Interaction between intestine and osteoarthritis of the hand and the effect of Sustained Release Calcium Butyrate

Chronic inflammatory diseases are often associated with impaired barrier
function of the intestine (*leaky gut*), with dysbiosis of the intestinal
microbiome, with impaired intestinal associated immune tolerance and with low,
but elevated chronic systemic inflammation(2016 Thaiss Zmora). The association
between impaired intestinal barrier function and OA have been described in
various studies and it was postulated that amelioration of the impaired barrier
function would ameliorate OA (2012 Metcalfe Harte, 2016 Huang Kraus, 2017 Huang
Stabler, 2018 Huang Perry). Dysbiosis of the intestinal microbiome is also
associated with OA (2018 Biver Berenbaum). Boer et al (2019) demonstrated very
clearly that the microbiome of patients with OA of the knee was dysbiotic, as
it was marked by an overrepresentation of Streptococcus spp. (2019 Boer
Radjabzadeh).
The intestine associated immune system is essential for immune tolerance. A
part of this system is the balance between T helper cells (like Th17) and T
regulatory cells (Treg). Dysbiosis causes a shift towards T helper cells
contributing to low chronic systemic inflammation and impaired immune tolerance
(2016 Li Wan, 2017 Omenetti Pizarro).

An important question is the one about causality. Will it be possible to
ameliorate chronic inflammatory diseases by treating the deviant functioning of
the intestine? Or is the impaired functioning of the intestine a consequence of
the disease? Or has each chronic inflammatory disease with an intestinal
component its own specific causality?
Various experimental and clinical studies demonstrated that amelioration /
improving of the various functions of the intestine also ameliorate/affect
chronic inflammatory diseases. Treatment with dietary fibres resulted in
restoration of a balanced microbiome and amelioration of OA in a murine model
(2018 Schott Farnsworth). Also in a well-designed and well performed clinical
study, treatment with probiotics for a period of six months resulted in
amelioration of inflammation, pain and function of patients with OA of the knee
(2017 Lei Guo).

Short chain fatty acids (SCFAs, mainly acetate, propionate and butyrate) are of
major importance In the homeostasis of the intestine. These SCFAs are formed in
the intestinal microbiome by fermentation of non-digestible dietary fibres.
Besides a major energy supply (10% of the daily need), butyrate has specific
and crucial functions. Butyrate is a specific energy source for the colonocytes
and the integrity of the colonic epithelium is butyrate dependent. Butyrate is
a potent histone acetylase inhibitor and is essential for the prevention of
intestinal cancer (2016 Gonçalves Martel). Butyrate has a central role in the
functioning and integrity of the barrier of the intestinal epithelial cells, in
the synthesis of anti-microbial proteins (AMP and sIgA) and in immune
tolerance. AMP and sIgA are two aspects of the indirect effects of butyrate on
the composition of the intestinal microbiome. Additionally, butyrate affects
the microbiome also directly. It reduces the toxicity of Salmonella enterica by
downregulation of pathogenicity Island 1 (2006 Gantois Ducatelle).
Butyrate affects cells of the intestinal epithelium and of the immune cells
associated with the intestine by binding on G-Protein coupled Receptors (GPRs,
like GPR41, GPR43, GPR109a). Butyrate has also important intracellular effects.
It was shown to act as a major histone deacetylase inhibitor (2014 Donahoe
Holley, 2018 Yuille Reichart).

Butyrate is transported in and out of cells by various transporters (MCT1,
MCT4, SMCT1, BCRP, (2013 Gonsalves Martel)). Butyrate induces also the
formation of these transporters (2002 Cuff Lambert). These transporters (like
ABCRP2) have a major role in secretion of uric acid into the intestinal lumen
(2016 Matsuo Tsunoda). Improvement of intestinal functioning will improve uric
acid secretion (2020 Ferrer Picon Dotti). Serum concentrations of uric acid are
associated with the severity of OA of the knee (2017 Ma Leung), and it has a
direct effect on the inflammasome and pain sensitization (2019 Yoshida
Hagiwara). We postulate that the systemic decrease in uric acid (urate)
concentration by Sustained Release Calcium Butyrate (SRCaBu) will contribute to
less pain in OA patients.

The application of butyrate as medicine has a long history. Initially it was
studied as a as anti-cancer agent (1987 Miller Kurshel). However, taken orally
it is almost impossible to reach the needed systemic concentrations because the
high first pass effect in the liver; the liver scavenged the butyrate present
in the portal blood. Butyrate has a pKa value of 4.8. This means that in the
stomach it will become butyric acid and in the acid form it will easily and
passively pass the epithelial layers. Also, the quantity of butyrate that will
enter the small intestine will be very limited. Therefore, the effect of
butyrate will be limited when it is taken orally in an unprotected form. The
unprotected form of butyrate is only used as additive in artificial calf milk.
The protected forms, sodium or calcium butyrate with a fat coating, are used as
feed additive. It is released in the small intestine where it affects
epithelial and immune cells, reinforces the immune system (makes poultry and
pigs less sensitive to Salmonella infections), improves the intestinal
functions and improves reproductive success (See 2018 Moquet Thesis for
extensive overview).
If we take the quantities added to pig or chicken feed and we adjust them
pro-rata to the energy consumption by humans (2000 Kcal) a daily dose of 600 mg
of butyrate will be equivalent to that consumed by chickens and pigs. Several
effective clinical studies have been performed with daily doses varying from
237 mg to 2.4 grams of butyrate.

Three randomized placebo control studies in patients with various inflammatory
intestinal diseases in which various forms of protected butyrate were used, are
known to us (All studies had a positive outcome, i.e. amelioration of the
disease, less pain, less obstipation (2000 Vernia Monteleone, 2013 Banasiewicz
Krkowicz, 2014 Krokowicz Stojcev).
In addition, Bouter et al (2018 Bouter Bakker) treated obese and lean people
with 4 grams Sustained Release Na butyrate for a period of 4 weeks and found
that only lean people showed an improved glucose tolerance. In the mentioned
studies no unwanted side effects were observed.

The results of the animal and clinical studies indicate that daily doses round
600mg butyrate in sustained release form will be a good starting dose for
clinical studies. Additionally, not only the total dose of butyrate given
should be taken into account, but also the release rate of butyrate out of the
formulation into the lumen of the small intestine. This release rate determines
the amount of butyrate locally available in the small intestine and therefore
the concentration of butyrate that can affect the microbiome, the intestinal
epithelial cells and the immune cells present in the small intestine. The
necessary release rate of butyrate was studied in advance using a mathematical
model (2020 Korsten). The release rate of the sustained release tablet used in
this study is in line with the proposed release rate of the before mentioned
study, namely 0.08-0.2 mmol/h. This release rate will make it possible to reach
pharmacologically active concentrations in the small intestine, based on in
vitro experiments.

We will perform a clinical study in which we will test the effects of 600 mg
butyrate in a sustained release tablet (SRCaBu) on three aspects of the
functioning of the intestine: composition of the microbiome, barrier function,
and immune tolerance. The study will be performed in patients with OA of the
hand. The role of synovial inflammation in the pathophysiology of OA is well
recognized, in particular in hand OA. Inflammatory aspects, such as effusion,
gray-scale synovitis and power Doppler signal assessed by ultrasonography
studies are present in 96-100% of hand OA patients and are associated with pain
(Kortekaas 2014; Kortekaas 2010). In the etiology of OA mechanical damage
(caused by high body weight) and systemic factors are of importance. According
to Visser et al. in patients with hand OA surrogates for systemic processes are
the most important risk factors (2015 Visser de Mutsert). These systemic
processes are related to functioning of the intestine and the intestinal
microbiome. We hypothesise that 600 mg dd SRCaBu will result in positive
effects with respect to microbiome, barrier function and immune tolerance.

This proof of concept study is to estimate the effect of SRCaBu (600 mg daily
for four weeks) on compositional and functional characteristics of the
microbiome for future sample size calculation.

The secondary objectives:
1) To evaluate the short-term effects (i.e. 4 weeks) of SRCaBu (600 mg dd)
compared with placebo on pain and functioning of the hands in hand OA patients.
2) To evaluate whether SRCaBu (600 mg dd) lowers systemic inflammation in hand
OA.
3) To evaluate whether immune tolerance will improve while lowering
inflammation by characterizing the phenotype of T-cells and monocytes and
determining the response of activated PBMCs of patients before and after intake
of 600 mg dd SRCaBu.
4) To examine the preliminary safety profile of (600 mg dd) SRCaBu in patients
with hand OA over 4 weeks.
5) To examine the associations between intestine functioning and pain and
functioning of the hands in hand OA patients.
6) To examine the effect of SRCaBu intake on stool behaviour.

proof of concept, randomized, (double-)blinded, placebo-controlled trial design
with follow-up of 4 weeks.

Sustained Release Calcium Butyrate (600mg/day) for a period of 4 weeks

Burden; 2 visits to Sint Maartenskliniek (consultation and physical
examination; blood pressure, blood sampling (2x), faecal sampling (at home
2x)). Online questionnaires (daily, weekly). Daily intake of 4x 150 mg SRCaBu
or placebo.