CHAPTER 12

뼈건강 개선

Functions of Bone

• Structural

– Support

– Protection

– Movement

• Mineral Storage

– Calcium

– Phosphate

Skeletal Problems

• Disease / genetics – Osteoporosis (Type I)

– Multiple myeloma

– Metastatic bone cancer

– Rheumatoid arthritis

– Paget’s Disease

• Hormone ablative therapy

• Spinal cord or nerve injury

• Surgery and rehabilitation

• Aging (Type II Osteoporosis)

• Bedrest

• Microgravity

Bone • Bone composition

– 70% mineral (Ca2+ and PO4- as hydroxyapatitie)

– 22% protein (95% Type I collagen + 5% proteoglycans and other materials) – 8% water

• Two major types of bone – Compact (cortical, i.e., long bones)

• Mechanical and protective functions

– Cancellous (spongy, i.e., vertebrae) • Metabolic regulation of calcium

• Four types of cells – Osteoblasts – Osteoclasts – Osteocytes – Bone lining cells

제1절 골다공증 개선

1. 골다공증의 정의 및 개요 골다공증

뼈로부터 칼슘의 배출로 인해 뼈의 밀도와 강도가 약해지게 되어 골절 가능성

이 높은 상태

골다공증의 원인

- 호르몬 불균형

- 노화

- 기타 위험인자

- 뼈의 교체율 증가

골밀도의 정도

- 세계보건기구에서 정한 기준에 따라 같은 인종과 같은 성별의 젊은 사람의

평균 골밀도에서 위, 아래 표준편차를 나타내는 T값으로 표시

- T값이 -2.5 미만일 경우 골다골증으로 진단

Background

• The problem

– Osteoporosis is common

– Over 50% of women and 30-45% of men over age 50 have osteopenia/osteoporosis

– White woman over age 50: 50 % lifetime risk of osteoporotic fracture, 25% risk vertebral fracture, 15% risk of hip fracture

– Man over age 60 has 25% risk osteoporotic fracture

– 70% over age 80 have osteoporosis

Background

• Hip fractures are bad

– 20% patients with hip fracture die within the year

– 25-30% need placement in skilled nursing facility

What is Osteoporosis?

• Loss in total mineralized bone • Disruption of normal balance of bone

breakdown and build up • Osteoclasts: bone resorption, stimulated by

PTH • Calcitonin: inhibits osteoclastic bone resorption • Major mechanisms:

– Slow down of bone build up: osteoporosis seen in older women and men (men after age 70)

– Accelerated bone breakdown: postmenopausal • Normal loss .5% per year after peak in 20s • Up to 5% loss/year during first 5 years after menopause

Defining Osteoporosis

• “systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk”

• True Definition: bone with lower density and higher fracture risk

• WHO: utilizes Bone Mineral Density as definition (T score <-2.5); surrogate marker

Who Gets Osteoporosis?

• Age • Estrogen deficiency • Testosterone deficiency • Family history/genetics • Female sex • Low calcium/vitamin D intake • Poor exercise • Smoking • Alcohol • Low body weight/anorexia • Hyperthyroidism • Hyperparathyroidism • Prednisone use • Liver and renal disease (think about vit d synthesis) • Low sun exposure • Medications (antiepileptics, heparin) • Malignancies (metastatic disease; multiple myeloma can present as

osteopenia!) • Hemiplegia s/p CVA/ immobility

Diagnosing Osteoporosis

• Outcome of interest: Fracture Risk!

• Outcome measured (surrogate): BMD – Key: Older women at higher risk of fracture than

younger women with SAME BMD!

– Other factors: risk of falling, bone fragility not all related to BMD

– Osteoporosis: disease of bone that increases risk of fracture; more than BMD goes into causing a fracture; BMD is important, but in reducing fractures must also consider falls risk, age and other factors!!!

Reducing Fractures

• 1. Decrease osteoporosis/improve BMD

• 2. Decrease risk of break: hip protectors

• 3. Decrease risk of fall

Hip Protectors

• Padding that fits under clothing

• Multiple studies demonstrate effectiveness at preventing hip fractures

• Likely cost effective

• Problem: adherence!

2. 기능성 평가 방법

1) 시험관 내 실험

- 세포를 이용하는 생체 외 시험방법을 통해 평가

- 사람의 유사 조골세포주를 이용하여 조골세포의 증식능력 및 분화 촉진 인

자 등을 살펴봄으로써 이루어짐

2) 동물 실험

- 흰쥐 이용 : 성장과 대사 속도가 빨라 골의 대사 변화를 신속하게 볼 수 있음

- 골다공증 치료를 위한 기능성 평가가 다양함

- Sham operation

Bone Cell Types Osteoblasts Osteoclasts Osteocytes Bone Lining

Cells

• Matrix formation

• Secretes Type I

collagen

• Regulates

mineralization

• Positioned

above osteoid

matrix

• Matrix usually

polarized but can

surround cells

• Differentiates to

become osteocyte

• Digests bone

•Large multi-

nucleated

• Exhibits ruffled

border and clear

zone

• Exhibits polarity

with nuclei away

from bone surface

• High density of

Golgi stacks,

mitochondria and

lysozomal vesicles

• Born from

osteoblasts

• Maintains bone

matrix

• Occupies

lucunae

• Extends

filopodia through

canaliculi

• Forms gap

junctions with

neighboring cells

• Flat, elongated

cells

• Generally

inactive

• Cover surfaces

of inactive bone

• Thought to be

precursor cells to

osteoblasts

Haversian

System

Cancellous or Trabecular Bone

Why Remodel Bone

• Allows bone to respond to loads (stresses)

• Maintain materials properties

• Allows repair of microdamage

• Participates in serum Ca2+ regulation

Remodeling of Bone • Resorption accomplished by osteoclasts

– Form cutting cones to “drill” holes – Haversian system

– Filled in holes become new osteons

• Allows bone to respond to physical stress • Allows repair of micro damage • Participates in plasma calcium control • Random remodelling turns over bone

– Prevent accumulation of brittle material – Skeleton is cycled every 4-5 years

Bone Remodeling – A Coupled Control System

Osteoprogenitor cells

Osteoblasts Osteoclasts Mononuclear progenitor cells

• Osteoblasts have receptors for osteolytic agents

• Osteoclasts in culture are activated by stimulating osteoblasts

• Osteoblasts deposit factors in newly formed matrix

• Osteoclasts produce factors that recruit and activate osteoblasts

• Factors released as osteoclasts age and die (apoptosis)

Bone Turnover •Bone Turnover Relative to Development

•Formation

•Resorption

•Formation > Resorption •High Turnover

•Formation = Resorption •Formation < •Resorption

•Formation < Resorption •Low Turnover

•Female

•Male

Bone Strength

• Determinants of strength

– Geometry

– Bone mineral density

– Materials properties

• Bone growth

– Growth needed during development

– Growth also needed to withstand increased loads

Support of Osteocyte-based Mechanism

• Osteocyte network – Large surface area in contact with bone

• 2 orders of magnitude more than any other cell type

– Provides intracellular and extracellular route of communication

• Isolated turkey ulna stimulated with loading causes significant activation of osteocytes – 1 Hz at 500-2,000 (10-6) strain (l/l)

– Osteocytes do not appear to respond to static loads

– Intermittent stresses cause significant changes in osteocytes which suggest function as mechanosensors

Osteocyte Candidate Signaling Molecules

• Nitric Oxide – Small molecule, diffuses quickly – Produced rapidly – Stimulates production of IGF via both autocrine and paracrine mechanisms

• Sclerostin – Protein produced only by osteocytes – Powerful inhibitor of osteoblasts – In new bone (Haversian), osteocytes closer to center of channel produce most

sclerostin

Summary of Bone Feedback Control System

Bone

mechanical

properties

Strain

(Deformation)

Canaliculi

network

resistance

Osteocytes produce

Nitrous oxide /

Prostaglandins

Osteoblasts

External

Loads

Hormones /

Cytokines

Osteoclasts

+ -

Streaming

flows and osteocytes deformed

SGPs or direct strain

Hormones /

Cytokines

Osteocytes produce

sclerostin

-

Stress Shielding • Occurs with artificial implants

– Stiffness of implant much greater than natural bone

– Does not transmit stress uniformly and fully into native bone at interface

– Bone becomes resorbed at interface and implant becomes “loose”

Effects of Exercise on Bone

• Two types of studies conducted – Compare trained athletes with sedentary people

• Athletes and chronic exercisers have higher BMD

• Competitive runners in 60s have ~40% greater BMD than controls

• Weight lifters have 10-35% greater spine BMD

• Tennis players have 30% greater thickness of dominant humerous

– Correlate level of fitness with BMD (Effect not obvious)

• Early life experience is important (Peak BMD)

– Women who get hip fractures have lower levels of occupational or leisure activity from 15-45 years old

– Significant associations between hip BMD and early-life exercise both men and women

Skeletal Response to Exercise

Bone d

ensity

(%

)

0

-40

30

Normal

Range

Sedentary Moderately

Active

Changes only occur with significant habitual changes in activities over several months

Spinal injury, immobolization, bed rest, space flight.

Lazy zone

Mechanisms of Exercise Effects

• Increased habitual strain causes an increase in net bone formation – Returns bone strain to normal control

setpoint

• Studies with intact bone – Mechanical loading causes: – Formation on periosteal surface without

initial resorption

– Periosteal cell proliferation

Interaction of Age with Exercise • Increasing age causes deficits in response

(I.e., gain of system goes down) – Probably caused by multiple factors – Women from 60-80 show BMD increase of only

5-8% with exercise

• Increases in BMD with exercise reverts to normal within a few months of terminating training

• Exercise clearly helps maintain bone as system gain or setpoint is reduced

Osteoporosis

• Defined as reduction in bone mass and micro-architecture that leads to susceptibility to fracture

Normal Osteoporotic

Costs of Osteoporosis • 10,000,000 cases in U.S. alone • Affects 1 in 2 women and 1 in 8 men > 50 years old • Causes 1.5 million fractures/year - 700,000 spine,

300,000 hip and 300,000 wrist, 25,000 deaths from complications

• Menopause is the biggest risk factor for disease • Disease often not diagnosed until after 1 or more

fractures have occurred • Prevalence could rise to 41 million by 2015 from 28

million today • Cost to health care estimated at $14 billion ($38M/day) • Psychological and social effects of disease are immense

Development of Osteoporosis • Formation takes 3-4 months to replace

bone resorbed in 2-3 weeks • Osteoclast recruitment is increased • Osteoblast-osteoclast Coupling is

interrupted – Factors recruiting osteoclasts may not adequately

recruit osteoblasts – Lack of estrogen may lead to less IGF-1 incorporated

into new bone – reduces later osteoblast recruitment – Gain or setpoint in mechanosensory feedback loop

may be reduced

Issue of Peak Bone Mass

• Bone mass peaks in the 20’s, starts dropping in the late 30’s and accelerates significantly after menopause

• Risk for osteoporosis depends on peak mass and rate of loss

• Peak bone mass depends on

– Genetics

– Calcium, diet, exercise, etc. in youth

Bone Remodeling – A Coupled Control System

Extra OPG Normal OPG Lack of OPG

Osteoprotegerin (OPG)

• Seminal paper published in 1997 – “Osteoprotegerin: A novel secreted protein involved in the

regulation of bone density”, Simonet et al, Cell, 234:137-142

• OPG member of TNF receptor superfamily – soluble receptor

• Shown to affect bone density

OPG / RANKL / RANK Receptor

• RANKL and OPG are secreted by osteoblasts and bone marrow stromal cells

• RANKL functions to promote osteoclast formation and activation and inhibit apoptosis

• OPG functions as a decoy receptor to prevent RANKL signaling; ratio of RANKL to OPG dictates bone mass and structural properties

• Current extensive research is elucidating the role of OPG and RANKL in a wide variety of bone-related diseases

OPG

Osteoclast Precursor

Bone

Osteoblasts

Osteoclast

RANK Ligand

RANK

Hormones Cytokines

RANK

Figure. Schematic representation of the pathways regulating osteoclast differentiation.

Denosumab (OPG mimetic)

• Fully human monoclonal antibody to RANK Ligand

• IgG2

• High affinity for RANK Ligand (Kd 3 x 10–12 M)

• Does not bind to TNFα, TNFß, TRAIL, or CD40L

Monoclonal Antibody Model

Bekker PJ, et al. J Bone Miner Res. 2004;19:1059-1066.

Boyle WJ, et al. Nature. 2003;423:337-342.

Mechanism of Action for Denosumab

Osteoclast Formation, Function and

Survival Inhibited Osteoclast Activation

Adapted from Boyle WJ, et al. Nature. 2003;423:337-42.

Mature

Osteoclast

CFU-M

Pre-Fusion

Osteoclast

Multinucleated

Osteoclast Growth Factors

Hormones

Cytokines

RANK

RANKL

OPG

Bone

Denosumab

3) 임상 시험

- 정상군의 경우 폐경하지 않은 여성을 시험대상으로 선정

- 시험군의 경우 약물, 또는 에스트로겐을 복용하지 않은 폐경 여성 혹은 난소 절제 여성으로

선정

- 기본조사 : 연령, 신장, 체중, 체질량지수, 폐경 기간, 폐경 시작 나이 및 출산 횟수

- 생화학적 검사 : 골형성 및 골흡수 지표 관찰

- 조직학적 검사 : 골밀도, 방사선 관찰

(1)골형성지표 분석

①Bone alkaline phosphatase(BALP)

- 혈정에 소맥배아 응집소를 용해하고 렉틴용액을 첨가한 뒤 희석된 트리톤-X 100용액을

첨가하여 원심분리하여 상층액에 있는 ALP 수치를 측정하는 것

②오스테오칼신(Osteocalcin)

- 혈중 오스테오칼신은 osteocalcin myria 키트를 이용하여 방사면역분석 시험법에 따라

측정

③콜라겐 프로펩타이드 유형Ⅰ

- 효소면역검사법(ELISA) 키트로 측정

3) 임상 시험

(2)골흡수지표 분석

①콜라겐 텔로펩타이드 유형Ⅰ

- 뇨 중 콜라겐 텔로펩타이드 유형을 효소면역검사법 키트로 측정

②피리디놀린(pyridinoline)

- 뇨 중 피리디놀린의 측정을 콜라겐 교차결합 키트를 이용해 효소면역검사법으로 측정

③데옥시피리디놀린(deoxypyridinolin)

- 노 중 데옥시피리디놀린의 측정은 원심분리하여 뇨량을 잰 다음 pyrilinks-D 키트를 사용

하여 효소면역검사법에 의해 분석

(3)칼슘대사

- 혈청 중 칼슘 함량은 회화시킨 후 AAS로 측정한다.

- 칼슘생체이용률은 방사성동위원소(radio-isotype)를 이용하여 분석

(4)호르몬

①부갑상선호르몬(parathyroid hormone)

- DSL-8000 ACTIVE TM Intact PTH IRMA 키트를 이용하여 비경쟁적 방사 면역분석시험을

수행

②혈중 칼시토닌(calcitonin)

- DSL-7500 ACTIVE TM Calcitonine IRMA 키르를 이용하여 비경쟁적 방사 면역분석시험

을 수행

③에스트로겐(estrogen)

- 혈청 중 에스트라디올(estradiol) 함량은 estradiol RIA 키트를 이용하여 방사면역분석시

험에 따라 측정

(5)골밀도, 골무기질 함량 및 총골칼슘 측정

- 시험 후 척추 및 골반, 오른쪽 대퇴골 등과 총골칼슘량을 이중에너지 X-선 흡수계측법을

이용하여 척추 및 골반 등과 같은 체중이 실리는 부위와 전신 골밀도를 측정

hormone

3. 골다공증 개선 건강기능식품 및 효능

1) 고시형 건강기능식품

(1)칼슘

- 우유 및 유제품, 채소 및 과일, 뼈째 먹는 생선, 두류 등에 다량 함유

- 최근, 칼슘 강화 주스, 칼슘 고형두부 등과 같은 강화식품이 개발되는 추세

- “칼슘은 뼈와 치아를 형성하는 데 필요하다.”

- “칼슘은 신경과 근육의 기능을 유지하는 데 필요하다.”

- “칼슘은 정상적인 혈액응고에 필요하다.”

(2) 비타민 D

- 비타민 D는 종류가 최소 10가지 이상으로, 대표적인 것으로는 비타민

D2 (ergo-calciferol)와 비타민 D3 (cholecalciferol)가 생리적으로 중요한 기능

을 함

- “비타민 D는 칼슘과 인이 흡수되고 이용되는 데 필요하다.”

- “비타민 D는 뼈를 형성하고 유지하는 데 필요하다.”

Fracture Reduction

• Goal: prevent fracture, not just treat BMD

• Osteoporosis treatment options

– Calcium and vitamin D

– Calcitonin

– Bisphosphonates

– Estrogen replacement

– Selective Estrogen Receptor Modulators

– Parathyroid Hormone

Osteoporosis Treatment: Calcium and Vitamin D

• Fewer than half adults take recommended amounts

• Higher risk: malabsorption, renal disease, liver disease

• Calcium and vit D supplementation shown to decrease risk of hip fracture in older adults

• 1000 mg/day standard; 1500 mg/day in postmenopausal women/osteoporosis

• Vitamin D (25 and 1,25): 400 IU day at least; – Frail older patients with limited sun exposure may

need up to 800 IU/day

Osteoporosis Treatment: Calcitonin

• Likely not as effective as bisphosphonates

• 200 IU nasally/day (alternating nares)

• Decrease pain with acute vertebral compression fracture

Osteoporosis Treatment: Bisphosphonates

• Decrease bone resorption • Multiple studies demonstrate decrease in hip

and vertebral fractures • Alendronate, risodronate • IV: pamidronate, zolendronate (usually used for

hypercalcemia of malignancy, malignancy related fractures, and multiple myeloma related osteopenia)

• Ibandronate (boniva): once/month • Those at highest risk of fracture (pre-existing

vertebral fractures) had greatest benefit with treatment

Bisphosphonates: Contraindications

• Renal failure • Esophageal erosions

– GERD, benign strictures, most benign GI problems are NOT a contraindication

– Concern for esophageal irritation/erosions from direct irritation, recommendations to drink water after and not lie down at least 30 minutes

– Reality: no increased GI side effects compared to placebo group in multiple studies

Osteoporosis Treatment: Selective Estrogen Receptor Modulators

• Raloxifene

• FDA recommended

• Decrease bone resorption like estrogen

• No increased risk cancer (decrease risk breast cancer)

• Increase in vasomotor symptoms associated with menopause

Osteoporosis Treatment: PTH

• Teriparatide

• Why PTH when well known association with hyperparathyroidism and osteoporosis???

• INTERMITTENT PTH: overall improvement in bone density

– Optimal bone strength relies upon balance between bone breakdown and bone build up; studies with increased density but increased fracture risk/fragility with flouride show that just building up bone is not enough!!!

Intermittent PTH: Teriparatide

• Studies suggest improved BMD and decreased fractures

• ?risk osteosarcoma with prolonged use (over 2 years): studies with rats

• SQ, expensive • Option for severe osteoporosis, those on

bisphophonates for 7-10 years, those who can not tolerate oral bisphosphonate

• Optimal effect requires bone uptake • Not for use in combination with

Bisphosphonate! – May need to stop bisphosphonate up to 1 year

prior

(3) 글루코사민

- 아미노산과 당이 결합한 형태인 아미노당의 일종으로 관절의 연골을 구성하는 성분

- 새우나 게와 같은 갑각류의 껍질에 존재하는 키틴 성분으로부터 추출

- ‘관절 및 연골 건강’의 기능성이 인정됨

(4) N-아세틸글루코사민

- 새우나 게와 같은 갑각류의 껍질에 존재하는 키틴을 효소분해하여 생산

- ‘관절 및 연골 건강’의 기능성이 인정됨

(5)뮤코다당∙단백

- 동물 점액성 다당류의 일종으로 뮤코다당체, 뮤코다당질의 약칭

- 소, 돼지, 양, 사슴, 상어, 가금류, 오징어, 게, 어패류의 연골 조직을 열수 추출 및 효소

분해하여 여과, 농축, 건조 등의 공정을 거쳐 식용에 적합하도록 정제하고 건조한 것

- ‘관절 및 연골 건강’의 기능성이 인정됨

(6)프락토올리고당

- 과일 및 채소와 버섯등에 존재

- 설탕에 과당을 전이시키거나, 이눌린을 이눌레이스로 부분 가수분해하여 생성됨

- ‘칼슘 흡수에 도움’의 기능성이 인정됨

(7)대두이소플라본 추출물

- 발효된 대두 배아를 주정추출하여 생성

- 다이드제인과 제니스테인이 지표성분으로서, 둘의 총합이 30~40%가 되게 함

- “뼈 건강에 도움을 줄 수 있습니다” - 기타기능Ⅱ로 기능성이 인정됨

• Estrogens decrease osteoclast formation by down-regulating RANKL-induced activation of JNK and subsequent phosphorylation (and activation) the Jun transcription factor.

• This occurs within 5 minutes of estrogen treatment in vitro and is reversed by treatment with estrogen antagonist.

2) 개별인정형 건강기능식품

(1)차조기 등 복합추출물(KD-28)

- 갈근, 인진 및 차조기 세가지 재료를 주정을 이용하여 추출

- 푸에라린, 스코폴레틴, 아피제닌이 각각 원료의 지표성분임

- “관절 건강에 도움을 줄 수 있습니다” - 기타기능Ⅱ 로 기능성이 인정됨

(2)로즈힙 분말

- 건조시킨 로즈힙 열매로 만든다.

- 하이페로사이드가 지표 성분으로 알려져 있다.

- “관절 및 연골 건강에 도움을 줄 수 있습니다” – 기타기능Ⅱ로 기능성이 인정됨

(3)황금 등 복합물

- 황금물추출 분말(80%), 아선약 물추출분말(20%)을 합하여 만듦

- 바이탈린과 카테킨이 지표 성분으로 각각 18%, 3%가 되도록 함

- “관절 건강에 도움이 될 수 있습니다” - 기타기능Ⅱ 로 기능성이 인정됨

(4)초록입홍합 추출 오일복합물

- 초록입홍합 초임계 추출물, 올리브오일, D-a-토코페롤 세 가지 원료를 혼합하여 만듦

- EPA, DHA, a-리놀렌산 등의 오메가-3-불포화지방산 혼합물이 지표 성분으로, 25%이

상이 되도록 함

- “관절 건강에 도움이 될 수 있습니다” - 기타기능Ⅱ 로 기능성이 인정됨

(5)기타

- 칼슘-PGA: “체내 칼슘 흡수 촉진에 도움을 줄 수 있다”로 기능성을 인정 받음

- 호프 추출물: “관절 건강에 도움을 줄 수 있다”로 기능성을 인정 받음

- 지방산복합물: “관절 건강에 도움을 줄 수 있다”로 기능성을 인정받음

reference

• Funtional food 이형주 외 수학사

• handouts