The dermal-epidermal junction (DEJ): - Is the largest epithelial-mesenchymal junction, attaching the epidermis and papillary dermis. - Consists of collagenous and non-collagenous molecules that provide a selective permeability barrier and structural foundation securing the epidermis. - Its main components are the basal plasma membrane, basement membrane with lamina lucida, densa and fibroreticularis layers, and hemidesmosomes which thickened the keratinocyte plasma membrane.

1. DERMODERMO
EPIDERMALEPIDERMAL
JUNCTIONJUNCTION

2. •Largest epithelial
mesenchymal junction
•Attachment between the
epidermis and papillary
dermis
•Consist of collagenous
and non collagenous
macro molecule

3. Functions of basement
membrane
- Firm attachment of
dermis to epidermis
– Selective permeability
barrier
– Structural foundation for
the secure attachment
and polarity of epidermal
basement membrane

4. –Barrier function
separating the
epidermis and dermis
–Modifications of cellular
function
–Wound healing

5. • Visualisation
–Light Microscope –
Magenta colored linear
band

6. Components of DEJ
1.Basal plasma membrane
and hemi desmosome
2.Basement membrane
• Lamina lucida
• Lamina densa
• Lamina fibro reticularis

8. •Hemidesmosomes
–Focal thickening of plasma
membrane of keratinocytes
–High magnification
•Inner plaque
•Outer plaque
•Subbasal dense plaque

10. • Lamina Lucida
–Anchoring filaments [fine
structure, oriented –
perpenticularly] max
corresponding to HD
–Weakest part of DEJ
• Lamina densa
–Electron dense layer
–Made up of collagen IV

11. • Lamina fibro reticularis
–Anchoring fibrils [ curved structure]
•Can extend to upper part of
dermis/ lamina densa
•Also inserted to anchoring plaque
•Strongest tie for securing
epidermis to dermis
–Elastic micro fibrils [ fibrilin]

13. Ultrastructure ofUltrastructure of
epidermal basementepidermal basement
membranemembrane

14. •Intermediate filament
component
–Keratin 5 and Keratin
14
•Hemidesmosomal
plaque components
–BPAG1 [BP 230]
–Plectin

15. •Transmembrane
component
–BPAG2
α6 β4 integrin
α3 β1 integrin
–Type XIII collagen

16. •Lamina lucida,
lamina densa
component
–Laminin – 5
–Laminin – 6
–Laminin – 2
–Laminin - 1

17. • Lamina densa component
–Type IV collagen
–Nidogen [ entactin]
–Perlecan
• Anchoring fibril
components
–Type VIII collagen

19. • Plectin
–500 Kda protein
–Carboxy terminal and amino
terminal
–Promoting adhesion
–Mutation – EBS associated
with limb girdle muscular
dystrophy

20. BPAG1
•Non collagenous protein
•Carboxy and
aminoterminal
•Auto antibodies - BP

21. BPAG2 [ 180Kda
• transmembrane collagen[17]
• Intracellular / extracellular part
• Collagenous / non collagenous
domain
• NC-16A – immunodominant
epitope

23. Autoantibodies
–Bullous pemphigoid
–Cicatricial pemphigoid
–Pemphigoid gestationis
–Linear IgA bullous dermatosis
Mutation –
– Junctional epidermolysis bullosa [
Non- Herlitz type]

24. •Integrin
–Heterodimeric transmembrane
glycoprotein [α , β]
–Promote cell – cell and cell
matrix interaction
–Mutation – junctional EB with
pyloric atresia
–Auto antibody – ocular CP

26. • Laminins
–Hetero trimeric glycoprotein [αβγ]
–Structural component of extra
cellular matrix stabilized by
interchain disulphide bonds
–Laminin 1 - α1β1γ1
–Laminin 5 - α 3 β3 γ2
–Auto antibody – anti epiligrin CP
–Mutation - Junctional EB herlitz
type

27. • Type VII collagen
–Major component of anchoring
fibrils
–Three identical alpha1 chain
–Mutation - Epidemolysis bullosa
dystrophic
–Auto antibodies
•Epidemolysis bullosa acquisita
•Bullous SLE

28. •Collagen IV
–Main constituent of lamina densa
–2 polypeptide [α1 and α2]
–Large C terminal globular domain
–Aminoterminal at the other end
–Bind covalently at amino terminal to
form tetramers or spiders
–Point of overlap is referred to as 7s
domain

30. •Nidogen
–150 Kda glycoprotein
–Stabilizer of basement membrane,
binding to Type IV collagen, perlecan
and laminin
• Perlecan [ Heparan sulphate
proteoglycan]
–Stabilizer of basement membrane
–Help for turn over and synthesis of
basement membrane

32. Target common to autoimmune andTarget common to autoimmune and
inherited blistering diseasesinherited blistering diseases
Protein
target
Auto immune
disease
Genetic disease
1 Plectin EB asso. Muscle
dystrophy
2 BPAG1 BP EB [Non-Herlitz]
3 BPAG2 BP, PG, CP, LABD
4 Laminin – 5 Antiepiligrin CP Junctional EB [ Herlitz]
5 α6 β4 integrin Ocular CP Junctional EB with
pyloric atresia
6 Type VII
collagen
EB acquisita
Bullous SLE
Dystrophic EB

33. Sub – Epidermal ImmunobullousSub – Epidermal Immunobullous
diseasesdiseases
Disease Antigen
Bullous pemphigoid BPAG1
BPAG2
Pemphigoid gestations BPAG2
Cicatricial pemphigoid BPAG2
LABD BPAG2
Anti epiligrin CP Laminin 5
EB acquisita Type VII collagen
Bullous – SLE Type VII collagen

34. Salt split skin techniqueSalt split skin technique
•Split in a laboratory with
1M Nacl, studied by both
direct and indirect IF
•Spilt occurs at lamina
lucida