Efficacy of romosozumab in patients with osteoporosis on maintenance hemodialysis in Japan; an observational study

The Relationship between Sclerostin and Kidney Transplantation Mineral Bone Disorders: A Molecule of Controversies

Kidney transplantation is the most effective treatment option for most patients with end-stage kidney disease due to reduced mortality, decreased cardiovascular events and increased quality of life compared to patients treated with dialysis. However, kidney transplantation is not devoid of both acute and chronic complications including mineral bone disorders (MBD) which are already present in patients with chronic kidney disease (CKD) before kidney transplantation. The natural history of MBD after kidney transplantation is variable and new markers are needed to define MBD after kidney transplantation. One of these promising molecules is sclerostin. The main action of sclerostin is to inhibit bone formation and mineralization by blocking osteoblast differentiation and function. In kidney transplant recipients (KTRs), various studies have shown that sclerostin is associated with graft function, bone parameters, vascular calcification, and arterial stiffness although non-uniformly. Furthermore, data for inhibition of sclerostin with monoclonal antibody romosozumab for treatment of osteoporosis is available for general population but not in KTRs which osteoporosis is highly prevalent. In this narrative review, we have summarized the studies investigating the change of sclerostin before and after kidney transplantation, the relationship between sclerostin and laboratory parameters, bone metabolism and vascular calcification in the context of kidney transplantation. We also pointed out the uncertainties, explained the causes of divergent findings and suggest further potential study topics regarding sclerostin in kidney transplantation.

Real-world effects, safety, and predictors of the effectiveness of romosozumab in primary and secondary osteoporosis: An observational study

Romosozumab is an anti-sclerostin antibody that increases bone formation and decreases bone resorption. It became available for patients at high risk of osteoporotic fractures in Japan in 2019. The aim of this study was to clarify the clinical effects, safety, and predictors of the effectiveness of 12 months of romosozumab therapy. The study had an observational pre-post design and included 460 patients. Romosozumab was administered at a dose of 210 mg subcutaneously every 4 weeks for 12 months. The incidence of new fractures, safety, and changes in bone mineral density (BMD) and bone turnover markers were recorded. New fractures occurred in 11 cases (3.0 %). Nine patients (2.0 %) experienced cardiovascular events, which were fatal in 3 (0.65 %). Percent changes in BMD at the spine and total hip at 12 months from baseline were +7.7 % and +1.8 %, respectively. Romosozumab had better effects in patients with good renal function, low spine BMD, and high TRACP-5b at baseline and low TRACP-5b or high P1NP after 1 month of treatment. The percent change in spine BMD at 12 months was significantly lower in patients transitioning from denosumab than in those not previously treated with other anti-osteoporosis agents. Romosozumab is considered to be relatively safe in patients with primary osteoporosis compared to those with secondary osteoporosis. Romosozumab resulted in larger increases in spine BMD in patients with primary osteoporosis who were not previously treated with other anti-osteoporosis therapies and those with low spine BMD at the start of treatment.

Effect of RANKL on Lower Depressive Symptoms In Hemodialysis Patients

Depression and osteoporosis are common diseases in dialysis patients. In addition, patients with osteoporosis are more susceptible to depression. Contrary to previous anti-osteoporosis agents, denosumab and romosozumab could be used in dialysis patients and have similar action mechanisms for blocking RANKL. RANKL causes bone resorption after binding RANKL, but binding with OPG leads to suppress of bone resorption. In recent mice study, inhibition of RANKL with denosumab improved depressive-like phenotype. Besides, it was found that OPG was associated with depression. Therefore, this study aimed to investigate the association of depressive symptoms with RANKL and OPG in hemodialysis patients. We conducted a cross-sectional study with a total of 172 hemodialysis patients. The participants were measured for plasma RANKL, OPG, MMP-2, and MMP-9 levels. Logistic regression analysis was performed to evaluate the effect of RANKL and OPG on the presence of depressive symptoms. The depressive symptoms were observed in 90 (52.3%) subjects. RANKL tertile 3 had negative association with BDI score (β - 4.527, 95% CI - 8.310 to - 0.743) in univariate analysis, and this association persisted even after multivariate adjustments (β - 5.603, 95% CI - 9.715 to -1.491) in linear regression. In logistic regression between RANKL tertiles and depressive symptoms, RANKL tertile 3 had significantly lower unadjusted OR (0.40, 95% CI 0.19-0.86), and multivariate-adjusted OR (0.31, 95% CI 0.12-0.82) for depressive symptoms. OPG was not significantly associated with depressive symptoms. Higher plasma RANKL concentrations were significantly associated with lower depressive symptoms in HD patients.Trial registration WHO registry, No. KCT0003281, date: January 12, 2017.

Romosozumab rescues impaired bone mass and strength in a murine model of diabetic kidney disease

As international incidence of diabetes and diabetes-driven comorbidities such as chronic kidney disease (CKD) continue to climb, interventions are needed that address the high-risk skeletal fragility of what is a complex disease state. Romosozumab (Romo) is an FDA-approved sclerostin inhibitor that has been shown to increase bone mineral density and decrease fracture rates in osteoporotic patients with mild to severe CKD, but its effect on diabetes-weakened bone is unknown. We aimed to test Romo's performance in a model of combined diabetes and CKD. 6-week old male C57BL/6 mice were randomly divided into control (CON) and disease model (STZ-Ad) groups, using a previously established streptozotocin- and adenine-diet-induced model. After 16 weeks of disease induction, both CON and STZ-Ad groups were subdivided into two treatment groups and given weekly subcutaneous injections of 100 μL vehicle (phosphorus buffered saline, PBS) or 10 mg/kg Romo. Mice were euthanized after 4 weeks of treatment via cardiac exsanguination and cervical dislocation. Hindlimb bones and L4 vertebrae were cleaned of soft tissue, wrapped in PBS-soaked gauze and stored at -20C. Right tibiae, femora, and L4s were scanned via microcomputed tomography; tibiae were then tested to failure in 4-pt bending while L4s were compression tested. Romo treatment significantly increased cortical and trabecular bone mass in both STZ-Ad and CON animals. These morphological improvements created corresponding increases in cortical bending strength and trabecular compression strength, with STZ-Ad treated mice surpassing vehicle CON mice in all trabecular mechanics measures. These results suggest that Romo retains its efficacy at increasing bone mass and strength in diabetic kidney disease.

A practical approach for anabolic treatment of bone fragility with romosozumab

BACKGROUND

Romosozumab, a fully humanized anti-sclerostin-antibody, is a bone-builder stimulating osteoblasts and inhibiting osteoclast by activation of the canonical Wnt-beta catenin signaling. This unique mechanism of action has the potential to address unmet needs in osteoporosis management.

METHODS

The multifaceted practical clinical issues related to romosozumab are discussed, especially focusing on the rationale of employing a sclerostin inhibitor to target bone fragility as first line or second line treatment in post-menopausal osteoporosis and in males at increased risk of fractures.

RESULTS

Four randomized clinical trials with several post-hoc analyses and more than ten observational studies have consistently demonstrated that romosozumab is effective in rapidly increasing bone mineral density (BMD) and decreasing risk of vertebral, non-vertebral and hip fractures in post-menopausal women at very-high risk of fractures. In male osteoporosis, only data on BMD are available. Noteworthy, romosozumab was shown to be more effective and rapid than teriparatide in improving BMD, bone structure and strength at the hip, especially in women already treated with anti-resorptive drugs. Interestingly, even if romosozumab displays best results in treatment-naïve patients, its favourable effects on BMD were observed even in women previously treated with teriparatide or denosumab, although to a lesser extent.

CONCLUSIONS

Based on the available evidence, romosozumab could be proposed as ideal drug in several clinical settings, such as non-fractured post-menopausal women at very-high risk of fractures, patients with recent hip fracture, patients non responder to bisphosphonates and short-term denosumab therapy.

Clinical Outcomes of Lateral Lumbar Interbody Fusion with Percutaneous Pedicle Screw for Dialysis-Related Spondyloarthropathy

Background: The usefulness and problems with lateral lumbar interbody fusion (LLIF) with a percutaneous pedicle screw (PPS) for dialysis-related spondyloarthropathy are not clear. Therefore, we investigated the usefulness and problems with LLIF with PPS in dialysis-related spondyloarthropathy. Methods: In total, 77 patients who underwent LLIF with PPS were divided into two groups: the dialysis-related spondyloarthropathy group ("Group D") consisted of 15 patients (10 males and 5 females) with a mean age of 70.4 years and a mean duration of hemodialysis of 10.8 years; and the lumbar degenerative disease group ("Group L") included 62 patients (31 males and 31 females) with a mean age of 71.0 years. The mean follow-up period was 4 years in Group D and 3 years 9 months in Group L. We compared surgical invasiveness (operative time, blood loss), perioperative complications, clinical outcomes (Improvement ratio of the JOA score), bone fusion rate, reoperation, sagittal alignment, and coronal imbalance between the two groups. Results: There were no significant differences in operative time, blood loss, or the improvement ratio of the JOA score, but dialysis-related spondyloarthropathy was observed in one patient with superficial infection, three patients with endplate failure, and one patient with restenosis due to cage subsidence. Conclusions: We consider LLIF with PPS for dialysis-related spondyloarthropathy to be an effective treatment option because its surgical invasiveness and clinical outcomes were comparable to those for cases of lumbar degenerative disease. However, as endplate failure due to bone fragility and a reduced bone fusion rate were observed in dialysis spondylolisthesis cases, we advise a careful selection of indications for indirect decompression as well as the application of suitable pre- and postoperative adjuvant therapies.

[Osteoporosis: treatment of high-risk patients]

Nowadays, different drugs are available for specific treatment of osteoporosis. On the one hand, antiresorptives (raloxifene, bisphosphonates, denosumab) and, on the other hand, bone anabolic drugs (teriparatide and romosozumab) can be used. For both bone anabolic agents, superiority over oral bisphosphonates in high-risk patients was shown in randomized comparative studies. High-risk patients represent a subgroup of osteoporosis patients requiring treatment with a particularly high fracture risk. The very high risk can be recognized by the clinical manifestation (hip or vertebral fracture), the very low T‑score and/or the clinical risk factors (exceeding the bone anabolic threshold of the DVO risk calculator). High-risk patients should be treated with bone anabolic drugs in the first line of treatment. Patients treated with antiresorptives, who develop a very high risk in the course of the disease should be escalated to bone anabolic compounds. Every bone anabolic treatment requires an antiresorptive follow-up treatment. Drug holidays are only possible in exceptional cases for high-risk patients.

[Diagnosis and treatment of osteoporosis in patients with chronic kidney disease : Joint guidelines of the Austrian Society for Bone and Mineral Research (ÖGKM), the Austrian Society of Physical and Rehabilitation Medicine (ÖGPMR) and the Austrian Society of Nephrology (ÖGN)]

DEFINITION AND EPIDEMIOLOGY

Chronic kidney disease (CKD): abnormalities of kidney structure or function, present for over 3 months. Staging of CKD is based on GFR and albuminuria (not graded). Osteoporosis: compromised bone strength (low bone mass, disturbance of microarchitecture) predisposing to fracture. By definition, osteoporosis is diagnosed if the bone mineral density T‑score is ≤ -2.5. Furthermore, osteoporosis is diagnosed if a low-trauma (inadequate trauma) fracture occurs, irrespective of the measured T‑score (not graded). The prevalence of osteoporosis, osteoporotic fractures and CKD is increasing worldwide (not graded). PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENT OF CHRONIC KIDNEY DISEASE-MINERAL AND BONE DISORDER (CKD-MBD): Definition of CKD-MBD: a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following: abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism; renal osteodystrophy; vascular calcification (not graded). Increased, normal or decreased bone turnover can be found in renal osteodystrophy (not graded). Depending on CKD stage, routine monitoring of calcium, phosphorus, alkaline phosphatase, PTH and 25-OH-vitamin D is recommended (2C). Recommendations for treatment of CKD-MBD: Avoid hypercalcemia (1C). In cases of hyperphosphatemia, lower phosphorus towards normal range (2C). Keep PTH within or slightly above normal range (2D). Vitamin D deficiency should be avoided and treated when diagnosed (1C).

DIAGNOSIS AND RISK STRATIFICATION OF OSTEOPOROSIS IN CKD

Densitometry (using dual X‑ray absorptiometry, DXA): low T‑score correlates with increased fracture risk across all stages of CKD (not graded). A decrease of the T‑score by 1 unit approximately doubles the risk for osteoporotic fracture (not graded). A T-score ≥ -2.5 does not exclude osteoporosis (not graded). Bone mineral density of the lumbar spine measured by DXA can be increased and therefore should not be used for the diagnosis or monitoring of osteoporosis in the presence of aortic calcification, osteophytes or vertebral fracture (not graded). FRAX can be used to aid fracture risk estimation in all stages of CKD (1C). Bone turnover markers can be measured in individual cases to monitor treatment (2D). Bone biopsy may be considered in individual cases, especially in patients with CKD G5 (eGFR < 15 ml/min/1.73 m2) or CKD 5D (dialysis).

SPECIFIC TREATMENT OF OSTEOPOROSIS IN PATIENTS WITH CKD

Hypocalcemia should be treated and serum calcium normalized before initiating osteoporosis therapy (1C). CKD G1-G2 (eGFR ≥ 60 ml/min/1.73 m2): treat osteoporosis as recommended for the general population (1A). CKD G3-G5D (eGFR < 60 ml/min/1.73 m2 to dialysis): treat CKD-MBD first before initiating osteoporosis treatment (2C). CKD G3 (eGFR 30-59 ml/min/1.73 m2) with PTH within normal limits and osteoporotic fracture and/or high fracture risk according to FRAX: treat osteoporosis as recommended for the general population (2B). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) with osteoporotic fracture (secondary prevention): Individualized treatment of osteoporosis is recommended (2C). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) and high fracture risk (e.g. FRAX score > 20% for a major osteoporotic fracture or > 5% for hip fracture) but without prevalent osteoporotic fracture (primary prevention): treatment of osteoporosis may be considered and initiated individually (2D). CKD G4-5D (eGFR < 30 ml/min/1.73 m2 to dialysis): Calcium should be measured 1-2 weeks after initiation of antiresorptive therapy (1C).

PHYSICAL MEDICINE AND REHABILITATION

Resistance training prioritizing major muscle groups thrice weekly (1B). Aerobic exercise training for 40 min four times per week (1B). Coordination and balance exercises thrice weekly (1B). Flexibility exercise 3-7 times per week (1B).

Romosozumab in osteoporosis: yesterday, today and tomorrow

Osteoporosis is a systemic bone disease characterized by low bone mass, microarchitectural deterioration, increased bone fragility, and fracture susceptibility. It commonly occurs in older people, especially postmenopausal women. As global ageing increases, osteoporosis has become a global burden. There are a number of medications available for the treatment of osteoporosis, categorized as anabolic and anti-resorptive. Unfortunately, there is no drugs which have dual influence on bone, while all drugs have limitations and adverse events. Some serious adverse events include jaw osteonecrosis and atypical femoral fracture. Recently, a novel medication has appeared that challenges this pattern. Romosozumab is a novel drug monoclonal antibody to sclerostin encoded by the SOST gene. It has been used in Japan since 2019 and has achieved promising results in treating osteoporosis. However, it is also accompanied by some controversy. While it promotes rapid bone growth, it may cause serious adverse events such as cardiovascular diseases. There has been scepticism about the drug since its inception. Therefore, the present review comprehensively covered romosozumab from its inception to its clinical application, from animal studies to human studies, and from safety to cost. We hope to provide a better understanding of romosozumab for its clinical application.

Pathophysiology of bone disease in chronic kidney disease: from basics to renal osteodystrophy and osteoporosis

Chronic kidney disease (CKD) is a highly prevalent disease that has become a public health problem. Progression of CKD is associated with serious complications, including the systemic CKD-mineral and bone disorder (CKD-MBD). Laboratory, bone and vascular abnormalities define this condition, and all have been independently related to cardiovascular disease and high mortality rates. The "old" cross-talk between kidney and bone (classically known as "renal osteodystrophies") has been recently expanded to the cardiovascular system, emphasizing the importance of the bone component of CKD-MBD. Moreover, a recently recognized higher susceptibility of patients with CKD to falls and bone fractures led to important paradigm changes in the new CKD-MBD guidelines. Evaluation of bone mineral density and the diagnosis of "osteoporosis" emerges in nephrology as a new possibility "if results will impact clinical decisions". Obviously, it is still reasonable to perform a bone biopsy if knowledge of the type of renal osteodystrophy will be clinically useful (low versus high turnover-bone disease). However, it is now considered that the inability to perform a bone biopsy may not justify withholding antiresorptive therapies to patients with high risk of fracture. This view adds to the effects of parathyroid hormone in CKD patients and the classical treatment of secondary hyperparathyroidism. The availability of new antiosteoporotic treatments bring the opportunity to come back to the basics, and the knowledge of new pathophysiological pathways [OPG/RANKL (LGR4); Wnt-ß-catenin pathway], also affected in CKD, offers great opportunities to further unravel the complex physiopathology of CKD-MBD and to improve outcomes.

Updates in the chronic kidney disease-mineral bone disorder show the role of osteocytic proteins, a potential mechanism of the bone-Vascular paradox, a therapeutic target, and a biomarker

The chronic kidney disease-mineral bone disorder (CKD-MBD) is a complex multi-component syndrome occurring during kidney disease and its progression. Here, we update progress in the components of the syndrome, and synthesize recent investigations, which suggest a potential mechanism of the bone-vascular paradox. The discovery that calcified arteries in chronic kidney disease inhibit bone remodeling lead to the identification of factors produced by the vasculature that inhibit the skeleton, thus providing a potential explanation for the bone-vascular paradox. Among the factors produced by calcifying arteries, sclerostin secretion is especially enlightening. Sclerostin is a potent inhibitor of bone remodeling and an osteocyte specific protein. Its production by the vasculature in chronic kidney disease identifies the key role of vascular cell osteoblastic/osteocytic transdifferentiation in vascular calcification and renal osteodystrophy. Subsequent studies showing that inhibition of sclerostin activity by a monoclonal antibody improved bone remodeling as expected, but stimulated vascular calcification, demonstrate that vascular sclerostin functions to brake the Wnt stimulation of the calcification milieu. Thus, the target of therapy in the chronic kidney disease-mineral bone disorder is not inhibition of sclerostin function, which would intensify vascular calcification. Rather, decreasing sclerostin production by decreasing the vascular osteoblastic/osteocytic transdifferentiation is the goal. This might decrease vascular calcification, decrease vascular stiffness, decrease cardiac hypertrophy, decrease sclerostin production, reduce serum sclerostin and improve skeletal remodeling. Thus, the therapeutic target of the chronic kidney disease-mineral bone disorder may be vascular osteoblastic transdifferentiation, and sclerostin levels may be a useful biomarker for the diagnosis of the chronic kidney disease-mineral bone disorder and the progress of its therapy.

One-Year Romosozumab Treatment Followed by One-Year Denosumab Treatment for Osteoporosis in Patients on Hemodialysis: An Observational Study

There is limited evidence on the use of romosozumab (ROMO) in the treatment of osteoporosis in patients on hemodialysis (HD); thus, we aimed to investigate this topic. This prospective, observational, single-center cohort study included 13 prior osteoporosis treatment-naïve patients on HD with osteoporosis. They first received ROMO once monthly for 12 months (210 mg; subcutaneously once every month). Thereafter, they received denosumab (DENO) for an additional 12 months (60 mg; subcutaneously once every 6 months). We examined the incidence of new fractures; treatment safety; and temporal changes in the bone mineral density (BMD), bone metabolism markers, and vascular calcification. No new cases of fractures were noted. The median one-year percentage changes (from the baseline) in the BMDs at the lumbar spine (LS), total hip (TH), and femoral neck (FN) were + 9.0%, + 2.5%, and + 4.7%, respectively. These changes were maintained for 24 months. The corresponding relative changes from the baseline to 24 months thereafter were + 14.9%, + 5.4%, and + 6.5%, respectively. The percentage changes in TH BMD and FN BMD were negatively correlated with baseline BMD. Coronary artery and thoracic aorta calcification scores increased slightly from baseline to 12 months thereafter. However, fatal events (cardiovascular disease-associated and all-cause deaths) did not occur during ROMO treatment. Effectiveness of ROMO was better in patients who had severe osteoporosis with low TH BMD, low FN BMD, and high tartrate-resistant acid phosphatase 5b level at ROMO initiation.

Clinical Utility of Romosozumab in the Management of Osteoporosis: Focus on Patient Selection and Perspectives

As one of the most potent osteoanabolic agents with a unique mechanism of action, romosozumab has high efficacy for osteoporosis treatment. It is a monoclonal antibody against sclerostin, a natural inhibitor of the Wnt signaling pathway, and by inhibiting sclerostin, activation of Wnt signaling occurs with a cascade of changes ultimately leading to bone mineral density (BMD) gains. Romosozumab stimulates bone modeling and has a dual effect of activating bone formation while inhibiting bone resorption. With this unique mechanism of action, treatment with romosozumab leads to a rapid and significant gain in BMD; these gains are higher than seen with bisphosphonates, denosumab, or parathyroid hormone (PTH) analogs. The FRAME and ARCH studies represent two pivotal trials demonstrating the efficacy of romosozumab in treating osteoporosis. Treatment with romosozumab should be followed by an antiresorptive agent, as this approach has demonstrated maintenance of or greater increases in BMD and reduced fracture risk even after finishing romosozumab treatment. As an osteoanabolic agent, romosozumab has shown superiority to alendronate in reducing fracture risk, increasing bone density, and potentially more rapid fracture risk reduction. Recent data have suggested that romosozumab prior to antiresorptive therapy may be the ideal treatment sequence, especially in high-risk patients and patients at imminent risk of fracture. Carrying a black box warning, romosozumab should be avoided in patients who have had myocardial infarction or stroke in the past year. Further studies are needed to clarify the increased cardiovascular risk attributed to this drug. Romosozumab has expanded our osteoporosis armamentarium and has enabled novel approaches, including "treat to target." Future studies are needed to evaluate the optimal use sequence and to assess its safety, especially in patients with cardiovascular risk factors.

Romosozumab successfully regulated progressive osteoporosis in a patient with autosomal dominant polycystic kidney disease undergoing hemodialysis

Osteoporosis is a crucial complication in patients with chronic kidney disease (CKD), similar to that in the general population. Although romosozumab, a monoclonal antibody targeting sclerostin, has been administered for patients with CKD, its clinical effectiveness in these patients, especially in patients on hemodialysis (HD), remains to be studied. Herein, we report the case of a 42-year-old man on HD who developed severe osteoporosis. Serum calcium levels were extremely high, bone metabolic markers were abnormal, and the patient had pathological fractures. The bone biopsy indicated a bone metabolism disorder and high bone turnover. We administered romosozumab once a month as an intervention for bone alteration. Through the 10-month usage, bone metabolic markers improved, and the decrease in bone mineral density was ameliorated. We hypothesized that romosozumab could be a therapeutic option for osteoporosis in patients undergoing HD, especially in those with bone mineralization disorders.

[Nephrological management and drug dosing in patients with rheumatic diseases and renal insufficiency]

BACKGROUND

In patients with inflammatory rheumatic diseases and renal insufficiency there are two challenges for physicians: to adapt the antirheumatic medication to the renal function and to carry out a nephroprotective treatment that prevents long-term deterioration of renal function and reduces the elevated cardiovascular risk.

METHODS

A literature search (in PubMed) was carried out and the current state of knowledge on nephroprotective treatment strategies and the treatment of rheumatic diseases in the presence of renal insufficiency was collated, evaluated and summarized.

RESULTS

Lifestyle interventions, especially the cessation of smoking and drug treatment strategies form the basis of nephroprotection including the control of diabetes mellitus with metformin, sodium glucose transporter 2 (SGLT2) inhibitors, glucagon-like peptide 1 (GLP1) analogues and control of hypertension with blockade of the renin-angiotensin-aldosterone system (RAAS), hyperlipidemia, hyperphosphatemia and metabolic acidosis. The SGLT2 inhibitors are also effective for nondiabetic nephropathy. The elevated cardiovascular risk is further reduced by effective control of inflammatory rheumatic activity. Numerous conventional disease modifying antirheumatic drugs, especially methotrexate and the Janus kinase (JAK) inhibitors baricitinib and filgotinib, must mostly be adapted to the renal function. In contrast, biologics can be given in standard doses with the exception of anakinra. The increased cardiovascular risk currently limits the use of tofacitinib in patients with renal insufficiency.

CONCLUSION

The antirheumatic medication should be modified and a complex nephroprotective treatment concept is mandatory in the management of patients with rheumatic disease and renal insufficiency, that in the best-case scenario can be guaranteed by a close interdisciplinary cooperation of rheumatologists and nephrologists.

Is Adynamic Bone Always a Disease? Lessons from Patients with Chronic Kidney Disease

Renal osteodystrophy (ROD) is a common complication of end-stage kidney disease that often starts early with loss of kidney function, and it is considered an integral part in management of patients with chronic kidney disease (CKD). Adynamic bone (ADB) is characterized by suppressed bone formation, low cellularity, and thin osteoid seams. There is accumulating evidence supporting increasing prevalence of ADB, particularly in early CKD. Contemporarily, it is not very clear whether it represents a true disease, an adaptive mechanism to prevent bone resorption, or just a transitional stage. Several co-players are incriminated in its pathogenesis, such as age, diabetes mellitus, malnutrition, uremic milieu, and iatrogenic factors. In the present review, we will discuss the up-to-date knowledge of the ADB and focus on its impact on bone health, fracture risk, vascular calcification, and long-term survival. Moreover, we will emphasize the proper preventive and management strategies of ADB that are pivotal issues in managing patients with CKD. It is still unclear whether ADB is always a pathologic condition or whether it can represent an adaptive process to suppress bone resorption and further bone loss. In this article, we tried to discuss this hard topic based on the available limited information in patients with CKD. More studies are needed to be able to clearly address this frequent ROD finding.

Management of osteoporosis in patients with chronic kidney disease

Patients with CKD have a 4-fivefold higher rate of fractures. The incidence of fractures increases with deterioration of kidney function. The process of skeletal changes in CKD patients is characterized by compromised bone strength because of deterioration of bone quantity and/or quality. The fractures lead to a deleterious effect on the quality of life and higher mortality in patients with CKD. The pathogenesis of bone loss and fracture is complex and multi-factorial. Renal osteodystrophy, uremic milieu, drugs, and systemic diseases that lead to renal failure all contribute to bone damage in CKD patients. There is no consensus on the optimal diagnostic method of compromised bone assessment in patients with CKD. Bone quantity and mass can be assessed by dual-energy x-ray absorptiometry (DXA) or quantitative computed tomography (QCT). Bone quality on the other side can be assessed by non-invasive methods such as trabecular bone score (TBS), high-resolution bone imaging methods, and invasive bone biopsy. Bone turnover markers can reflect bone remodeling, but some of them are retained by kidneys. Understanding the mechanism of bone loss is pivotal in preventing fracture in patients with CKD. Several non-pharmacological and therapeutic interventions have been reported to improve bone health. Controlling laboratory abnormalities of CKD-MBD is crucial. Anti-resorptive therapies are effective in improving BMD and reducing fracture risk, but there are uncertainties about safety and efficacy especially in advanced CKD patients. Accepting the prevalent of low bone turnover in patients with advanced CKD, the osteo-anabolics are possibly promising. Parathyroidectomy should be considered a last resort for intractable cases of renal hyperparathyroidism. There is a wide unacceptable gap in osteoporosis management in patients with CKD. This article is focusing on the updated management of CKD-MBD and osteoporosis in CKD patients. Chronic kidney disease deteriorates bone quality and quantity. The mechanism of bone loss mainly determines pharmacological treatment. DXA and QCT provide information about bone quantity, but assessing bone quality, by TBS, high-resolution bone imaging, invasive bone biopsy, and bone turnover markers, can guide us about the mechanism of bone loss.

Alkaline Phosphatase: An Old Friend as Treatment Target for Cardiovascular and Mineral Bone Disorders in Chronic Kidney Disease

Alkaline phosphatase (ALP) is an evolutionary conserved enzyme and widely used biomarker in clinical practice. Tissue-nonspecific alkaline phosphatase (TNALP) is one of four human isozymes that are expressed as distinct TNALP isoforms after posttranslational modifications, mainly in bone, liver, and kidney tissues. Beyond the well-known effects on bone mineralization, the bone ALP (BALP) isoforms (B/I, B1, B1x, and B2) are also involved in the pathogenesis of ectopic calcification. This narrative review summarizes the recent clinical investigations and mechanisms that link ALP and BALP to inflammation, metabolic syndrome, vascular calcification, endothelial dysfunction, fibrosis, cardiovascular disease, and mortality. The association between ALP, vitamin K, bone metabolism, and fracture risk in patients with chronic kidney disease (CKD) is also discussed. Recent advances in different pharmacological strategies are highlighted, with the potential to modulate the expression of ALP directly and indirectly in CKD–mineral and bone disorder (CKD-MBD), e.g., epigenetic modulation, phosphate binders, calcimimetics, vitamin D, and other anti-fracture treatments. We conclude that the significant evidence for ALP as a pathogenic factor and risk marker in CKD-MBD supports the inclusion of concrete treatment targets for ALP in clinical guidelines. While a target value below 120 U/L is associated with improved survival, further experimental and clinical research should explore interventional strategies with optimal risk–benefit profiles. The future holds great promise for novel drug therapies modulating ALP.

Secondary Osteoporosis and Metabolic Bone Diseases

Fragility fracture is a worldwide problem and a main cause of disability and impaired quality of life. It is primarily caused by osteoporosis, characterized by impaired bone quantity and or quality. Proper diagnosis of osteoporosis is essential for prevention of fragility fractures. Osteoporosis can be primary in postmenopausal women because of estrogen deficiency. Secondary forms of osteoporosis are not uncommon in both men and women. Most systemic illnesses and organ dysfunction can lead to osteoporosis. The kidney plays a crucial role in maintaining physiological bone homeostasis by controlling minerals, electrolytes, acid-base, vitamin D and parathyroid function. Chronic kidney disease with its uremic milieu disturbs this balance, leading to renal osteodystrophy. Diabetes mellitus represents the most common secondary cause of osteoporosis. Thyroid and parathyroid disorders can dysregulate the osteoblast/osteoclast functions. Gastrointestinal disorders, malnutrition and malabsorption can result in mineral and vitamin D deficiencies and bone loss. Patients with chronic liver disease have a higher risk of fracture due to hepatic osteodystrophy. Proinflammatory cytokines in infectious, autoimmune, and hematological disorders can stimulate osteoclastogenesis, leading to osteoporosis. Moreover, drug-induced osteoporosis is not uncommon. In this review, we focus on causes, pathogenesis, and management of secondary osteoporosis.

Advances in pathogenesis and therapeutic strategies for osteoporosis

Osteoporosis, is the most common bone disorder worldwide characterized by low bone mineral density, leaving affected bones vulnerable to fracture. Bone homeostasis depends on the precise balance between bone resorption by osteoclasts and bone matrix formation by mesenchymal lineage osteoblasts, and involves a series of complex and highly regulated steps. Bone homeostasis will be disrupted when the speed of bone resorption is faster than bone formation. Based on various regulatory mechanisms of bone homeostasis, a series of drugs targeting osteoporosis have emerged in clinical practice, including bisphosphonates, selective estrogen receptor modulators, calcitonin, molecular-targeted drugs and so on. However, many drugs have major adverse effects or are unsuitable for long-term use. Therefore, it is very urgent to find more effective therapeutic drugs based on the new pathogenesis of osteoporosis. In this review, we summarize novel mechanisms involved in the pathological process of osteoporosis, including the roles of gut microbiome, autophagy, iron balance and cellular senescence. Based on the above pathological mechanism, we found promising drugs for osteoporosis treatment, such as: probiotics, alpha-ketoglutarate, senolytics and hydrogen sulfide. This new finding may provide an important basis for elucidating the complex pathological mechanisms of osteoporosis and provide promising drugs for clinical osteoporosis treatment.

Cardiovascular Safety of Anti-Sclerostin Therapy in Chronic Kidney Disease

The significance of sclerostin for bone and cardiovascular health in patients with chronic kidney disease (CKD) is complex and incompletely understood. Experimental evidence suggests that anti-sclerostin therapy shows diminished efficacy on bone in the setting of CKD. Limited clinical evidence suggests that the osteoanabolic and anti-resorptive activity is attenuated, but hypocalcemia is more prevalent in patients with advanced CKD (eGFR < 30 mL/min) treated with anti-sclerostin (romosozumab) therapy as compared to patients without kidney disease. Furthermore, sclerostin is prominently expressed in uremic arteries. Whether the inhibition of sclerostin has adverse effects on cardiovascular health in CKD is currently unknown. This review summarizes the current understanding of the physiology and pathophysiology of sclerostin in CKD, with a focus on the cardiovascular safety of anti-sclerostin therapy in patients with or without CKD.