Prediction of Type 1 Diabetes (T1DM) & related Autoimmune Diseases (AD)

Marco Songini, MD

Diabetes Unit

Azienda Ospedaliera Brotzu Cagliari (Italy)

Type 1 diabetes develops from the interaction between susceptibility genes and enviromental determinants. The major genetic susceptibility to type 1 diabetes is conferred by markers from HLA locus, but other genes are involved. The non genetic contribution to the disease (i.e. nutritional factors and infective agents) is even less wll-defined. This may imply aetiological heterogeneity in patients so that particular combinations of genetic susceptibility factors require exposure to specific non-genetic factors in order to initiate the disease developing process in type 1 diabetes. It is well known that immune markers (ICA, GADA, IA2, IAA) appear many years before clinical onset of type 1 diabetes. These “windows” offers the chance to pinpoint subjects at risk eventually suitable to preventive therapies. At present, intervention trials are recommended in the small subset of the population at high risk identified by genetic and immune markers.

Complementary strategies in the prediction of T1DM

Strategy 1

AIM:

TEST INTERVENTIONSTRATEGIES

High specificity/low sensitivity

families

immune markers

high risk subgroup

Strategy 2

AIM:

REDUCE INCIDENCE OF IDDM

Low specificity/high sensitivity

general population

genetic + immune markers

moderate risk subgroupBingley, E. Bonifacio & E. Gale;Diabetes, vol. 42, feb. 1993

Preventive strategies for T1DM (1)Selective immunosuppression, using depleting or nondepleting monoclonal antibodies to lymphocyte cell surface molecules such as CD3, CD4, CD8, T cell receptor and major histocompatibility complex (MHC) antigens, or blocking peptides to T cell receptors

Immunostimulation by viruses, cytokines, calcitriol, concanavalin A, bacille Calmette-Guèrin (BCG), Freund’s adjuvant or tranfusion of deficient lymphocyte subsets B-Cell rest by suppressive therapy with insulin

E. Bosi & G.F. Bottazzo; Clin. Immunother. 3 (2) 1995

Preventive strategies for T1DM (2)

Protection from oxygen radical-mediated and nitric oxide-mediated damage by nicotinamide, deferoxamine (desferrioxamine) and aminoguanidine

Environmental intervention by manipulation of temperature, diet (gluten free) and hormonal milieu

Induction of tolerance to B-cells by bone marrow transplantation, lymphocyte transfusion, intrathymic islet transplantation, neonatal B-cell stimulation and administration (intravenous, intrathymic, intraperitoneal or oral) of putative B-cell autoantigens such as insulin or glutamic acid decarboxylase

E. Bosi & G.F. Bottazzo; Clin. Immunother. 3 (2) 1995

Tests to predict T1 DM & AD

Autoantibodies: ICA, GADA, IA2-A, IAA, AD-Abs

HLA-phenotype: DR3/DR4 (DQ2/DQ8), AD phenos

HLA-genotype: Eterodimers 57Non Asp/53Arg DQ beta/DQ Alfa, AD genos

? Cell mediated markers: Alteration of lymphocyte subsets CD4/CD8, etc.

Immunological markers for T1DM

ICAIslet Cell Abs

Indirectimmunofluorescence on human pancreaticcryosections

Risk at 10 yrs FH+>10 JDFU 41%>80 JDFU 80%

IAAInsulin AutoAbs

R.I.A.In Childrenfirst antibodiesto appear

Risk at 5 yrs FH+ 44%

Risk at 10 yrs ICA + IAA 81%

GADAGlutamic Acid Decarboxilase AutoAbs

Immunological markers for T1DM

R.I.A.Morecommon among adults

High sensitivitylow specificity

IA2-AProtein TyrosinPhosphatase AutoAbs

R.I.A.Morecommon among children

High specificitylow sensitivity

Immunological markers for T1DMCombined markers in FH+

Positivity for 3 or 4 antibodies yelds a risk of 88-100% to become diabetic in 10 years

The best association of autoantibodies is:GADA + IA2-A

GADA + IA2-A + IAA in young children

Pastore MR et al Diabetes Care 1998, 9; 1445-50

We are able to assay GADA + IA2-A on blood spots

E. Bosi, E. Bonifacio et al . Diabetes Care - March 1999

The preclinical stage of type 1 diabetes and related AD can last even many years

These “windows” offers the chance to pinpoint subjects at risk eventually suitable to

preventive therapies

Background

HLA typing

predisposing:HLA DR3-DQ2, DR4-DQ8

protective:HLA DR2-DQ6

Lernmark A Diabetes Metabolism Rev 1998, 14,3-29

Genetic markers for T1DM

Molecular biology of DQ chains of class second

DQ A301, DQ B302, DQ B501 Alleles: 99% of diabetic patients 50% of normal people

DQ B602 is fully protective for T1DM

Lernmark A Diabetes Metabolism Rev 1998, 14,3-29

Gianani R et al. J Autoimmunity 1996, 9; 423-425

HLAGenetic markers for T1DM

6p21 IDDM1 2,6 35 Davies (1994)

15q IDDM3 - - Field (1994)

11q13 IDDM4 1,07 2,5 Hashimoto (1994), Davies (1994)

6q25 IDDM5 1,16 5,5 Davies (1994)

2q31 IDDM7 1,13 4,5 Davies (1994), Copeman (1994),

Owerbach and Gabbay (1995)

6q27 IDDM8 1,42 12,9 Luo (1995), Davies (1996)

18q IDDM6 1,1 3,5 Meriman (unpub.), Davies (1994)

11p21 IDDM2 1,29 9,4 Davies (1994), Bennet (1995)

Locus s % References

Genetic markers for T1DM (1)

Genetic markers for T1DM (2)

1,45

3q21-q25 IDDM9 1,26 8,5Gough and Todd (unpubl.)

10p11.2-q11.2 IDDM10 13,7 Davies, Hashimoto (1994)

Reed and Todd (unpubl.)

14141414 95.595.595.595.5TOT.TOT.TOT.TOT.

s %

7p GCK Rowe (1995)

IDDM12 (CTLA-4)2q33 Nistico (1996)

14q24.3-q31 IDDM11 Field (1996)

2q34 IDDM13 Morahan (1996)6q21 IDDM15 Delepine (1997)

Locus References

Identical Twins 100%Tun RY, BMJ 1994

1st degree relatives (FH+) 70% ICARUS Group Study

Polyendocrinopathy (FH-) 25% Bosi E, Diabetes 1991

Polyendocrinopathy (FH+) 70% Bosi E, Diabetes 1991

High risk newborns (FH+) 50% BABYDIAB (Germany)

High risk newborns (gene+) 50% DIPP Project (Finland)

Sardinian school children (gen) 24% SSI Study (Sardinia)

Natural History of T1DM

2 yrs

2 yrs

Popul islet-related Abs+ Follow- Risk References

10 yrs

5 yrs

7 yrs

10 yrs

10 yrs

up

Natural history of T1DM

tt

Beta cell mass

50%

25%

75%

Triggers ?Triggers ?

TYPE 1 DIABETES

Auto Abs +

FPIR

OGTT +

Time0

Triggers ?Triggers ?

Triggers ?Triggers ?

GENES (susc)

Screening for pre-T1DM and related AD

Schoolchildren

Newborn

• DAISY (USA)• BABYDIAB (Germany, Australia) • SNI (Sardinia)• DIPP (Finland)• DIABFIN (Italy)

•France • Sweden • Spain • Oxford• Holland • Estonia • SSI • USA• Finland • Germany

Cost of predicting T1DM Cost of insulin

therapies

(per year)

•Conventional Therapy (CT) $1450

•Intensive Therapy (ICT) $ 2 x CT

•CSII $ 3 x CT

Cost of Screening(for each enrolled case)

•DPT-1 $1751

•DIPP (follow up=10 yrs) (newborns) $245 $733

Birth

Genetic+Absscreening

Counselling

Abs follow up

100%

13%

Birth

Abs screening

Abs follow up

100%

100%

Cost of DM (?AD)

Hahl et al. Diabetologia (1998) 41:79-85

•$ 92 billions

Prevention of T1DM and other related AD

T1DM&AD are theoretically preventable

• Because there are environmental causes

• Because we are beginning to understand the genetic and immune basis

• Because they develops very slowly

• Because we have good predictive tests

• Because we can stop them in animals

• Because we can run clinical trials

T1DM & AD are suitable diseases for preclinical screening and intervention

• Serious consequences (in USA 50 deaths yearly from DKA)

• Treatment following diagnosis expensive, demanding, limited effect on complications

• Identifiable preclinical phase also for AD

• Identifiable subjects “not at risk” also for AD

• ...but as yet no preventive therapy of proved efficacy (no penicillin for prediabetes!)

Assigning risk

• Primary prevention: must be based on family history or high risk HLA - and will miss a lot of cases!

• Secondary prevention: immune-markers relatively stable after age 5; almost inevitable progression with multiple antibodies; excellent screening efficiency (islet imaging)

Setting up an intervention: in whom?

• Primary: Neonates with family history or high risk HLA

• Secondary:– Infants: HLA DR3/4 with antibodies

– Children/young adults with multiple Abs (T1DM&AD)

– Older adults with LADA

Setting up an intervention: with what?

Should work:– In animal models

– In newly diagnosed type 1

– In pilot trials (assessed how?)

Must have:– An acceptable safety profile

– Ease of administration

Setting up an intervention: conclusions

• At present trials must be large, structured, costly and long term

• Will depend on international collaboration

• We need a disciplined consensus process for evaluating and prioritizing new therapies

• Role of pharmaceutical industry? clinicians should have a say

T1DM prevention trials

PrimaryCow’s milk avoidance: TRIGR

Gluten free diet: PREVFIN

SecondaryNicotinamide: DENIS, ENDIT, New Zealand

Insulin: DPT-1, EPLL SCIT; Schwabing, Brunetti 1999

TertiaryCyclosporin: GETREM, French and Canadian studies

Linomide : Franco-Swedish trial

Intervention trials: assumptions

Trial N Yr Diabetes RRR % %

ENDIT 530 5 40:26 35

DENIS 130 3 30:6 80

DPT (high) 340 4 84:55 35

DPT (inter) 490 4 24:12 50

Mahon and Dupre,1997

Cyclosporin before onset of T1DM

• 6 relatives vs 9 historical controls

• All controls developed diabetes in 12 months

• 4/6 cyclosporin treated patients developed diabetes within 4 years (5, 24, 24 and 47 months)

Carel et al., 1996

Intervention in early infancy?

• Level of risk?

• Safety of intervention? Long term data?

• Acceptability/compliance?

• Efficacy demonstrated in other AD?

• Can the intervention be tested effectively in this category of patient?

FOLLOW-UP, MONTHS

3 6 9 12 18 24 TOTAL

CASEIN 0/83 0/75 1/72 3/71 1/67 1/62 3/84

HYDROLYSATE (3.6%)

p=0.06

CM-BASED 0/87 1/84 6/79 7/78 6/77 7/76 10/89

FORMULA (11.2%)

Emergence of at least one auto-Abby the age of 2 years (n=173)

The Second TRIGR Pilot Study

EURODIAB Sardinia (1989-98)birth seasonality

02468

101214161820

Jan-March Apr-June Jul-Sept Oct-Dec

Seasons of birth

No.

of

bir

ths/

mon

th

N=1928, 0-29yr

P<0.001

Jan-March Apr-June Jul-Sept Oct-Dec

Future Directions?• Surrogate end-points

• Safety and acceptability need to be balanced against efficacy

• Early “one-off” therapy would be ideal

• Explicit standards for performance of trials

• Fewer, better quality studies based on international consensus

• Lessons from other human autoimmune disease?