Autoimmune diseases Flashcards
name 2 blistering diseases
pemphigus
pemphigoid
name 2 CT diseases
Sjogrens Syndrome
SLE
name 2 vasculitis
erythema multiforme
Behcets disease
give 4 causes of blistering diseases
trauma extreme temp chemical exposure medical conditions -infective -genetic -autoimmune
definition of AMBDs
Ig-mediated diseases with autoantibodies against desmosomal or basement membrane zone molecules
what is the classification of pemphigus based on?
different clinical and histopathological features
give the 5 broad types of pemphigus
pemphigus vulgaris pemphigus foliaceus drug-induced pemphigus paraneoplastic pemphigus IgA pemphigus
which is the most common type of pemphigus and the one that gives oral lesions?
pemphigus vulgaris
give a subtype of pemphigus vulgaris
pemphigus vegetans
give 2 subtypes of pemphigus foliaceus
pemphigus erythematosus - localised
fogo selvagem - endemic
pathogenesis of pemphigus
autoantibodies against proteins that constitute desmosomes
intraepithelial blister and acantholysis
autoantibodies deposited in epithelium - complement activated and plasmin
2 types of intraepithelial blister in pemphigus
supra basal (lower) sub corneal (higher)
what is acantholysis?
when desmosomes separate
why are there different types of pemphigus?
because desmosomes are complex - attack against a specific desmosome protein gives you a specific type of pemphigus
not just a single attack on a single protein
anti-Dsg3 IgG
autoantibodies against Dsg3 attack desmosomes
how many self-antigens are recognised by IgGs in patients with PV and/or PF?
more than 50
what does the severity and exact clinical picture of pemphigus depend on?
ratio of different kinds of autoantibodies in each particular pt
what type of surface does pemphigus affect?
any stratified squamous epithelium
pemphigus epidemiology
uneven geographic and ethnic distribution
high incidence in Ashkenazi jews and those of mediterranean origin
what age group does pemphigus usually affect?
40-60 years
gender distribution of pemphigus
M=F
where does the mucosal phenotype of pemphigus typically begin and progress to?
usually begins oral cavity
can spread to skin - face, back, chest, genitals
pemphigus features in the oral cavity
desquamative gingivitis
soreness, blistering, erosions
can be covered by yellow fibrinous slough
rare to see intact blisters in oral cavity (trauma) - see erosions
lesions can be painful to brush, but plaque irritates lesions
can easily peel off - leaves haemorrhagic erosion underneath
which sites in the oral cavity are most affected by pemphigus?
buccal mucosa
tongue
pemphigus - what is spongiosis?
blister about to form
cells in epithelium full of fluid
does the mucosal phenotype of pemphigus affect just the skin?
rarely
pemphigus prognosis
untreated often fatal due to dehydration/infection
pemphigus prognosis mucosal lesions
may persist even though skin lesions are controlled
topical CS/tacrolimus may then help
BM zone
hemidesmosomes
lamina lucida
lamina densa - sub epithelial split
sublamina densa
pathogenesis of pemphigoid
autoantibodies against hemidesmosomes deposited in epithelium
complement activated, leukocytes recruited - damage to BM
sub epithelial blister or sub-lamina densa (deeper) split
what age group is pemphigoid most common in?
> 75s
is pemphigoid common?
no
gender distribution of pemphigoid
F>M
epidemiology of MM pemphigoid
extremely rare
prevalence 25 per million
clinical presentation of MM pemphigoid
mostly affects mucosae - conjunctiva, nasal, oral, genital
occasionally skin
why do blisters in pemphigoid persist longer?
blister has thicker roof and is more attached to the floor of blister
which areas of the oral cavity are often affected by MM pemphigoid?
interface of hard and soft palate soft palate
uvula
gingivae
pemphigoid prognosis without treatment?
may persist with periods of remission and flare ups for many years
pemphigoid prognosis with treatment?
immune response and inflammation can be suppressed
is pemphigoid fatal?
no
what is Nikolsky’s sign?
induce an erosion by rubbing on the skin
2 types of Nikolsky sign sites?
marginal - next to blister
direct - perform on healthy skin
Nikolsky’s sign in oral cavity
PD probe/spatula under roof - can extend and peel roof off v easily
positive Nikolsky sign
indicator you might be dealing with blistering diseases
sensitivity and specificity of Nikolsky sign
poor sensitivity - means you miss a lot of cases
good specificity - pts with no disease test negative
aim of biopsy of suspected AMBDs and why is this difficult?
aim for intact blister to send to pathologist so they can determine whether intra or sub epithelial
difficult as tissues fragile
biopsy procedure for suspected AMBDs
2 parallel incisions
hold blister with tweezers and cut underneath
why is biopsy of suspected AMBDs easier on attached gingiva?
there is bone underneath
what is needed in addition to biopsy/Nikolsky sign to confirm diagnosis of AMBDs?
autoimmmune diagnosis
What is direct immunofluorescence done on?
specimen - pts perilesional oral mucosa
- you send some for H and E and some for DIF
added primary antibody labelled with a fluorescent probe - intercellular epithelial staining
aim of DIF
to detect tissue bound immunodeposits
- inside epithelium if pemphigus vulgaris
- along BM zone if pemphigoid
what is indirect immunofluorescence done on?
pts sera - take blood
aim of IIF?
to detect circulating IgG antibodies in bloodstream - identify immunologic signal
procedure of IIF
on specific substrate
added a secondary antibody labelled with fluorochrome to recognise a primary antibody from patients serum
substrates used in IIF
monkey oesophagus, normal skin or rat uroepithelium
diagnosis of pemphigus - DIF
fishnet like pattern
presence of IgG and/or C3 as well as IgA deposition within the intercellular spaces throughout the epithelium
may also get IgM or IgA (in the IgA variant get this expression)
diagnosis of pemphigus - IIF
high % will be positive
IgG, C3, IgM, IgA
histopathology of pemphigus
intraepithelial blisters
if DIF in pemphigus shows intercellular epithelial staining and IgA, what is the diagnosis?
IgA pemphigus
if DIF in pemphigus shows intercellular epithelial staining and DSG1?
PF
if DIF in pemphigus shows intercellular epithelial staining and DSG-3?
OPV
if DIF in pemphigus shows intercellular epithelial staining and DSG-1 and 3?
MCPV
if DIF in pemphigus shows intercellular epithelial staining and desmocollins 1-3?
PNP/PAMS
diagnosis of pemphigoid - DIF
linear pattern at BM zone - u or n serrated
IgG and/or C3 as well as IgA deposition along the BM zone
DIF in pemphigoid - u serrated
EBA
bullous lupus
DIF in pemphigoid - n serrated
bullies pemphigoid
MM pemphigoid
P200 pemphigoid
pemphigoid - IIF salt split
mucosal sample incubated at 4 degrees in 5cc NaCl for 24-48hrs
NaCl acts like scissors at lamina lucida - get roof and floor
pemphigoid IIF - floor blister (dermal)
bullous lupus
deeper MM pemphigoid
epidermolysis bullosa
pemphigoid IIF - mixed floor and roof blister
MM pemphigoid - autoantibody attack between lamina lucida and lamina dura (middle of BP180)
pemphigoid IIF - roof blister (epidermal)
bullous pemphigoid
MM pemphigoid
LP pemphigoid
pemphigoid histopathology
sub epithelial blister
pemphigoid - if DIF shows IgA pattern at BM zone
linear - LAD
granular - DH
what is ELISA?
enzyme-linked immunosorbent assay
detects anti-Dsg antibodies
advantages of ELISA
quantitative method for measuring specific circulating antibody levels
plates read automatically and results do not depend on observer
disadvantages of ELISA
may not detect all subtypes of autoantibodies involved in the pathogenesis of AMBDs
e.g. negative result for anti-Dsg1 and 3 does not rule out possibility of other auto antigens in different subtypes of pemphigus
how should ELISA be used?
as a complementary test to IIF and not as a substitute
ELISA process
plates precoated with recombinant antigen (Dsg1, 3, BP230, BP180)
add pt sera (containing antibodies)
antigen-antibody complex formed
add enzyme (HRPO) conjugated anti-antibody
antigen-antibody-antiantibody complex formed
add substrate (TMB) to enzyme
substrate converted by enzyme to detectable coloured product
why is early diagnosis of AMBDs important?
may not be AMBDs
- mucocutaneous side effect of meds e.g. sunitinib for breast cancer
- secondary syphilis
prevent mucosal spread
-nasal, anogenital, ocular, voice box, oesophagus (dysphagia)
prevent mucocutaneous spread
mucosal scarring phenotype of MMP
which AMBD can cause scarring and why?
pemphigoid
subepithelial so BM zone affected - get scar tissue
does pemphigus cause scarring?
no as intraepithelial
consequences of mucosal scarring phenotype of MMP
oesophageal stricture if scarring
eye scarring - if reaches corneal limbus (contains corneal SCs) pt will develop blindness. opacification of iris and pupil, inflammation of conjunctiva
what type of syndrome is Paraneoplastic Autoimmune Multiorgan Syndrome?
mucocutaneous
what is PAMS?
a distinct clinical entity characterised by heterogeneous group of S+S including -severe desquamative stomatitis -a polymorphous cutaneous eruption -ofren a progressive respiratory failure develop due to an underlying malignancy
when may PAMS occur?
well before the discovery of occult malignancy or lymphoproliferative disorder
need extended clinical follow-up
haematological malignancies that can cause PAMS
NHL
chronic lymphocytic leukaemia
Castleman disease
non-haematological malignancies that can cause PAMS
carcinomas
sarcomas
malignant melanoma
pathogenesis of PAMS
cancer cells activate a wide number of immune cells
activated auto reactive T cells induce both humeral and cell-mediated immunity
PAMS - how do humoral and cell-mediated immunity cause its features?
humoral immunity (mostly autoantibodies) - acantholysis (resembles pemphigus)
cell-mediated immunity - lichenoid dermatitis (resembles lichenoid)
both - bronchiolitis obliterates (life-threatening)
get these features based on % of 2 types of immunity
what is the major antigenic target in PAMS?
plakins
- desmoplakin 1 and 2, envoplakin, periplakin, pectin, BP230
how many clinical phenotypes of PAMS
may have at least 5 - both humoral and cytotoxic immunities involved in development of PAMS
give some clinical phenotypes of PAMS
autoantibody mediated cytotoxicity
pemphigus like (aka PNP) bullous pemphigoid like EM like GvHD like LP like
cell-mediated cytotoxicity
clinical features of PAMS
ocular - inflammation of conjunctiva, ectropion (eyelid turns outward)
lip lesions
oral lesions
is there a diagnostic criteria for PAMS?
no generally accepted diagnostic criteria
Components of the suggested diagnostic criteria for PAMS
clinical signs histopathology DIF IIF detection of circulating autoantibodies against detection of a neoplasm
suggested diagnostic criteria for PAMS - clinical signs
severe stomatitis - MANDATORY
blisters
LP like plaques
bronchiolitis obliterans
suggested diagnostic criteria for PAMS - histopathology
supra basal blistering, acantholysis, lichenoid interface dermatitis with keratinocyte necrosis
suggested diagnostic criteria for PAMS - DIF
IgG intercellular in epithelium / and IgG/C3 at BM zone
suggested diagnostic criteria for PAMS - IIF
IgG intercellular in epithelium
suggested diagnostic criteria for PAMS - detection of circulating autoantibodies against
envoplakin or periplakin - MANDATORY
Dsg 1, 3
desmoplakin 1+2, plectin, BP230, 170-KDa protein
suggested diagnostic criteria for PAMS - detection of a neoplasm
MANDATORY
mandatory components of suggested diagnostic criteria for PAMS
severe stomatitis
detection of circulating autoantibodies against envoplakin or periplakin
detection of a neoplasm
suggested diagnostic criteria for PAMS - if specific detection of antibodies against envoplakin or periplakin is not available what do you use as mandatory criterion?
DIF or IIF - needs to be positive
why is PAMS usually non-responsive to immunosuppressive therapies?
related to an underlying neoplasm
treatment of PAMS
treat underlying malignancy
not always sufficient
why is early diagnosis of PAMS essential?
early diagnosis and treatment of underlying malignancy - more favourable prognosis
coordinated MDT in AMBDs
oral med dermatology ENT ophthalmology gynecology gastroenterology infectivology endocrinology urology psychiatry
what should you do before making a treatment plan for AMBDs?
determine the extent of disease
determining the extent of disease in AMBDs
routine lab work screening for infections tumour markers and instrumental exams - EKG, CT, DEXA medical consults additional exams for biologic therapies
why do you need to screen for infections before treating AMBDs?
don’t want to reactivate any silent infections as you will be using immunosuppressive meds
why do you need to carry out instrumental exams and tumour markers before treating AMBDs?
ensure no underlying malignancy
what do you need to screen for before using biologic therapies to treat AMBDs?
thrombophilia
conventional therapy in PV
attack phase - CSs immunosuppressive
+/- adjuvant CS sparing agents
CHX 0.12% alcohol free rinse
topical and/or systemic anti-mycotic agents if you see candidiasis overgrowth
PV - first line attack phase of treatment
corticosteroids: prednisolone 1-2.5mg/kg
PV - adjuvant corticosteroid sparing agents
azathioprine mycophenolic acid cyclophosphamide methotrexate cyclosporine dapsone tetracycline nicotinamide (vitB3)
PV - adjuvant corticosteroid sparing agents - dose of azathioprine
1-2.5 mg/kg
PV - adjuvant corticosteroid sparing agents - dose of mycophenolic acid
35-40 mg/kg
PV - adjuvant corticosteroid sparing agents - dose of cyclophosphamide
2-2.5 mg/kg
PV - adjuvant corticosteroid sparing agents - dose of methotrexate
10-20 mg/wk
PV - adjuvant corticosteroid sparing agents - dose of cyclosporine
3-5 mg/kg
PV - adjuvant corticosteroid sparing agents - dose of dapsone
50-200mg
PV - adjuvant corticosteroid sparing agents - dose of tetracycline
2g
PV - adjuvant corticosteroid sparing agents - dose of nicotinamide (vit B3)
1.5g
intra and perilesional injections of triamcinolone in PV
often used if stubborn remnant lesions and you want to taper the systemic corticosteroids
reduces healing time
indications for advanced therapeutic options in AMBDs
- pts non-responders to at least one standard regimen inc the combination of systemic glucocorticoids (at min dose of 1mg/kg body weight prednisolone equivalent) and other immunosuppressants or immunomodulators
- pts who developed significant SE from conventional systemic therapies
- pt unable to achieve a sustained clinical remission on standard regimens
types of advanced therapeutic options in AMBDs
IV IgG rituximab antiTNFa plasmapheresis immunoadsorption
IvIgG in AMBDs
anti-inflammatory properties
increases catabolism of autoantibodies
decreases synthesis of autoantibodies
neutralises pathogenic autoantibodies
AMBDs - rituximab contraindications
active severe infections
severely immunocompromised
severe heart failure/uncontrolled cardiac disease
pregnancy
AMBDs - rituximab action
anti-CD20 medication - monoclonal antibodies that attack molecule on B cells
2 ways in which rituximab works as an anti-CD20 medication
- directly targets CD20+ autoreactive B cells as progenitors of autoantibody secreting plasma cells
- B cells destroyed so don’t get autoantibodies produced - ADCC cytotoxicity, complement-dependent cytotoxicity, apoptosis - indirectly decreases the freq of autoreactive T cells, which initiate and perpetuate the autoimmune response in pemphigus
effectiveness of rituximab in AMBDs
low rate of relapses and side effects
what is the issue with treating MM pemphigoid?
lack of evidence
low risk MM pemphigoid
oral mucosa only
oral mucosa and limited skin
no ocular, genital, oesophageal, laryngeal
high risk MM pemphigoid
diffuse oral mucosa
progressive oral mucosa
ocular, genital, oesophageal, laryngeal
initial treatment of low risk MM pemphigoid
topical CS dapsone tetracycline and nicotinamide sulphametoxypyridazine sulphapyridine
can also use high risk txs if needed
initial treatment of high risk MM pemphigoid
CS +/- (0.5-1.5mg/kg)
azathioprine\cyclophosphamide
mycophenolic acid
can also use low risk txs
tx of MM pemphigoid if partial response or progressive disease
IvIgG
RTX
IvIgG dose in MM pemphigoid
2-3g/kg/day diluted on 3-5 days, monthly
RTX dose in MM pemphigoid
375mg/sqm²/day, 4 weekly infusions
or
1g/day, 2 infusions (TO-TIS)
MMP treatment - biologics as a first line adjuvant indications
contraindication to systemic CS
paediatric/young pts
rapid progression (ocular, laryngeal, oesophageal)
Primary SS triad
exocrinopathy (often results in dryness of mouth and eyes)
fatigue
joint pain
- main features but there are others
what does the prevalence of SS vary depending on?
classification criteria used
most common age for SS
40-60yrs
incidence of SS
4 per 100 000
gender distribution of SS
much higher in F
proposed immunopathogenic mechanisms of SS
microbial trigger
destroys salivary gland epithelium
produces autoantigens - nucleic acid and T1 interferon
triggers reaction of B cell and CD4 T cell
differentiation of B cells in plasma cells
produce autoantibodies - form immunocomplex with autoantigens
captured by DCs - produces T1 interferon amplifying immune response
activation of cytotoxic CD8 - directly destroys salivary gland epithelium through cytotoxic granules
produces new neoantigens and amplifies immune response
innate and adaptive immunity pathways
SS env factors
no single causative env factor identified
data continue to support infections as an important risk factor
biological factors
organic chemical factors
inorganic chemical factors
lots interact in a temporal contribution
SS biological factors
bacteria viruses vaccination hormones vit D stress
SS organic chemical factors
alcohol
smoking
solvents
SS inorganic chemical factors
silicone
silica
SS genetic factors
may both determine the baseline disease susceptibility and disease phenotype as well as interact with the different types of env factors
what 2 broad factors may contribute to the development of SS?
env factors
genetic factors
in what % of SS pts do systemic manifestations occur?
about 30-40%
systemic manifestations of SS
constitutional symptoms lymph nodes renal articular cutaneous peripheral neuropathy muscular pulmonary glandular CNS
systemic manifestations of SS - constitutional symptoms
fever
weight loss
night sweats
systemic manifestations of SS - LNs
benign lymphadenopathy/lymphoma
systemic manifestations of SS - renal
interstitial nephritis
systemic manifestations of SS - articular
arthralgia with morning stiffness or synovitis
systemic manifestations of SS - cutaneous
purpura
vasculitis
subacute cutaneous lupus
systemic manifestations of SS - muscular
myositis
pain/weakness