Chapter 20: The Kidney - Glomerular Diseases Flashcards
What is the most common and second most common causes of Chronic Renal Failure and End-Stage Renal Disease?
- Diabetes = MOST common
- High BP = second most common
What is the single most important question to ask a patient suspected of having renal disease?
Why?
- “Have you had this before?”
- Hx of disease can imply a significantly worse prognosis!
What is the major mediator of injury in Glomerular disease vs. Tubular/Interstitial?
- Glomerular is typically immunologically mediated
- Tubular/interstitial is frequently due to toxins or infectious agents
Elevated BUN and creatinine, largely realted to decreased GFR is known as?
Azotemia
Hypoperfusion of the kindeys (i.e., hypotension, shock, CHF, or cirrhosis of liver) in the absence of parenchymal damage is known as?
Pre-renal Azotemia
When azotemia becomes associated with a constellation of clinical signs and sx’s and biochemical abormalities resulting from renal damage, it is termed?
Uremia
Diabetes typically affects which morphological component of the kidney?
Primarily glomerular disease (microvasculature) manifestations
Systemic HTN, is primarily a disease affecting which morphological component of the kidney?
Primarily, vascular (arteriolar) disease –> Tubulointerstitial
Nephritic syndrome is characterized by what main findings?
- Hematuria (micro/macroscopic) + variable proteinuria
- Diminshed GFR —> Azotemia + Oliguria
- Edema
- HTN
Nephritic syndrome is the classic presentation of disease state?
Hint: What type of glomerulonephritis?
Acute poststreptococcal glomerulonephritis
What characterized rapidly progressive glomerulonephritis?
Nephritic syndrome w/ rapid decline in GFR (within hours to days)
Nephrotic syndrome is characterized by what main findings?
One major difference from Nephritic syndrome?
- HEAVY proteinuria (>3.5 g/day) = major difference from Nephritic*
- HYPOalbuminemia —-> SEVERE edema
- HYPERlipidemia —> Lipiduria
Injury to what morphological structure of the kidney is the most common cause of Acute Kidney Injury?
Acute tubular injury (ATN)
Diminished GFR that is persistently <60 mL/min/1.73 m2 for at least 3 months and/or persistent albuminuria, defines what?
Chronic kindey disease
Glomerular disease is often associated with what 4 main systemic disorders?
- SLE
- Diabetes
- Amyloidosis
- Vasculitis
Which cells of the glomerulus are contractile, phagocytic, capable of proliferation, and laying down both matrix and collagen?
Mesangial cells
Which cells are important for maintenance of the glomerular barrier function?
Injury to these cells results in?
- Visceral epithelial cells (podocytes)
- Injury results in —> proteinuria
What is a diffuse vs. global glomeruopathy?
- Diffuse = involves ALL of the glomeruli in kidney
- Global = involves the entirety of individual glomeruli
What is focal vs. segmental glomerulopathy?
- Focal = involving only a fraction of glomeruli in kidney
- Segmental = affecting a part of each glomerulus
In diabetic glomerulosclerosis there is increased synthesis of which components of the glomerulus?
Protein components of the basement membrane
Chronic glomerular responses to injury include what 3 morphological changes?
- Basement membrane thickening
- Hyalinosis
- Sclerosis
Glomerular basement membrane thickening is best seen with what stain?
PAS
What morphological change to the glomerulus is characterized by the accumulation of homogenous/eosinophilic material under light microscopy and is typically the end result of many forms of glomerular injury?
Hyalinosis
The major cause of glomerulonephritis resulting from formation of antigen-antibody complexes is the consquence of?
In situ immune complex formation
In the Heymann mode of glomerulonephritis, Abs reacts to what Ag?
This Ag is normally found where?
Megalin, normally present in epithelial cell (podocyte) foot processes
Which Ag has been found to be the one underlying most cases of primary human membranous nephropathy?
M-type phospholipase A2 receptor (PLA2R)
Ab binding to PLA2R in glomerular epithelial cell membranes, followed by complement activation, leads to immune complex formation where on the BM?
Characteristic BM appearance on light microscopy?
- SUBepithelial aspect of BM
- THICKENED BM appearance on light microscopy
In viewing membranous nephropathy (in-situ immune complex deposition) with immunofluorescence microscopy what is the pattern of immune deposition seen?
Reflects what?
- Immune deposition in GRANULAR pattern (not linear)
- Reflective of very localized and LARGE complexes of Ag-Ab interaction.
What is the antigen associated with anti-GBM nephritis?
NC1 domain of type IV collagen Ag
In situ immune complex deposition against “planted” Ags may occur, what are examples of exogenous sources of these Ags?
- Infectious agents (viral, bacterial and parasitic products)
- Drugs/toxins
In situ immune complex deposition against “planted” Ags may occur, what are examples of endogenous sources of these Ags?
- DNA
- Nuclear proteins
- Immunoglobulins
- Immune complexes themselves can serve as Ags!
- IgA
Characteristic pattern seen with immunofluorescence in diseases caused by Abs directed against normal glomerular BM components (i.e., anti-GBM)?
Diffuse linear pattern as Abs bind intrinsic Ags along entire legnth of GBM
Often anti-GBM Abs cross react with other BM’s, especially where?
What syndrome does this occur in?
- Lung alveoli, results in simultaneous lung and kidney lesions
- Goodpasture syndrome
What kind of glomerular damage occurs due to anti-GBM Abs?
Leading to which clinical syndrome?
- Causes severe necrotizing and crescentic glomerular damage
- Leading to rapidly progressive glomerulonephritis (RPGN)
Microbial Ags from which bacteria/viruses may act as exogenous sources that trigger circulating immune complexes leading to glomerulonephritis?
- Streptococcal proteins
- Surface Ag of HBV and viral antigens of HCV
- Ags of Treponema pallidum and Plasmodium falciparum
How do highly cationic Ags vs. highly anionic Ags vs. neutral Ags differ in where they get deposited and in turn where immune-complexes form within the glomerulus?
- Cationic–> cross the GBM and resultant complexes aresubepithelial
- Anionic–> excluded from GBM and trappedsubendothelially
- Neutral charge –> tend to accumulate in the mesangium
Immune complexes deposited in which locations of the glomerulus are more likely to be involved in an inflammatory response due to be accessible to the circulation?
- Subendothelial portions of capillaries
- Mesangial locations
Why are large circulating complexes usually NOT nephritogenic?
They are cleared by the mononuclear phagocyte system and do not enter the GBM in significant quantities
Lupus nephritis and membranoproliferative glomerulonephritis lead to immune-complex deposition in which part of the glomerulus?
Subendothelial deposits = membranoproliferative pattern
*#3 in the figure
Which coagulation factor may act as the stimulus for crescent formation associated w/ glomerular injury?
Thrombin
Which GF’s seem to be critical in the ECM deposition and hyalinization leading to glomerulosclerosis in chronic kidney injury?
- TGF-β
- Connective tissue GF
- Fibroblast GF
In most forms of glomerular injury, loss of what is a key event in the development of proteinuria?
Loss of normal slit diaphragms
What is the principal glomerular manifestation of progressive glomerular injury?
Focal segmental glomerulosclerosis
Which mediator of chronic inflammation plays a particularly important role in the induction of scleroris seen in Focal Segmental Glomerulosclerosis?
TGF-β
What is the drug of choice for Focal Segmental Glomerulosclerosis?
RAAS inhibitors
What is the most frequent clinical presentation of Focal Segmental Glomerulosclerosis?
- Nephrotic syndrome
- Nonnephrotic proteinuria
The extent of damage to what renal structures is more correlated to decline in renal function?
Tubulointerstitial damage rather than the severity of glomerular injury
What plays a major role in the direct injury and activation of tubular cells seen in Tubulointerstitial Fibrosis?
What do activated tubular cells do?
- Proteinuria can cause direct injury and activation of tubular cells
- Tubular cells then express adhesion molecules and elaborate pro-inflammatory cytokines, chemokines, and GF’s –> interstitial fibrosis
Most common type of glomerular injury causing nephritic syndrome?
Immunologically mediated
How does Acute Proliferative (Poststreptococcal) Glomerulonephritis typically present (signs/sx’s and findings)?
What is seen in urine?
Typical age group?
- Malaise + fever + nausea + oliguriaandhematuria –> 1-2 wksafter recovery fromsore throat or skin infection
- Dysmorphic red cells or RBC casts, mild proteinuria, perioribital edema, and mild/moderate HTN
- Children ages 6-10 yo
What has been discovered as the principal antigenic determinant in most cases of Poststreptococcal Glomerulonephritis?
This antigen can directly activate what?
Pyogenic exotoxin B (SpeB) –> directly activates complement
What class of streptococcus is the cause of Poststreptococcal Glomerulonephritis?
Group A, β-hemolytic Strep –> types 12, 4, or 1
Acute proliferative (postreptococcal) glomerulonephritis is characterized by what 2 findings histologically?
- Marked hypercellularity: ranging from simple mesangial to complex endocapillary cell infiltrate
- Leukocyte infiltration: both neutrophils and monocytes
The proliferation and leukocyte infiltration are seen in which parts of the glomeruli during acute proliferative (postreptococcal) glomerulonephritis?
Typically involving ALL lobules of ALL glomeruli
What is seen on immunofluorescence microscopy in acute proliferative (postreptococcal) glomerulonephritis?
Granular deposits of IgG and C3, and sometimes IgM in the mesangium and along the GBM
What is the characteristic findings on electron microscopy in acute proliferative (postreptococcal) glomerulonephritis?
Discrete, amorphous, electron-dense deposits = subepithelial “humps” = Ag-Ab complexes
What is the onset of acute proliferative (postreptococcal) glomerulonephritis like in an adult?
Clinical course?
- More atypical –> sudden HTN or edema, frequently w/ elevated BUN
- Only 60% recover completely, while many cases manifest as persistent proteinuria, hematuria, and HTN —> chronic glomerulonephritis or even rapidly progressiving glomerulonephritis