Sepsis and Vitamin D Flashcards

Question

how is IL-6 implicated in COVID?

Answer 1

IL-6 concentrations in patients with COVID-19 showed moderate heterogeneity with a range of 6·5–357·2 pg/mL - 80·0% of the COVID-19 studies reported a mean IL-6 concentration lower than 100 pg/mL. - Tocilizumab was effective in COVID as it IL-6 wasn’t excessively high and could be mopped up, whereas its not effective in sepsis as IL-6 is too high

Answer 2

IL-6 conc is massively increased in ARDS and sepsis compared to COVID - in ARDS, levels are over 1000pg/mL - COVID levels can't be seen on the chart because they are so low in comparison Error bars massive in sepsis – not a great biomarker for sepsis

Answer 3

Yes: tocilizumab in the recovery trial: - tocilizumab significantly reduced deaths: 596(29%) of the patients in the tocilizumab group died within 28 days compared with 694(33%) patients in the usual care group (rate ratio 0·86; [95% confidence interval [CI]0·77to 0·96]; p=0·007) - an absolute difference of 4% - 4% reduction in mortality - This means that for every 25 patients treated with tocilizumab, one additional life would be saved. anti-IL-6R is beneficial in COVID, reducing risk of death

Answer 4

very large cohort of people infected with the same virus - less heterogeneity - treats same infectious disease

Answer 5

With the complexities of the immune response, it may be that single therapies are inadequate and that combinations of several agents will be necessary Combination approach needed - Test multiple arms with placebo, and add to standard care - Dex in covid saved 2 million lives worldwide - 50p per dose - could be used in sepsis

Answer 6

Early aggressive fluid resuscitation Antibiotics early Inotropes for BP support (Dopamine, vasopressin, norepinephrine) – organ support

Answer 7

Albumin instead of saline to resuscitate fluid - IV - No mortality difference between colloid vs. crystalloid - In severe sepsis patients (N=1218): mortality 35.3% (NS) vs. 30.7% (alb)… 95% CI .74-1.02 p=0.09 - Albumin didn’t work better than saline

Answer 8

Abx within 1 hr hypotension: 79.9% survival - Survival decreased 7.6% with each hour of delay - Mortality increased by 2nd hour post hypotension - Time to initiation of Antibiotics was the single strongest predictor of outcome - Delays in giving antibiotics significantly affect outcome

Answer 9

Predictors of in hospital mortality: SOFA scores Respiratory failure within 24 hrs. Inadequate Empiric Antimicrobial Therapy - choice of antibiotic is crucial for better outcome Independent Variables related to administration of inadequate Abx… Fungal Infection & previous Abx within the last month Antibiotic that is correct for the infection = better survival No antifungals in UK would cover fungal infection More antimicrobials = more resistance

Answer 10

Steroids for non-responders reduced mortality 10% without an increase in adverse events e.g. low-dose HCQ can help in septic shock, dex works in covid - Repeat studies have not supported routinely testing for relative adrenal insufficiency

Answer 11

Dexamethasone 8mg BD IV for 10 days - This cheap, readily available steroid was shown to reduce deaths of hospitalised COVID-19 patients by one third. - It’s estimated that dexamethasone saved the lives of around 22,000 COVID-19 patients in the UK and one million lives globally by March 2021, 2 million lives saved by now

Answer 12

- follow specific care pathways and bundles - constantly evolving - adhering to these protocols can reduce mortality

Answer 13

Two forms of Vitamin D – Vitamin D2 and Vitamin D3 Two different isoforms that differ in biological potency Vitamin D2 is largely found in vegetable sources such as mushrooms Vitamin D3 is largely found in animal sources such as oily fish

Answer 14

half an hour of sun exposure can top VD up eggs cod liver oik multivitamins

Answer 15

Pre-cholesterol precursor hydroxylated step by step to active form in kidney or immune cells: - VD made in response to sunlight where 7-Dehydrocholesterol is converted to VD in the skin, or from diet or supplements in the gut - VD is converted to 25-OH VD in the liver via hydroxylation - kidney converts to 1,25OH2 VD to maintain calcium balance in body - immune cells convert to 1,25OH2 VD to regulate the immune function 25-OH VD is the circulating, precursor inactive form of VD (present in nanomoles) 1,25 VD is what regulates immune function - biologically active form (present in picomoles)

Answer 16

UV light used to treat lupus tuberculosis Fish oil shown to reduce risk of death from TB

Answer 17

ITU at the QE: - ~60% of beds have no natural ambient light - Windows are small and slit like HOE - When in hospital, no natural light - Small windows where barely any light gets through, so patients may become VD-deficient

Answer 18

Endocrine action of 1,25-OH2 VD produced in kidney - Calcium regulation - regulates interaction of phosphate, calcium and parathyroid hormone (PTH) which affect 1a-hydroxylase enzyme - low PO4+, low Ca2+ high PTH = activate hydroxylase, and vice versa

Answer 19

Effects of VD: complex hormone, not just a supplement - Antimicrobial function - forms defensins - epigenetic regulation - steroid efficacy - tissue remodelling - Calcium regulation in bone - Immune modulation - Muscle function HOWEVER: 100nM is major dose used in experiments – these actions may not be true in vivo

Answer 20

- induces monocyte to macrophage differentiation and bacterial killing, whilst reducing cytokine release and antigen presentation - downregulates DC maturation - Alteration of Th1/2 cytokine balance - reduces Th1, upregulates Th2 - VD can influence Th17 and Tregs – promote/downregulate either - reduces immunoglobulins, inflammation and autoimmunity - suppresses Th cells widespread effects

Answer 21

Alveolar macrophages are responsive to VD - VD bound to VD-binding protein binds surface receptors to become internalised - VD is then split off and hydroxylated in macrophages to form 1,25 VD3 - this binds VD-receptor to regulate gene expression - 800 genes are significantly altered by VD - e.g. LL37 regulates TB phagocytosis – this is drove by VD

Answer 22

VD implicated in infections, COPD (lung, muscle), heart problems - in general population: respiratory infections e.g. TB, COPD, myopathy, myalgia, myocardial infarction, heart failure, sudden cardiac death - in critically ill patients: sepsis, SIRS, respiratory failure, cardiogenic shock, arrhythmia

Answer 23

this is the national standard of VD: <50nmol/L = deficient 50-75nmol/L = insufficient >75nmol/L = sufficient - nM/L to ng/L = divide by 2.5 - Need to stick to one unit in exam - nM is more accepted 1ng/L = 2.5nM/L

Answer 24

In a 2007 study, 60-87% of a cohort of 45 year olds in the UK had Vitamin D levels <75nmol/L - 3-15% were highly deficient with levels <25nmol/L - Scottish and obese participants were more likely to be deficient - VD levels so vary based on age and race - lower in non-hispanic black people, whites have higher levels. the older you are, the levels fall - VD can affect risk for COVID infection: higher VD levels = lower COVID mortality

Answer 25

- Vitamin D reduces endothelial neutrophil interactions. - Vitamin D blocks pro-fibrotic effects of TGF beta on lung fibroblasts. - Vitamin D (via LL-37 (anti-microbial peptide)) can promote lung epithelial wound repair. - 1,25D3 inhibits NF-kb signalling and suppress macrophage TLR expression suggests that Vitamin D may also play a key role as a feedback regulator of macrophage responses Vit D alters metabolism levels within body and cells - At high levels, it means more active vit D isn’t made by body

Answer 26

VDR KO mice have increased mortality following IV LPS to mimic sepsis - Vit D receptor k/o mice are bald and die quickly with IV LPS compared to WT mice - Lack of vit D leads to worse outcome in infection

Answer 27

ARDS is uncontrolled neutrophil inflammation in lung - severe inflammatory lung injury - Caused by sepsis - Can be caused by pneumonia, covid, blood trauma/transfusion, smoke inhalation - acute lung injury (ALI) Alveolar tissue slide: - Pink = oedema fluid - Neutrophil inflammation in alveoli leads to holes in alveolar, which become leaky and fluid builds up - fibrosis - fluid in alveolar sacs - most inflammatory disease

Answer 28

plasma samples: 25-OH Vitamin D and 1,25-OH2 Vitamin D levels were measured in 52 patients with ARDS and 65 patients who underwent oesophagectomy (risk of ARDS) Vitamin D levels were compared with clinical and laboratory data - 50 oesophagectomy cases (BALTI-prevention). 50 BALTI-1 and BALTI 2 cases.

Answer 29

at risk condition -> severe VDD -> ALI

Answer 30

surgical human model of lung injury: post-one lung ventilation following oesophagectomy: - Oesophagectomy performed in oesophageal cancer – cut it out - Aggressive surgical procedure - involves one lung ventilation, where one lung is collapsed to access the oesophagus, and the other is ventilated to keep oxygen up - there is increased lung permeability during oesophagectomy, less than ARDS but similar alveolar epithelial damage - Blood flow from the collapsed lung is lost and then comes back – ischaemia/reperfusion - 28% patients with the surgery go on to get ARDS - useful model permeability: Blood protein level in normal = low With oesophagectomy with little lung injury – some high protein level High in ARDS

Answer 31

following one-lung ventilation, early post-op lung injury, and later injury due to infection - overall incidence of ALI was 28%

Answer 32

- people with risk of ALI/ARDS had low VD - people with ALI/ARDS had severely low VD compared to normals - ALI/ARDS patients are severely deficient in VD – 15-18nM/L - non had levels of insufficiency - Normal have sufficient VD

Answer 33

1,25 D3 is significantly reduced in ALI/ARDS compared to at risk cases p-0.000 Patients who survived had higher 125D3 - ITU survivors have significantly increased plasma 1,25 D3 at admission compared to those who died - VD directly relates to severity of illness

Answer 34

Oesophagectomy patients who went on to get ARDS – pre-op VD level was lower than those with no-post op ALI - Pre-operative 25D3 is lower in those who subsequently develop lung injury post-OLV.

Answer 35

Post-op (OLV) plasma IL-6 and VD: - The more deficient in VD, the more IL-6 accumulation post-op - link between systemic inflammation post-op and VD levels - 3-fold differences in IL-6 levels in plasma across patients with same syndrome – highly polymorphic soluble RAGE (type 1 epithelial lung marker) is elevated post-operatively in those with severe VDD - 25D3 lower than 15 = increased epithelial damage markers in blood Perioperative increases in EVLWI (extravascular lung water - measures how much water has leaked into the lung) are higher in severe VDD

Answer 36

severe VDD leads to: Increased systemic IL-6 release Evidence of increased alveolar epithelial damage (soluble RAGE) Increased EVLWI (lung water) suggestive alveolar epithelial damage. - flooding of alveolar compartment

Answer 37

Risk of post-OLV ALI 40% (<20nM) versus 15% (>20nM) p=0.04 - over double risk of ARDS/ALI if 25VD less than 20nM/L - VDD can determine post-op clinical syndrome of lung injury

Answer 38

in vitro upon ATII cells, vitamin D alters expression of 600 genes by microarray involved in cell cycle, proliferation, wound repair and apoptosis Wound repair assay with scratch model – when giving physiological levels of VD, VD promotes epithelial wound repair dose-response to VD VD can abrogate FasL-induced cell death to protect from lung injury and improve viability

Answer 39

The third National Health and Nutrition Examination Survey (NHANES; cross-sectional survey on 14 091 healthy US civilians >20 years of age). - After adjustment for potential confounders, a strong relationship between serum levels of 25-OHD and pulmonary function, as assessed by FEV1 and FVC - Strong relation between serum 25D3 and pulmonary function (PF) PF is strongest determinant of human life span - 25 years old = peak lung function - Lose 300ml of FVC every year after 25 – loss of lung function - However, longitudinal studies are conflicting - strongest predictor is FEV1, and VD relates to this

Answer 40

COPD patients: - more VD = better FEV1 - GOLD1 = mild disease, GOLD4 = severe - As disease gets worse, VDD increases correlation between lung function and VDD - as disease severity goes up, VDD goes down - may be due to ill person not going outside as much, but defo involved in lung disease

Answer 41

VD levels significantly lower in those patients who die from sepsis than those who survive - but this is mainly true in the acute stages of sepsis, around 30 day survival - 365 days sepsis = low VDD on the whole Sepsis mortality at 1 year is 40% - Tends to be in older people - Influence of VD may be limited here

Answer 42

give low VD diet for a month to reduce VD levels to 15-20nmol/L - Restrict dietary intake by using a deficient diet then give either: Caecal ligation and puncture (CLP) – tie off caecum, puncture with needle to release bacteria into peritoneum to cause peritonitis/sepsis(abdominal polymicrobial sepsis) - Releases e. coli into gut to drive inflammation Intratracheal LPS 50 ug - sterile model which causes brisk neutrophilic inflammation within lung

Answer 43

Diet leads to significant deficiency of 10nM – similar to ARDS patients - there is no accepted normal VD level for mouse 1,25D3 and 25-D3 are significantly reduced in diet-deficient mice compared to sufficient

Answer 44

PLF = peritoneal lining fluid - Wash out with saline and culture to see bacterial levels - More bacteria in VDD mice in PLF and blood and gut bacterial translocation into lung compared to sufficient - VDD increases bacterial load, bacteremia and translocation to the lung in CLP model VD is important in containing bacterial infection

Answer 45

PLF cell count: - Untreated control - SHAM = open peritoneum but no puncture - increased cell count in peritoneum of VDD CLP mice - Neutrophil count higher in full VDD+CLP, and increased no. macropahges recruited in VDD+CLP - more cellular infiltration into peritoneum of CLP mice when VDD

Answer 46

VDD mice have dysregulated neutrophil apoptosis and clearance - Necrosis and inflammation – NET release - more apoptotic neutrophils in the PLF of VDD CLP mice

Answer 47

CRAMP is equiavelent of LL37 - In VDD mice, reduced antibacterial response in peritoneal cavity, alveolar compartment and blood - VDD is associated with reduced antibacterial peptide release

Answer 48

CLP mice cant be kept alive for long enough, so use LPS model as it is less severe so could be kept alive

Answer 49

give VD 6 hours after intrathecal-LPS administration (sepsis model) - VD supplement vigantol given via intraperitoneal injection after 6 hours - looked at endpoint at 48 hr post-IT-LPS

Answer 50

Vigantol therapy reduces lung injury 48hrs post IT-LPS - Vigantol reduces RAGE epithelial damage marker - vigantol reduces alveolar permeability index at 48 hrs - vigantol reduced the apoptotic neutrophil count, reversing lung effects - Vigantol reduced alveolar TNF, MIP2, but increased CXCL1 - anti-inflammatory action mouse oximeter: - LPS injury reduces oxygen in lung to 85% in VDD - Vigantol therapy 6 hrs post-treatment rescues this, reducing lung hypoxia at 24 hours, and restoring oxygen saturation in VDD mice similar to WT mice

Answer 51

Cod liver oil is good for VD and omega-3 - In-patients were treated with cod liver oil in a dose of 1 drachm (3.6 ml) three times a day - Cod liver oil improved TB outomes - 40% reduction in mortality - standard treatment = 33% mortality, standard treatment + cod liver oil = 18% mortality - cod liver can control pulmonary consumption

Answer 52

Lupus pernio – tuberculomas eating skin on face, enter brain and cause meningitis Millions of VD units given, no calcium toxicity, improves symptoms and suppresses infection

Answer 53

Several small studies looking in Africa – only 1 is positive. Recent paper by Adrian Martineau: - 100,000 IU vitamin D as an adjunct to 4 antibiotics. - Primary endpoint – time to sputum conversion not significant (In TB trials, measure how long it takes for TB in sputum to disappear after treatment) - Response to vitamin D was seen in a subgroup of patients homozygous for a polymorphism Taq1 in the vitamin D receptor gene - Normal TB nowadays = 98% cure with 6-month treatment - Multi-drug resistant treatment requires 18-month treatment with 40% mortality

Answer 54

Critically ill people with VD supplementation had a trend towards improved survival

Answer 55

VD has some affect on ARTI: - 400 units a day can prevent 1/10 infections over a year - New meta analysis in press suggests 11% reduction ARTI if taking 400 IU per day. - studies are conflicting

Answer 56

392 participants, 15.6% had VDD - VDD had worse COVID symptoms, including body aches, fatigue and extended duration of symptoms - VDD and age are independently associated with extended duration of body aches - VDD, age and seroconversion were independently associated with extended durations of fatigue - More likely to seroconvert with VDD Males tend to have more VDD and prolonged disease VDD = worse COVID symtpoms