3. Causes of Allograft Failure
Primary Nonfunction – slightly more common in
Living Donors
Vascular Complications – 10% of patients
Hepatic Artery Thrombosis/Stricture
Portal Vein Thrombosis/Stricture
Hepatic Vein Thrombosis/Stricture
Biliary Complications –
Donors after Cardiac Death
Living Donors
Anastomotic vs nonanastomotic strictures
4. Causes of Allograft Failure-
Rejection
Antibody Mediated Rejection – hours to
days
10-20% Acute Rejection
Risk 1st 3months>1st year>subsequent
years
Chronic Rejection – a primary RF is prior
episodes of Acute Rejection.
Acute vs Chronic –
○ time course
○ pattern of liver enzyme abnormalities
○ response to therapy
5. Transplant Rejection – Issues for Critical Care
Single organ dysfunction of organ under Rejection
MOF related to single organ dysfunction
Extended Immunosuppression
Infections
Drug Interaction
Toxicity
Sepsis and MOF
Drug Toxicity
Renal Failure
7. Late Hepatic Allograft Dysfunction : Wiesner et al. Liver Transpl
2001
Rejection
Causes reduction or withdrawal of immunosuppressants,
erratic absorption
poor compliance
Poor prognosis Rejection in Hep C Tx
High risk for Ac rejection Age less than 30 years
Tx for an autoimmune liver disease
ALD
Child’s A at the time of Tx
Interferon for Hep C
Low Risk for Ac Rejection Age more than 60 years
Tx for Alcoholic liver disease
Child’s class C at the time of Tx
Immunospp. Regimen high-dose steroids response 80%
Others require antilymphocyte therapy
Less rejection with tacrolimus than
cyclosporine regimens
14% rejection rate with Tacro and
sirolimus combination
8. Late Hepatic Allograft Dysfunction
Russell H. Wiesner and K.V. Narayanan Menon
Liver Transplantation, Vol 7, No 11, Suppl 1 2001
9. Types of Transplant
Autograft is self-tissue transferred from one
body site to another in the same individual.
Isograft is tissue transferred between
genetically identical individuals.
Allograft is tissue transferred between
genetically different members of the same
species.
Xenograft is tissue transferred between
different species
10. Immunology of Transplant Rejection
Components of the Immune system involved in graft Rejection :
1) Antigen presenting cells –
○ Dendritic cells
○ Macrophages
○ Activated B Cells
2) B cells and antibodies –
○ Preformed antibodies
○ Natural antibodies
○ Preformed antibodies from prior sensatization
○ Induced antibodies
3) T cells
4) Other cells –
○ Natural killer cells
○ T cells that express NK cell – associated Markers
○ Monocytes/Macrophages
11. Recognition of
Alloantigens
Direct Presentation
Recognition of an intact MHC molecule displayed by donor APC
in the graft
Basically, self MHC molecule recognizes the structure of an
intact allogeneic MHC molecule
Involves both CD8+ and CD4+ T cells.
12. Indirect Presentation
Donor MHC is processed and presented by recipient
APC
Basically, donor MHC molecule is handled like any other
foreign antigen
Involve only CD4+ T cells.
Antigen presentation by class II MHC molecules.
13. Activation of Alloreactive T cells
and Rejection of Allografts
Donor APCs migrate to regional lymph nodes
and are recognized by the recipient’s TH
cells.
Alloreactive TH cells in the recipient induce
generation of TDTH cell and CTLs then
migrate into the graft and cause graft
rejection.
14. Activation of Alloreactive T
cells and Rejection of
Allografts
(SENSATIZATION)
Passenger leukocyte
Class II MHC.
antigen
H H T T
IL 2
H T H T
Donar kidney
CTL
CTL
T DTH DTH T
EFFECTOR LYMPH NODE
15. Role of Cytokines in Graft Rejection
IL – 2, IFN – , and TNF - are important mediators of graft
rejection.
IL – α promotes T-cell proliferation and generation of T –
Lymphocytes.
IFN - is central to the development of DTH response.
TNF - has direct cytotoxic effect on the cells of graft.
A number of cytokines promote graft rejection by inducing
expression of class – I or class – II MHC molecule on graft cell.
The interferon (α, and ), TNF – α and TNF - all increases
class – I MHC expression, and IFN - increases class – II MHC
expression as well.
17. Hyperacute Rejection
Characterized by thrombotic occlusion of the graft
Begins within minutes or hours after anastamosis
Pre-existing antibodies in the host circulation bind
to donor endothelial antigens
Activates Complement Cascade
1.Preformed Ab
2.complement activation
3.neutrophil margination
4.inflammation,
5.Thrombosis
18. Acute Rejection
Vascular and parenchymal injury mediated by T
cells and antibodies that usually begin after the
first week of transplantation if there is no
immunosuppressant therapy
Incidence is high (30%) for the first 90 days
T-cell, macrophage
and Ab mediated,
myocyte and endothelial
damage,
Inflammation
19. Chronic Rejection
Occurs in most solid organ transplants
Heart
Kidney
Lung
Liver
Characterized by fibrosis and vascular abnormalities with
loss of graft function over a prolonged period.
Macrophage – T cell mediated
Concentric medial hyperplasia
Chronic DTH reaction
20. Graft vs. Host Disease
Caused by the reaction of grafted
mature T-cells in the marrow inoculum
with alloantigens of the host
Acute GVHD
Characterized by epithelial cell death in the
skin, GI tract, and liver
Chronic GVHD
Characterized by atrophy and fibrosis of one
or more of these same target organs as well
as the lungs
23. Causes of Liver Test Abnormalities in
Asymptomatic Recipient
Allograft parenchymal damage
Immune-mediated disease
rejection and de novo AIH)
Recurrent Liver disease
Drug toxicity
immunosuppressive drugs
Alcohol and other toxins
De novo infection
Bacterial, Viral (de novo HBV and
HCV)
Space-occupying lesion
De novo or recurrent NAFLD
Biliary damage
Biliary strictures , anastomotic strictures,
Hep A Stricture
Biliary stones/cast syndrome
Recurrent PSC
Vascular disease
Hepatic artery thrombosis
Portal or hepatic vein thrombosis
Metabolic disease of Graft
Gilbert’s syndrome
Nonhepatic disease
Hemolysis –
indirect bilirubin
Bone disease
raised ALP
Nonhepatic disease
Celiac disease
Diabetes
24. Late Hepatic Allograft Dysfunction
Russell H. Wiesner and K.V. Narayanan Menon
Liver Transplantation, Vol 7, No 11, Suppl 1 (November), 2001
Time to first rejection episode among adult liver
recipients who rejected following liver transplantation.
26. Episodic Treatment of
Rejection
Immunotherapy is truly a treatment
that delays the inevitability of graft
rejection.
Rejection Episodes can be treated by
the one of the following treatments:
Corticosteroid
Polyclonal and Monoclonal Antibodies
Antiproliferatives
Alternative Therapies
Xenotransplantation
Tissue Engineering
Stem Cell Research
Induction of Tolerance
27. Recommendations for Prevention and Tt of Rejection
Immunosuppressants recipients should be prescribed and
monitored by expertis in that area
The choice of agents is multi-factorial, and no one regimen
can be recommended for any patient (grade 2, level A)
Reviewed at least every 6 months and modified as required
Goal of minimizing long term toxicities (grade 1, level B).
Rejection can be diagnosed only on the basis of liver biopsy
classified according to Banff criteria (grade 1, level A)
Long-Term Management of the Successful Adult Liver Transplant: 2012 Practice
Guideline by the ASSLD and AST. Michael R. Lucey:
LIVER TRANSPLANTATION 19:3-26, 2013
28. Clinical Immunosuppression
Two types of immunosuppression are used in transplantation:
Induction and Maintenance immunosuppresion
Adverse side-effects that include
high incidence of opportunistic infection
transplant-related malignancies in patients
Major goal of immunosuppression
Identify the optimal balance of therapy
Effective prevention of allograft rejection
Minimized Adverse effects, infection & malignancies
29. A cute cellular rejection (ACR) is a very common
event that occurs in utpo 70% of orthotopicl iver
transplant (OLT) recipients within the first year.l The
highest incidence is around 7 to 10 days posttransplantation.
ACR occurs i n 10% to 70% of patients,
depending on the primary immunosuppression used,
the indication for the transplantation, and the definition
of rejection.
histologic features of portali nfiltrate and endotheliitis, which suggest
mild
ACR, but without biochemical graft dysfunction, often
resolves without adjuvant immunosuppression.3
So, liver biopsies should be delayed until patients
develop biochemical graft dysfunction, unexplained
fever, or other surrogate markers of rejection.
Liver Transplantation, Vol8, No 12 (December), 2002:pp 1147-1 153
31. Timeline for the introduction of immunosuppression
medications.
Immunosuppression in Liver Transplantation. Post et al. LiverTransplantation, Vol 11, No 11,2005: pp
1307-1314
33. Immunosuppressive Drugs
Three main immunosuppressant drugs
Cyclosporins act by inhibiting T-cell activation, thus
preventing T-cells from attacking the transplanted
organ
Azathioprines disrupt the synthesis of DNA and RNA
and cell division
Corticosteroids such as prednisolone suppress the
inflammation associated with transplant rejection
34. Organ Specific Immunosuppressant
Classification
Kidney transplants
○ Basiliximab in combination with cyclosporin and
corticosteroids
Kidney transplants
○ Daclizumab in combination with cyclosporin and
corticosteroids
Kidney, liver and heart transplants
○ muromonab CD3 (Orthoclone OKT3) along with cyclosporin
Liver transplants Tacrolimus
○ under study for kidney, bone marrow, heart, pancreas,
pancreatic island cell, and small bowel transplantation.
35. Induction Therapy
Def: prophylactic application of periop antibodies in
addition to baseline immunosuppression. (immediate
posttransplant)
The goal : induce hyporesponsiveness in the organ
recipient toward the transplanted organ in order to
prevent early post-transplant rejection
Only T cells are inhibited and the rest of the patient's
immune system would remain fully functional
Agents: Earlier nonspecific polyclonal antibodies
Today, however, murine monoclonal anti-lymphocyte
antibodies, such as OKT3, are often used
Antimicrobials are a necessary component
36. Maintenance immunosuppression
Drugs administered to maintain immuno-suppression
once recipients have recovered
from the operative procedure.
Agents are either
Biological Monoclonal and polyclonal
antibodies
Generally used in induction
protocols
Nonbiological agents
Mainstay of maintenance protocols.
corticosteroids
azathioprine
cyclosporines
37. Maintenance Therapy
Maintenance immunosuppression refers to the classic
combination therapy (known clinically as Triple Therapy) to
which transplant recipients usually adhere for the rest of their
lives.
The Combination includes
a corticosteroid
a calcineurine inhibitor
an antiproliferative
The Goal Balance between underimmunosuppression and
overimmunosuppression
Consider potential interactions
38. Calcineurin Inhibitors (CNIs)
Calcineurine (cytokines activator ) Inhibitors are used in
maintenance immunosuppression.
Cyclosporin A From fungus Tolypocladium inflatum
selective suppression of CMI via inhibition
of T-cell activation
standard formulation (Sandimmune) emulsion
depends on bile flow, GI motility & food
intake
Unpredictable bioavailability
Microemulsion in lipophilic solvent (Neoral)
Predictable bioavailability
Drug Interactions
Nephrotoxicity – up to 20% post OLT Renal failure
Neurological manifestations – 10-28%
hyperkalemia, hypomagnesemia, hyperglycemia
Hypertension, gingival hyperplasia and hirsutism
Immunosuppression in Liver Transplant. Post et al. LiverTransplantation, 2005
40. Tacrolimus
From fungus Streptomyces tsukubaensis in Japan
Tacrolimus is a microlide antibiotic
100 times more potent than CyA
Inhibits calcineurin
TAC absorption uninfluenced by presence of bile
Lower first year rejection rate better with TAC compared to
CyA
Hepatitis C infected patients on TAC have longer graft
survival Immunosuppression in Liver Transplantation. Post et al. LiverTransplantation, Vol 11,
No 11,2005: pp 1307-1314
41. Common Side Effects of Tacrolimus
Post-transplant diabetes mellitus
Nausea, vomiting, diarrhea
Hyperkalemia
Tremor
Hypertension
Hypomagnesemia
Headache
Renal dysfunction
42. Sirolimus
Binds to same immunophilin as Tac (FKBP12) but with a
different mechanism of action
○ blocks response of T and B Cell Activation by cytokines
Theoretical (lab based) antineoplastic and antifungal
effects.
Early excitement about renal protective effect- subsequent
studies have not confirmed this
Black Box warning – possible increased risk of Hepatic
Artery Thrombosis in immediate post-OLT setting
Recent study of switch from CNI to SRL suggests possible
increased mortality
Currently using in those intolerant to CNIs, and in some
patients for theoretical antineoplastic and renoprotective
actions
Hepatology. 2010 Oct;52(4)
45. Corticosteroids
Prednisone and Methylprednisolone
Corticosteriods Maintenance immunosuppression
Teatment of acute rejection
Diffuse into cells and bind to specific
cytoplasmic receptors progress to the
nucleus, inhibit the transcription of the genes
of the cytokines
Block T cell, APC and Macrophase cytokines
IL-1, IL-6, IL-2, INF-γ , and TNF-α
Non-specific anti-inflammatory agents
acutely reduce lymphocytes & monocytes
Pretransplant bolus dose of methylprednisolone 500 to 1,000 mg,
followed by rapid taper over next few weeks to minimal dose, i.e.,
25-50 mg/day.
46. Common Side Effects of Corticosteroids
Hypertension
Mental status changes
Lipid abnormalities
Impaired wound healing
Hyperglycemia
Cushingoid syndrome
Ulcers
Myopathy
Osteoporosis
Fluid retention
Cataracts
47. Antiproliferative Agents / Antimetabolites
Mycophenolate Mofetil, Azathioprine, Sirolimus
Antiproliferative Block the proliferative phase of ACR
Maintenance immunosuppression
Treatment of rejection
Azathioprine Mercaptopurine derivative & antagonises purine metabolism
Significant myelosuppression and hepatotoxicity
Use decreased dramatically
Mycophenolate mofetil and Mycophenolic acid
Mycophenolate Mofetil (MMF)
Rapidly hydrolyzed in the blood to its active form: MPA
MPA inhibits enzyme IMPDH in the pathway of purine biosynthesis
Activated lymphocytes are selectively inhibited
Nausea, vomiting, diarrhea, Pancytopaenia
48. Antibody Induction
Antithymocyte Globulin – induction/rejection.
Polyclonal antilymphocyte globulin – multiple
epitopes on T cell receptor – lead to apoptosis
of T-cells
ATGAM (of equine origin)
Thymoglobulin (of rabbit origin)
Monoclonal anti T-Cell antibodies –
induction/rejection
Muromonab-CD3 (OKT3) – binds CD3 Antigen
on T-Cell receptor – inactivates adjacent T-Cell
– leads to rapid drop in T-Cells
IL-2 Receptor Antibodies – induction
Basiliximab (Simulect)
daclizumab (Zenapax).
49. Monoclonal Antibodies
Muromonab-CD3 (Orthoclone OKT3®)
Used in LTx in 1987 for prophylaxis against acute cellular rejection
and later to reduce CNI exposure and treatment of steroid-resistant rejection.
OKT3 use today is much lower, with many centers preferring treatment
regimens
for acute cellular rejection to increasing TAC blood levels and then adding
corticosteroid boluses if rejection is still present
Daclizumab (Zenapax®)
Interleukin-2 Receptor Antagonist (Basiliximab, Simulect®)
Monoclonal Antibodies are used in early rejection prophylaxis and treatment
of rejection.
Monoclonal antibodies are antigen-specific immunosuppressants that will
reduce immune response to alloantigens of the graft while preserving the
response to alloantigens to unrelated antigens.
These agents are specific to blocking T-cell activation, resulting in rapid
depletion of T cells from the circulation by binding of antibody coated T cells
to Fc receptors on phagocytic cells. The most recently FDA approved
monoclonal antibodies are the IL-2 receptor antagonists genetically
engineered to possess both human and murine antibody sequences. The
chimerization of these antibodies is an attempt to decrease the
immunogenicity of the agent. Other monoclonal antibody-based drugs are
50. Monoclonal Antibodies
Muromonab-CD3 is the first type of murine monoclonal antibody directed
against the ε chain of the CD3 molecule (an integral part of the T Cell
Receptor complex) and modulates the receptor and inactivates T-cell
function blocking both naïve T cells and CTLs. This results in rapid depletion
of T cells from circulation and cytokine release. This antibody is used to treat
acute rejection and steroid resistant rejection.
Basiliximab is a chimeric (70% human and 30% murine) monoclonal
antibody utilized in the prevention of acute organ rejection. This monoclonal
antibody has a specificity and high affinity for the α subunit of the interleukin
(IL)-2 receptor (IL-2Rα, also known as CD25 or Tac) preventing IL-2 from
binding to the receptor on the surface of activated T cells. By acting as an
IL-2Ra antagonist, Basiliximab inhibits IL-2-mediated activation and
proliferation of T cells, the critical step in the cascade of cellular immune
response of allograft rejection. Therefore, Basiliximab has a long half-life of
approximately 7-12 days and saturates the IL-2 receptor for up to 59 days.
Due to its high percentage of humanization in its antibody sequences the
occurrence and acuteness of adverse effects is significantly lower when
used with standard immunotherapy.
51. Monoclonal Antibodies
Muromonab – CD3 Daclizumab is a similar agent to Basiliximab, but is a more
humanized IgG monoclonal antibody (90% human and 10% murine). It also binds to
and inhibits the α-subunit of IL-2 receptor and thus works in a manner similar to
Basiliximab. Daclizumab is able to saturate the IL-2 receptor twice as long as
Basiliximab. Because it is more humanized, there are less side effects associated
with Daclizumab.
Side Effects – HAMA One of the major problems affecting monoclonal therapy is the
side effects associated with the HAMA (Human anti-Murine Antibody) response and
serum sickness. These are both directly caused by the structure of the antibodies.
Laboratories routinely use murine antibodies as a starting point for monoclonal
antibodies.
A counteractive measure includes humanizing (or chimerizing) the antibody. Because
the only immunologically offensive portion of the antibody is the constant region,
recombinant techniques can be used to splice and replace the constant region of the
murine antibody with that of a characteristic human antibody. Current drugs have been
developed that are more favorably humanized. They are also shown to be more
effective with less adverse side effects. Further chimerization and other
improvements in antibody therapy are active fronts of current research.
This poses a problem: human immune system is able to identify the murine antibody
as non-self and eliminate the treatment from circulation. This renders the monoclonal
therapy ineffective.
52. Immunosuppressive Therapy
Monoclonal antibodies
To suppress the activity of subpopulation of T-cells.
To block co-stimulatory signals.
Ab to the CD3 molecule of TCR (T cell receptor) complex results in
a rapid depletion of mature T-cells from the circulation.
Ab specific for the high-affinity IL-2 receptor is expressed only on
activated T-cell, blocks proliferation of T-cells activated in response
to the alloantigens of the graft.
To treat donor’s bone marrow before it is transplanted.
Molecules present on particular T-cells subpopulation may also be
targeted for immunosuppressive therapy.
Antibody to CD4 shown to prolong graft survival.
Ab specific for implicated cytokine can prolong the survival of graft.
53. Polyclonal Antibodies
Antithymocyte globulin-equine (Atgam®)
Antithymocyte globulin-rabbit (RATG, Thymoglobulin®)
Polyclonal Antibodies are used in early rejection prophylaxis, treatment
of rejection.
Polyclonal antibodies are directed against lymphocyte antigens
instead of the single-specificity of the monoclonal antibodies, these
anitlymphocyte antibodies are directed against multiple epitopes.
Antithymocyte globulin is a polyclonal antibody derived from either
horses (Atgam®) or rabbits (Thymoglobulin®). The agents contain
antibodies specific for many common T cell surface antigens including
CD2, CD3, CD4, CD8, CD11a, CD18. The antithymocyte globulin binds
lymphocytes that display the surface antigens previously listed. This
effectively depletes T-cell concentration in the body through
complement-dependent cytolysis and cell mediated opsonization
following with T cell clearance from the circulation by the
reticuloendothelial system (RES).
Side effects can include
first-dose effect (cytokine release syndrome) and is related to cytokines
release by these lymphocytes upon their demise.
fever, chills, tachycardia, gastrointestinal disturbances,bronchospasm,
54. Summary
CsA, Tac or Sirolimus are the backbone
of maintenance immunosuppresion
Addition of other agents (Steroids, MMF,
Azathioprine) can be used to decrease
risk of rejection or allow for lower doses
of the primary agents.
50% of post-OLT deaths are
directly/indirectly related to
immunosuppressive medications.
55. Reading
McGuire BM et al. Long-term Management of
the Liver Transplant Patient:
Recommendations for the Primary Care Doctor
American Journal of Transplantation 2009; 9:
1988–2003
Post DJ. Immunosuppression in Liver
Transplantation. Liver Transplantation, 2005; 11:
1307-1314