endotoxin - adsorbent used for the treatment of patients with autoimmune diseases requires the following criteria : 1 ) a high endotoxin - binding capacity , 2 ) suitable physiological features for oral administration usage and 3 ) a high margin of safety without any adverse effects . the number of microorganisms residing in the human gastrointestinal tract is believed to be approximately 100 trillion , and the number of endotoxin - containing microorganisms among these bacteria is also massive . therefore , in order to remove large portions of endotoxin in the gastrointestinal tract , the endotoxin - adsorbent must have a high binding capacity of endotoxin . in order to satisfy these requirements , new endotoxinadsorbents , which have a high endotoxin - binding capacity , high margin of safety , and suitable physical features for oral administration use , are provided in this invention . the toxic core of an endotoxin molecule is located in the lipid a region . this invention consists of a lipid a - binding substance and insoluble carrier particles in order to adsorb and eliminate large amounts of endotoxin from the gastrointestinal tract into feces by oral administration , for preventing and treating autoimmune diseases such as rheumatoid arthritis . the endotoxin - adsorbent suitable for the usage of above purposes is as follows : 1 . endotoxin binding capacity of the particles is not less than 10 × 10 6 endotoxin units ( eu ) per 1 g of dry particles in an in - vitro test tube assay . 2 . endotoxin binding capacity of the particles is not less than 50 × 10 6 endotoxin units ( eu ) per 1 g of dry particles in an in - vitro test tube assay . 3 . endotoxin binding capacity of the particles is not less than 100 × 10 6 endotoxin units ( eu ) per 1 g of dry particles in an in - vitro test tube assay . 4 . the endotoxin - adsorbent consists of an endotoxin - binding substance and carrier particles . 5 . the endotoxin - adsorbent consists of a lipid a binding substance , that is capable of binding endotoxin . 6 . the endotoxin - adsorbent , which is a lipid a binding substance , is polymixin b . 7 . the endotoxin - adsorbent consists of a lipid a binding substance , polymixin b , and carrier particles which are a weakly acidic cation exchange resin with a carboxy residue . 8 . the methods for prevention and treatment of autoimmune diseases by administrating pharmacologically effective doses of an endotoxin - adsorbent to patients by the oral route . several materials such as polymixin b or a peptide antibiotic , and endotoxin - binding peptides ( jp - a 11 - 335396 , jp - a 2002 - 263486 , jp - a 2002 - 311029 , jp - a 2004 - 292357 and jp - a 2002 - 512140 ) have been known as lipid a - binding substances . all these materials can be used for the purpose of this invention . the carrier of the endotoxin - binding substance is desired to be small particles or powder suitable and convenient for oral administration usage . a variety of polysaccharides and their derivatives , such as cellulose , agarose , mannan , glucan , and chitin , or a variety of synthetic polymers , such as polyacrylate , polystyrene , polypropylene , polyamide , and polyvinyl , can be used as the carrier of an endotoxin - binding substance . there is no definite method required to conjugate the lipid a binding substance to the carrier particles . cross - linkers which have been widely used for immobilizing enzymes onto the solid surfaces , like water - soluble carbodiimides such as ecdi , hexamethylene diisocyanate , propyleneglycol di - glycidylether , which contains 2 epoxy residues , and epichlorohydrin , can be used . the features of lipid a - binding substance - carrier complexes are desired to be non - toxic , non - absorbable , and non - digestible by digestion enzymes and by microorganisms and resistant to other intestinal components such as gastric acid . “ non - digestible ” means resistant to both digestion enzymes of animals and enzymes produced by microorganisms . the microorganisms residing in the gastrointestinal tract possess enzymes which are capable of digesting cellulose and other substances that are resistant to the digestion enzymes of animals ( kopecny j et al . detection of cellulolytic bacteria from the human colon . folia microbiol ( praha ) 49 : 175 - 7 , 2004 , nakajima n et al . dietary - fiber - degrading enzymes from a human intestinal clostridium and their application to oligosaccharide production from nonstarchy polysaccharide using immobilized cells . appl microbiol biotechnol 59 : 182 - 9 , 2002 ). therefore , in this invention , the materials used as a carrier of the lps - binding substance should be restricted to materials , which are resistant to bacterial digestion , and usage of polysaccharides such as cellulose , agarose , mannan , glucan , and chitin as a carrier of an endotoxin - binding substance should be excluded . compared to naturally occurring polymers , synthetic polymers are generally resistant to digestion enzymes secreted into the gastrointestinal tract of animals and even to various bacterial enzymes . therefore , it is desired to choose a synthetic polymer as a carrier of the lipid a - binding substance . in fact , synthetic polymers such as polystyrene sulfonate calcium and anion exchange resin are widely used as a potassium adsorbent and as a cholesterol adsorbent for treatment of patients with high potassium and high cholesterols , respectively . the particle size of the endotoxin - adsorbent is an important factor that should be considered , since it has been known that small size particles , such as yeast , of less than 5 μm in diameter , are phagocytized by m cells , which reside on the surface of peyer &# 39 ; s patches scattered along small and large bowel regions ( gerbert a . et al . m cells in peyer &# 39 ; s patches of the intestine . int rev cytol . 167 : 91 - 159 , 1996 ). therefore , a particle size of endotoxin - adsorbent of not more than 5 μm in a diameter is excluded according to the specification of polystyrene sulfonate calcium defined in japanese pharmacopoeia . the molecular weight of endotoxin is more than 10 , 000 daltons , and assumed to bind mainly on the surfaces of endotoxin - adsorbent particles rather than the inside of the particles . therefore , if the particle size is smaller , the endotoxin - binding capacity is larger due to the larger surface area per unit weight of particles . this evidence is shown in example 12 . there are two classes of fine grinding techniques , dry and wet methods . the impact method , screen method , grind method and others are known as dry methods , whereas the catalyst - stirring method is an example of a typical wet method . there are several other methods , but there is no limitation in the methods for grinding the particles of the endotoxin - adsorbent , and any of these methods can be used for preparing fine powder or small particles of the endotoxin - adsorbent . the particle size of the endotoxin - adsorbent was determined based on the particle size distribution method . the particle distribution analysis was performed according to “ the method for determining particle size distribution . method 1 : microscopic method ” in the second supplement of the general test procedures , section 65 , japanese pharmacopoeia , 13 th issue . the 50 % particle size ( μm ) was explained as the diameter of particles of the corresponding values of the accumulative volume of particles is 50 %. the lps binding capacity of the endotoxin - adsorbent in a test tube was determined according to the method described in “ endotoxin test procedures ” in japanese pharmacopoeia , in addition to a simple assay method of lps by measuring od values , which was developed during this invention . the experimental procedures and results are shown in example 10 and 11 in detail . the therapeutic effect of the endotoxin - adsorbent on autoimmune diseases can be determined in the mouse arthritis model as described in our previous invention , jp - a 2006 - 151914 . briefly , arthritis can be induced in 100 % of mice by ip injection of enough amounts of anti - type ii collagen monoclonal antibody cocktail ( chondrex inc ., redmond , wash ., usa ) within 3 days ( terato k et al . induction of arthritis with monoclonal antibodies to collagen . j . immunol . 148 : 2103 - 2108 , 1992 ). by reducing the dose of the monoclonal antibody cocktail to 2 mg , all mice remained normal without developing arthritis . however , oral administration of 3 mg of lps on 3 consecutive days from day 0 , day 1 , day 2 and day 3 into these mice induced clinically apparent arthritis , which reached the peak on day 6 - 7 . furthermore , one group of mice was co - administered with indomethasin and ovoinhibitor , a protease - inhibitor purified from egg white . the combination of indomethasin and ovoinhibitor was used to increase the mucosal permeability of gastro - intestinal mucosa . in these mice , the effect of lps was more significant , and more severe arthritis was induced by oral administration of a same dose of lps . using this arthritis model induced by a combination of monoclonal antibody and lps , the therapeutic effect of the endotoxin - adsorbent can be determined . the benefit of this model is multifold : time of experimentation is short compared with an authentic collagen - induced arthritis model , the standard deviation of severity of arthritis among individual mice is much less , and the effect of the lps - adsorbent is clearly determined . since the endotoxin - adsorbent is used as a therapeutic agent for human patients by oral administration , various formulas , which are currently employed in medicines used by oral administration , can be applied : for example , a powdered or suspended powdered form , capsule , tablet and solution . these formulas can be provided using authentic methods by mixing the endotoxin - adsorbent with various vehicles and additives within a range that is acceptable with respect to pharmaceutical guidelines . the endotoxin - adsorbent can be administered orally at 10 mg - 10 g per adult by a single or three administrations per day . the individual examples of this invention are described in detail in the following sections , but the invention is not to be considered limited to these examples as described below . polymixin b sulfate ( 3 million units , maruko pharmaceuticals ) was dissolved in 200 ml of 0 . 1m nacl , and then the ph was adjusted to 8 by adding naoh . four grams of a polyacryl resin with an epoxy residue ( amberzyme , rohm and haas , usa ) was added to the solution and stirred using a blade propeller for 72 hours . the resin was washed with 1000 ml of distilled water on a membrane filter with a 5 μm pore size , and suspended in 50 ml of 1m glycine solution , ph 8 . 0 , adjusted by naoh . after incubation overnight , the resin was washed with 2 liters of distilled water on a filter , and dried in a desiccator . the yield of polymixin b - conjugated resin ( this is called as rpmb ) was 3 . 9 g . polymixin b sulfate ( 3 million units , maruko pharmaceuticals ) was dissolved in 200 ml of 0 . 1m nacl , and ph adjusted to 8 by adding naoh . four grams of a polyacryl resin with an epoxy residue ( amberzyme , rohm and haas , usa ) was transferred into a mortar , and ground with a pestle by adding polymixin b sulfate solution drop - wise . the polymixin b and epoxyacryl resin were stirred for 72 hours using a magnetic stirring bar . the resin was washed with 1 liter of distilled water on a membrane filter with a 5 μm pore size , then suspended in 50 ml of 1m glycine solution , ph 8 . 0 , adjusted with naoh . after incubation overnight , the resin was washed with 2 liters of distilled water on a filter and dried in a desiccator . the yield of polymixin b - conjugated resin ( this is called as rpmb - 1 ) was 3 . 2 g . one gram of a polyacryl resin containing an epoxy residue ( amberzyme , rohm and haas , usa ) was ground with a mortar and pestle . the powdered resin was suspended in 20 ml of distilled water , reacted with 0 . 6 g of epichlorohydrin and 0 . 3 ml of 50 % naoh for 2 hours . the resin was washed with 100 ml of distilled water on a membrane filter with a 5 μm pore size , and then mixed with in 5 ml of 1m phosphate buffer , ph 10 . 0 , containing 3 million units of polymixin b , and stirred at 40 ° c . for 16 hours . after the reaction , the resin suspension was added by 50 ml of 1m glycine solution , ph 8 . 0 , adjusted with naoh , and kept overnight . the resin was washed with 2 liters of distilled water on a filter and dried in a desiccator . the yield of polymixin b - conjugated resin ( this is called rpmb - 2 ) was 0 . 5 g . four grams of a weakly acidic cation - exchange resin with carboxyl residues ( dowex mac - 3 ), was suspended in 50 ml of 0 . 1m mops ( 3 - morpholinopropanesulfonic acid ) solution , ph 7 . 5 , and then reacted with 1 g of 1 - ethyl - 3 -( 3 - dimethylaminopropyl ) carbodiimide hydrochloride ( sigma , usa ), a coupling agent , at 4 ° c . for 2 hours with stirring . the activated resin was collected on a membrane filter with a 5 μm pore size and washed with 200 ml of distilled water . the washed activated resin was then suspended in 50 ml of 0 . 1m mops , ph 7 . 5 , and then mixed with 3 million units of polymixin b dissolved in 10 ml of 0 . 1m mops solution , ph 7 . 5 , and reacted at 4 ° c . for 16 hours with stirring . the resin was collected on a membrane filter with a 5 μm pore size and then suspended in 50 ml of 1m glycine solution , ph 8 . 0 , adjusted with naoh , and kept at 4 ° c . overnight , washed with 2 liters of distilled water and then dried in a desiccator . the yield of polymixin - conjugated weakly acidic cation exchange resin ( this preparation is called 4 / 300 ) was 3 . 8 g . using the same resin ( dowex mac - 3 ) and same procedures shown in the example 4 , except for reducing the amount of resin from 4 to 1 g , 0 . 9 g of polymixin b - conjugated weakly acidic cation exchange resin was obtained . this preparation is called 1 / 300 . four grams of weakly acidic cation - exchange resin with carboxyl residues ( dowex mac - 3 ), was ground with a mortar and pestle , and suspended in 50 ml of 0 . 1m mops , ph 7 . 5 . the resin was reacted with 1 g of 1 - ethyl - 3 -( 3 - dimethyl - aminopropyl ) carbodiimide hydrochloride ( sigma , usa ), a coupling agent , at 4 ° c . for 2 hours with stirring . the activated resin was collected on a membrane filter with a 5 μm pore size and washed with 200 ml of distilled water . the resin was suspended in 50 ml of 0 . 1m mops , ph 7 . 5 , and then added to 10 ml 0 . 1m mops , ph 7 . 5 , containing 3 million units of polymixin b . polymixin b and the resin were reacted at 4 ° c . for 16 hours with stirring . the resin was collected on a membrane filter with a 5 μm pore size and then suspended in 50 ml of 1m glycine solution , ph 8 . 0 , adjusted with naoh , and kept overnight , washed with 2 liters of distilled water , and then dried in a desiccator . the yield of polymixin b - conjugated weakly acidic cation exchange resin was 3 . 1 g . this preparation is called 4m / 300 . using the same resin and same procedures as described in example 6 , except for reducing the amount of resin from 4 to 1 g , 0 . 52 g of polymixin b - conjugated weakly acidic cation exchange resin was obtained . this preparation is called 1m / 300 . dowex mac - 3 resin ( diameter : 300 - 1200 mm ), 3300 liters , was ground using a dalton neamill , nea - 48 type . the yield of powdered mac - 3 was 1400 kg and the average particle size was 30 μm , ranging from 10 to 50 μm . the particle size distribution was measured according to “ measurement of particle size distribution . method 1 : microscopic method ” in the second supplement of the general test procedures , section 65 , japanese pharmacopoeia , 13 th issue . the microscope and camera used for this experiment was nikon eclipse e600 and victor ky - f55b , respectively . the collected data was analyzed using nano hunter ns2k - pro . the result of analysis of 1006 particles of rpme prepared in example 1 by this method is shown in table 1 . the 50 % particle size of rpmb was 213 μm , and the content of small particles not more than 5 μm in a diameter was 0 %. endotoxin was assayed by an end point colorimetric assay method using endospecy - es24s kit ( seikagaku kogyo , japan ). lipopolysaccharide ( lps ) from e . coli o - 111 ( sigma l4130 ) was dissolved in pyrogen - free water at 5 μg / ml . one ml of this lps solution was mixed with 50 μg and 100 μg of rpmb - 1 , and 100 μg of polymixin b - unconjugated resin ( control ) and incubated at 37 ° c . with stirring . endotoxin levels were determined in the supernatant before , 10 and 20 minutes after adding the resins . as shown in table 2 , lps was specifically adsorbed by rpmb - 1 . the endotoxin - binding capacity of polymixin b conjugates was also studied . lps ( sigma l4130 ) was dissolved in pyrogen - free water at 0 . 2 mg / ml , and 4 ml of this solution was added to a test tube containing 20 . 6 mg of rpmb - 1 , and incubated at 37 ° c . with stirring . the supernatant was collected every 30 minutes by centrifugation and the od values at 210 nm was determined . the od210 value was dropped from 1 to 0 . 6 within the first 30 minutes of incubation and remained unchanged afterwards . by adding 20 . 5 mg of fresh rpm - 1 into the supernatant , the od value was slightly reduced from 0 . 6 to 0 . 4 . therefore , it was assumed that 20 . 6 mg of lps adsorbent added in the first test tube was saturated with lps . accordingly , an lps adsorption capacity of rpmb - 1 was calculated based on the od value changes of lps solution . since the lps preparation used in this experiment was not pure and contaminated by dna and proteins , it was assumed that the final od value of 0 . 4 reflected the od value of such contaminants . based on this assumption , it was calculated that 1 g of rpmb is capable of binding approximately 25 . 9 mg of lps ( sigma l4130 ) using the following formula : since the endotoxin unit of this lps preparation is 1 . 1 × 10 6 eu / mg , it was calculated that 1 g of rpmb - 1 is capable of binding 29 × 10 6 eu of endotoxin . polymixin b - conjugated resins prepared in examples 1 - 7 were analyzed for their particle size distribution by the method described in example 9 and assayed for the endotoxin - binding capacity by the method described in example 11 to study the relationship between particle size and lps - binding capacity . affiprep poplymixin b ( biorad , usa ) was used as a reference . the endotoxin - binding capacity of individual batches of endotoxin - adsorbents prepared by conjugating with 3 million units of polymixin b was compared and expressed as endotoxin units ( eu ) per gram weight of resin as well as lps weight per gram resin . the weight of lps was obtained by converting the eu values based on the eu value per mg of lps preparation ( sigma l4130 , lps preparation from e . coli o - 111 , b4 , by trichloroacetic acid extraction ) used for this experiment . in spite of using the same amount of 3 million units of polymixin b to make conjugates as described in example 1 - 7 , it was apparent that the endotoxin - binding capacity of polymixin b - conjugated resin is higher if the 50 % particle size is smaller as shown in table 3 . dba / 1jncrj mice ( japan charles river ) were divided into 5 groups ( g1 - g5 , 5 mice per group ). in order to increase the mucosal permeability , all mice received 40 μg of indomethasin ( sigma ) and 2 mg of ovomucoid ( sigma ) for 5 consecutive days from day − 6 to − 2 by the oral route . on day 0 , all mice received an iv injection of 0 . 2 ml of arthritogenic monoclonal antibody cocktail ( 10 mg / ml ). endotoxin derived from e . coli o - 111 ( phenol extracted lps , sigma ) was dissolved in pbs at 7 . 5 mg / ml , and 0 . 2 ml of this solution was administered into g1 - g4 mice by the oral route for 3 consecutive days from day 0 to 2 . endotoxin - adsorbent , rpmb - 1 , was suspended in distilled water at 100 mg / ml , and deaerated by a vacuum pump to keep the particles in uniform suspension by preventing the aggregation of the particles . the rpmb - 1 suspension was administered to mice at doses of 0 . 125 ml ( g2 ), 0 . 25 ml ( g3 ) and 0 . 5 ml ( g4 ) twice a day for 4 consecutive days from day 0 to 3 after lps administration . g1 received 0 . 25 ml of water alone . mice in g5 , a positive control of arthritis , received ip injection of 0 . 1 ml of lps solution ( 0 . 5 mg / ml in pbs ) on day 3 . all mice were observed for the development of arthritis every day from day 0 to 14 . severity of arthritis was scored by 5 grades , 0 : normal without any swelling , 1 : clinically apparent swelling of one digit , 2 : moderate redness and swelling of more than 2 digits or moderate redness and swelling of the entire paw , 3 : severe redness and swelling of the entire paws , and 4 : maximum inflamed limb with involvement of multiple joints . the sum of the arthritis score ( maximum 16 per mouse ) of individual animals was calculated . the effect of the endotoxin - adsorbent was calculated based on the average score of 5 mice using the following equation : since the arthritis scores reached a maximum on day 7 , the effect of the endotoxin - adsorbent was calculated using the scores on day 7 . the suppression of arthritis by rpmb prepared in example 2 at 25 mg , 50 mg and 100 mg per mouse by oral administration is shown in table 3 . none of the five mice which received 100 mg of rpmb - 1 developed arthritis , whereas 2 out of 5 mice which received 50 mg of rpmb - 1 developed mild arthritis ( average score : 2 ), and 4 out of 5 mice which received 25 mg of rpmb - 1 developed moderate arthritis ( average score : 9 ) ( table 3 , experiment 1 ), indicating a dose response effectiveness of rpmb - 1 . similarly , rpmb - 2 , 1m / 300 and 4m / 300 , which have higher binding capacities of lps then rpmb - 1 , were also tested for their effect on arthritis at a dose of 10 mg per mouse . all three preparations were equally effective and suppressed the development of arthritis almost completely ( table 3 , experiment 2 ) the tablets were prepared by mixing 15 g of 1m / 300 , which was prepared in example 7 , 2 . 5 g of lactose , 2 . 4 g of corn starch , and 0 . 1 g of magnesium stearate . these four components were mixed well and compressed by a single punch tableting machine to make tablets containing 200 mg of 1m / 300 per a tablet . rpmb - 2 powder shown in example 3 was dispensed into hard capsules at 150 mg per a capsule .
it is believed that the abnormal absorption of endotoxin present in the gastrointestinal tract relates to the pathogenesis of autoimmune diseases such as rheumatoid arthritis . in an animal model for rheumatoid arthritis , it is observed that arthritis is improved by removing endotoxin . the present invention provides an endotoxin - adsorbent , which is capable of removing endotoxin in the gastrointestinal tract and can be administered to humans safely . by using a non - digestible and non - absorbable , and therefore , safe endotoxin - adsorbent , which has a high endotoxin - binding capacity for removing large amounts of endotoxin present in the gastrointestinal tract , it is possible to prevent and treat autoimmune diseases such as rheumatoid arthritis .