various bodily systems, including the heart, central nervous system, muscles, and bones, all of which harbor angiotensin-converting enzyme 2 (ACE-2) receptors similar to those in the respiratory system. However, research on the inflammatory response and its impact on systems such as the musculoskeletal one is relatively scarce. Our study aimed to investigate bone and muscle metrics as well as handgrip strength in individuals who recuperated from COVID-19 infection.

METHODS

The pilot case-control study was conducted from June 2021 to September 2022, involving 25 adult patients aged 18-60 years who had recovered from COVID-19 infection, alongside 25 age- and gender-matched controls. Participants were recruited from a tertiary care hospital in Pune, and data on demographics, anthropometry, medical history, diet, and physical activity were recorded using standardized questionnaires. Dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) were used to assess bone and muscle parameters, whereas a handgrip dynamometer was used to measure muscle strength. Statistical analysis was performed using SPSS version 26.0 (IBM Corp., Armonk, NY).

RESULTS

Post-COVID-19 recovered female patients exhibited lower lean mass, muscle density, and handgrip strength, alongside higher body fat levels.

CONCLUSION

Lean mass, muscle density, and handgrip strength were lower and body fat was higher in post-COVID-19 recovered females, thus indicating the need to focus on improving the musculoskeletal health of females post-hospitalization due to a serious illness such as COVID-19 infection.

Bone Mineral Density, Bone Biomarkers, and Joints in Acute, Post, and Long COVID-19: A Systematic Review

SARS-CoV-2 is highly transmissible and affects the respiratory system. People with COVID-19 are at higher risk of physical and mental health conditions, which could impact bone health. The aim of this review was to explore the effects of COVID-19 on BMD, BTMs, and joints. An electronic search of the PubMed, Web of Science, Scopus, and Ovid Medline databases considered studies published between 1 January 2020 and 1 November 2023. The search was limited to English, original studies in adult humans. The title and abstract of the identified papers were screened, followed by a full-text review using inclusion and exclusion criteria. The data extracted included the study and participant characteristics, BTMs, BMD, and joint abnormalities. The Newcastle-Ottawa scale quality assessment tool was used to assess the risk of bias. Five studies involving 305 out of 495 infected individuals observed a reduced BMD after COVID-19, with the most significant reduction occurring a year later. Both bone resorption and bone formation markers decreased, while regulatory markers showed higher levels in infected patients. COVID-19 may harm bone health by increasing bone regulatory markers and reducing bone formation and absorption, leading to a lower BMD. Elderly, frail, and osteopenic or osteoporotic individuals are at higher risk and should be regularly monitored for bone loss if they have long COVID.

Serum proinflammatory cytokines, receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG) and RANKL/OPG ratio in mild and severe COVID-19

INTRODUCTION

Osteoporosis, a systemic skeletal disease, is characterized by a quantitative and qualitative, and progressive decrease in bone mass, which is related to inflammation. Since a cytokine storm is triggered in Coronavirus disease 2019 (COVID-19), this study aims to evaluate pro-inflammatory cytokines (TNF-α, IL-1β), Receptor activator of nuclear factor-κB ligand (RANKL)/serum osteoprotegerin (OPG) ratio, and their relationship in mild and severe COVID-19.

METHODS

This study was performed on 48 adult patients (18 mild, 18 severe COVID-19, and 12 healthy subjects as a control group). Serum OPG, RANKL, TNF-α, IL-1β, 25-OH vitamin D, and ALKp were measured by ELISA and colorimetric assay.

RESULTS

COVID-19 patients had a significant increase in RANKL, and RANKL/OPG in mild and severe form (p < 0.001) while OPG decreased significantly in severe form compared to healthy controls (p < 0.05). Inflammatory cytokines (TNF-α and IL-1β) increased in both groups of patients whereas Alkaline phosphatase (ALKp) increased only in severe patients (p < 0.001). Both groups had 25-OH vitamin D deficiency in comparison to healthy ones (p < 0.001). Pearson's correlation coefficient was performed to determine the relationship between RANKL, OPG, ALKp, and 25-OH vitamin D with TNF-α and IL-1β in mild and severe COVID-19, which was statistically significant.

CONCLUSION

Serum RANKL/OPG ratio was elevated in COVID-19 individuals and is assumed to be a risk factor for BMD reduction and osteoporosis in these patients. Correlations between IL-1β, TNF-α, ALKp, 25-OH vitamin D, OPG, RANKL, and RANKL/OPG ratio offered the potential role of these proinflammatory markers in the mechanism of osteoporosis in COVID-19 patients.

Novel insights into vancomycin-loaded calcium sulfate and negative pressure wound therapy in preventing infections in open fractures

BACKGROUND

Open fractures are challenging due to susceptibility to Staphylococcus aureus infections. This study examines the impact of Vancomycin-Loaded Calcium Sulfate (VLCS) and negative pressure wound therapy (NPWT) on macrophage behavior in enhancing healing and infection resistance. Both VLCS and NPWT were evaluated individually and in combination to determine their effects on macrophage polarization and infection resistance in open fractures.

METHODS

Through single-cell RNA sequencing, genomic expressions in macrophages from open fracture patients treated with VLCS and NPWT were compared to a control group. The analysis focused on MBD2 gene changes related to macrophage polarization.

RESULTS

Remarkable modifications in MBD2 expression in the treatment group indicate a shift towards M2 macrophage polarization. Additionally, the combined treatment group exhibited greater improvements in infection resistance and healing compared to the individual treatments. This shift suggests a healing-promoting atmosphere with improved infection resilience.

CONCLUSIONS

VLCS and NPWT demonstrate the ability to alter macrophage behavior toward M2 polarization, which is crucial for infection prevention in open fractures. The synergistic effect of their combined use shows even greater promise in enhancing outcomes in orthopedic trauma care.

Exploring the Pathophysiology of Long COVID: The Central Role of Low-Grade Inflammation and Multisystem Involvement

Long COVID (LC), also referred to as Post COVID-19 Condition, Post-Acute Sequelae of SARS-CoV-2 Infection (PASC), and other terms, represents a complex multisystem disease persisting after the acute phase of COVID-19. Characterized by a myriad of symptoms across different organ systems, LC presents significant diagnostic and management challenges. Central to the disorder is the role of low-grade inflammation, a non-classical inflammatory response that contributes to the chronicity and diversity of symptoms observed. This review explores the pathophysiological underpinnings of LC, emphasizing the importance of low-grade inflammation as a core component. By delineating the pathogenetic relationships and clinical manifestations of LC, this article highlights the necessity for an integrated approach that employs both personalized medicine and standardized protocols aimed at mitigating long-term consequences. The insights gained not only enhance our understanding of LC but also inform the development of therapeutic strategies that could be applicable to other chronic conditions with similar pathophysiological features.

The Long-Term Effect of COVID-19 Infection on Body Composition

BACKGROUND

The effect of COVID-19 infection versus the indirect effect of the pandemic on body composition remains unclear. This study investigates the long-term changes in body composition in COVID-19 survivors compared to a contemporary control group.

METHOD

This is a prospective study involving adults who underwent a pre-pandemic whole-body DXA scan (DXA#1) between 2017 and 2019. Participants were asked to return for a repeat whole-body DXA scan (DXA#2) after the pandemic. Detailed data were collected including their medical and COVID-19 history. Inflammation markers and fasting lipids were measured. For those participants who experienced a COVID-19 infection between the two DXAs, DXA#2 was acquired at least one year after COVID-19 infection.

RESULTS

Overall, 160 adults were enrolled; 32.5% females, 51.8% non-white, with mean age of 43.2 years. Half (n = 80) of the participants experienced a COVID-19 infection between their two DXA scans (COVID-19+ group), and the other half had never had COVID-19. COVID-19-negative participants displayed an increase in annualized trunk fat (g) [922.5 vs. 159.7; p = 0.01], total fat (g) [1564.3 vs. 199.9; p = 0.2], and LBM (g) [974.9 vs. -64.5; p = 0.0002] when compared to the COVID-19+ group. However, among the COVID-19+ group, no differences were seen in annualized trunk fat, total fat mass, or LBM between those with PASC and without (p > 0.05).

CONCLUSION

During the pandemic, both the COVID-19 survivors and the COVID-19-negative group exhibited increases in weight, total fat, and trunk fat, likely associated with pandemic-linked lifestyle modifications. However, only COVID-19 survivors displayed a decline in lean body mass over the same period, regardless of PASC symptoms.

The abortive SARS-CoV-2 infection of osteoclast precursors promotes their differentiation into osteoclasts

The Coronavirus Disease 2019 (COVID-19) pandemic has resulted in the loss of millions of lives, although a majority of those infected have managed to survive. Consequently, a set of outcomes, identified as long COVID, is now emerging. While the primary target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the respiratory system, the impact of COVID-19 extends to various body parts, including the bone. This study aims to investigate the effects of acute SARS-CoV-2 infection on osteoclastogenesis, utilizing both ancestral and Omicron viral strains. Monocyte-derived macrophages, which serve as precursors to osteoclasts, were exposed to both viral variants. However, the infection proved abortive, even though ACE2 receptor expression increased postinfection, with no significant impact on cellular viability and redox balance. Both SARS-CoV-2 strains heightened osteoclast formation in a dose-dependent manner, as well as CD51/61 expression and bone resorptive ability. Notably, SARS-CoV-2 induced early pro-inflammatory M1 macrophage polarization, shifting toward an M2-like profile. Osteoclastogenesis-related genes (RANK, NFATc1, DC-STAMP, MMP9) were upregulated, and surprisingly, SARS-CoV-2 variants promoted RANKL-independent osteoclast formation. This thorough investigation illuminates the intricate interplay between SARS-CoV-2 and osteoclast precursors, suggesting potential implications for bone homeostasis and opening new avenues for therapeutic exploration in COVID-19.

Multicentric reticulohistiocytosis post-COVID-19: a case report

Background

Multicentric reticulohistiocytosis (MRH) stands as a rare and challenging systemic granulomatous disease characterized by its predilection for skin and joint involvement, confounding clinicians with its infrequent presentation and systemic manifestations.

Case Description

This compelling case presentation unravels the intricate complexity of MRH, exemplifying its unique clinical course. Following mild upper respiratory coronavirus disease 2019 (COVID-19) symptoms, the patient manifested purplish-pink papular lesions on both the skin and mucosa, accompanied by debilitating arthralgias. A diagnostic skin biopsy, a pivotal tool in MRH diagnosis, confirmed the presence of this granulomatous disorder, underlining its systemic impact. Strategic therapeutic intervention involving a combination of steroids and methotrexate demonstrated remarkable efficacy, culminating in the resolution of symptoms within 3-month. The absence of malignancy upon thorough screening further amplifies the perplexing nature of MRH.

Conclusions

This seminal case not only bridges the realms of rare systemic disorders but also marks the first known instance of MRH emerging post-COVID-19. It underscores the imperative consideration of MRH in analogous scenarios and provides invaluable insights into the nuanced interplay of MRH symptoms, diagnosis, and therapeutic strategies following viral triggers. This comprehensive exploration enriches our scientific understanding, offering nuanced perspectives on the manifestations and intricate dynamics of MRH in the context of post-viral sequelae.

SARS-CoV-2 and its Multifaceted Impact on Bone Health: Mechanisms and Clinical Evidence

PURPOSE OF REVIEW

SARS-CoV-2 infection, the culprit of the COVID-19 pandemic, has been associated with significant long-term effects on various organ systems, including bone health. This review explores the current understanding of the impacts of SARS-CoV-2 infection on bone health and its potential long-term consequences.

RECENT FINDINGS

As part of the post-acute sequelae of SARS-CoV-2 infection, bone health changes are affected by COVID-19 both directly and indirectly, with multiple potential mechanisms and risk factors involved. In vitro and preclinical studies suggest that SARS-CoV-2 may directly infect bone marrow cells, leading to alterations in bone structure and osteoclast numbers. The virus can also trigger a robust inflammatory response, often referred to as a "cytokine storm", which can stimulate osteoclast activity and contribute to bone loss. Clinical evidence suggests that SARS-CoV-2 may lead to hypocalcemia, altered bone turnover markers, and a high prevalence of vertebral fractures. Furthermore, disease severity has been correlated with a decrease in bone mineral density. Indirect effects of SARS-CoV-2 on bone health, mediated through muscle weakness, mechanical unloading, nutritional deficiencies, and corticosteroid use, also contribute to the long-term consequences. The interplay of concurrent conditions such as diabetes, obesity, and kidney dysfunction with SARS-CoV-2 infection further complicates the disease's impact on bone health. SARS-CoV-2 infection directly and indirectly affects bone health, leading to potential long-term consequences. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

COVID-19 and Bone Loss: A Review of Risk Factors, Mechanisms, and Future Directions

PURPOSE OF REVIEW

SARS-CoV-2 drove the catastrophic global phenomenon of the COVID-19 pandemic resulting in a multitude of systemic health issues, including bone loss. The purpose of this review is to summarize recent findings related to bone loss and potential mechanisms.

RECENT FINDINGS

The early clinical evidence indicates an increase in vertebral fractures, hypocalcemia, vitamin D deficiencies, and a loss in BMD among COVID-19 patients. Additionally, lower BMD is associated with more severe SARS-CoV-2 infection. Preclinical models have shown bone loss and increased osteoclastogenesis. The bone loss associated with SARS-CoV-2 infection could be the result of many factors that directly affect the bone such as higher inflammation, activation of the NLRP3 inflammasome, recruitment of Th17 cells, the hypoxic environment, and changes in RANKL/OPG signaling. Additionally, SARS-CoV-2 infection can exert indirect effects on the skeleton, as mechanical unloading may occur with severe disease (e.g., bed rest) or with BMI loss and muscle wasting that has also been shown to occur with SARS-CoV-2 infection. Muscle wasting can also cause systemic issues that may influence the bone. Medications used to treat SARS-CoV-2 infection also have a negative effect on the bone. Lastly, SARS-CoV-2 infection may also worsen conditions such as diabetes and negatively affect kidney function, all of which could contribute to bone loss and increased fracture risk. SARS-CoV-2 can negatively affect the bone through multiple direct and indirect mechanisms. Future work will be needed to determine what patient populations are at risk of COVID-19-related increases in fracture risk, the mechanisms behind bone loss, and therapeutic options. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

The Influence of Obesity on Bone Health in Post-COVID-19 Recovery- Single-Center Experience

Introduction

The ongoing repercussions of the COVID-19 pandemic include potentially deleterious impacts on bone health.

Aim

This research aimed to ascertain the effects of COVID-19 on the bone health of obese and non-obese Indian individuals.

Methods

We executed a case-control study enrolling individuals who recovered from COVID-19. Participants were stratified into obese and non-obese groups based on their BMI. Comprehensive assessments encompassed anthropometric evaluations, laboratory tests, and bone mineral density (BMD) measurements using dual-energy X-ray absorptiometry (DEXA).

Results

From April to July 2022, we enrolled obese (n = 27, mean BMI = 30.54 ± 4.51 kg/m 2) and non-obese (n = 23, mean BMI = 21.97 ± 2.20 kg/m 2) individuals. The cohort's average age was 36.08 ± 15.81 years, with a male-to-female ratio of 1.6:1. There was a difference in BMD, especially at the total hip, between the two groups. BMD at the spine (L1-L4), the neck of the femur, and ultra-distal radius were consistent across both groups. Weight exhibited a significant positive correlation with BMD at L1-L4 (r = 0.40, p = 0.003) and the left femur total (r = 0.27, p = 0.001). Haemoglobin levels were lower in the obese group compared to their non-obese counterparts (12.3 ± 2.0 vs 13.6 ± 1.9, p = 0.01). Multivariate analysis underscored weight as a crucial predictor for BMD at the spine (L1-L4, p = 0.003) and total hip (p = 0.001).

Conclusion

Even with advanced age, obese post-COVID-19 individuals demonstrate a higher bone mineral density (BMD) at the hip than non-obese subjects.

A review: Mechanism and prospect of gastrodin in prevention and treatment of T2DM and COVID-19

Gastrodin is an extract from the dried tuber of the Chinese herb Gastrodia elata (Tian ma), with anti-inflammatory, antioxidant, and antiviral properties. Recent studies have shown that, compared to commonly used diabetes drugs, gastrodin has antidiabetic effects in multiple ways, with characteristics of low cost, high safety, less side effects, protection of β-cell function, relieving insulin resistance and alleviating multiple complications. In addition, it is confirmed that gastrodin can protect the function of lung and other organs, enhance antiviral activity via upregulating the type I interferon (IFN-I), and inhibit angiotensin II (AngII), a key factor in "cytokine storm" caused by COVID-19. Therefore, we reviewed the effect and mechanism of gastrodin on type 2 diabetes mellitus (T2DM), and speculated other potential mechanisms of gastrodin in alleviating insulin resistance from insulin signal pathway, inflammation, mitochondrial and endoplasmic reticulum and its potential in the prevention and treatment of COVID-19. We hope to provide new direction and treatment strategy for basic research and clinical work: gastrodin is considered as a drug for the prevention and treatment of diabetes and COVID-19.

Long COVID-19 Pathophysiology: What Do We Know So Far?

Long COVID-19 is a recognized entity that affects millions of people worldwide. Its broad clinical symptoms include thrombotic events, brain fog, myocarditis, shortness of breath, fatigue, muscle pains, and others. Due to the binding of the virus with ACE-2 receptors, expressed in many organs, it can potentially affect any system; however, it most often affects the cardiovascular, central nervous, respiratory, and immune systems. Age, high body mass index, female sex, previous hospitalization, and smoking are some of its risk factors. Despite great efforts to define its pathophysiology, gaps remain to be explained. The main mechanisms described in the literature involve viral persistence, hypercoagulopathy, immune dysregulation, autoimmunity, hyperinflammation, or a combination of these. The exact mechanisms may differ from system to system, but some share the same pathways. This review aims to describe the most prevalent pathophysiological pathways explaining this syndrome.

The Influence of Combined Sterilization Factors on the Structural and Functional Characteristics of Bone Implants

The results of a comprehensive study of the patterns of structural and functional changes in bone tissue samples after combined (ozone + radiation) sterilization are presented. The study used a different approach to the sterilization process with selective ozone or radiation exposure and an integral, combined one, based on a combined ozone-oxygen treatment of bone samples at the first stage and radiation at the second. The methods of IR spectroscopy, scanning electron microscopy with a prefix for elemental analysis, atomic force microscopy, and mechanical analysis with determination of elastic-plastic properties (Vickers microhardness index) were used in the work. It is shown that the ozone exposure used at the first stage of the combined sterilization process of bone implants does not lead to negative consequences with respect to their properties and characteristics. The results obtained serve as a scientific and methodological basis for the further improvement and optimization of sterilization technologies (including combined). They also offer a comprehensive justification of the parameters of sterilization regimes to ensure the safety of using bone implants during reconstructive operations, minimizing structural and functional changes in bone matter, and creating effective health-saving technologies and the possibility of using them for various biomedical applications.

Development of nanozymes for promising alleviation of COVID-19-associated arthritis

The COVID-19 pandemic caused by SARS-CoV-2 has been identified as a culprit in the development of a variety of disorders, including arthritis. Although the emergence of arthritis following SARS-CoV-2 infection may not be immediately discernible, its underlying pathogenesis is likely to involve a complex interplay of infections, oxidative stress, immune responses, abnormal production of inflammatory factors, cellular destruction, etc. Fortunately, recent advancements in nanozymes with enzyme-like activities have shown potent antiviral effects and the ability to inhibit oxidative stress and cytokines and provide immunotherapeutic effects while also safeguarding diverse cell populations. These adaptable nanozymes have already exhibited efficacy in treating common types of arthritis, and their distinctive synergistic therapeutic effects offer great potential in the fight against arthritis associated with COVID-19. In this comprehensive review, we explore the potential of nanozymes in alleviating arthritis following SARS-CoV-2 infection by neutralizing the underlying factors associated with the disease. We also provide a detailed analysis of the common therapeutic pathways employed by these nanozymes and offer insights into how they can be further optimized to effectively address COVID-19-associated arthritis.

The Potential Value of Probiotics after Dental Implant Placement

Dental implantation is currently the optimal solution for tooth loss. However, the health and stability of dental implants have emerged as global public health concerns. Dental implant placement, healing of the surgical site, osseointegration, stability of bone tissues, and prevention of peri-implant diseases are challenges faced in achieving the long-term health and stability of implants. These have been ongoing concerns in the field of oral implantation. Probiotics, as beneficial microorganisms, play a significant role in the body by inhibiting pathogens, promoting bone tissue homeostasis, and facilitating tissue regeneration, modulating immune-inflammatory levels. This review explores the potential of probiotics in addressing post-implantation challenges. We summarize the existing research regarding the importance of probiotics in managing dental implant health and advocate for further research into their potential applications.

Osteoporosis and Covid-19: Detected similarities in bone lacunar-level alterations via combined AI and advanced synchrotron testing

While advanced imaging strategies have improved the diagnosis of bone-related pathologies, early signs of bone alterations remain difficult to detect. The Covid-19 pandemic has brought attention to the need for a better understanding of bone micro-scale toughening and weakening phenomena. This study used an artificial intelligence-based tool to automatically investigate and validate four clinical hypotheses by examining osteocyte lacunae on a large scale with synchrotron image-guided failure assessment. The findings indicate that trabecular bone features exhibit intrinsic variability related to external loading, micro-scale bone characteristics affect fracture initiation and propagation, osteoporosis signs can be detected at the micro-scale through changes in osteocyte lacunar features, and Covid-19 worsens micro-scale porosities in a statistically significant manner similar to the osteoporotic condition. Incorporating these findings with existing clinical and diagnostic tools could prevent micro-scale damages from progressing into critical fractures.

Causal relationships between COVID-19 and osteoporosis: a two-sample Mendelian randomization study in European population

Introduction

The causal relationship between Coronavirus disease 2019 (COVID-19) and osteoporosis (OP) remains uncertain. We aimed to assess the effect of COVID-19 severity (severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, COVID-19 hospitalization, and severe COVID-19) on OP by a two-sample Mendelian randomization (MR) study.

Methods

We conducted a two-sample MR analysis using publicly available genome-wide association study (GWAS) data. Inverse variance weighting (IVW) was used as the main analysis method. Four complementary methods were used for our MR analysis, which included the MR-Egger regression method, the weighted median method, the simple mode method, and the weighted mode method. We utilized the MR-Egger intercept test and MR pleiotropy residual sum and outlier (MR-PRESSO) global test to identify the presence of horizontal pleiotropy. Cochran's Q statistics were employed to assess the existence of instrument heterogeneity. We conducted a sensitivity analysis using the leave-one-out method.

Results

The primary results of IVW showed that COVID-19 severity was not statistically related to OP (SARS-CoV-2 infection: OR (95% CI) = 0.998 (0.995 ~ 1.001), p = 0.201403; COVID-19 hospitalization: OR (95% CI) =1.001 (0.999 ~ 1.003), p = 0.504735; severe COVID-19: OR (95% CI) = 1.000 (0.998 ~ 1.001), p = 0.965383). In addition, the MR-Egger regression, weighted median, simple mode and weighted mode methods showed consistent results. The results were robust under all sensitivity analyses.

Conclusion

The results of the MR analysis provide preliminary evidence that a genetic causal link between the severity of COVID-19 and OP may be absent.

Identification of 3 key genes as novel diagnostic and therapeutic targets for OA and COVID-19

Background

Corona Virus Disease 2019 (COVID-19) and Osteoarthritis (OA) are diseases that seriously affect the physical and mental health and life quality of patients, particularly elderly patients. However, the association between COVID-19 and osteoarthritis at the genetic level has not been investigated. This study is intended to analyze the pathogenesis shared by OA and COVID-19 and to identify drugs that could be used to treat SARS-CoV-2-infected OA patients.

Methods

The four datasets of OA and COVID-19 (GSE114007, GSE55235, GSE147507, and GSE17111) used for the analysis in this paper were obtained from the GEO database. Common genes of OA and COVID-19 were identified through Weighted Gene Co-Expression Network Analysis (WGCNA) and differential gene expression analysis. The least absolute shrinkage and selection operator (LASSO) algorithm was used to screen key genes, which were analyzed for expression patterns by single-cell analysis. Finally, drug prediction and molecular docking were carried out using the Drug Signatures Database (DSigDB) and AutoDockTools.

Results

Firstly, WGCNA identified a total of 26 genes common between OA and COVID-19, and functional analysis of the common genes revealed the common pathological processes and molecular changes between OA and COVID-19 are mainly related to immune dysfunction. In addition, we screened 3 key genes, DDIT3, MAFF, and PNRC1, and uncovered that key genes are possibly involved in the pathogenesis of OA and COVID-19 through high expression in neutrophils. Finally, we established a regulatory network of common genes between OA and COVID-19, and the free energy of binding estimation was used to identify suitable medicines for the treatment of OA patients infected with SARS-CoV-2.

Conclusion

In the present study, we succeeded in identifying 3 key genes, DDIT3, MAFF, and PNRC1, which are possibly involved in the development of both OA and COVID-19 and have high diagnostic value for OA and COVID-19. In addition, niclosamide, ciclopirox, and ticlopidine were found to be potentially useful for the treatment of OA patients infected with SARS-CoV-2.

Acute coronavirus infection triggers a TNF-dependent osteoporotic phenotype in mice

AIMS

Millions of people died during the COVID-19 pandemic, but the vast majority of infected individuals survived. Now, some consequences of the disease, known as long COVID, are been revealed. Although the respiratory system is the target of Sars-CoV-2, COVID-19 can influence other parts of the body, including bone. The aim of this work was to investigate the impact of acute coronavirus infection in bone metabolism.

MAIN METHODS

We evaluated RANKL/OPG levels in serum samples of patients with and without acute COVID-19. In vitro, the effects of coronavirus in osteoclasts and osteoblasts were investigated. In vivo, we evaluated the bone phenotype in a BSL2 mouse model of SARS-like disease induced by murine coronavirus (MHV-3).

KEY FINDINGS

Patients with acute COVID-19 presented decreased OPG and increased RANKL/OPG ratio in the serum versus healthy individuals. In vitro, MHV-3 infected macrophages and osteoclasts, increasing their differentiation and TNF release. Oppositely, osteoblasts were not infected. In vivo, MHV-3 lung infection triggered bone resorption in the femur of mice, increasing the number of osteoclasts at 3dpi and decreasing at 5dpi. Indeed, apoptotic-caspase-3⁺ cells have been detected in the femur after infection as well as viral RNA. RANKL/OPG ratio and TNF levels also increased in the femur after infection. Accordingly, the bone phenotype of TNFRp55^-/- mice infected with MHV-3 showed no signs of bone resorption or increase in the number of osteoclasts.

SIGNIFICANCE

Coronavirus induces an osteoporotic phenotype in mice dependent on TNF and on macrophage/osteoclast infection.

“Long COVID-19” and viral “fibromyalgia-ness”: Suggesting a mechanistic role for fascial myofibroblasts (Nineveh, the shadow is in the fascia)

The coronavirus pandemic has led to a wave of chronic disease cases; “Long COVID-19” is recognized as a new medical entity and resembles “fibromyalgia” which, likewise, lacks a clear mechanism. Observational studies indicate that up to 30%–40% of convalescent COVID-19 patients develop chronic widespread pain and fatigue and fulfill the 2016 diagnostic criteria for “fibromyalgia.” A recent study suggested a theoretical neuro-biomechanical model (coined “Fascial Armoring”) to help explain the pathogenesis and cellular pathway of fibromyalgia, pointing toward mechanical abnormalities in connective tissue and fascia, driven by contractile myo/fibroblasts and altered extracellular matrix remodeling with downstream corresponding neurophysiological aberrations. This may help explain several of fibromyalgia’s manifestations such as pain, distribution of pain, trigger points/tender spots, hyperalgesia, chronic fatigue, cardiovascular abnormalities, metabolic abnormalities, autonomic abnormalities, small fiber neuropathy, various psychosomatic symptoms, lack of obvious inflammation, and silent imaging investigations. Pro-inflammatory and pro-fibrotic pathways provide input into this mechanism via stimulation of proto/myofibroblasts. In this hypothesis and theory paper the theoretical model of Fascial Armoring is presented to help explain the pathogenesis and manifestations of “long COVID-19” as a disease of immuno-rheumo-psycho-neurology. The model is also used to make testable experimental predictions on investigations and predict risk and relieving factors.

Musculoskeletal involvement: COVID-19 and post COVID 19

The worldwide pandemic of coronavirus disease 2019 (COVID-19) was known to predominantly affect the lungs, but it was realized that COVID-19 had a large variety of clinical involvement. Cardiovascular, gastrointestinal, neurological, and musculoskeletal systems are involved by direct or indirect mechanisms with various manifestations. The musculoskeletal involvement can manifest during COVID-19 infection, due to medications used for the treatment of COVID-19, and in the post/long COVID-19 syndrome. The major symptoms are fatigue, myalgia/arthralgia, back pain, low back pain, and chest pain. During the last two years, musculoskeletal involvement increased, but no clear consensus was obtained about the pathogenesis. However, there is valuable data that supports the hypothesis of angiotensinconverting enzyme 2, inflammation, hypoxia, and muscle catabolism. Additionally, medications that were used for treatment also have musculoskeletal adverse effects, such as corticosteroid-induced myopathy and osteoporosis. Therefore, while deciding the drugs, priorities and benefits should be taken into consideration. Symptoms that begin three months from the onset of the COVID-19 infection, continue for at least two months, and cannot be explained by another diagnosis is accepted as post/long COVID-19 syndrome. Prior symptoms may persist and fluctuate, or new symptoms may manifest. In addition, there must be at least one symptom of infection. Most common musculoskeletal symptoms are myalgia, arthralgia, fatigue, back pain, muscle weakness, sarcopenia, impaired exercise capacity, and physical performance. In addition, the female sex, obesity, elderly patients, hospitalization, prolonged immobility, having mechanical ventilation, not having vaccination, and comorbid disorders can be accepted as clinical predictors for post/long COVID-19 syndrome. Musculoskeletal pain is also a major problem and tends to be in chronic form. There is no consensus on the mechanism, but inflammation and angiotensin-converting enzyme 2 seem to play an important role. Localized and generalized pain may occur after COVID-19, and general pain is at least as common as localized pain. An accurate diagnosis allows physicians to initiate pain management and proper rehabilitation programs.