mod 1 slide 2 (macrophages, DC, & T-cells)

recall cells derived from hematopoiesis — myeloid pathway and therapeutics

• neutrophils — what 2 things are associated with it?

• neutropenia

  • G-CSFs

recall cells derived from hematopoiesis — myeloid pathway and therapeutics

• erythrocytes — what 2 things are associated with it?

• anemia

  • ESAs

recall cells derived from hematopoiesis — myeloid pathway and therapeutics

• eosinophils — what 2 things are associated with it?

• eosinophilic asthma most mature

  • IL-5 Mab inhibitors

cytokines - prefixes: IL

• is the molecular weight high or low?

• hundreds known

• _____ proteins or glycoproteins (IL, growth factors)

• secreted by and utilized by ____ cells (neutrophils, macrophage, lymphocytes) and various other cells (epithelial cells. fibroblasts) in response to a number of stimuli

• low — < 20 kD

• regulatory

• immune

a more relevant example: IL-6 and SARS-CoV2

• ______ is a proinflammatory cytokine produced by a variety of cells types, including lymphocytes, monocytes, and fibroblasts - normal levels in blood range from 1-5 pg/mL

• infection by SARS-CoV2 induces _____ of ____ from bronchial epithelial cells (lung)

• COVID-19-associated systemic inflammation and respiratory failure can be associated with increased _____ release, as indicated by elevated blood levels of IL-6

• it was hypothesized that modulating IL-6 levels may reduce the ____ and/or ______ of COVID-19

• interleukin (IL) 6

• overproduction of IL-6

• cytokine

• duration; severity

a more relevant example: IL-6 and SARS-CoV2

• on Dec. 1, 2022, the FDA approved the use of intravenous (IV) (ACTEMRA) tocilizumab for the treatment of COVID-19 in _____ adults who are receiving systemic corticosteroids and require supplemental oxygen, mechanical ventilation, or extracorporeal membrane oxygenation (ECMO)

• this drug is a biologic-monocolonal antibody that _____ _____ IL-6

• ACTEMRA was initially indicated for ______ _____ years earlier and for other IL-6 associated inflammatory disorders

• repurposed therapeutic

• hospitalized

• specifically blocks

• rheumatoid arthritis

macrophages

• large, mononuclear cell derived from _____ in bone marrow

  • once monocyte leaves circulation and enters tissue, it can differentiate to a _____

• macrophages are scavenger immune cells that ___ ____ and other cellular debris generated during tissue remodeling and clear cells that have undergone apoptosis (through process of ____)

• macrophages clear approx. 2 × 10¹¹ aged erythrocytes each day; this equates to almost 3 kg of iron and hemoglobin per year tat is “recycled“ for the host to use

• function as a professional antigen-presenting cells (APC) — recognized by and communicate with __ ____

• express ___ ___ ___

• monocytes

  • macrophage

• digest bacteria; phagocytosis

• T-cells

• class II MHC (major histocompatibility complex)

macrophages

• what are the 2 main subsets or phenotypes?

1. M1 — classically activated (microbial activity)

2. M2 wound-healing (tissue repair)

macrophage differentiation: distinct phenotypes - M1 and M2

• M1

  • what does it do?

  • pro or anti inflammatory?

• M2

  • what does it do?

  • pro or anti inflammatory?

• kill-digest bacteria

• pro inflammatory

• wound healing-tissue repair

• ant inflammatory

macrophage differentiation: distinct phenotypes - M1 and M2

• _______, also known as endotoxins, are complex molecules found in the outer membrane of gram-negative bacteria

  • ____ is a cytokine that is produced by T-cells and NK cells

• ____ ____ ____ is a blood test used to detect infection with mycobacterium tuberculosis (MTB), the bacteria that cause tuberculosis (TB)

• lipopolysaccharides (LPS)

  • IFN-γ

• IFN-γ release assay (IGRA)

bone

osteoclasts

bone marrow/blood

monocytes

central nervous system

microglia

liver

kupffer cells

skin and mucosa

langerhans cells

tissue-specific names given to macrophages

• kupffer cells (KC) are liver-resident macrophages

  • they are the ___ cells that are in contact with compounds absorbed from the gastrointestinal tract

• once they are activated, KCs can differentiate into M1-like macrophages or M2-like macrophages depending on what?

• first

• depending on the signals they receive from their environment (cytokine signaling)

dendritic cells (DC)

• some DC are derived from _____, just like monocytes

  • bridge ____/_____

• what do they function as?

• found in ALL tissues, higher in those that have ___ ___ ____ ____ ___, such as lung mucosa, epithelial cells of the skin, and the linings of the nose and the GI tract

• what 2 distinct functional states are they found in?

• cancer vaccine development: patients own DCs are used as a cell therapy — matures and activated in vitro with tumor antigens and given back to patient — DCs are now ____ to tumor antigens

• monocytes

  • innate/adaptive

• professional antigen-presenting cells (APC), recognized by T-cells — highly specialized

• contact with the outside environment

• mature and immature

• specific

what cells are adaptive — cells derived from lymphoid pathway?

• B-cell

• T-cell

• NK

what cells come from the myeloid pathway?

• monocyte

• basophil

• eosinophil

• neutrophil

what cells are derived from monocytes?

• dendritic cell

• macrophage

T-cells

• what are T-cells?

• by expressing membrane-bound proteins and secretin soluble cytokines, what do they control?

• certain T-cell subsets perform ___ functions and limit the ____ of immune responses

• what is the hallmark of adaptive response?

  • what is their role?

• central regulators of the adaptive immune response

• control antibody responses, activate innate immune cells, and lyse target cells

• suppressive; duration

• memory T-cells

• to distinguish SELF from NON-SELF

major T-cell subtypes

• the function and identity of a given T-cell can be broadly determined by what beginning in early development?

• originating from the bone marrow, T-lymphocyte precursors migrate to the ___ where they mature and undergo further selection based on cytokine signals and interactions with antigens

• the majority of new T-cell that successfully leave the thymus can be broadly sorted into what 2 groups?

• its cell surface proteins

• thymus

• CD4+ helper T-cells (4 flavors)

• CD8+ cytotoxic T-cells

what are the 4 types of the CD4+ helper T-cell?

1. TH1 cell

2. TH2 cell

3. Treg cell

4. TH17 cell

clusters on differentiation: CD markers on immune cells

• what are clusters of differentiation (CD)?

• CD molecules play key roles in immune ___ ___ ____ and are essential markers for the ____ and ____ of the different cell types in the immune system

• they are ____ of immune cells — many different CD types on specifically cells - change phenotype during differentiation

• over 300 CDs identified

• HIV infects CD4+ T-cells (T-helper cells), with a preference for TH17 and Treg cells

• cell surface proteins expressed on cells of the immune system such as lymphocytes (T-cells, B-cells, and NK-cells), neutrophils, and monocytes/macrophages

• cell-cell communication; identification and isolation

• fingerprints

CD markers are diagnostic and prognostic

• CD markers, and the antibodies directed against them, are widely used in research in human and animal models

• these markers play a crucial role (___ ____) by enabling researching t identify and track specific cell population infiltrating within tumors

• note - CD45 is referred to as ____ common antigen

• CD34 is associated with hematopoietic ___ ___

• cancer research

• leukocyte

• stem cells

example: CD44 and breast cancer

• CD44 is a cell surface glycoprotein that is _____ in breast cancer and is associated with cancer progression and metastasis

• it is one of many tumor biomoarkers - in this instance, the tissue (tumor) is ____ observed throuh histology staining (see brown color on OUTSIDE of cells)

• studies have shown that targeting CD44 using _____ ____ can do what?

• overexpressed

• CD44+

• monoclonal antibodies

  • inhibit breast cancer cell migration and invasion, thereby reducing metastasis and improving patient outcomes

adaptive immune system — T-cell communication, activation, and responses

• T-cell activation fundamentally relies on communication between what 2 cells?

  • the APC family consists of what 3 things?

• antigen presenting cells (APC) and T-cells

  1. dendritic cells (DCs)

  2. B-cells

  3. macrophages/monocytes

lets look at antigen presentation

• all nucleated cells are _____ reporting their cellular contents by using ____ on their surface

• ____ processed inside the cell are shuttled to the surface for presentation — this is called ___ ____

• most antigen recognized by immune cells are what?

• T-cells will “sample“ cells via their ____ ___ ___ to determine if the antigen presented is SELF or NONSELF

• ____ = peptides derived from pathogens (viruses, bacteria)

• continuously; MHS

• peptides; antigen (Ag) presentation

• small peptides

• T-cell receptor (TCR)

• nonself

major histocompatibility complex

• major histocompatibility complex (MHC) is a glycoprotein cell surface complex that is located on the surface of the cells

• MHC role is to present ___ ___ of intracellularly digested protein antigens to T-cells — there are 2 classes

  • what MHC class is expressed by antigen presenting cells and important for presentation of peptide fragments to CD4+ T-cells which help to decide on how to proceed with a possible immune response (antibody production)?

  • what MHC is expressed by all nucleated cells and important for presentation of peptides to CD8+ cytotoxic T-cells, which can kill the presenting cell directly in case of viral infection

  • T-cells contain cell surface T-cell receptor (TCP) which recognizes what?

• peptide fragments

  • MHC class II (MHC-II)

  • MHC class I (MHC-I)

  • peptide-MHC complex

how are peptides presented on surface of all nucleated cells? example of MHC 1-6 steps for success

• put them in order

  a. the proteasome degrades ubiquitylated proteins into small peptides

  b. peptide-based MHC class I molecules are transported via the golgi complex to the cell surface

  c. acquisition of proteins with errors

  d. the peptides are delivered to the endoplasmic reticulum (ER) by the transporter associated with antigen processing (TAP) complex

  e. misfolded protein tagged with ubiquitin for degradation

  f. peptide is loaded onto MHC class I molecules

• peptides are displayed for sampling by CD8+ T-cells

• cells are continually reporting their ____ ___:

  • if self-peptide, what does T-cell do?

  • if non-self, what does T-cell do?

1. c

2. e

3. a

4. d

5. f

6. b

• intracellular events

  • they ignore (hopefully)

  • they kill cell that displays the foreign peptide directly

MHC classes

• MHC class I

  • display peptides from ____ and ___ peptides

  • expressed on surface of ALL nucleated cells including antigen presenting cells (APC)

  • recognized by T-cell receptor (TCR) cytotoxic T-lymphocytes (___)

  • peptides displayed are short (8-11 amino acids long)

  • ___ ____ response — direct killing of cell containing viral peptides

• MHC class II

  • display peptides from ____ antigens take into APCs (macrophages, dendritic cells) by endocytosis or phagocytosis

  • expression on ____ of antigen presenting cells

  • recognized by TCR of ___ T-cells (___)

  • peptides displayed are 12-20 amino acids long

  • _____ response

I

• self and viral

• CD8+

• cell mediated

II

• bacterial

• surface

• helper; CD4+

• antibody

once peptide is loaded to NHC — what happens next?

• the so-called “three-signal model” is usually used to define what?

  • engagement between the MHC-peptide complex and T-cell receptor (TCR) provides ___ ___

  • while this is necessary, it is ___ ____; and signal 2 is thus required, through interactions between costimulatory receptors (CDs) between APCs and T-cells

  • activated APCs can secrete cytokines as signal 3 that drive __ ___ to decide what to do

  • typical APCs need to have at least signal ___ and ___ to have the capacity to stimulate T-cells — the cytokine-priming function by signal ___ primarily determines the nature of the T-cel responses generated

• the APC function required for the activation of T-cells

  • signal 1

  • not sufficient

  • T-cells

  • 1 and 2; 3

cytotoxic T-lymphocytes (CD8+): effector functions

• CD8+ T-cells can ___ ___ cells that are infected with viral pathogens

• name the signal:

  a. co-stimulation - requires additional signals between T-cell and APC

  b. CD8+ T-cells release perforin (creates pore in infected cells) and granzymes (pro-apoptotic enzymes) that kill infected cell

  c. sampling - interacting of APC with T-cell (via class I MHC with TCR)

• lead to ____ T-cells (and memory T-cells) that can directly kill infected cells more aggressively with repeated exposure to same pathogen

• good for pathogen clearance — what is it bad for?

• directly kill

  1. c

  2. a

  3. b

• activated

• bad for autoimmune disease and organ transplantation

dendritic cells - Yin and Yang

• dual role of dendritic cells in disease progression

  • dendritic cells (DC) are the most effective antigen-presenting cells to initiate immune responses, which lead to the activation of the ___ ___ driven by T-cells?

  • this event is crucial to recognize tumor antigens and kill cancer cells — however, in the environment produced by gut inflammation, dendritic cells have an opposite behavior and promote what?

• cytotoxic machinery

• promote a cascade of pro-inflammatory signals that ultimately induce IBD

CD4+ (helper T-cells) cells — major subsets

• naive CD4+ T-cells can be activated and differentiate into:

  • ____ cells — produce IFN-γ, enhances macrophage activation

    • implicated in autoimmune disease

  • ____ cells — produce IL-4, IL-5, and IL-13, which are responsible for activation of B-cells (antibody response) and recruitment of eosinophils (allergic response)

  • ____ cells — produce IL-17, IL-17F, IL-21, and IL-22, implicated in tissue inflammation, autoimmune response

  • ____ cells — by inhibiting self-reactive T-cells, these cells enable the body to develop active tolerance of its own antigens, preventing the occurrence of autoimmune diseases

• TH1 cells

• TH2 cells

• TH17 cells

• Treg cells

Economy of MHC class I processing: per cell

• the economy of MHC class I molecule is extraordinarily ____ with only 1-2 out of every 10,000 peptides generated binding to MHC class I molecules

• but in reality, it’s a good method to do what?

• wasteful

• recycle misfolded proteins — use the peptide pieces for MHC display