Study: Antibiotics destroy immune cells and worsen oral infection

New research shows that the body's own microbes are effective in maintaining immune cells and killing certain oral infections.
A team of Case Western Reserve University researchers found that antibiotics actually kill the "good" bacteria keeping infection and inflammation at bay.
Scientists have long known that overuse of antibiotics can do more harm than good. For example, overuse can cause antibiotic resistance. But research into this phenomenon in oral health was uncharted territory.
Pushpa Pandiyan, an assistant professor of biological sciences in the School of Dental Medicine, led a team of researchers to examine "resident" bacteria, their fatty acids and their effect on certain types of white blood cells that combat infections in the mouth.
Specifically, researchers looked at the "short-term maintenance" of Tregs and Th-17 cells in fighting fungal infections, such as Candida, in a laboratory setting.
They found that those natural defenses were very effective in reducing infection and unwanted inflammation-- and antibiotics can prevent such natural defenses. Their work was recently published in Frontiers in Microbiology.
"We set out to find out what happens when you don't have bacteria to fight a fungal infection," Pandiyan said. "What we found was that antibiotics can kill short-chain fatty acids produced by body's own good bacteria."
"We have good bacteria doing good work every day, why kill them?" Pandiyan added. "As is the case with many infections, if you leave them alone, they will leave on their own."
"Of course, antibiotics are still needed for life threatening infections. No question about that. Our bodies have many natural defenses that we shouldn't meddle with," she said. However, needless overuse of antibiotics is not helpful, she said.
"Also, we know there is a definite link between oral health and overall health," she added.
Pandiyan said the study could have broader implications on protective effects of "resident microbiota" in other types of infections.
Pandiyan is concurrently working on a National Institutes of Health research project examining HIV patients who have developed oral-health conditions as a result of weakened immune systems.
She was joined in the study by dental school research staff Natarajan Bhaskaran, Cheriese Quigley, and Elizabeth Schneider, and students Clarissa Paw and Shivani Butala.

Smoking weakens the ability for pulp in teeth to fight illness and disease.

As if lung cancer, emphysema and heart disease weren't enough, there's more bad news for cigarette smokers.

Researchers at the Case Western Reserve University School of Dental Medicine found that smoking also weakens the ability for pulp in teeth to fight illness and disease.

In other words, smokers have fewer defense mechanisms on the inside of their teeth.

"That might explain why smokers have poorer endodontic outcomes and delayed healing than non-smokers," said Anita Aminoshariae, associate professor of endodontics and director of predoctoral endodontics. "Imagine TNF-α and hBD-2 are among the soldiers in a last line of defense fortifying a castle. Smoking kills these soldiers before they even have a chance at mounting a solid defense."
The results of the study were published in the Journal of Endodontics.

Aminoshariae said that, previously, there was little research into the endodontic effects of smoking--the inside of teeth. Smokers had worse outcomes than nonsmokers, with greater chances of developing gum disease and nearly two times more likely to require a root canal.

This new preliminary research set out to explain the possible contributing factors.

Thirty-two smokers and 37 nonsmokers with endodontic pulpitis--more commonly known as dental-tissue inflammation--were included in the study.

"We began with a look at the dental pulp of smokers compared with nonsmokers," she said. "We hypothesized that the natural defenses would be reduced in smokers; we didn't expect them to have them completely depleted."
One interesting find, Aminoshariae noted, was that for two patients who quit smoking, those defenses returned.
Joining Aminoshariae in the study were former students Caroline Ghattas Ayoub and Mohammed Bakkar; faculty members Tracey Bonfield, Catherine Demko, Thomas A. Montagnese and Andre K. Mickel; and research Santosh Ghosh--all from the School of Dental Medicine.

Chalky teeth

Depending on symptomatic and phenotypic severity the condition of chalky teeth is categorised into three levels. The symptoms of chalky teeth were first described in 1978, with the term molar-incisor hypomineralisation (MIH) introduced in 2001. The condition is the consequence of a deline-ated defect in tooth enamel development which affects at least one of the permanent back teeth (molars) and, under certain circumstances, will also comprise the incisors. According to recent media coverage such tooth defects are claimed to be attributable to the uptake of Bisphenol A (BPA).
Amongst a wide range of various products BPA can also occur in food contact materials. Its use in the manufacture of baby bottles has been banned since 2011. Reports of a possible connection between MIH and BPA-exposure are based on a study by Jedeon et al. (2013) which examined the connection between BPA exposure and mineralisation defects of tooth enamel in rats. In subsequent publications the authors reported that the mineralisation dis-turbances occurred mainly in male (up to 71%) and less frequently in female rats (only up to 31%) (Jedeon et al., 2016a; Jedeon et al., 2014), and identified selected hormone-controlled signalling pathway as potential molecular targets (Houari et al., 2016).
The German Federal Institute for Risk Assessment (BfR) has evaluated the study (Jedeon et al., 2013) and concludes that there is currently no scientific reason to assume a connection between the uptake of BPA the occurrence of MIH in children. According to recent data from the Netherlands, oral uptake of BPA in highly-exposed children amounts to 0.14 micrograms (μg) per kilogram (kg) body weight and day. This is is 35 times lower than the dose used by Jedeon et al. (2013). In conjunction with the different toxicokinetic behaviour of BPA in hu-mans a direct connection between BPA and MIH therefore appears unlikely in humans under conditions of expectable real-life exposure.
It should be noted that the study of Jedeon et al. is subject to several limitations, which limit its transferability. The examination in 2013 was conducted exclusively on male rats with only one dose of BPA being used. Later studies showed that the respective findings were considerably weaker or non-existent in females (Jedeon et al., 2014). It also appears that missing effects on day 100 of postnatal development were not put sufficiently into context. The findings of other groups from multigenerational studies on rats and mice, some of which used very high BPA doses with no reported tooth damage, were not taken into consideration.
The condition of MIH occurs in Europe with a frequency of 3-22 %, with a worldwide occurrence of 2-40 % (Elhennawy et al., 2017). Various reasons are assumed to contribute to this occurrence. Epidemiological studies point for example to maternal diseases during the last quarter of pregnancy, complications during birth or frequent illness in the first year of the born child (possibly also connected too high fever). Other reasons discussed are low blood levels of vitamin D as well as early intake of the antibiotic amoxicilli. Other studies report on a possible connection between MIH and increased exposure to dioxin, for under 5-year olds with high serum levels of tetrachlorodibenzo dioxin (TCDD) in Seveso later showed an in-creased prevalence of MIH.
Altogether it appears that MIH is caused by a variety of factors and thus has to be considered a multifactorial condition (Schneider and Silva, 2018).

New findings re chronic oral pain condition known as Burning Mouth Syndrome

The picture is becoming clearer regarding the chronic oral pain condition known as Burning Mouth Syndrome, or BMS, which mainly affects women who are middle-aged and older. In a dissertation at Sahlgrenska Academy, additional steps are being taken toward better diagnosis and treatment.

"Our hope is that the new findings will contribute to the development of objective diagnostic criteria and effective individualized treatment both that are currently lacking," says Shikha Acharya, who has a PhD in oral microbiology and immunology at the Institute of Odontology.

Burning Mouth Syndrome (BMS) is a chronic pain syndrome in the oral cavity that affects approximately 4% of the Swedish population. This chronic condition mainly affects middle-aged and elderly women.

The pain is experienced as burning or stinging. The tongue is most often afflicted, but the palate, lips and gums also may be affected. Other common symptoms include dry mouth and altered taste sensation, such as a bitter or metallic taste in the mouth.

BMS is a challenge for health care providers, particularly in dental care, and a debilitating condition for many of the patients. When they estimate their problem on a visual analogue scale (VAS) where 0 is "not at all difficult" and 100 is "unbearable," the average response is 66, the dissertation indicates. The findings came from 56 women with BMS.

In her work Shikha Acharya also connected clinical findings and self-reported reported findings from questionnaires from patients with BMS about their symptoms and background (other diseases, use of medications, etc.) along with saliva-related factors. The results have been compared with a gender- and age-matched control group.

It turns out that 45 percent of the BMS patients reported to have altered taste sensations. A total of 73 percent experienced pain that was burning or stinging or a combination of the two, but stinging and numbness also occurred.

In addition to BMS, they have a higher incidence of other types of diseases, use more medications, are more prone to grinding their teeth and report more allergies than the control group. However, more advanced analyses show that BMS was strongly associated to self-reported skin diseases and subjective oral dryness.

The fact that the BMS patients, compared with people in the control group, report that they suffer considerably more from skin diseases and skin problems is a new discovery. Similarly, that the mucin proteins in BMS patients' saliva are altered and contain lower amounts of carbohydrate structures that affect the oral cavity's immune system.

Analysis of inflammatory constituents in saliva shows complex relationship between BMS and background inflammation, with some of the BMS patients having higher levels of inflammation than the control group while others had lower.

The dissertation work is part of a larger project aimed at finding a model for BMS that can facilitate diagnosis and treatment in the future. The new pieces of the puzzle are helping to characterize the disease and the persistent mouth pain associated with it.

"It's important because the afflicted patients often feel that their surroundings and health care professionals doubt their ailment," says Shikha.

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Title: On Characteristics of Burning Mouth Syndrome Patients; http://hdl.handle.net/2077/55387

Regrowing dental tissue with stem cells from baby teeth

Sometimes kids trip and fall, and their teeth take the hit. Nearly half of children suffer some injury to a tooth during childhood. When that trauma affects an immature permanent tooth, it can hinder blood supply and root development, resulting in what is essentially a "dead" tooth.
Until now, the standard of care has entailed a procedure called apexification that encourages further root development, but it does not replace the lost tissue from the injury and, even in a best-case scenario, causes root development to proceed abnormally.
New results of a clinical trial, jointly led by Songtao Shi of the University of Pennsylvania and Yan Jin, Kun Xuan, and Bei Li of the Fourth Military Medicine University in Xi'an, China, suggest that there is a more promising path for children with these types of injuries: Using stem cells extracted from the patient's baby teeth. The work was published in the journal Science Translational Medicine.
"This treatment gives patients sensation back in their teeth. If you give them a warm or cold stimulation, they can feel it; they have living teeth again," says Shi, professor and chair in the Department of Anatomy and Cell Biology in Penn's School of Dental Medicine. "So far we have follow-up data for two, two and a half, even three years and have shown it's a safe and effective therapy."
Shi has been working for a decade to test the possibilities of dental stem cells after discovering them in his daughter's baby tooth. He and colleagues have learned more about how these dental stem cells, officially called human deciduous pulp stem cells (hDPSC), work and how they could be safely employed to regrow dental tissue, known as pulp.
The Phase I trial, conducted in China, which has a research track for clinical trials, enrolled 40 children who had each injured one of their permanent incisors and still had baby teeth. Thirty were assigned to hDPSC treatment and 10 to the control treatment, apexification.
Those that received hDPSC treatment had tissue extracted from a healthy baby tooth. The stem cells from this pulp were allowed to reproduce in a laboratory culture, and the resulting cells were implanted into the injured tooth.
Upon follow-up, the researchers found that patients who received hDPSCs had more signs than the control group of healthy root development and thicker dentin, the hard part of a tooth beneath the enamel. Blood flow increased as well.
At the time the patients were initially seen, all had little sensation in the tissue of their injured teeth. A year following the procedure, only those who received hDPSCs had regained some sensation. Examining a variety of immune-system components, the team found no evidence of safety concerns.
As further support of the treatment's efficacy, the researchers had the opportunity to directly examine the tissue of a treated tooth when the patient reinjured it and had to have it extracted. They found that the implanted stem cells regenerated different components of dental pulp, including the cells that produce dentin, connective tissue, and blood vessels.
"For me the results are very exciting," Shi says. "To see something we discovered take a step forward to potentially become a routine therapy in the clinic is gratifying."
It is, however, just a first step. While using a patient's own stem cells reduces the chances of immune rejection, it's not possible in adult patients who have lost all of their baby teeth. Shi and colleagues are beginning to test the use of allogenic stem cells, or cells donated from another person, to regenerate dental tissue in adults. They are also hoping to secure FDA approval to conduct clinical trials using hDPSCs in the United States.
Eventually, they see even broader applications of hDPSCs for treating systemic disease, such as lupus, which Shi has worked on before.
"We're really eager to see what we can do in the dental field," Shi says, "and then building on that to open up channels for systemic disease therapy."

Biomaterial could keep tooth alive after root canal (video)

A root canal ranks high on most people's list of dreaded dental procedures. Although the lengthy and sometimes painful surgery relieves the agony of an infection, a root canal results in a dead tooth with no living soft tissue, or dental pulp, inside. Today, scientists report development of a peptide hydrogel designed to stimulate the growth of new blood vessels and dental pulp within a tooth after the procedure. The researchers are presenting their results today at the 256th National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world's largest scientific society, is holding the meeting here through Thursday. It features more than 10,000 presentations on a wide range of science topics.
A brand-new video on the research is available at http://bit.ly/acsrootcanal.
"What you end up with after a root canal is a dead tooth," Vivek Kumar, Ph.D., the project's principal investigator, says. "It's no longer responsive. There are no nerve endings or vascular supply. So the tooth is very susceptible to subsequent infection and, ultimately, falling out."
During a root canal, the dentist drills off the top of an infected tooth to access the soft tissue inside. The dentist then removes the infected dental pulp and fills the space with tiny rubber rods called gutta percha and caps the repaired tooth with a crown.
Kumar and Peter Nguyen, Ph.D., who is presenting the work at the meeting, wanted to develop a material that could be injected in place of the gutta percha. The material would stimulate both angiogenesis, or new blood vessel growth, and dentinogenesis, or proliferation of dental pulp stem cells, within the tooth. Both Kumar and Nguyen are at the New Jersey Institute of Technology.
Kumar drew on his previous experience developing a hydrogel that stimulates angiogenesis when injected under the skin of rats and mice. The hydrogel, which is liquid during injection, contains peptides that self-assemble into a gel at the injection site. The peptides contain a snippet of a protein called vascular endothelial growth factor, which stimulates the growth of new blood vessels. Kumar, then a postdoctoral researcher at Rice University, and his coworkers showed that the self-assembling peptide hydrogel stimulated angiogenesis and persisted under the rodents' skin for as long as three months.
"We asked the question, if we can stimulate angiogenesis in a limb, can we stimulate angiogenesis in other regions that have low blood flow?" Kumar says. "One of the regions we were really interested in was an organ in and of itself, the tooth." So Kumar and Nguyen added another domain to the self-assembling angiogenic peptide: a piece of a protein that makes dental pulp stem cells proliferate.
When the team added the new peptide to cultured dental pulp stem cells, they found that the peptide not only caused the cells to proliferate, but also activated them to deposit calcium phosphate crystals -- the mineral that makes up tooth enamel. However, when injected under the skin of rats, the peptide degraded within one to three weeks. "This was shorter than we expected, so we went back and redesigned the peptide backbone so that we currently have a much more stable version," says Kumar.
Now, the team is injecting the peptide hydrogel into the teeth of dogs that have undergone root canals to see if it can stimulate dental pulp regeneration in a living animal. If these studies go well, the researchers plan to move the hydrogel into human clinical studies. They have filed a patent for the redesigned peptide.
The hydrogel in its current form likely won't reduce the invasiveness or pain of a root canal, but Kumar and Nguyen are planning future versions of the peptide that contain antimicrobial domains. "Instead of having to rip out everything inside the tooth, the dentist could go in with a smaller drill bit, remove a little bit of the pulp and inject our hydrogel," Kumar says. The antimicrobial portion of the peptide would kill the infection, preserving more of the existing dental pulp, while helping grow new tissue. And the root canal may no longer be such a dreaded procedure.
A press conference on this topic will be held Wednesday, August 22, at 9 a.m. Eastern time in the Boston Convention & Exhibition Center. Reporters may check-in at the press center, Room 102 A, or watch live on YouTube http://bit.ly/ACSLive_Boston2018. To ask questions online, sign in with a Google account.

Bioengineered tooth replacement opens doors to new therapies

Tooth loss is a significant health issue currently affecting millions of people worldwide. While artificial dental implants are the existing standard tooth replacement therapy, they do not exhibit many properties of natural teeth and can be associated with complications leading to implant failure. Two articles published in the September 2018 issue of the Journal of Dental Research share recent advances in bioengineering teeth.

In the article "Bioengineered Tooth Buds Exhibit Features of Natural Tooth Buds" Pamela Yelick, Tufts University School of Dental Medicine, Boston, Mass., USA and co-authors explored new methods to create highly cellularized bioengineered tooth bud constructs that include features that resemble natural tooth buds such as the dental epithelial stem cell niche, enamel knot signaling centers, transient amplifying cells and mineralized dental tissue formation. The constructs were composed of postnatal dental cells encapsulated within a hydrogel material that were implanted subcutaneously into immunocompromised rats.

This is the first report that describes the use of postnatal dental cells to create bioengineered tooth buds that exhibit evidence of these features of natural tooth development, pointing to future bioengineered tooth buds as a promising, clinically relevant tooth replacement therapy.

In the article "Bone Marrow Stromal Cells Promote Innervation of Bioengineered Teeth" Sabine Kuchler-Bopp, French National Institute of Health and Medical Research and Fédération de Médecine Translationnelle de Strasbourg, France, and co-authors developed a strategy where autologous mesenchymal cells coming from bone marrow can be used to supply nerves to bioengineered teeth without treatment that uses an immunosuppressor. The innervation of teeth is essential for their function and protection but does not occur spontaneously after injury. This new method provides innervation while avoiding multiple side effects associated with immunosuppressors.

"These exciting studies point to a promising future for bioengineered teeth," said Journal of Dental Research Editor-in-Chief William V. Giannobile. "This cutting-edge research has the potential to advance tooth replacement therapy and the science base to bring such regenerative medicine treatments to improve clinical care."

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