AFLAGELLARY FORMS OF TRICHOMONAS SPECIES AS CAUSATIVE AGENT OF CYSTIC FIBROSIS-MUCOVISCIDOSIS

ŠUKRIJA KRVAVAC


Department of Gynecology,Public Health Center Stari Grad,

University and Medical Center, Sarajevo



In aprox 15.000 cases of chronic hypertrophic cervicitis with pathologic mucous hypersecretion,during 1974-1988 in Outpatient Department, in about 95% cases trichomonal infection of cervix uteri with aflagellary round,pseudocystic forms of those parasites has been found. In the remaining 5% Trichomonas negative cases, temporary mucorrhea in respiratory tract with trichomonal infection of mucus has been noticed.

In the 11 observed cases  of Cystic Fibrosis-Mucoviscidosis (CF), chronic trichomoniasis of respiratory tract has been also found.

All 11 mothers of CF patients have had genital trichomoniasis and by majority of other members of the family, infection with some of the 3 existing species of trichomonads has been found. In all cases it was about aflagellary round forms of parasites, and very rarely, in liquid medium, about flagellary,trophozoit forms.

In the comparative research of pathologic mucus by genital trichomoniasis, as well as in children ill from CF, strong association of trichomonal infection, pathologic mucous hypersecretion, fibrous hyperplasia and cystogenesis has been noticed. Comparison of the clinical symptoms, pathoanatomic macro and microscopic findings and especially of immunologic phenomenon speaks in favor of trichomonal etiology of CF.

Out of more than 100 species belonging to the family of Trichomonadidae, 24 of them parasite on mammals and only 3 species on humans: Trichomonas vaginalis Donne 1836, T.hominis-intestinalis Davaine 1860, and T. tenax-buccalis-elongata Steinberg 1926. There are two basic biological forms of those parasites: flagellary and aflagellary (round, pseudocystic, regressive). Round forms are considered as saprophytes,commensals and often could be found in the urogenital, respiratory and digestive tract of the patients from various diseases, as well as in, at first sight, healthy persons of all ages.

There is a justified dilemma whether it is correct to consider as a saprophyte microbe which considerably activates immune apparatus of the host, as it is the case with trichomonads of all species, i.e. isn’t the aflagellary form a result of the host immune apparatus action, controlling in such way invasiveness of the parasites. From this arises the final question, what happens if the immune apparatus is not able to resist that agent? That happens especially in the early phase of ontogenetic development, in time of maturation of immunity mechanisms.

Extraurogenital trichomonal infection of newborns has not been systematically investigated, nor any possible consequences have been entirely perceived. Longstanding clinical observations led me to the idea of a possible causal relation between the intrauterine, i.e. peripartal trichomonal infection and later appearance of CF.

CF is generalized exocrinopathy in which the most of clinical manifestations are the consequence of obstruction or abnormal secretion in respiratory tract, salivary gland, digestive and biliarytract, pancreas and urogenital tract, along with the increased level of NaCl in sweat.

Nowadays dominates attitude that CF is a hereditary disorder of metabolism. Pathogenetic mechanism and the place on chromosome where supposed gene responsible for CF could be found, has not been précised to the present day.

Every proposed mechanism tending to solve the enigma of etiopathogenesis of CF must allow large variations in severity of the characteristic pathogenic changes and must explain: (a) generalized dysfunction of exocrine glands, present at or before birth, (b) abnormal quantities of electrolytes in sweat, (c) accumulation of tenatious mucus which has long been considered responsible for obstruction of many organs affected by the disease, (d) various biochemical abnormalities which may influence cellular biochemical functions, and (e) susceptibility of patients to respiratory infections (1).

The idea that trichomoniasis and CF, at first sight, are two different diseases, could be brought into causal relation, resulting in systematic microscopic examinations of pathologic mucus from cervixuteri, in upper purt of respiratory tract of CF patients and other members of CF families. Pathoanatomic changes in hypertrophic cervicitis are strikingly similar to the changesin CF process. Macroscopic appearance and histologic structure of small cysts on cervix uteri and on pancreas in CF make the same impression.

MATHERIAL AND METHOD

During longstanding period, from 1974 to 1988, of comparative research, I have analyzed in the gynecology policlinic about 15.000 cases of hypertrophic cervicitis with pathologic mucorrhea, as well as 11 CF patients and their closer relatives. Immediately after taking mucus from cervical mucous membrane, fresh smear was colored by 1% of Briliantcresyl in physiologic solution. In order to well notice and identify parasites, the microscoping was made immediately after taking mucus and during 2-3 minutes after the coloring. Aflagellary trichomonadas are by their size and shape similar to leucocytes, but because of the active ejection of color, they remain for a certain time uncolored and that is how they differ from leucocytes which immediately take color. Besides, activity of microtubular apparatus in cytoplasm of the round aflagellary trichomonads, are manifested by microscopically visible, so called “Brown’s motion” of cytoplasm that is not present with leucocytes or in flagellary trophozoites. In women with pathologic bronchial mucorrhea and/or bowel disorders with mucus in stools, secretions has been microskopied over by the same method. Control examinations after ending of bronchorrhea, i.e. normalization of bowel disorders have been done with repeated microscopic examination of cervicovaginal secretion.

RESULTS

Round trichomonads have been found in the cervical mucus in about 95% cases. Rest of the cases, about 5%, were women with different pictures of disease of the respiratory and digestive tract. During the systematic examinations of mucus from respiratory organs, as well as of bowel disorders, round trichomonads were found here. After regression of extraurogenital diseases and disappearance of trichomonads from the mucus of respiratory and digestive tract, round trichomonads appeared again in cervical mucus.

Round trichomonads have been found in nasopharyngeal secretions, most impacted in mucus, in all cases, by 11 verified observed CF patients (NaCl in sweat higher than 70mMol/l). Cervical mucus has been taken from all 11 mothers and trichomoniasis was also ascertained. Anamnestically has been obtained the fact that all of them had intensified vaginal flora during pregnancy, and by 7 of them significant quantity of liquid, probably embryonic fluid, drained out of vagina several days before delivery. Round trichomonads were found in mucus of upper parts of the respiratory tract with the majority of the CF patients siblings.

Aflagellary forms of all three species of trichomonads are result of acting of unfavorable external factors, host immunity in the first place, and do not show microscopic differences. That is why I used common title Trichomonas species or round trichomonads.

It is as incorrect from the point of view of the existing morphological differences among the three species of trichomonads in flagellary phase, as it is justified from pathoanatomic and clinical immunologic point of view.

DISCUSSION

The known fact that hypersecretion of mucus in CF is not in correlation with colonization of bacteria and other microbes, and previously presented opinions and observations as well, are reasons from which I directed my research towards, since that moment, unsuspected trichomonads.

Data from the literature point that hypersecretion of mucus was noticed in various parasitoses: natural and experimental trichomoniasis of young mammals and poultry (2,3); coecidiesis of domestic and wild animals  (4), intestinal piroplasmosis and nutaliosis of ungulates (5); theileriosis of cattle, hexamitiasis of pigeons, turtles and laboratory mice, histomoniasis and amoebiasis of turkeys (6); experimental trichinelosis (7). Furthermore, larger quantities of mucus were noticed on gills of fish infected with Trichodina Fultoni, Chilodonella Cyprini, Trichodonella epizootica and Tetrahymena Corlisii Thompson (8,9,10,11). Increased mucous wasnoticed in human lambliasis, amoebiasis, and balantidiasis as well (6). Grys has already carried hypothesis about cervical mucous barrier against penetration of trichomonads into uterus (12).

Both by the humans and animals (13), young kids are less resistant to parasitic infection, probably because of nonmaturity of the immune apparatus. It could be supposed that mucorrhea is a reaction of the host to acting of proteolytic enzymes of the parasites, with which defense from hystolysis is made up. In his research, Honigberg noticed inhibition of trichomonads with 0.3% mucin (14).

Natural resistance of mollusks to parasitic infections is probably in connection with abundance of mucous cells. So, drowning of a snail into the culture of very virulent Acanthamoebe did not result in pathologic effect on it (15).

Along with mucous hypersecretion, another characteristic of CF process is accelerated fibroplasia. According to the relevant literature, it may be concluded that there is a tendency to fibrosis in all parasitoses, and it has a biological function of isolation, encapsulation of parasites in the organ infected. Accelerated fibroplasia was noticed in natural and experimental trichomonal infection (6,16,17,18). Accordingly, I think that the fibrous component in the CF process is a reaction of the host to presence of trichomonads, i.e. it has a biological meaning of encapsulation of those parasites which are most frequently found on mucous membrane of hollow organs.

Pathogenicity of Trichomonas vaginalis was proved in 1916 (19). Question of pathogenicity on intestinal trichomonads causes controversial opinions even today, but it is believed that tropical strains can initiate pathological process in digestive tract (20). As for the oral trichomonads, they are rather considered saprophytes.

Some authors (20,21) have noticed that during the lasting presence of oral (!) or intestinal trichomonads on their typical places,  the lasting genital trichomoniasis and vice versa, do not occur. Explanation for that phenomenon should be looked for in the existence of common immunity against all three human species of trichomonads (6,22). Namely, circulating antibodies protect the host from simultaneous infection of another organ with another species of trichomonads. Of course, it does not happen when immune status of the host is more significantly compromised (23). Numerous personal observations also confirm existence of this phenomenon.

There are many reports of finding trichomonads in the respiratory tract with tendency of entitling them Trichomonas species (6), although it is often about Trichomonas tenax with changed antigenic structure (24). It seems that earlier after birth the infection is discovered, more frequently it is about vaginal species of trichomonads in respiratory tract of the child, i.e. of CF patient. 

Obstetricians often observe premature ruptures of embryonic membranes. Besides, it is very probable that some cases of ruptures pass unnoticed even by pregnant women themselves if they don’t end in soon delivery. Regarding the fact of frequent trichomonal infection of pregnant women (it gets up to 25%), in this way, vital forms of trichomonads are allowed to penetrate into embryonic fluid long before the delivery. Infection of embryonal fluid by trichomonads does not occur rarely (25,26), and there are personal observations. This explains possibility of intrauterine infection of fetus, even in second trimenon of pregnancy, explaining so early fetal cases of CF.

When fetus swallows infected fluid, it results firstly in the sensitization and after that in mucous hypersecretion in digestive tract, as well as in known pathologic changes characteristic for CF. Such a way of infection explains appearance of meconial ileus immediately after delivery. And also great quantities of mucus in bowels of a stillborn.

In this etiopathogenetic mechanism of CF genesis, the key event should be pointed out, i.e. a possibility that swallowed trichomonads infect pancreas. Infection is especially alleviated, by only homo sapiens, characteristic posture of newborn on its back, and this has nonphysiological gravitational effect, i.e. alleviated penetration of infected intestinal contents into pancreatic channels, as well as impeded draining of products of biliary and pancreatic secretion.

Along with those factors, in experiment on mice was noticed the affinity of trichomonads to pancreatic tissue (23), resulting in glandular atrophy and interstitial fibrosis (27). It is not difficult to suppose that such damages may cause pancreatic (as well as hepatic) dysfunction, characteristic for CF. Cytolytic activity of trichomonads along with autolytic effect of pancreatic enzymes, cause destruction of the pancreas drain channels, leading to formation of cysts, i.e. the third characteristic of the CF process. The consequence of that mutual activity of trichomonal toxins and pancreatic autolyse explains very frequent forming (85-90%) of cysts on pancreas by CF. In such formed cysts, trichomonads continue to stimulate secretion of mucus resulting in destruction of parasites in the end.

Level of pathologic seize of pancreas or other organs and final result of the infection as well, depends on the initial infection extensiveness, the innate parasite virulence as well as immunobiological potwential of fetus. The known large variations of trichomonads pathogenicity, constitutional and race differences in immunity, enable a large spectrum of clinical and pathoanatomic phenomena as in human trichomoniasis, so in CF.

If the infection does not happen in uteri, but during delivery, then respiratory glands of the newborn are in physiologic state, and this happens very often by CF patients. In such a variant, only after the catarrhal phase of sensitization, mucous hypersecretion occurs in the organ infected and even in further organ reached only by toxin or parts of lysed trichomonads. Here it should be pointed out a very important data by Frommolt (28) that out of 1.500 Chinese women, he found only 2 cases of vaginal trichomoniasis, that is entirely in accordance with very low incidence of CF in yellow race. There is a similar relation with other populations as well: low incidence of vaginal trichomoniasis and low incidence of CF, that significantly supports proposed model of CF etiopathogenesis.

Trichomonal infections are often followed by appearance of circulating antibodies, while appearance of immune complex in CF is unsolvable enigma, because it is not in correlation with opportunistic infections. Accordingly to the pathogenesis explained, immune complex in CF is a composition of trichomonal toxin and antitrichomonadic antibodies of the host. Large variations of immunogenic potentials of trichomonads are the cause for a varying level of immune complex by CF patients. Significant variations of the immune capacity with CF patients contribute to complexity of interplay of those variable factors in the host-guest interaction.

Bacterial and other infections, more or less immunogenic, only complicate pathologic process, make further disturbance of the immune status and make clinical picture difficult (29). Polymicrobic, multiantigenic stimulation of the host causes immunodepression, pediatric “equivalent of AIDS”, that explains high mortality of CF patients.

After intrauterine infection and sensitization of fetus, peripartal reinfections of respiratory tract result in strong toxoallergic manifestations. In such cases, round trichomonads are hardly found in respiratory tract because they are submitted to destruction, resulting once more, in maximal toxin release. It is known though, that lysates of trichomonal cultures have outstanding pathogenic effect. When, because of massiveness of infection, especially with more virulent strain of trichomonads than in primal infection, new focus creates in the respiratory tract, and a stronger immune reaction happens, then regression of infective focus in digestive tract as well as regression or disappearance of symptoms from that side occurs. So, if a “breakdown” of immunobiological resistance does not occur, than the focus of infection moves to another organ, from where it stimulates the host to produce antibodies, at a higher level. In this option, trichomonads are hardly found in digestive tract and manifestations on those organs are mainly allergic. It should be stressed the importance of swallowing of the infected mucus from upper parts of the respiratory tract. This is why significant clinical alleviation with CF patients occurs after matinal postural expectoration of mucus (30).

Nowadays, it is claimed that CF is a metabolic disorder which is conditioned by autosomal recessive inheritance. Changes on chromosome 7 have been noticed with all members of CF families (31). This chromosome is the least known and very unstable, experiencing changes during the evolution of mammals and even human. It should be reminded that protozoa and probably trichomonads were present during the whole evolution of mammals and that the way of interaction between them is “written down” in the gene complex. Regarding that the immune apparatus of animals is not exposed to trichomonads in various nonphysiological ways as with humans, that is why CF does not develop in them.

Although both parents (24) and probably whole CF family are infected with the same immunogenic strain of trichomonads, though it often happens that one parent has symptomatic and another one asymptomatic trichomoniasis. What would be the reaction of a child to the family strain of parasites, depends on that from which parent inherits resistence or susceptibility. Expressed resistance of one parent will cause selection of significantly more virulent strains of parasites, that, with expressed susceptibility of another parent, may result in great differences, as in resistance by children and also in pathologic response to the family strain of parasites. Those quantitative differences between immunogenicity of parasite and immune reactivity of the host results as the interaction host-guest is expressed as CF.

This author believes that simultaneous action by three factors results in imitation of the genetic inheritance of CF, and these are: (a) relatively frequent familiar trichomoniasis, (b) possibility of congenital trichomonal infection, and (c) autosomal recessive heredity of susceptibility to parasitic infections. Furthermore, the author believes that the noticed chromosome changes with all members of a CF family are in fact, of a immunogenetic nature and as a response to a chronic family, symptomatic or asymptomatic trichomoniasis.

The fact that trichomonads in culture of tissue inhibits mitosis of cells in prophase, has an indicative and until now, unsolved significance (32).

Laboratory findings, considering CF characteristics, are the result of interaction of trichomonal factor and immunobiological mechanism of the host. Chronic exposition to trichomonads and their toxins causes a leucocytic dysfunction (33) so probably a disfunction of the mechanism of NaCl reabsorbing from the primary filtrate of sweat glands in which free trichomonal toxins, outside immune complex, are placed.

As a compensation for the loss of NaCl in sweat, stronger reabsorbing of NaCl occurs in kidnex tubules, which are by nature less sensitive to various toxins.

Because of local action of trichomonads, dysfunction of ciliary apparatus of mucous membrane is the most understandable, especially before sensitization, when mucous glands do not manage to “catch” all the parasites.

Already mentioned presence of round trichomonads in respiratory tract is best proved by examination of mucus which is a natural mediator of parasite expulsion. Some of the organs of upper part of the respiratory tract originate from embryonic equivalents of gills (larynx, pharynx), and as an interesting evolutionary parallel, fish-gills are just the place where various protozoa could be found impacted in mucus. Zoopathologists discussed whether in such cases it is about parasitic or saprophytic relation. So there is the same dilemma as in the case of trichomonads present in the respiratory tract of humans, as discussed earlier. The main reason for this dilemma is the fact that trichomonads have often a long subclinical phase of infection where sensitization occurs. Formation of immune antitrichomonal lysines results, in cases of reinfection, in causing a strong destruction of parasites and so maximal toxin release, so that secondary pathogenicity is more strongly expressed than the primary one because of that.

The author believes that exposed etiopathogenetic mechanism of CF genesis satisfies all of the conditions mentioned in the beginning, and that it will instigate further research in this field.

Sarajevo, 16th of June, 1988

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Article sent to "Acta Medica Jugoslavica". It was considered 1988  by three referees who have agreed the sent  draft to be rejected for a number of shortcomings.