Prevalence and Prevention of Avascular Necrosis of Bone

in SLE

 

H. Michael Belmont, M.D.Director, Bellevue Hospital Lupus Clinic

Chief Medical Officer, Hospital for Joint Diseases

Associate Professor of Medicine

New York University School of Medicine

Etiology of Bone Infarct/AVN/Osteonecrosis

Traumatic

Idiopathic (e.g. Legg-Calve-Perthes, Kienbock’s, etc.)

AtraumaticVasculopathyFat embolism/Adipose expansion

• Systemic lupus erythematosus (SLE) is characterized by immune dysregulation that results in the production of autoantibodies, generation of circulating immune complexes, and activation of the complement system.

• A pathological hallmark of SLE is the recurrence of widespread and diverse vascular lesions: inflammatory and thrombotic.

• The endothelial injury typical of SLE flares may serve as an inciting event, which predisposes to the accelerated atherosclerosis that is associated with the disorder as well as disrupt the microcirculation (e.g. end artery of the femoral head) to predispose to AVN.

PATHOBIOLOGY OF SLE

As a result, SLE patients exhibit rates of myocardial infarction and cerebrovascular accident that are up to 50-fold higher than age and gender matched controls.

The risk of developing avascular necrosis is 10-40 times greater than other patients on corticosteroids.

The increased frequency of coronary artery disease (CAD) and AVN observed in patients with SLE may be unified by the underlying vascular injury that distinguishes the disease.

Pathologic and Clinical Spectrum of Vasculopathy in SLE

Pathology Pathogenesis Clinical Phenomenon

Capillaritis Immune complex deposition Glomerulonehpritis, pulmonary alveolarVasculitis Activation of complement, hemorrhage

neutrophils, and endothelium Cutaneous purpura, polyarteritis nodosa-like Modeled by Arthus lesion systemic and cerebral vasculitis, AVN

Leukothrombosis Intravascular activation of complement, Widespread vascular injury, hypoxia, cerebral neutrophils, and vascular endothelium cerebral dysfunction, SIRS, AVN Absence of local immune complex deposition Modeled by Shwartzman lesion

Thrombosis Antibodies to anionic phospholipid-protein Arterial and venous thrombosis, fetal wastage,complexes interact with endothelial cells, thrombocytopenia, pulmonary hypertension, AVN platelets, or coagulation factors Modeled by APS Disseminated intravascular platelet TTP aggregation

Atherosclerosis Activated endothelium, increased endothelial cell adhesion molecules,

increased tissue factor, decreased MI, CVA 27-hydroxylase

Evidence for Shwartzman Phenomenon in SLE 

Increased C3a, C5a

Increased neutrophil CD11b/CD18 (beta 2 integrin, CR3)

Increased endothelial cell adhesion molecules

Increased endothelial cell nitric oxide synthase

Increased circulating endothelial cells

Histologic evidence of leukoaggregates (CNS, mesentery)

Neutrophil activation

Endothelial cell activation (priming)

Leukothrombosis

RestingEC

.

....

. .. ....

. .. ....

. ......

. .. ....

. ..ICAM-1CR3C5aIC

Resting PMN

IL-1ßTNFC1qC5aC5b-9aECaPL

E-selectin ....

. .. ....

. .. .. .. ...

....

. .. ...

..

.. ...

.. .. ...

.. ... ..

.. .....

.. .. .. .

... .Vaso-occlusive plug

. .. .. ..

Endothelial Cell Adhesion Molecule Expressionin Active versus Inactive SLE

0

0.5

1

1.5

2

2.5

ELAM-1 VCAM-1 ICAM-1

control (n=16) inactive SLE (n= 5) active SLE (n=11)

*P <0.01 active vs. control**P <0.025 active vs. inactive

T

*

*

***

Imm

unoh

isto

chem

ical

sco

re

Belmont, Buyon, Giorno, Abramson: Arthritis Rheum, 1994

Increased NO Accompanied by the Upregulation of iNOS in Vascular Endothelium of SLE Patients

0

0.5

1

1.5

2

2.5

Imm

unoh

isto

chem

ical

sco

re

cNOS iNOS

0

20

40

60

Nitr

ite re

leas

ed (u

M)

Control(n=5)

Inactive SLESLEDAI <5

(n=10)

Active SLESLEDAI >5

(n=9)

Control(n=11)

Inactive SLESLEDAI <5

(n=8)

Active SLESLEDAI >5

(n=17)

P <.05active vs. inactive P <.01

active vs. inactive

Belmont et al., Arthritis Rheum, 1997

Imm

unoh

isto

chem

ical

sco

re

Confirmation of Increased CEC in Peripheral Blood from Patients with Active SLE

( Positive Selection on P1H12 Magnetic Beads)

01020304050607080

HealthyControls

Inactive SLE(SLEDAI < = 4)

Active SLE(SLEDAI > 4)

b

bbbbCEC

/ml

N = 8 N = 15 N = 9Healthy Controls vs. Active SLE, P = 0.008Inactive SLE vs. Active SLE, P = 0.002Healthy Controls vs. Inactive SLE, P = 0.14)

SLE and Bone Infarct/AVN

• AVN is a frequent morbidity in lupus.

• The incidence is estimated to be between 5%-80%.

• SLE patients have the highest rate of AVN as compared to rheumatoid arthritis, pemphigoid, and asthma. 

Prevalence of AVN in SLE

• Two prospective studies of high dose corticosteroid treated SLE patients report a prevalence of AVN between 19-80%

Aranow J. Rheumatology 1997:24Nagasawa British Journal of Rheumatology 1994:33

• Aranow screened 62 SLE patients by MRI for AVN. 43 of 62 patients took 30mg/day of prednisone and 9 (19%) had evidence of AVN. Patients who had taken < 30mg/day had no evidence of AVN.

• Nagasawa studied 23 SLE patients treated with high dose corticosteroids ( 20mg/day), 8 (30%) had evidence of AVN by MRI. This cohort was followed prospectively for 3 years. Five of these patients received 30mg/day and 4 (80%) newly developed AVN

Risk Factors for AVN in SLE

- Daily steroid dosage- Cushingoid body habitus- Age- Ethnicity- Vasculitis- Raynauds- Thrombophlebitis- Presence of cardiolipin antibody- Increased disease activity

Bergstein, J Paediatrics 174;85Velayos, Ann Intern Med 1966;64Klipper Medicine 1976; 55Zizic Am J Med 1985; 79

Novel Paradigm

We propose the high prevalence and multifocal nature of AVN in SLE patients during high dose steroid treatment of disease exacerbation results from the co-occurrence of two processes

1. Vascular Injury with widespread activation of endothelium and inflammatory vasculopathy or thrombosis disrupting the microcirculation

2. Lipid Deposition with interosseous fat accumulation, secondary to glucocorticoid induced abnormal lipid metabolism, increasing intramedullary pressure (i.e. bony compartment syndrome) and decreasing perfusion

Materials and Methods

• The ICD-9 code for SLE, 710.0, and for AVN 733.40-44, 49 were cross-matched in a computer search of the medical records departments of Bellevue Hospital, Hospital for Joint Diseases (HJD), and the HJD faculty practice for the 18-month period between 08/99 and 02/00.

• In addition 170 charts were reviewed of patients who met ACR criteria for SLE

• 44 charts of patients with AVN and SLE were used to generate the case report forms.

RESULTS

• 44 patients, 42 female, 2 male and mean age 38 (19-61)

• 18 Hispanic, 13 African American, 12 Caucasian, 1 Asian

• 33 ascertained by MRI and 11 established at joint replacement

• 42 ANA (+), 36 dsDNA(+), 22 nephritis, 4 cerebritis, 10 ACA(+), 5 history of thrombotic event

• 18 Hyperlipidemia, 1CAD, 24 HTN, 5 Postmenospausal, 1 Diabetes Mellitus, 4 cigarette smoking, 5 Family History CAD, mean cholesterol 233+/-14 mg/dl

RESULTS

• 44 patients, 42 female, 2 male and mean age 38 (19-61)

• 18 Hispanic, 13 African American, 12 Caucasian, 1 Asian

• 33 ascertained by MRI and 11 established at joint replacement

• 42 ANA (+), 36 dsDNA(+), 22 nephritis, 4 cerebritis, 10 ACA(+), 5 history of thrombotic event

• 18 Hyperlipidemia, 1CAD, 24 HTN, 5 Postmenospausal, 1 Diabetes Mellitus, 4 cigarette smoking, 5 Family History CAD, mean cholesterol 233+/-14

RESULTS

• 5 Unifocal AVN, 25 bifocal AVN, with 24/25 bilateral femoral head, 15 multifocal with 3 or more joints affected

• 95% received prednisone 60 mg/day and 97% received 30 mg/day. 97% received high dose prednisone for a SLEDAI 8

SUMMARY

• AVN in SLE is unifocal in only 9% (5/44)

• AVN in SLE affects more than one joint in 82% (39/44)

• AVN in SLE affects bilateral femoral head in 50% (24/44)

• AVN in SLE is multifocal with 3 joints in 34% (15/44)

• AVN in SLE is associated with high dose steroid therapy for increased disease activity

CONCLUSION

The finding that AVN in steroid treated SLE patients is most often multifocal is consistent with our hypothesis that diffuse vascular injury during disease activity conspires with steroid induced marrow lipocyte accumulation to compress blood vessels and results in ischemic bone necrosis. Clinical trials with statins, which by preventing abnormal fat metabolism and endothelial injury may reduce this morbidity, are warranted.

Increased Adipogenesis and Abnormal Lipid Metabolism is Associated with Corticosteroid-induced Osteonecrosis

of Bone in Animal Models

• Clofibrate, decreased the corticosteroid-induced changes on marrow fat conversion and the increase in femoral head pressure

• In the group only treated with methylprednisilone, the percentage of fatty marrow was increased by an average of 28%, and the average intrafemoral head pressure increased from a baseline of 25 to 55.

• In the group treated with steroids and clofibrate there was almost no change in the percentage of fatty marrow and there was no increase in the intrafemoral head pressure.

•Cui showed that a lipid-clearing agent prevented osteonecrosis in a chicken model

•25 chickens were injected with methylprednisolone and 10 received methylprednisolone plus lovastatin.

•At autopsy 56% or 14/25 of the chickens only given corticosteroids had some evidence of necrosis, with 4/25 demonstrating evidence of sub-chondral death and resorption and new bone formation.

•In the group given lovastatin, there was a smaller conversion to fatty marrow and 10/10 had no evidence of osteonecrosis.

•In the study, the authors were able to show that lovostatin counteracted the effect of steroids on the differentiation of precursor cells in bone marrow into adipocytes.

• 14 of 20 rabbits with induced hypersensitivity vasculitis and high dose corticosteroid exposure developed evidence of AVN in the femoral metaphysis.

• In the groups only given corticosteroids without induction of hypersensitivity vasculitis, there was no evidence of AVN.

• Animal experiments done by Matsui, showed a possible synergy between vasculitis, high-dose cortocosteroids and AVN.

• Motomura Steroid induced osteonecrosis on rabbits No rx 14/20 (70%), warfarin 7/21 (33%), probucol 11/29 (37%), warfarin + probucol 1/21 (5%).

HUMAN STUDIES

• There is increasing evidence to suggest that relationship between fatty marrow content and AVN applies to humans.

• Vande Berg showed this using MRI, that lupus patients with evidence of AVN on high dose cortocosteroids have a greater increase in the percentage of fatty marrow and in the index of marrow conversion compared to both age matched controls and to lupus patients on comparative doses of corticosteroids who did not develop AVN.

• These findings support the notion that fat accumulation within the closed system of the bone marrow produces the increased medullary pressure that can result in AVN.

The Presence of Inflammation is a Newly Identified Risk Factor for Coronary Disease

• Increased C-reactive protein (CRP) significantly predicts myocardial infarction in men and women who did not have clinical evidence of atherosclerotic coronary disease.

• The risk reduction attributable to pravastatin was much larger among those patients with evidence of inflammation.

• Laboratory studies and experiments in animal models of atherosclerosis indicate that pravastatin may decrease inflammatory mediators.

• The inhibition of HMG-CoA reductase by statins also prevents the generation of mevalonate, the precursor of a complex series of isoprenoids that postranslationally modify certain proteins by isoprenylation with farnesyl or geranylgeranyl.

• The in vitro effects on endothelium (e.g. inhibiting adhesion molecule and iNOS expression) is consistent with the hypothesis that statin antagonism of prenylated proteins interferes with the activation of cellular components involved in the inflammatory process such as endothelial cells.

STATINS

• Inhibit HMGCo A reductase and both cholesterol and mevalonate synthesis (intracellular signalling)

• Reduce serum lipids

• Reduce risk of CAD

• Reduce risk of AVN

• Reduce risk of osteoporosis

• Modify disease activity and organ damage by preventing endothelial activation

APLLE Trial

 Four month randomized double-blind placebo controlled study of atorvostatin 40 mg po qd vs placebo to prevent AVN in steroid treated patients with active SLE (rolling enrollment of 30 patients per year for 3 years)

Active SLESteroid .75 mg./kg > 4 weeksNo current statinLFT < 2x normalBaseline MRI 10 testable sites (bilateral femoral head and chondyle, tibial plateau,

distal tibia and talus)Randomized to atorvostatin (lipitor) 40 mg po qd vs placebo Stratified by APS statusFollow-up MRI 10 testable sites at 4 months and greater than 6 months

Primary endpoint: New AVN at any of the 10 testable sites (i.e. 90% power toobserve 50% reduction in new AVN at any of the 10 testable sites per patientwith assumption that 50% will have at least 1 new site of AVN) Secondary endpoints: Cholesterol, TG, HDL, LDL, SLEDAI, ESR, hsCRP,dsDNA, C3, C4, activated CEC, soluble adhesion molecules

APLLE TRIALPatient Age E/G Stratum Clinical

Baseline MRI F/U MRI F/U MRI #2

1 DB 35 WF I fever, jts, heme 2/10 * 2/10 * 2/10*

2 PB 29 BF I renal, GI, heme 0/10 0/10

3 IR 32 HF II renal 0/10 0/10

4 MC 43 AF II renal 0/10 0/10

5 AR 35 HF II ILD 0/10 0/10 0/10

6 WW 20 BF II renal 0/10 0/10

7 AF 35 WM II renal 0/10 0/10 0/10

8 RM 31 BF ll renal 2/10 *** 2/10 *** 3/10***

9 SR 52 HF ll renal/skin/ILD 4 /10 ** 4/10** 6/10****

10 CM 45 BF II renal 0/10 E/W

11 AW 47 BM II renal/iritis 2 /10 *** 2/10 ***

12 DR 20 BM I renal/heme 0/10 0/10

13 MC 22 HF II renal/vasculitis 0/10 0/10

14 JP 19 AF II renal 0/10 0/10

15 MR 57 BF II renal 4/10*** N/A

16 HD 45 WF ll renal 0/10 N/A

17 AH 36 BF ll renal 1/10*** N/A

18 JF 33 HM II renal 1/10*** N/A

19 DR 20 BM ll renal 0/10 N/A

APLLE TRIAL

Summary• Enrollment n =20: 15 female, 5 male; 9 African-American, 6 Hispanic, 3

Caucasian, and 2 Asians

• 18/20 high dose steroids for renal flare

• 8/20 (40%) AVN on baseline MRI secondary to steroid treatment for prior disease exacerbation

• MRI (4 month f/u) 13/13 no new AVN

• MRI (6 month f/u) 2/5 patients (40%) demonstrate new AVN; 1 patient with 1 new and 1 patient with 2 new sites of AVN

• Atorvostatin well tolerated in this cohort with no significant elevation of transaminases or CPK

Conclusion

• Steroid treatment of SLE disease exacerbation is associated with high prevalence of AVN (i.e. 40% (8/20) at baseline and 40% (2/5) at longer term MRI follow-up

• Time to onset of AVN in steroid treated patients uncertain (Oinuma et al AVN in patients with SLE develops very early after starting high dose steroid treatment Ann Rheum Dis 2001;60:1145-1148) 72 steroid SLE patients with MRI 1, 3, 6 and 12 months and 32/72 patients (44%) develop ON between 1-5 months after starting steroids and no new AVN from 6-12 month

• Benefit of statins, atorvostatin 40 mg po qd, in preventing incidence of AVN and secondary outcomes (i.e. cholesterol, TG, LDL, HDL, ESR, hs-CRP, C4, C4, dsDNA, SLEDAI, Circulating endothelial cells) to be determined