Tag Archives: persistent lyme disease

research pov_lyme arthritis_Peptidoglycan

Research POV: Lyme Arthritis and Peptidoglycan

Important study identifies the Borrelia burgdorferi peptidoglycan as an immunogen likely to cause Lyme arthritis in some patients

 

by Mayla Hsu, Ph.D., Director of Research and Science, GLA

A longstanding mystery in Lyme disease is why some antibiotic-treated patients continue to suffer long-term symptoms, while others recover. It is possible that a hyperactive immune system in some patients causes inflammation-related tissue damage. Another possibility is that the bacteria, Borrelia burgdorferi, may still be alive in compartments of the body that are not readily accessible to antibiotics, and the bacteria’s continued replication causes ongoing symptoms.

A recent article found that a component of the bacterial cell wall, peptidoglycan (PG), might be driving the persistent inflammation that causes Lyme arthritis even after antibiotic treatment. The authors, who include a GLA-funded researcher, found B. burgdorferi PG antibodies in the synovial fluid that surrounds the knees of Lyme arthritis patients, which is evidence of an ongoing immune response against bacteria or fragments of its cell wall. In contrast, they did not find significant antibodies against PGs of any other bacteria. A strength of this study is that they compared synovial fluid from Lyme arthritis patients with that of other types of non Lyme-related arthritis. Only Lyme arthritis patients had synovial fluid B. burgdorferi PG antibodies.

Blood was also collected from the same Lyme patients whose synovial fluid was studied. Here, they found that sera (serums) of Lyme arthritis patients also had PG antibodies, although the levels were much lower than in the synovial fluid. Moreover, Lyme arthritis patient sera had much higher levels of PG antibodies than any detected in control patient sera. These findings indicate a continued immune response against PG, particularly in the synovial joints, specifically against B. burgdorferi.

Another asset of this study was its analysis of patient samples both before and after antibiotic treatment. The authors designed a way to detect PG itself, not only antibodies, in synovial fluid and sera. Using this test, they could not find PG in control synovial fluid, nor in Lyme arthritis patient sera. However, it was present in 92% of Lyme arthritis synovial fluids, both before and after treatment with antibiotics; and this was true of patients who had been treated with oral as well as intravenous antibiotics. In addition, the amount of PG strongly correlated with the level of PG antibodies in the same synovial fluid samples. This finding suggests that the bacterial cell wall itself is present in the synovia of patients, and that its presence elicits antibodies against PG.

Peptidoglycan_figure for blog
Comparison of B. burgdorferi PG antibodies for serum and synovial fluid, from Lyme arthritis patients (red) and from controls (black) (healthy and non-Lyme arthritis)

Do these results mean that B. burgdorferi is actively replicating in the patients in whom PG or PG antibodies were found? Testing for bacterial DNA was done on synovial fluid and blood, both before and after antibiotic treatment. Although both compartments were often positive for bacterial DNA before therapy, almost all samples became negative after therapy. This finding suggests that PG and PG antibodies persisted even after eliminating actively replicating B. burgdorferi at these sites, but it does not rule out bacterial replication elsewhere, and leaves open the question of how bacterial cell wall components could remain long after the bacterial DNA is no longer detectable.

This study also identified proinflammatory cytokines in synovial fluid, which play an important role in mediating immune responses. In vitro, the addition of purified B. burgdorferi PG to cultured peripheral blood mononuclear cells (PBMCs) caused increased levels of inflammatory cytokines like TNFα, IL1α, and IFNγ. These and others were also significantly elevated in the synovial fluid of Lyme arthritis patients, suggesting a possible mechanistic link between PG and inflammation. Finally, injection of purified PG in mice resulted in ankle swelling and inflammatory changes that are consistent with the established mouse model for Lyme arthritis.

In sum, these results make a strong case that B. burgdorferi PG may be responsible for driving inflammation and continued symptoms in post-antibiotic Lyme arthritis. Whether it is also implicated in promoting other long-term symptoms remains to be seen. These findings open up a new avenue of inquiry that may yield fruitful insights that will help us to better understand and care for people suffering from persistent symptoms.


Learn more about GLA’s research initiatives and accomplishments:

Research Report
Published Research Findings
Current Grantees 
First Observational Study for Lyme Disease Treatment
Post-treatment Lyme: Two Million by 2020
Blog: Why Good Science is Crucial

why is lyme so hard to treat_gla blog

Why Is Lyme Disease So Hard to Treat?

For many Lyme disease patients, the bacteria seem to outsmart antibiotic treatment. Why?

 

It’s a hotly debated topic, and one that is still not completely understood – what causes the persistent symptoms in many Lyme disease patients?  Why is it that 10-20% of patients, after early diagnosis and treatment with antibiotics, continue to face long-term, chronic, even debilitating, symptoms including joint or muscular pain, fatigue, and/or neurocognitive problems? And why do patients diagnosed later in their disease often have a more difficult time finding an effective treatment? Key possible culprits, persister bacteria, are under investigation, and researchers are uncovering their fascinating and diverse array of adaptive abilities, with the goal of one day eradicating them and more effectively helping patients.

Lying in Wait

Borrelia burgdorferi, the spirochete bacteria that cause Lyme disease, have an elaborate lifecycle, critical for their own day-to-day survival. They have evolved adaptations to multiple, sometimes harsh, environments – moving from bloodmeal-source host animals to ticks, repeating the cycle back into host animals, and sometimes into humans. Persistence is an essential and multi-faceted strategy that B. burgdorferi and other bacteria use to survive and adapt to their highly varied environments.

Unfortunately, these same adaptive abilities may also provide B. burgdorferi the ability to survive an onslaught of antibiotics. In vitro (in culture), treatment with antibiotics kills off most cells, but a small number survive because they adapt to have a new superpower – they are tolerant (although not resistant) to an aggressive antibiotic challenge. Their strategy is to lie dormant during an onslaught of antibiotics, changing their protein composition and shape. When the conditions are just right, and the antibiotics are cleared from the host’s system, they can then transform back into mobile spirochete form (thus giving them the freedom to resurge and multiply). GLA-funded research by Kim Lewis and his team at Northeastern University as well as research by GLA-funded Ying Zhang and his group at Johns Hopkins University revealed this amazing strategy. Their teams independently confirmed the existence in culture of dormant, persister B. burgdorferi, providing evidence that these persisters arise during antibiotic treatment and transform back into mobile spirochetes post-treatment. Whether this phenomenon occurs in patients remains to be shown, but it suggests a way to explain why antibiotic treatment is inadequate in a sizeable proportion of patients.

Interestingly, persistence is not unique to B. burgdorferi. The bacteria that cause other chronic diseases (e.g., tuberculosis, syphilis and leprosy) also form persisters.

A Master of Disguise

How do persisters survive harsh conditions such as antibiotic treatment? For one, they have an altered gene expression profile, producing key proteins which allow them to live in the presence of antibiotics. Throughout its life cycle, B. burgdorferi is a master chameleon, transforming itself from its corkscrew-shaped spirochete form into a variety of shapes, such as round (metacyclic), L-form bacteria, spore-like granules or cysts, and then back again into spirochetes. These different forms can impact diagnosis. For example, there is some limited evidence that B. burgdorferi takes on L-forms in spinal fluid, which could impact methods used for screening when a case of neuroborreliosis (a neurological manifestation of Lyme disease) is suspected, for example.

Borrelia bacteria in the blood
Borrelia bacteria in the blood

B. burgdorferi, similarly to other bacteria, may also transform itself into biofilms, which are a complex aggregate of bacteria with a protective slimy mucus layer surrounding it. Studies by Kim Lewis provided evidence of biofilms contributing to persistence in other diseases, such as Cystic Fibrosis and oral thrush. However, there is only minimal in vitro evidence in the case of B. burgdorferi, which is limited in usefulness until more research is done, and further studies will illuminate whether biofilm forms of B. burgdorferi exist in patients.

Yet another strategy used by the wily B. burgdorferi and other bacteria is to invade host cells. For example, the bacterium that causes tuberculosis (TB), Mycobacterium tuberculosis, can exist in a dormant persister state in TB lesions, which necessitates much longer antibiotic treatment in patients than is seen in vitro. Some preliminary findings suggested that in cultured neurons, glial cells, macrophages, and skin keratinocytes, atypical and cystic B. burgdorferi have been found.

Promising Research

Researchers have had very limited success in cultivating replicating B. burgdorferi directly from animals or humans post-antibiotic treatment, which is part of the difficulty in doing experiments on persisters. There is some indirect evidence of persisters from multiple studies in animals (mice, dogs, monkeys) infected with B. burgdorferi and treated with antibiotics. For example, using a mouse model of Lyme disease, after one month of antibiotic treatment, researchers isolated B. burgdorferi DNA and detected non-dividing but infectious spirochetes.

Researchers have also been able to isolate live B. burgdorferi from animals using xenodiagnostic ticks’, in which uninfected ticks feed from an infected animal or human and become infected after feeding. This offers proof that the host was infected with B. burgdorferi. In a study with infected animals who exhibited a clear resurgence of bacteria following antibiotic treatment, B. burgdorferi was then isolated using xenodiagnostic ticks, a strong indication that these are persisters.

When B. burgdorferi-infected nonhuman primates were treated with antibiotics, bacteria were also recovered from multiple tissues, suggesting that bacteria could survive. Signs of inflammation in and around these tissues were also observed.

In an exciting 2019 study, Ying Zhang and team isolated slow-growth forms of B. burgdorferi (including biofilm-like, round body and spirochetes) from culture and compared mice inoculated with these slow-growing forms versus mice inoculated with fast-growing spirochetal B. burgdorferi. The slow-growth persister B. burgdorferi were not only more tolerant to the standard Lyme disease antibiotic treatment with doxycycline or ceftriaxone but they were also associated with more severe arthritis in mice than the fast-growing spirochete form. However, a cocktail of antibiotics – Daptomycin, Doxycycline and Ceftriaxone – did successfully eradicate the infection in the mice infected with slow-growing persisters. Human studies modeled after these would be helpful in understanding the disease course, especially the response to antibiotics.

In other studies, different cocktails of antibiotics, as well as essential oils, have been successful in eradicating B. burgdorferi in vitro. Disulfiram, a drug used for treating alcoholism, has been shown to be extremely effective in eradicating many forms of B. burgdorferi in vitro and in mice, and in a small study in humans.

Despite all these promising results in culture and in animals, trials in humans have not advanced well. Based on research done to date, researchers cannot confirm or exclude that live persisters are present in antibiotic-treated patients who have persistent symptoms (i.e., patients with post-treatment Lyme disease symptoms). One large part of the problem is the shortage of confirmed Lyme disease patients for clinical trials, as many patients lack concrete clinical (serological) evidence of having Lyme disease. In three separate clinical trials, only 4% of 5457 patients made it through the screening process to enter a trial.

Altogether, some critical groundwork has been established in the study of persisters.  However, studies surrounding persisters are still in early stages, and their connection to ongoing symptoms of post-treatment Lyme and chronic Lyme still warrant more confirmation and extended studies. There is a great need for evidence-based research conducted at all levels of research involving persisters, from in vitro studies through clinical trials. Supporting these efforts calls for improved diagnostics and detection methods for persisters, and an incremental move into larger-scale human studies which confirm the presence of live persisters and explore treatment options. GLA is optimistic that with future studies, there will be new breakthroughs in this very important area.


By Global Lyme Alliance and Dana Barberio, M.S., Scientific/Medical Writer and Principal, Edge Bioscience Communications

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Learn more about GLA’s research initiatives and accomplishments:

Research Report
Published Research Findings
Current Grantees 
First Observational Study for Lyme Disease Treatment
Post-treatment Lyme: Two Million by 2020
Blog: Why Good Science is Crucial